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Sample records for bacillus amyloliquefaciens ga1

  1. Characterization of amylolysin, a novel lantibiotic from Bacillus amyloliquefaciens GA1.

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    Anthony Arguelles Arias

    Full Text Available BACKGROUND: Lantibiotics are heat-stable peptides characterized by the presence of thioether amino acid lanthionine and methyllanthionine. They are capable to inhibit the growth of Gram-positive bacteria, including Listeria monocytogenes, Staphylococcus aureus or Bacillus cereus, the causative agents of food-borne diseases or nosocomial infections. Lantibiotic biosynthetic machinery is encoded by gene cluster composed by a structural gene that codes for a pre-lantibiotic peptide and other genes involved in pre-lantibiotic modifications, regulation, export and immunity. METHODOLOGY/FINDINGS: Bacillus amyloliquefaciens GA1 was found to produce an antimicrobial peptide, named amylolysin, active on an array of Gram-positive bacteria, including methicillin resistant S. aureus. Genome characterization led to the identification of a putative lantibiotic gene cluster that comprises a structural gene (amlA and genes involved in modification (amlM, transport (amlT, regulation (amlKR and immunity (amlFE. Disruption of amlA led to loss of biological activity, confirming thus that the identified gene cluster is related to amylolysin synthesis. MALDI-TOF and LC-MS analysis on purified amylolysin demonstrated that this latter corresponds to a novel lantibiotic not described to date. The ability of amylolysin to interact in vitro with the lipid II, the carrier of peptidoglycan monomers across the cytoplasmic membrane and the presence of a unique modification gene suggest that the identified peptide belongs to the group B lantibiotic. Amylolysin immunity seems to be driven by only two AmlF and AmlE proteins, which is uncommon within the Bacillus genus. CONCLUSION/SIGNIFICANCE: Apart from mersacidin produced by Bacillus amyloliquefaciens strains Y2 and HIL Y-85,544728, reports on the synthesis of type B-lantibiotic in this species are scarce. This study reports on a genetic and structural characterization of another representative of the type B lantibiotic in B

  2. Bacillus amyloliquefaciens GA1 as a source of potent antibiotics and other secondary metabolites for biocontrol of plant pathogens

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    Brans Alain

    2009-11-01

    Full Text Available Abstract Background Phytopathogenic fungi affecting crop and post-harvested vegetables are a major threat to food production and food storage. To face these drawbacks, producers have become increasingly dependent on agrochemicals. However, intensive use of these compounds has led to the emergence of pathogen resistance and severe negative environmental impacts. There are also a number of plant diseases for which chemical solutions are ineffective or non-existent as well as an increasing demand by consumers for pesticide-free food. Thus, biological control through the use of natural antagonistic microorganisms has emerged as a promising alternative to chemical pesticides for more rational and safe crop management. Results The genome of the plant-associated B. amyloliquefaciens GA1 was sample sequenced. Several gene clusters involved in the synthesis of biocontrol agents were detected. Four gene clusters were shown to direct the synthesis of the cyclic lipopeptides surfactin, iturin A and fengycin as well as the iron-siderophore bacillibactin. Beside these non-ribosomaly synthetised peptides, three additional gene clusters directing the synthesis of the antibacterial polyketides macrolactin, bacillaene and difficidin were identified. Mass spectrometry analysis of culture supernatants led to the identification of these secondary metabolites, hence demonstrating that the corresponding biosynthetic gene clusters are functional in strain GA1. In addition, genes encoding enzymes involved in synthesis and export of the dipeptide antibiotic bacilysin were highlighted. However, only its chlorinated derivative, chlorotetaine, could be detected in culture supernatants. On the contrary, genes involved in ribosome-dependent synthesis of bacteriocin and other antibiotic peptides were not detected as compared to the reference strain B. amyloliquefaciens FZB42. Conclusion The production of all of these antibiotic compounds highlights B. amyloliquefaciens GA1 as

  3. Characterization of Bacillus amyloliquefacien contaminating 75% alcohol disinfectant

    Institute of Scientific and Technical Information of China (English)

    Wanming ZHANG; Yuesha YUAN; Cangli BIAN; Wen ZHANG; Lan WANG; Xianyu TU; Huqiang HUANG

    2008-01-01

    The clinical characterization of Bacillus amy-loliquefacien contaminating 75% alcohol disinfectants were studied. The bacteria were cultured and observed by using bacterial examination under the hospital infec-tion monitor. According to the regulations, the resistance of bacterial to physical and chemical factors was tested. Drug sensitivity tests for 20 commonly used medicines were carried out using a K-B method. The bacterial plas-mids were analyzed using the Birnboim method. The bac-teria were found after being cultured in the clinically-used 75% alcohol disinfectant fluid. Their total number was more than 800 cfu/mL and they were identified as Bacillus amyloliquefacien. The bacteria were also found to be resistant to boiling for 5 min. It grew well in 95% alcohol disinfectant and was insensitive to 84 disinfectant fluids containing chlorine (1000 mg/L) and such disinfec-tants as ozone. They were able to be sterilized better through routine ultraviolet exposure for 30 min or gas pressure. The bacteria contained a 2.5 kb plasmid and were sensitive to 13 drugs and insensitive to 7 drugs of the 20 drugs tested. It was suggested that alcohol dis-infectant fluid was easily contaminated by Bacillus amy-loliquefacien, and the bacteria was resistant to disinfectant fluids such as alcohol and 84 disinfectants.

  4. Degradation of ochratoxin A by Bacillus amyloliquefaciens ASAG1.

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    Chang, Xiaojiao; Wu, Zidan; Wu, Songling; Dai, Yanshi; Sun, Changpo

    2015-01-01

    Ochratoxin A (OTA) is widely found in food and feed products as a mycotoxin contaminant. It is produced by Penicillium species and several Aspergillus species. The identification OTA detoxification microorganisms is believed to be the best approach for decontamination. In this study, we isolated ASAG1, a bacterium with the ability to degrade OTA effectively, from grain depot-stored maize. A 16S rDNA sequencing approach was used to identify this strain as Bacillus amyloliquefaciens ASAG1. The degradation of OTA was detected in both medium and cell-free extracts after incubation with a culture of B. amyloliquefaciens ASAG1 cells. Subsequently, a hydrolysed enzyme (carboxypeptidase) related to the enzymatic conversion of OTA was cloned from the B. amyloliquefaciens ASAG1 genome. Using the Escherichia coli Expression System, we successfully expressed and purified this carboxypeptidase. When this enzyme was incubated with the engineered recombinant E. coli cells, the concentration of OTA was dramatically degraded. Our data therefore indicate that the carboxypeptidase produced by B. amyloliquefaciens ASAG1 is likely responsible for the biodegradation of OTA.

  5. Degradation of ochratoxin A by Bacillus amyloliquefaciens ASAG1.

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    Chang, Xiaojiao; Wu, Zidan; Wu, Songling; Dai, Yanshi; Sun, Changpo

    2015-01-01

    Ochratoxin A (OTA) is widely found in food and feed products as a mycotoxin contaminant. It is produced by Penicillium species and several Aspergillus species. The identification OTA detoxification microorganisms is believed to be the best approach for decontamination. In this study, we isolated ASAG1, a bacterium with the ability to degrade OTA effectively, from grain depot-stored maize. A 16S rDNA sequencing approach was used to identify this strain as Bacillus amyloliquefaciens ASAG1. The degradation of OTA was detected in both medium and cell-free extracts after incubation with a culture of B. amyloliquefaciens ASAG1 cells. Subsequently, a hydrolysed enzyme (carboxypeptidase) related to the enzymatic conversion of OTA was cloned from the B. amyloliquefaciens ASAG1 genome. Using the Escherichia coli Expression System, we successfully expressed and purified this carboxypeptidase. When this enzyme was incubated with the engineered recombinant E. coli cells, the concentration of OTA was dramatically degraded. Our data therefore indicate that the carboxypeptidase produced by B. amyloliquefaciens ASAG1 is likely responsible for the biodegradation of OTA. PMID:25517039

  6. N-terminal amino acid sequence of Bacillus licheniformis alpha-amylase: comparison with Bacillus amyloliquefaciens and Bacillus subtilis Enzymes.

    OpenAIRE

    Kuhn, H; Fietzek, P P; Lampen, J. O.

    1982-01-01

    The thermostable, liquefying alpha-amylase from Bacillus licheniformis was immunologically cross-reactive with the thermolabile, liquefying alpha-amylase from Bacillus amyloliquefaciens. Their N-terminal amino acid sequences showed extensive homology with each other, but not with the saccharifying alpha-amylases of Bacillus subtilis.

  7. Bacillus amyloliquefaciens SUBSP. plantarum PROBIOTIC STRAINS AS PROTEASE PRODUCERS

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    E. V. Маtseliukh

    2015-04-01

    Full Text Available Proteases from probiotic strains of the genus Bacillus, just like the antibiotics, bacteriocins and other hydrolytic enzymes, are one of the main factors that determine their biological activity. The aim of this work was to study the synthesis and biochemical properties of proteases from two strains Bacillus amyloliquefaciens subsp. plantarum UCM B-5139 and UCM B-5140 that included in the probiotic Endosporin. The cultivation of strains was carried out in flasks under rotating for two days. The influence of physico-chemical parameters of the reaction medium on proteolytic activity was studied on partially purified protease preparations. Lytic activity was determined by turbidimetric method. On the second day of cultivation B. amyloliquefaciens subsp. plantarum UCM В-5139 and UCM В-5140 synthesized the metal-dependent peptidase and serine protease, respectively. The optimum conditions of their action were the following: temperature 37–40 °C and pH 6.5–7.0. Isolated proteases are able to lyse the living cells of Staphylococcus aureus and Candida albicans. Thus we demonstrated that B. amyloliquefaciens subsp. plantarum UCM B-5140 and UCM B-5139, included in the probiotic veterinary preparation Endosporin, produced proteolytic enzymes that hydrolyze the native insoluble proteins (elastin, fibrin and collagen. These enzymes belong to the group of neutral metal-dependent and serine proteases. They are active under physiological conditions against gram-positive bacteria and yeasts. The application of these proteases in biotechnology is considered.

  8. Complete Genome Sequence for the Fusarium Head Blight Antagonist Bacillus amyloliquefaciens Strain TrigoCor 1448

    OpenAIRE

    Nelson, Beth A.; Ramaiya, Preethi; Lopez de Leon, Alfredo; Kumar, Ravi; Crinklaw, Austin; Jolkovsky, Eliana; Crane, Julia M.; Bergstrom, Gary C; Rey, Michael W.

    2014-01-01

    We present the complete genome sequence for Bacillus amyloliquefaciens TrigoCor 1448 (ATCC 202152), a bacterial biological control agent for Fusarium head blight in wheat. We compare it to its closest relative, B. amyloliquefaciens strain AS43.3.

  9. Statistical analysis of cellulase production in Bacillus amyloliquefaciens UNPDV-22

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    Vasudeo Zambare

    2011-06-01

    Full Text Available The production of cellulase in Bacillus amyloliquefaciens UNPDV-22 was optimized usingresponse surface methodology (RSM. Central composite design (CCD was used to study the interactiveeffect of fermentation medium components (wheat bran, soybean meal, and malt dextrin on cellulaseactivity. Results suggested that wheat bran, soybean meal, and malt dextrin all have significant impacton cellulase production. The use of RSM resulted in a 70% increase in the cellulase activity over thecontrol of non-optimized basal medium. Optimum cellulase production of 11.23 U/mL was obtained in afermentation medium containing wheat bran (1.03%, w/v, soybean meal (2.43%, w/v, and maltdextrin (2.95%, w/v.

  10. Complete Genome Sequence of Bacillus amyloliquefaciens Strain BH072, Isolated from Honey

    NARCIS (Netherlands)

    Zhao, Xin; de Jong, Anne; Zhou, Zhijiang; Kuipers, Oscar P

    2015-01-01

    The genome of Bacillus amyloliquefaciens strain BH072, isolated from a honey sample and showing strong antimicrobial activity against plant pathogens, is 4.07 Mb and harbors 3,785 coding sequences (CDS). Several gene clusters for nonribosomal synthesis of antimicrobial peptides and a complete gene c

  11. Whole genome shotgun sequence of Bacillus amyloliquefaciens TF28, a biocontrol entophytic bacterium.

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    Zhang, Shumei; Jiang, Wei; Li, Jing; Meng, Liqiang; Cao, Xu; Hu, Jihua; Liu, Yushuai; Chen, Jingyu; Sha, Changqing

    2016-01-01

    Bacillus amyloliquefaciens TF28 is a biocontrol endophytic bacterium that is capable of inhibition of a broad range of plant pathogenic fungi. The strain has the potential to be developed into a biocontrol agent for use in agriculture. Here we report the whole-genome shotgun sequence of the strain. The genome size of B. amyloliquefaciens TF28 is 3,987,635 bp which consists of 3754 protein-coding genes, 65 tandem repeat sequences, 47 minisatellite DNA, 2 microsatellite DNA, 63 tRNA, 7rRNA, 6 sRNA, 3 prophage and CRISPR domains. PMID:27688836

  12. Isolation and characterization of antifungal peptides produced by Bacillus amyloliquefaciens LBM5006.

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    Benitez, Lisianne Brittes; Velho, Renata Voltolini; Lisboa, Marcia Pagno; Medina, Luis Fernando da Costa; Brandelli, Adriano

    2010-12-01

    Bacillus amyloliquefaciens LBM 5006 produces antagonistic activity against pathogenic bacteria and phytopathogenic fungi, including Aspergillus spp., Fusarium spp., and Bipolaris sorokiniana. PCR analysis revealed the presence of ituD, but not sfp genes, coding for iturin and surfactin, respectively. The antimicrobial substance produced by this strain was isolated by ammonium sulfate precipitation, gel filtration chromatography and 1-butanol extraction. The ultraviolet spectrum was typical of a polypeptide and the infrared spectrum indicates the presence of peptide bonds and acyl group(s). The antimicrobial substance was resistant to proteolytic enzymes and heat treatment, and was reactive with ninhydrin. Mass spectroscopy analysis indicated that B. amyloliquefaciens LBM 5006 produces two antimicrobial peptides, with main peaks at m/z 1,058 Da and 1,464 Da, corresponding to iturin-like and fengycin-like peptides, respectively. B. amyloliquefaciens LBM 5006 showed significant activity against phytopatogenic fungi, showing potential for use as a biocontrol agent or production of antifungal preparations.

  13. Occurrence of Bacillus amyloliquefaciens as a systemic endophyte of vanilla orchids.

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    White, James F; Torres, Mónica S; Sullivan, Raymond F; Jabbour, Rabih E; Chen, Qiang; Tadych, Mariusz; Irizarry, Ivelisse; Bergen, Marshall S; Havkin-Frenkel, Daphna; Belanger, Faith C

    2014-11-01

    We report the occurrence of Bacillus amyloliquefaciens in vanilla orchids (Vanilla phaeantha) and cultivated hybrid vanilla (V. planifolia × V. pompona) as a systemic bacterial endophyte. We determined with light microscopy and isolations that tissues of V. phaeantha and the cultivated hybrid were infected by a bacterial endophyte and that shoot meristems and stomatal areas of stems and leaves were densely colonized. We identified the endophyte as B. amyloliquefaciens using DNA sequence data. Since additional endophyte-free plants and seed of this orchid were not available, additional studies were performed on surrogate hosts Amaranthus caudatus, Ipomoea tricolor, and I. purpurea. Plants of A. caudatus inoculated with B. amyloliquefaciens demonstrated intracellular colonization of guard cells and other epidermal cells, confirming the pattern observed in the orchids. Isolations and histological studies suggest that the bacterium may penetrate deeply into developing plant tissues in shoot meristems, forming endospores in maturing tissues. B. amyloliquefaciens produced fungal inhibitors in culture. In controlled experiments using morning glory seedlings we showed that the bacterium promoted seedling growth and reduced seedling necrosis due to pathogens. We detected the gene for phosphopantetheinyl transferase (sfp), an enzyme in the pathway for production of antifungal lipopeptides, and purified the lipopeptide "surfactin" from cultures of the bacterium. We hypothesize that B. amyloliquefaciens is a robust endophyte and defensive mutualist of vanilla orchids. Whether the symbiosis between this bacterium and its hosts can be managed to protect vanilla crops from diseases is a question that should be evaluated in future research.

  14. Occurrence of Bacillus amyloliquefaciens as a systemic endophyte of vanilla orchids.

    Science.gov (United States)

    White, James F; Torres, Mónica S; Sullivan, Raymond F; Jabbour, Rabih E; Chen, Qiang; Tadych, Mariusz; Irizarry, Ivelisse; Bergen, Marshall S; Havkin-Frenkel, Daphna; Belanger, Faith C

    2014-11-01

    We report the occurrence of Bacillus amyloliquefaciens in vanilla orchids (Vanilla phaeantha) and cultivated hybrid vanilla (V. planifolia × V. pompona) as a systemic bacterial endophyte. We determined with light microscopy and isolations that tissues of V. phaeantha and the cultivated hybrid were infected by a bacterial endophyte and that shoot meristems and stomatal areas of stems and leaves were densely colonized. We identified the endophyte as B. amyloliquefaciens using DNA sequence data. Since additional endophyte-free plants and seed of this orchid were not available, additional studies were performed on surrogate hosts Amaranthus caudatus, Ipomoea tricolor, and I. purpurea. Plants of A. caudatus inoculated with B. amyloliquefaciens demonstrated intracellular colonization of guard cells and other epidermal cells, confirming the pattern observed in the orchids. Isolations and histological studies suggest that the bacterium may penetrate deeply into developing plant tissues in shoot meristems, forming endospores in maturing tissues. B. amyloliquefaciens produced fungal inhibitors in culture. In controlled experiments using morning glory seedlings we showed that the bacterium promoted seedling growth and reduced seedling necrosis due to pathogens. We detected the gene for phosphopantetheinyl transferase (sfp), an enzyme in the pathway for production of antifungal lipopeptides, and purified the lipopeptide "surfactin" from cultures of the bacterium. We hypothesize that B. amyloliquefaciens is a robust endophyte and defensive mutualist of vanilla orchids. Whether the symbiosis between this bacterium and its hosts can be managed to protect vanilla crops from diseases is a question that should be evaluated in future research. PMID:25060609

  15. Gene cloning, expression, and characterization of the Bacillus amyloliquefaciens PS35 lipase

    OpenAIRE

    Palanisamy Kanmani; Kuppamuthu Kumaresan; Jeyaseelan Aravind

    2015-01-01

    Abstract Lipases are enzymes of immense industrial relevance, and, therefore, are being intensely investigated. In an attempt to characterize lipases at molecular level from novel sources, a lipase gene from Bacillus amyloliquefaciens PS35 was cloned, heterologously expressed in Escherichia coli DH5α cells and sequenced. It showed up to 98% homology with other lipase sequences in the NCBI database. The recombinant enzyme was then purified from E. coli culture, resulting in a 19.41-fold purifi...

  16. Inhibition of Bacillus cereus Growth and Toxin Production by Bacillus amyloliquefaciens RD7-7 in Fermented Soybean Products.

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    Eom, Jeong Seon; Choi, Hye Sun

    2016-01-01

    Bacillus cereus is a gram-positive, rod-shaped, spore-forming bacterium that has been isolated from contaminated fermented soybean food products and from the environment. B. cereus produces diarrheal and emetic toxins and has caused many outbreaks of foodborne diseases. In this study, we investigated whether B. amyloliquefaciens RD7-7, isolated from rice doenjang (Korean fermented soybean paste), a traditional Korean fermented soybean food, shows antimicrobial activity against B. cereus and regulates its toxin gene expression. B. amyloliquefaciens RD7-7 exhibited strong antibacterial activity against B. cereus and inhibited the expression of B. cereus toxin-related genes (groEL, nheA, nheC, and entFM). We also found that addition of water extracts of soybean and buckwheat soksungjang (Korean fermented soybean paste made in a short time) fermented with B. amyloliquefaciens RD7-7 significantly reduced the growth and toxin expression of B. cereus. These results indicate that B. amyloliquefaciens RD7-7 could be used to control B. cereus growth and toxin production in the fermented soybean food industry. Our findings also provide a basis for the development of candidate biological control agents against B. cereus to improve the safety of fermented soybean food products.

  17. Seed-borne endophytic Bacillus amyloliquefaciens RWL-1 produces gibberellins and regulates endogenous phytohormones of Oryza sativa.

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    Shahzad, Raheem; Waqas, Muhammad; Khan, Abdul Latif; Asaf, Sajjad; Khan, Muhammad Aaqil; Kang, Sang-Mo; Yun, Byung-Wook; Lee, In-Jung

    2016-09-01

    Some microorganisms are adapted to an endophytic mode, living symbiotically with plants through vertical transmission in seeds. The role of plant growth-promoting endophytes has been well studied, but those of seed-associated endophytic bacteria are less understood. The current study aimed to isolate and identify bacterial endophytes associated with rice (Oryza sativa L. 'Jin so mi') seeds, their potential to produce gibberellins (GAs), and role in improving host-plant physiology. The isolated bacterial endophyte RWL-1 was identified as Bacillus amyloliquefaciens by using 16S rRNA sequencing and phylogenetic analysis. The pure culture of B. amyloliquefaciens RWL-1, supplied with deuterated internal standards, was subjected to gas chromatography and mass spectrometric selected ion monitoring (GC-MS/SIM) for quantification of GAs. Results showed the presence of GAs in various quantities (ng/mL) viz., GA20 (17.88 ± 4.04), GA36 (5.75 ± 2.36), GA24 (5.64 ± 2.46), GA4 (1.02 ± 0.16), GA53 (0.772 ± 0.20), GA9 (0.12 ± 0.09), GA19 (0.093 ± 0.13), GA5 (0.08 ± 0.04), GA12 (0.014 ± 0.34), and GA8 (0.013 ± 0.01). Since endogenous seed GAs are essential for prolonged seed growth and subsequent plant development, we used exogenous GA3 as a positive control and water as a negative control for comparative analysis of the application of B. amyloliquefaciens RWL-1 to rice plants. The growth parameters of rice plants treated with endophytic bacterial cell application was significantly increased compared to the plants treated with exogenous GA3 and water. This was also revealed by the significant up-regulation of endogenous GA1 (17.54 ± 2.40 ng), GA4 (310 ± 5.41 ng), GA7 (192.60 ± 3.32 ng), and GA9 (19.04 ± 2.49 ng) as compared to results of the positive and negative control treatments. Rice plants inoculated with B. amyloliquefaciens RWL-1 exhibited significantly higher endogenous salicylic acid (1615.06 ± 10.81 μg), whereas

  18. Recruiting a new strategy to improve levan production in Bacillus amyloliquefaciens

    OpenAIRE

    Jun Feng; Yanyan Gu; Yufen Quan; , Wei Zhang; Mingfeng Cao; Weixia Gao; Cunjiang Song; Chao Yang; Shufang Wang

    2015-01-01

    Microbial levan is an important biopolymer with considerable potential in food and medical applications. Bacillus amyloliquefaciens NK-ΔLP strain can produce high-purity, low-molecular-weight levan, but production is relatively low. To enhance the production of levan, six extracellular protease genes (bpr, epr, mpr, vpr, nprE and aprE), together with the tasA gene (encoding the major biofilm matrix protein TasA) and the pgsBCA cluster (responsible for poly-γ-glutamic acid (γ-PGA) synthesis), ...

  19. Resistance of Bacillus amyloliquefaciens spores to melt extrusion process conditions

    OpenAIRE

    Ciera, Lucy Wanjiru; Beladjal, Lynda; Almeras, Xavier; Gheysens, Tom; Nierstrasz, Vincent; Van Langenhove, Lieva; Mertens, Johan

    2014-01-01

    With the increasing demand for functionalised textile materials, industry is focusing on research that will add novel properties to textiles. Bioactive compounds and their benefits have been and are still considered as a possible source of unique functionalities to be explored. However, incorporating bioactive compounds into textiles and their resistance to textile process parameters has not yet been studied. In this study, we developed a system to study the resistance of Bacillus amyloliquef...

  20. Atividade antibacteriana do extrato bruto de Bacillus amyloliquefaciens frente a diferentes indicadores.

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    D. SCHULZ

    2008-10-01

    Full Text Available

    O presente estudo teve como objetivo obter um extrato bruto de Bacillus amyloliquefaciens, padronizado pela dosagem de proteínas, e quantificar sua atividade antibacteriana pelo halo de inibição do crescimento de Listeria monocytogenes NCTC 098630, Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212 Enterobacter aerogenes ATCC 13048 e Pseudomonas aeruginosa ATCC 9027. O extrato bruto de Bacillus amyloliquefaciens somente apresentou atividade antibacteriana frente Listeria monocytogenes NCTC 098630. Constatou-se que a concentração responsável por 50% da máxima atividade antibacteriana foi 29,22 g do extrato bruto, com um halo de inibição de aproximadamente 4 mm.

  1. Efisiensi Penggunaan Energi Metabolis Ransum Berbasis Onggok yang Difermentasi Bacillus amyloliquefaciens pada Ayam Broiler

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    Wizna

    2008-12-01

    Full Text Available An experiment was conducted to determine the effects of using Bacillus amyloliquefaciens-fermented tapioca by-products (onggok on the metabolism energy differences in the diets to the performance of broilers. Eighty unsexed three day old broiler chicks were randomly allocated into 20 pens (four chicks/pen. This experiment was arranged in a completely randomized design with four dietary treatments (3000, 2900, 2800 and 2700 kkal/kg for broilers of energy metabolism in diets and five replications. Measured variables were feed consumption, average body weight gain, feed conversion, carcass percentage, abdominal fat percentage and income over feed cost (IOFC. Results of the experiment indicated that feed consumption, average body weight gain, feed conversion, carcass percentage, abdominal fat percentage and income over feed cost (IOFC were not affected (P>0.05 by levels of metabolism energy in the diets for broilers. In conclusion, Bacillus amyloliquefaciens-fermented tapioca by-products (onggok can be included up to 40% with energy metabolism 2700 kkal/kg in broilers diets and improved the efficiency of metabolizable energy.

  2. Transcriptomic profiling of Bacillus amyloliquefaciens FZB42 in response to maize root exudates

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    Fan Ben

    2012-06-01

    Full Text Available Abstract Background Plant root exudates have been shown to play an important role in mediating interactions between plant growth-promoting rhizobacteria (PGPR and their host plants. Most investigations were performed on Gram-negative rhizobacteria, while much less is known about Gram-positive rhizobacteria. To elucidate early responses of PGPR to root exudates, we investigated changes in the transcriptome of a Gram-positive PGPR to plant root exudates. Results Bacillus amyloliquefaciens FZB42 is a well-studied Gram-positive PGPR. To obtain a comprehensive overview of FZB42 gene expression in response to maize root exudates, microarray experiments were performed. A total of 302 genes representing 8.2% of the FZB42 transcriptome showed significantly altered expression levels in the presence of root exudates. The majority of the genes (261 was up-regulated after incubation of FZB42 with root exudates, whereas only 41 genes were down-regulated. Several groups of the genes which were strongly induced by the root exudates are involved in metabolic pathways relating to nutrient utilization, bacterial chemotaxis and motility, and non-ribosomal synthesis of antimicrobial peptides and polyketides. Conclusions Here we present a transcriptome analysis of the root-colonizing bacterium Bacillus amyloliquefaciens FZB42 in response to maize root exudates. The 302 genes identified as being differentially transcribed are proposed to be involved in interactions of Gram-positive bacteria with plants.

  3. Antagonistic Activities of Novel Peptides from Bacillus amyloliquefaciens PT14 against Fusarium solani and Fusarium oxysporum.

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    Kim, Young Gwon; Kang, Hee Kyoung; Kwon, Kee-Deok; Seo, Chang Ho; Lee, Hyang Burm; Park, Yoonkyung

    2015-12-01

    Bacillus species have recently drawn attention due to their potential use in the biological control of fungal diseases. This paper reports on the antifungal activity of novel peptides isolated from Bacillus amyloliquefaciens PT14. Reverse-phase high-performance liquid chromatography revealed that B. amyloliquefaciens PT14 produces five peptides (PT14-1, -2, -3, -4a, and -4b) that exhibit antifungal activity but are inactive against bacterial strains. In particular, PT14-3 and PT14-4a showed broad-spectrum antifungal activity against Fusarium solani and Fusarium oxysporum. The PT14-4a N-terminal amino acid sequence was identified through Edman degradation, and a BLAST homology analysis showed it not to be identical to any other protein or peptide. PT14-4a displayed strong fungicidal activity with minimal inhibitory concentrations of 3.12 mg/L (F. solani) and 6.25 mg/L (F. oxysporum), inducing severe morphological deformation in the conidia and hyphae. On the other hand, PT14-4a had no detectable hemolytic activity. This suggests PT14-4a has the potential to serve as an antifungal agent in clinical therapeutic and crop-protection applications.

  4. Molecular characterization of alkaline protease of Bacillus amyloliquefaciens SP1 involved in biocontrol of Fusarium oxysporum.

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    Guleria, Shiwani; Walia, Abhishek; Chauhan, Anjali; Shirkot, C K

    2016-09-01

    An alkaline protease gene was amplified from genomic DNA of Bacillus amyloliquefaciens SP1 which was involved in effective biocontrol of Fusarium oxysporum. We investigated the antagonistic capacity of protease of B. amyloliquifaciens SP1, under in vitro conditions. The 5.62 fold purified enzyme with specific activity of 607.69U/mg reported 24.14% growth inhibition of F. oxysporum. However, no antagonistic activity was found after addition of protease inhibitor i.e. PMSF (15mM) to purified enzyme. An 1149bp nucleotide sequence of protease gene encoded 382 amino acids of 43kDa and calculated isoelectric point of 9.29. Analysis of deduced amino acid sequence revealed high homology (86%) with subtilisin E of Bacillus subtilis. The B. amyloliquefaciens SP1 protease gene was expressed in Escherichiax coli BL21. The expressed protease was secreted into culture medium by E. coli and exhibited optimum activity at pH8.0 and 60°C. The most reliable three dimensional structure of alkaline protease was determined using Phyre 2 server which was validated on the basis of Ramachandran plot and ERRAT value. The expression and structure prediction of the enzyme offers potential value for commercial application in agriculture and industry. PMID:27294522

  5. Transcriptomic profiling of Bacillus amyloliquefaciens FZB42 in response to maize root exudates

    LENUS (Irish Health Repository)

    Fan, Ben

    2012-06-21

    AbstractBackgroundPlant root exudates have been shown to play an important role in mediating interactions between plant growth-promoting rhizobacteria (PGPR) and their host plants. Most investigations were performed on Gram-negative rhizobacteria, while much less is known about Gram-positive rhizobacteria. To elucidate early responses of PGPR to root exudates, we investigated changes in the transcriptome of a Gram-positive PGPR to plant root exudates.ResultsBacillus amyloliquefaciens FZB42 is a well-studied Gram-positive PGPR. To obtain a comprehensive overview of FZB42 gene expression in response to maize root exudates, microarray experiments were performed. A total of 302 genes representing 8.2% of the FZB42 transcriptome showed significantly altered expression levels in the presence of root exudates. The majority of the genes (261) was up-regulated after incubation of FZB42 with root exudates, whereas only 41 genes were down-regulated. Several groups of the genes which were strongly induced by the root exudates are involved in metabolic pathways relating to nutrient utilization, bacterial chemotaxis and motility, and non-ribosomal synthesis of antimicrobial peptides and polyketides.ConclusionsHere we present a transcriptome analysis of the root-colonizing bacterium Bacillus amyloliquefaciens FZB42 in response to maize root exudates. The 302 genes identified as being differentially transcribed are proposed to be involved in interactions of Gram-positive bacteria with plants.

  6. Complete genome sequence of Bacillus amyloliquefaciens strain Co1-6, a plant growth-promoting rhizobacterium of Calendula officinalis

    Energy Technology Data Exchange (ETDEWEB)

    Koeberl, Martina; White, Richard A.; Erschen, Sabine; Spanberger, Nora; El-Arabi, Tarek F.; Jansson, Janet K.; Berg, Gabriele

    2015-08-13

    The genome sequence of Bacillus amyloliquefaciens strain Co1-6, a plant growth-promoting rhizobacterium (PGPR) with broad-spectrum antagonistic activities against plant pathogenic fungi, bacteria and nematodes, consists of a single 3.9 Mb circular chromosome. The genome reveals genes putatively responsible for its promising biocontrol and PGP properties.

  7. Whole-Genome Shotgun Sequence of Bacillus amyloliquefaciens Strain UASWS BA1, a Bacterium Antagonistic to Plant Pathogenic Fungi

    OpenAIRE

    Lefort, F; Calmin, G.; Pelleteret, P.; Farinelli, L.; Osteras, M; Crovadore, J.

    2014-01-01

    We report here the whole-genome shotgun sequence of Bacillus amyloliquefaciens strain UASWS BA1, isolated from inner wood tissues of a decaying Platanus × acerifolia tree. This strain proved to be antagonistic to several plant pathogenic fungi and oomycetes and can be developed as a biological control agent in agriculture.

  8. Complete Genome Sequence of Bacillus amyloliquefaciens Strain Co1-6, a Plant Growth-Promoting Rhizobacterium of Calendula officinalis.

    Science.gov (United States)

    Köberl, Martina; White, Richard A; Erschen, Sabine; Spanberger, Nora; El-Arabi, Tarek F; Jansson, Janet K; Berg, Gabriele

    2015-01-01

    The genome sequence of Bacillus amyloliquefaciens strain Co1-6, a plant growth-promoting rhizobacterium (PGPR) with broad-spectrum antagonistic activity against plant-pathogenic fungi, bacteria, and nematodes, consists of a single 3.9-Mb circular chromosome. The genome reveals genes putatively responsible for its promising biocontrol and PGP properties. PMID:26272562

  9. Complete Genome Sequence of Bacillus amyloliquefaciens Strain Co1-6, a Plant Growth-Promoting Rhizobacterium of Calendula officinalis

    OpenAIRE

    Köberl, Martina; White, Richard A.; Erschen, Sabine; Spanberger, Nora; El-Arabi, Tarek F.; Jansson, Janet K.; Berg, Gabriele

    2015-01-01

    The genome sequence of Bacillus amyloliquefaciens strain Co1-6, a plant growth-promoting rhizobacterium (PGPR) with broad-spectrum antagonistic activity against plant-pathogenic fungi, bacteria, and nematodes, consists of a single 3.9-Mb circular chromosome. The genome reveals genes putatively responsible for its promising biocontrol and PGP properties.

  10. Draft Genome Sequence of Bacillus amyloliquefaciens XK-4-1, a Plant Growth-Promoting Endophyte with Antifungal Activity.

    Science.gov (United States)

    Sun, Zhengxiang; Hsiang, Tom; Zhou, Yi; Zhou, Jinglong

    2015-01-01

    Here, we report the draft genome sequence of a bacterial plant-growth-promoting endophyte, Bacillus amyloliquefaciens XK-4-1, which consists of one circular chromosome of 3,941,805 bp with 3,702 coding sequences (CDSs). The data presented highlight multiple sets of functional genes associated with its plant-beneficial characteristics. PMID:26564038

  11. Deciphering the conserved genetic loci implicated in plant disease control through comparative genomics of Bacillus amyloliquefaciens subsp. plantarum strains

    Directory of Open Access Journals (Sweden)

    Mohammad J Hossain

    2015-08-01

    Full Text Available To understand the growth-promoting and disease-inhibiting activities of plant growth-promoting rhizobacteria (PGPR strains, the genomes of 12 Bacillus subtilis group strains with PGPR activity were sequenced and analyzed. These B. subtilis strains exhibited high genomic diversity, whereas the genomes of B. amyloliquefaciens strains (a member of the B. subtilis group are highly conserved. A pairwise BLASTp matrix revealed that gene family similarity among Bacillus genomes ranges from 32- 90%, with 2,839 genes within the core genome of B. amyloliquefaciens subsp. plantarum. Comparative genomic analyses of B. amyloliquefaciens strains identified genes that are linked with biological control and colonization of roots and/or leaves, including 73 genes uniquely associated with subsp. plantarum strains that have predicted functions related to signaling, transportation, secondary metabolite production, and carbon source utilization. Although B. amyloliquefaciens subsp. plantarum strains contain gene clusters that encode many different secondary metabolites, only polyketide biosynthetic clusters that encode difficidin and macrolactin are conserved within this subspecies. To evaluate their role in plant pathogen biocontrol, genes involved in secondary metabolite biosynthesis were deleted in B. amyloliquefaciens subsp. plantarum strain, revealing that difficidin expression is critical in reducing the severity of disease, caused by Xanthomonas axonopodis pv. vesicatoria in tomato plants. This study defines genomic features of PGPR strains and links them with biocontrol activity and with host colonization.

  12. Deciphering the conserved genetic loci implicated in plant disease control through comparative genomics of Bacillus amyloliquefaciens subsp. plantarum strains

    OpenAIRE

    Hossain, Mohammad J.; Chao eRan; Ke eLiu; Choong-Min eRyu; Rasmussen-Ivey, Cody R.; Williams, Malachi A.; Mohammad K. Hassan; Soo-Keun eChoi; Haeyoung eJeong; Molli eNewman; Kloepper, Joseph W.; Mark R Liles

    2015-01-01

    To understand the growth-promoting and disease-inhibiting activities of plant growth-promoting rhizobacteria (PGPR) strains, the genomes of 12 Bacillus subtilis group strains with PGPR activity were sequenced and analyzed. These B. subtilis strains exhibited high genomic diversity, whereas the genomes of B. amyloliquefaciens strains (a member of the B. subtilis group) are highly conserved. A pairwise BLASTp matrix revealed that gene family similarity among Bacillus genomes ranges from 32- 90%...

  13. Unraveling Aspects of Bacillus amyloliquefaciens Mediated Enhanced Production of Rice under Biotic Stress of Rhizoctonia solani.

    Science.gov (United States)

    Srivastava, Suchi; Bist, Vidisha; Srivastava, Sonal; Singh, Poonam C; Trivedi, Prabodh K; Asif, Mehar H; Chauhan, Puneet S; Nautiyal, Chandra S

    2016-01-01

    Rhizoctonia solani is a necrotrophic fungi causing sheath blight in rice leading to substantial loss in yield. Excessive and persistent use of preventive chemicals raises human health and environment safety concerns. As an alternative, use of biocontrol agents is highly recommended. In the present study, an abiotic stress tolerant, plant growth promoting rhizobacteria Bacillus amyloliquefaciens (SN13) is demonstrated to act as a biocontrol agent and enhance immune response against R. solani in rice by modulating various physiological, metabolic, and molecular functions. A sustained tolerance by SN13 primed plant over a longer period of time, post R. solani infection may be attributed to several unconventional aspects of the plants' physiological status. The prolonged stress tolerance observed in presence of SN13 is characterized by (a) involvement of bacterial mycolytic enzymes, (b) sustained maintenance of elicitors to keep the immune system induced involving non-metabolizable sugars such as turanose besides the known elicitors, (c) a delicate balance of ROS and ROS scavengers through production of proline, mannitol, and arabitol and rare sugars like fructopyranose, β-D-glucopyranose and myoinositol and expression of ferric reductases and hypoxia induced proteins, (d) production of metabolites like quinazoline and expression of terpene synthase, and (e) hormonal cross talk. As the novel aspect of biological control this study highlights the role of rare sugars, maintenance of hypoxic conditions, and sucrose and starch metabolism in B. amyloliquefaciens (SN13) mediated sustained biotic stress tolerance in rice. PMID:27200058

  14. Gene cloning, expression, and characterization of the Bacillus amyloliquefaciens PS35 lipase

    Directory of Open Access Journals (Sweden)

    Palanisamy Kanmani

    2015-01-01

    Full Text Available AbstractLipases are enzymes of immense industrial relevance, and, therefore, are being intensely investigated. In an attempt to characterize lipases at molecular level from novel sources, a lipase gene from Bacillus amyloliquefaciens PS35 was cloned, heterologously expressed in Escherichia coli DH5α cells and sequenced. It showed up to 98% homology with other lipase sequences in the NCBI database. The recombinant enzyme was then purified from E. coli culture, resulting in a 19.41-fold purification with 9.7% yield. It displayed a preference for long-chain para-nitrophenyl esters, a characteristic that is typical of true lipases. Its optimum pH and temperature were determined to be 8.0 and 40 °C, respectively. The half-lives were 2.0, 1.0 and 0.5 h at 50 °C, 60 °C and 70 °C, respectively. The metal ions K+and Fe3+ enhanced the enzyme activity. The enzyme displayed substantial residual activity in the presence of various tested chemical modifiers, and interestingly, the organic solvents, such as n-hexane and toluene, also favored the enzyme activity. Thus, this study involves characterization of B. amyloliquefaciens lipase at molecular level. The key outcomes are novelty of the bacterial source and purification of the enzyme with desirable properties for industrial applications.

  15. Unraveling Aspects of Bacillus amyloliquefaciens Mediated Enhanced Production of Rice under Biotic Stress of Rhizoctonia solani

    Science.gov (United States)

    Srivastava, Suchi; Bist, Vidisha; Srivastava, Sonal; Singh, Poonam C.; Trivedi, Prabodh K.; Asif, Mehar H.; Chauhan, Puneet S.; Nautiyal, Chandra S.

    2016-01-01

    Rhizoctonia solani is a necrotrophic fungi causing sheath blight in rice leading to substantial loss in yield. Excessive and persistent use of preventive chemicals raises human health and environment safety concerns. As an alternative, use of biocontrol agents is highly recommended. In the present study, an abiotic stress tolerant, plant growth promoting rhizobacteria Bacillus amyloliquefaciens (SN13) is demonstrated to act as a biocontrol agent and enhance immune response against R. solani in rice by modulating various physiological, metabolic, and molecular functions. A sustained tolerance by SN13 primed plant over a longer period of time, post R. solani infection may be attributed to several unconventional aspects of the plants’ physiological status. The prolonged stress tolerance observed in presence of SN13 is characterized by (a) involvement of bacterial mycolytic enzymes, (b) sustained maintenance of elicitors to keep the immune system induced involving non-metabolizable sugars such as turanose besides the known elicitors, (c) a delicate balance of ROS and ROS scavengers through production of proline, mannitol, and arabitol and rare sugars like fructopyranose, β-D-glucopyranose and myoinositol and expression of ferric reductases and hypoxia induced proteins, (d) production of metabolites like quinazoline and expression of terpene synthase, and (e) hormonal cross talk. As the novel aspect of biological control this study highlights the role of rare sugars, maintenance of hypoxic conditions, and sucrose and starch metabolism in B. amyloliquefaciens (SN13) mediated sustained biotic stress tolerance in rice. PMID:27200058

  16. Biological Control of Apple Ring Rot on Fruit by Bacillus amyloliquefaciens 9001

    Directory of Open Access Journals (Sweden)

    Yan Li

    2013-06-01

    Full Text Available Apple ring rot disease, caused by Botryosphaeria dothidea (Moug. ex. Fr Ces. et de Not., is one of the most important diseases on apple fruits. In this study, strain 9001 isolated from healthy apple fruits from an infested orchard was evaluated for its biocontrol activity against apple ring rot in vitro and in vivo. Strain 9001 showed obvious antagonistic activity to B. dothidea YL-1 when plated on potato dextrose agar. Soaking healthy apples in the bacterial suspensions of strain 9001 prior to artificial inoculation of fungal pathogen resulted in a dramatic decrease in disease incidence when compared to the control. Moreover, either field application in the growth season or postharvest treatment of apples from infected orchards with bacterial suspensions of strain 9001 resulted in significantly reduced disease incidence within the storage period for 4 months at room temperature. Based on the phylogenetic analysis of 16S rRNA and the gyrA gene, strain 9001 was identified as Bacillus amyloliquefaciens. These results indicated that B. amyloliquefaciens 9001 could be a promising agent in biocontrol of apple ring rot on fruit, which might help to minimize the yield loss of apple fruit during the long postharvest period.

  17. Biological Control of Apple Ring Rot on Fruit by Bacillus amyloliquefaciens 9001.

    Science.gov (United States)

    Li, Yan; Han, Li-Rong; Zhang, Yuanyuan; Fu, Xuechi; Chen, Xinyi; Zhang, Lixia; Mei, Ruhong; Wang, Qi

    2013-06-01

    Apple ring rot disease, caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., is one of the most important diseases on apple fruits. In this study, strain 9001 isolated from healthy apple fruits from an infested orchard was evaluated for its biocontrol activity against apple ring rot in vitro and in vivo. Strain 9001 showed obvious antagonistic activity to B. dothidea YL-1 when plated on potato dextrose agar. Soaking healthy apples in the bacterial suspensions of strain 9001 prior to artificial inoculation of fungal pathogen resulted in a dramatic decrease in disease incidence when compared to the control. Moreover, either field application in the growth season or postharvest treatment of apples from infected orchards with bacterial suspensions of strain 9001 resulted in significantly reduced disease incidence within the storage period for 4 months at room temperature. Based on the phylogenetic analysis of 16S rRNA and the gyrA gene, strain 9001 was identified as Bacillus amyloliquefaciens. These results indicated that B. amyloliquefaciens 9001 could be a promising agent in biocontrol of apple ring rot on fruit, which might help to minimize the yield loss of apple fruit during the long postharvest period.

  18. Recruiting a new strategy to improve levan production in Bacillus amyloliquefaciens.

    Science.gov (United States)

    Feng, Jun; Gu, Yanyan; Quan, Yufen; Zhang, Wei; Cao, Mingfeng; Gao, Weixia; Song, Cunjiang; Yang, Chao; Wang, Shufang

    2015-01-01

    Microbial levan is an important biopolymer with considerable potential in food and medical applications. Bacillus amyloliquefaciens NK-ΔLP strain can produce high-purity, low-molecular-weight levan, but production is relatively low. To enhance the production of levan, six extracellular protease genes (bpr, epr, mpr, vpr, nprE and aprE), together with the tasA gene (encoding the major biofilm matrix protein TasA) and the pgsBCA cluster (responsible for poly-γ-glutamic acid (γ-PGA) synthesis), were intentionally knocked out in the Bacillus amyloliquefaciens NK-1 strain. The highest levan production (31.1 g/L) was obtained from the NK-Q-7 strain (ΔtasA, Δbpr, Δepr, Δmpr, Δvpr, ΔnprE, ΔaprE and ΔpgsBCA), which was 103% higher than that of the NK-ΔLP strain (ΔpgsBCA) (15.3 g/L). Furthermore, the NK-Q-7 strain also showed a 94.1% increase in α-amylase production compared with NK-ΔLP strain, suggesting a positive effect of extracellular protease genes deficient on the production of endogenously secreted proteins. This is the first report of the improvement of levan production in microbes deficient in extracellular proteases and TasA, and the NK-Q-7 strain exhibits outstanding characteristics for extracellular protein production or extracellular protein related product synthesis. PMID:26347185

  19. Bacillus amyloliquefaciens ssp. plantarum strains as potential protective starter cultures for the production of Bikalga, an alkaline fermented food

    DEFF Research Database (Denmark)

    Compaor, C.S.; Nielsen, D.S.; Sawadogo-Lingani, H.;

    2013-01-01

    and fungi. Antimicrobial activity against Bacillus cereus was produced in H. sabdariffa seed-based medium. PCR results revealed that the isolates have potential for the lipopeptides iturin, fengycin, surfactin, the polyketides difficidin, macrolactin, bacillaene and the dipeptide bacilysin production. Ultra......-highperformance liquid chromatography-time of flight mass spectrometry analysis of antimicrobial substance produced in BHI broth allowed identification of iturin, fengycin and surfactin. Conclusions: The Bacillus amyloliquefaciens ssp. plantarum exhibited broadspectrum antifungal and antibacterial properties....... They produced several lipopeptide antibiotics and showed good potential for biological control of Bikalga. Significance and Impact of the Study: Pathogenic bacteria often occur in spontaneous food fermentations. This is the first report to identify indigenous B. amyloliquefaciens ssp. plantarum strains...

  20. Auxin secretion by Bacillus amyloliquefaciens FZB42 both stimulates root exudation and limits phosphorus uptake in Triticum aestivum

    OpenAIRE

    Talboys, Peter J.; Owen, Darren W; Healey, John R; Withers, Paul JA; Jones, David L.

    2014-01-01

    Background The use of auxin-producing rhizosphere bacteria as agricultural products promises increased root production and therefore greater phosphate (Pi) uptake. Whilst such bacteria promote root production in vitro, the nature of the bacteria-plant interaction in live soil, particularly concerning any effects on nutrient uptake, are not known. This study uses Bacillus amyloliquefaciens FZB42, an auxin-producing rhizobacterium, as a dressing on Triticum aestivum seeds. It then examines the ...

  1. Bacillus amyloliquefaciens COMO POTENCIAL BIOCONSERVANTE DE ALIMENTOS: DETERMINAÇÃO DO PERFIL DE PROTEÍNAS E AMINOGRAMA

    Directory of Open Access Journals (Sweden)

    D. SCHULZ

    2008-09-01

    Full Text Available

    Avaliou-se o perfil de proteínas em gel de poliacrilamida e o aminograma do extrato bruto de Bacillus amyloliquefaciens. O extrato bruto de Bacillus amyloliquefaciens foi obtido por precipitação, centrifugação, diálise e esterilização por filtração. Como microrganismo indicador foi utilizado Listeria monocytogenes NCTC 098630 a 105 UFC/mL. Na determinação da composição global de aminoácidos em eletroforese SDS (10%/PAGE (7,5 a 20% foram constatadas seis bandas com pesos moleculares aparentes de: 14,8; 20; 29; 30; 34 e 56,2 kDa e composto principalmente de aminoácidos hidrofóbicos (não polares, incluindo a prolina (446,77 ppm, leucina (11,03 ppm, valina (6,27 ppm, isoleucina (4,59 ppm, alanina (2,91 ppm e glicina (1,87 ppm. Os resultados obtidos sugerem que o extrato bruto de Bacillus amyloliquefaciens é composto principalmente de proteases e outras enzimas bacteriolíticas.

  2. Optimization of Thermostable Alpha-Amylase Production Via Mix Agricultural-Residues and Bacillus amyloliquefaciens

    Directory of Open Access Journals (Sweden)

    Shalini RAI

    2014-03-01

    Full Text Available This study reports utilization of mixture of wheat and barley bran (1:1 for the production of thermostable alpha-amylase enzyme through a spore former, heat tolerant strain of Bacillus amyloliquefaciens in solid state fermentation. Maximum yield of alpha-amylase (252.77 U mL-1 was obtained in following optimized conditions, inoculums size 2 mL (2 × 106 CFU/mL, moisture 80%, pH 7±0.02, NaCl (3%, temperature 38±1°C, incubation for 72 h, maltose (1% and tryptone (1%. After SSF crude enzyme was purified via ammonium sulfate precipitation, ion exchange and column chromatography by DEAE Cellulose. Purified protein showed a molecular weight of 42 kDa by SDS-PAGE electrophoresis. After purification, purified enzyme was characterized against several enzymes inhibitors such as temperature, NaCl, pH, metal and surfactants. Pure enzyme was highly active over broad temperature (50-70°C, NaCl concentration (0.5-4 M, and pH (6-10 ranges, indicating it’s a thermoactive and alkali-stable nature. Moreover, CaCl2, MnCl2, =-mercaptoethanol were found to stimulate the amylase activity, whereas FeCl3, sodium dodecyl sulfate (SDS, CuCl3 and ethylenediaminetetraacetic acid (EDTA strongly inhibited the enzyme. Moreover, enzyme specificity and thermal stability conformed by degradation of different soluble starch up to 55°C. Therefore, the present study proved that the extracellular alpha-amylase extracted through wheat flour residues by organism B. amyloliquefaciens MCCB0075, both have considerable potential for industrial application owing to its properties.

  3. Unraveling aspects of Bacillus amyloliquefaciens mediated enhanced production of rice under biotic stress of Rhizoctonia solani

    Directory of Open Access Journals (Sweden)

    Suchi eSrivastava

    2016-05-01

    Full Text Available Rhizoctonia solani (RS is a necrotrophic fungi causing sheath blight in rice leading to substantial loss in yield. Excessive and persistent use of preventive chemicals raises human health and environment safety concerns. As an alternative, use of biocontrol agents is highly recommended. In the present study an abiotic stress tolerant, plant growth promoting rhizobacteria Bacillus amyloliquefaciens (SN13 is demonstrated to act as a biocontrol agent and enhance immune response against RS in rice by modulating various physiological, metabolic and molecular functions. A sustained tolerance by SN13 primed plant over a longer period of time, post RS infection may be attributed to several unconventional aspects of the plants’ physiological status. The prolonged stress tolerance observed in presence of SN13 is characterized by (a involvement of bacterial mycolytic enzymes, (b sustained maintenance of elicitors to keep the immune system induced involving non-metabolizable sugars such as turanose besides the known elicitors, (c a delicate balance of ROS and ROS scavengers through production of proline, mannitol and arabitol and rare sugars like fructopyranose, β-d glucopyranose and myoinositol and expression of ferric reductases and hypoxia induced proteins, (d production of metabolites like quinozoline and expression of terpene synthase and (e hormonal cross talk. As the novel aspect of biological control this study highlights the role of rare sugars, maintenance of hypoxic conditions, and sucrose and starch metabolism in Bacillus amyloliquifaciens (SN13 mediated sustained biotic stress tolerance in rice.

  4. Functional role of an endophytic Bacillus amyloliquefaciens in enhancing growth and disease protection of invasive English ivy (Hedera helix L.)

    Science.gov (United States)

    Soares, Marcos Antonio; Li, Jai-Yan; Bergen, Marshall; da Silva, Joaquim Manoel; Kowalski, Kurt P.; White, James Francis

    2015-01-01

    BackgroundWe hypothesize that invasive English ivy (Hedera helix) harbors endophytic microbes that promote plant growth and survival. To evaluate this hypothesis, we examined endophytic bacteria in English ivy and evaluated effects on the host plant.MethodsEndophytic bacteria were isolated from multiple populations of English ivy in New Brunswick, NJ. Bacteria were identified as a single species Bacillus amyloliquefaciens. One strain of B. amyloliquefaciens, strain C6c, was characterized for indoleacetic acid (IAA) production, secretion of hydrolytic enzymes, phosphate solubilization, and antibiosis against pathogens. PCR was used to amplify lipopeptide genes and their secretion into culture media was detected by MALDI-TOF mass spectrometry. Capability to promote growth of English ivy was evaluated in greenhouse experiments. The capacity of C6c to protect plants from disease was evaluated by exposing B+ (bacterium inoculated) and B− (non-inoculated) plants to the necrotrophic pathogen Alternaria tenuissima.ResultsB. amyloliquefaciens C6c systemically colonized leaves, petioles, and seeds of English ivy. C6c synthesized IAA and inhibited plant pathogens. MALDI-TOF mass spectrometry analysis revealed secretion of antifungal lipopeptides surfactin, iturin, bacillomycin, and fengycin. C6c promoted the growth of English ivy in low and high soil nitrogen conditions. This endophytic bacterium efficiently controlled disease caused by Alternaria tenuissima.ConclusionsThis study suggests that B. amyloliquefaciens plays an important role in enhancing growth and disease protection of English ivy.

  5. Bacillus amyloliquefaciens SQR9 induces dendritic cell maturation and enhances the immune response against inactivated avian influenza virus

    Science.gov (United States)

    Huang, Lulu; Qin, Tao; Yin, YinYan; Gao, Xue; Lin, Jian; Yang, Qian; Yu, Qinghua

    2016-01-01

    The objective of this study was to evaluate the stimulatory effects of Bacillus amyloliquefaciens SQR9 on dendritic cells (DCs) and to verify its ability to enhance the immune response by modulating DC maturation. The results demonstrated that B. amyloliquefaciens SQR9 can adhere to the nasal epithelium and be taken up by DCs in the nasal mucosa, thereby inducing DC maturation and resulting in increased CD80, CD86, CD40 and MHCII expression and cytokine secretion. The frequencies of CD4+ and CD8+ T cells and CD69+ memory T cells were increased in spleens after nasal immunization with virus plus B. amyloliquefaciens SQR9 compared to immunization with inactivated H9N2 AIV alone. Moreover, the levels of sIgA in the nasal cavity, the trachea, and the lung and the levels of IgG, IgG1, and IgG2a in serum were significantly increased in mice administered WIV plus SQR9 compared to mice administered H9N2 WIV alone. The results of this study demonstrated that B. amyloliquefaciens SQR9 can stimulate DC maturation to effectively induce an immune response. In conclusion, an effective immune response may result from the uptake of H9N2 by DCs in the nasal mucosa, thereby stimulating DC maturation and migration to cervical lymph nodes to initiate immune response. PMID:26892720

  6. Isolation and Characterization of a Broad Spectrum Bacteriocin from Bacillus amyloliquefaciens RX7

    Directory of Open Access Journals (Sweden)

    Kong Boon Lim

    2016-01-01

    Full Text Available We isolated a Bacillus strain, RX7, with inhibitory activity against Listeria monocytogenes from soil and identified it as Bacillus amyloliquefaciens based on 16S rRNA gene sequencing. The inhibitory activity was stable over a wide range of pH and was fully retained after 30 min at 80°C, after which it decreased gradually at higher temperatures. The activity was sensitive to the proteolytic action of α-chymotrypsin, proteinase-K, and trypsin, indicating its proteinaceous nature. This bacteriocin was active against a broad spectrum of bacteria and the fungus Candida albicans. Direct detection of antimicrobial activity on a sodium dodecyl sulfate-polyacrylamide gel suggested an apparent molecular mass of approximately 5 kDa. Ammonium sulfate precipitation and anion-exchange and gel permeation chromatography integrated with reverse phase-high-performance liquid chromatography were used for bacteriocin purification. Automated N-terminal Edman degradation of the purified RX7 bacteriocin recognized the first 15 amino acids as NH2-X-Ala-Trp-Tyr-Asp-Ile-Arg-Lys-Leu-Gly-Asn-Lys-Gly-Ala, where the letter X in the sequence indicates an unknown or nonstandard amino acid. Based on BLAST similarity search and multiple alignment analysis, the obtained partial sequence showed high homology with the two-peptide lantibiotic haloduracin (HalA1 from Bacillus halodurans, although at least two amino acids differed between the sequences. A time-kill study demonstrated a bactericidal mode of action of RX7 bacteriocin.

  7. Antifungal Activity of Isolated Bacillus amyloliquefaciens SYBC H47 for the Biocontrol of Peach Gummosis

    Science.gov (United States)

    Zhang, Yanzhou; Wei, Zhiwen; Guan, Zhengbing; Cai, Yujie; Liao, Xiangru

    2016-01-01

    The gummosis disease is caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., and it is one of the most important diseases of stone fruits worldwide. The use of biocontrol as an alternative approach to synthetic chemical fungicides has aroused general concern about how to control plant diseases that are caused by phytopathogens. The aim of this study is to isolate Bacillus strains from raw honeys with the capacity to inhibit B. dothidea and to explore the mechanisms by which they could be used in the biocontrol of peach gummosis. Bacillus amyloliquefaciens SYBC H47 was isolated and identified on the basis of its physiological and biochemical characteristics and its 16S rRNA and gyrB gene sequences. The cell suspension and the cell-free supernatant of its culture showed significant antifungal activity against Aspergillus niger, Mucor racemosus, Fusarium oxysporum, Penicillium citrinum, and Candida albicans by agar-diffusion assays. The primary antifungal substances were bacillomycin L, fengycin, and surfactin, which were analyzed by HPLC LC/ESI-MS/MS. Bacillomycin L showed the best inhibitory effect against conidial germination of B. dothidea, followed by fengycin and surfactin. Surfactin had limited effects on mycelial growth, contrary to those of bacillomycin L and fengycin. However, a mixture of the three lipopeptides had a synergistic effect that disrupted the structure of the conidia and mycelia. In order to reduce the production cost, the use of waste frying peanut oil and soy oil as the sole carbon source increased the lipopeptide yield levels by approximately 17% (2.42 g/L) and 110% (4.35 g/L), respectively. In a field trial, the decreases in the infected gummosis rate (IGR) and the disease severity index (DSI) through cell suspension treatments were 20% and 57.5% (in 2014), respectively, and 40% and 57.5% (in 2015), respectively, in comparison with the control. In conclusion, B. amyloliquefaciens SYBC H47 could inhibit the germination of conidia

  8. Antifungal Activity of Isolated Bacillus amyloliquefaciens SYBC H47 for the Biocontrol of Peach Gummosis.

    Science.gov (United States)

    Li, Xunhang; Zhang, Yanzhou; Wei, Zhiwen; Guan, Zhengbing; Cai, Yujie; Liao, Xiangru

    2016-01-01

    The gummosis disease is caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., and it is one of the most important diseases of stone fruits worldwide. The use of biocontrol as an alternative approach to synthetic chemical fungicides has aroused general concern about how to control plant diseases that are caused by phytopathogens. The aim of this study is to isolate Bacillus strains from raw honeys with the capacity to inhibit B. dothidea and to explore the mechanisms by which they could be used in the biocontrol of peach gummosis. Bacillus amyloliquefaciens SYBC H47 was isolated and identified on the basis of its physiological and biochemical characteristics and its 16S rRNA and gyrB gene sequences. The cell suspension and the cell-free supernatant of its culture showed significant antifungal activity against Aspergillus niger, Mucor racemosus, Fusarium oxysporum, Penicillium citrinum, and Candida albicans by agar-diffusion assays. The primary antifungal substances were bacillomycin L, fengycin, and surfactin, which were analyzed by HPLC LC/ESI-MS/MS. Bacillomycin L showed the best inhibitory effect against conidial germination of B. dothidea, followed by fengycin and surfactin. Surfactin had limited effects on mycelial growth, contrary to those of bacillomycin L and fengycin. However, a mixture of the three lipopeptides had a synergistic effect that disrupted the structure of the conidia and mycelia. In order to reduce the production cost, the use of waste frying peanut oil and soy oil as the sole carbon source increased the lipopeptide yield levels by approximately 17% (2.42 g/L) and 110% (4.35 g/L), respectively. In a field trial, the decreases in the infected gummosis rate (IGR) and the disease severity index (DSI) through cell suspension treatments were 20% and 57.5% (in 2014), respectively, and 40% and 57.5% (in 2015), respectively, in comparison with the control. In conclusion, B. amyloliquefaciens SYBC H47 could inhibit the germination of conidia

  9. Plantazolicin, a novel microcin B17/streptolysin S-like natural product from Bacillus amyloliquefaciens FZB42.

    Science.gov (United States)

    Scholz, Romy; Molohon, Katie J; Nachtigall, Jonny; Vater, Joachim; Markley, Andrew L; Süssmuth, Roderich D; Mitchell, Douglas A; Borriss, Rainer

    2011-01-01

    Here we report on a novel thiazole/oxazole-modified microcin (TOMM) from Bacillus amyloliquefaciens FZB42, a Gram-positive soil bacterium. This organism is well known for stimulating plant growth and biosynthesizing complex small molecules that suppress the growth of bacterial and fungal plant pathogens. Like microcin B17 and streptolysin S, the TOMM from B. amyloliquefaciens FZB42 undergoes extensive posttranslational modification to become a bioactive natural product. Our data show that the modified peptide bears a molecular mass of 1,335 Da and displays antibacterial activity toward closely related Gram-positive bacteria. A cluster of 12 genes that covers ∼10 kb is essential for the production, modification, export, and self-immunity of this natural product. We have named this compound plantazolicin (PZN), based on the association of several producing organisms with plants and the incorporation of azole heterocycles, which derive from Cys, Ser, and Thr residues of the precursor peptide.

  10. Complete genome sequence of Bacillus amyloliquefaciens L-S60, a plant growth-promoting and antifungal bacterium.

    Science.gov (United States)

    Qin, Yuxuan; Han, Yuzhu; Yu, Yaqiong; Shang, Qingmao; Zhang, Bao; Li, Pinglan

    2015-10-20

    Bacillus amyloliquefaciens L-S60, a gram-positive plant-associated bacterium, which could stimulate plant growth and shows strong antifungal function, was isolated from the turfy soil in Beijing, China. The genome of B. amyloliquefaciens L-S60 comprises a 3903,017bp long circular chromosome that consists of 3909 protein-coding genes and 117 RNA genes. Based on genomic analysis, we identified gene clusters responsible for the biosynthesis of numerous bioactive metabolites with well-established in-vitro activity such as surfactin, iturin and fengycins. Additionally, we also found functionally related genes in the genome of L-S60, which play key roles in the process of plant growth promotion hormone secretion, biofilm formation and volatile compounds production. PMID:26297906

  11. [Identification and characterization of a Bacillus amyloliquefaciens with high antifungal activity].

    Science.gov (United States)

    Quan, Chun-shan; Wang, Jun-hua; Xu, Hong-tao; Fan, Sheng-di

    2006-02-01

    Plant disease can cause serious crop losses, and chemical control of disease is costly both to the environment and to the farmer. Some microorganism can produce the substance which has the preventing and exterminating functions to plant pathogens. These substances are valid to plant pathogens with only lower concentration, in addition the substances do not remain in soil and crops without being decomposed. If composization is performed with the microorganism, or the microorganism is mixed into compost, the functional compost having preventing and exterminating action will be made out and that can be more useful to environmental preservation. In order to screen antifungal bacteria for use in biological control, 200 compost samples were taken from different regions in China, over 10 bacterium with clear antifungal activity were isolated from composts, among them, strain Q-12 exhibited the highest antifungal activity which was strongly inhibits the growth of many plant pathogenic fungi such as Fusarium oxysporum and Rhizoctonia solan. According to the characteristics of morphology, physiology and biochemistry tests (API 50 CHB/E system) and the comparison of 16S rDNA sequence, the strain Q-12 was similar to B. subtilis and B. amyloliquefaciens. Some specific genes yyaR, yyaO and tetB, which have previously been shown to be effective for resolving these closely related taxa of the B. subtilis group, were analysed to clarify further the classification of Q-12, and two pairs of primers YyaR _ F/TetB _ R and YyaO _ F/TetB _ R were designed. From the analysis of fingerprints obtained with the two primers, strain Q-12 and B. amyloliquefaciens showed identical genomic fingerprints with primers YyaR _ F/TetB R, indicating their closely genetic relationship, and was identified as B. amyloliquefaciens. In the investigation of the culture condition, growth was carried out in a basal medium and gradually supplemented with the various ingredients to be investigated. The major

  12. Construction of a Bacillus amyloliquefaciens strain for high purity levan production.

    Science.gov (United States)

    Feng, Jun; Gu, Yanyan; Han, Lifang; Bi, Kexin; Quan, Yufeng; Yang, Chao; Zhang, Wei; Cao, Mingfeng; Wang, Shufang; Gao, Weixia; Sun, Yang; Song, Cunjiang

    2015-06-01

    Bacillus amyloliquefaciens NK-1 has the potential to produce levan and poly-gamma-glutamic acid (γ-PGA) simultaneously. However, it is not possible to purify each single product from the same strain because the extraction process is identical. We deleted the pgs cluster (for γ-PGA synthesis) from the NK-1 strain and constructed a γ-PGA-deficient NK-ΔLP strain. Nuclear magnetic results showed that the NK-ΔLP strain could produce high purity levan product. However, its levan titer was only 1.96 g L(-1) in the basal medium. Single-factor experimental and response surface methodology was used to optimize the culture condition, leading to levan titer of 13.9 and 22.6 g L(-1) in flask culture and in a 5-L bioreactor, respectively. The levan purity can reach to 92.7% after 48 h cultivation. Furthermore, the relationship between levanase (LevB) and levan molecular weight was studied. The results showed that LevB resulted in the production of low molecular weight levan and its expression level determined the ratio of high and low molecular weight levan. We also deleted the sac cluster (for levan synthesis) from the NK-1 strain and constructed a levan-deficient NK-L strain. The NK-L strain exhibited increased purity of γ-PGA product from 79.5 to 91.2%. PMID:25953857

  13. Induced maize salt tolerance by rhizosphere inoculation of Bacillus amyloliquefaciens SQR9.

    Science.gov (United States)

    Chen, Lin; Liu, Yunpeng; Wu, Gengwei; Veronican Njeri, Kimani; Shen, Qirong; Zhang, Nan; Zhang, Ruifu

    2016-09-01

    Salt stress reduces plant growth and is now becoming one of the most important factors restricting agricultural productivity. Inoculation of plant growth-promoting rhizobacteria (PGPR) has been shown to confer plant tolerance against abiotic stress, but the detailed mechanisms of how this occurs remain unclear. In this study, hydroponic experiments indicated that the PGPR strain Bacillus amyloliquefaciens SQR9 could help maize plants tolerate salt stress. After exposure to salt stress for 20 days, SQR9 significantly promoted the growth of maize seedlings and enhanced the chlorophyll content compared with the control. Additional analysis showed that the involved mechanisms could be the enhanced total soluble sugar content for decreasing cell destruction, improved peroxidase/catalase activity and glutathione content for scavenging reactive oxygen species, and reduced Na(+) levels in the plant to decrease Na(+) toxicity. These physiological appearances were further confirmed by the upregulation of RBCS, RBCL, H(+) -PPase, HKT1, NHX1, NHX2 and NHX3, as well as downregulation of NCED expression, as determined by quantitative reverse transcription-polymerase chain reaction. However, SQR9 counteracted the increase of abscisic acid in response to salt stress. In summary, these results show that SQR9 confers plant salt tolerance by protecting the plant cells and managing Na(+) homeostasis. Hence, it can be used in salt stress prone areas, thereby promoting agricultural production. PMID:26932244

  14. Biocontrol mechanism by root-associated Bacillus amyloliquefaciens FZB42 - a review

    Directory of Open Access Journals (Sweden)

    Soumitra ePaul Chowdhury

    2015-07-01

    Full Text Available Bacillus amyloliquefaciens subsp. plantarum FZB42 is a gram-positive model bacterium for unraveling plant-microbe interactions in Bacilli. In addition, FZB42 is used commercially as biofertilizer and biocontrol agent in agriculture. Genome analysis of FZB42 revealed that nearly 10% of the FZB42 genome is devoted to synthesizing antimicrobial metabolites and their corresponding immunity genes. However, recent investigations in planta demonstrated that - except surfactin - the amount of such compounds found in vicinity of plant roots is relatively low, making doubtful a direct function in suppressing competing microflora including plant pathogens. These metabolites have been also suspected to induce changes within the rhizosphere microbial community, which might affect environment and plant health. However, sequence analysis of rhizosphere samples revealed only marginal changes in the root microbiome, suggesting that secondary metabolites are not the key factor in protecting plants from pathogenic microorganisms. On the other hand, adding FZB42 to plants compensate, at least in part, changes in the community structure caused by the pathogen, indicating an interesting mechanism of plant protection by beneficial Bacilli.Sub-lethal concentrations of cyclic lipopeptides and volatiles produced by plant-associated Bacilli trigger pathways of induced systemic resistance (ISR, which protect plants against attacks of pathogenic microbes, viruses and nematodes. Stimulation of ISR by bacterial metabolites is likely the main mechanism responsible for biocontrol action of FZB42.

  15. More than anticipated - production of antibiotics and other secondary metabolites by Bacillus amyloliquefaciens FZB42.

    Science.gov (United States)

    Chen, Xiao-Hua; Koumoutsi, Alexandra; Scholz, Romy; Borriss, Rainer

    2009-01-01

    The genome of environmental Bacillus amyloliquefaciens FZB42 harbors numerous gene clusters involved in synthesis of antifungal and antibacterial acting secondary metabolites. Five gene clusters, srf, bmy, fen, nrs, dhb, covering altogether 137 kb, direct non-ribosomal synthesis of the cyclic lipopeptides surfactin, bacillomycin, fengycin, an unknown peptide, and the iron siderophore bacillibactin. Bacillomycin and fengycin were shown to act against phytopathogenic fungi in a synergistic manner. Three gene clusters, mln, bae, and dif, with a total length of 199 kb were shown to direct synthesis of the antibacterial acting polyketides macrolactin, bacillaene, and difficidin. Both, non-ribosomal synthesis of cyclic lipopeptides and synthesis of polyketides are dependent on the presence of a functional sfp gene product, 4'-phosphopantetheinyl transferase, as evidenced by knockout mutation of the sfp gene resulting in complete absence of all those eight compounds. In addition, here we present evidence that a gene cluster encoding enzymes involved in synthesis and export of the antibacterial acting dipeptide bacilysin is also functional in FZB42. In summary, environmental FZB42 devoted about 340 kb, corresponding to 8.5% of its total genetic capacity, to synthesis of secondary metabolites useful to cope with other competing microorganisms present in the plant rhizosphere. PMID:18957859

  16. Antimicrobial Activity of Culture Filtrate of Bacillus amyloliquefaciens RC-2 Isolated from Mulberry Leaves.

    Science.gov (United States)

    Yoshida, S; Hiradate, S; Tsukamoto, T; Hatakeda, K; Shirata, A

    2001-02-01

    ABSTRACT A potential antagonist, Bacillus amyloliquefaciens strain RC-2, against Colletotrichum dematium, mulberry anthracnose fungus, was obtained from healthy mulberry leaves by in vitro and in vivo screening techniques. Application of culture filtrate of RC-2 inhibited disease on mulberry leaves, indicating that suppression was due to antifungal compounds in the filtrate. Development of mulberry anthracnose on mulberry leaves was inhibited only when the culture filtrate was applied before fungal inoculation, and it was not inhibited by application after inoculation. These results suggest that the antifungal compounds in the filtrate exhibit a preventive effect on the disease. Peptone significantly increased production of the antifungal compounds. The culture filtrate of RC-2 also inhibited the growth of several other phytopathogenic fungi and bacteria, such as Rosellinia necatrix, Pyricularia oryzae, Agrobacterium tumefaciens, and Xanthomonas campestris pv. campestris, in vitro. From the culture filtrate of RC-2, seven kinds of antifungal compounds were isolated by high performance liquid chromatography analysis, and one of the compounds was determined as iturin A2, a cyclic peptide, by nuclear magnetic resonance and fast atom bombardment mass analysis. PMID:18944392

  17. Improving the neutral phytase activity from Bacillus amyloliquefaciens DSM 1061 by site-directed mutagenesis.

    Science.gov (United States)

    Xu, Wei; Shao, Rong; Wang, Zupeng; Yan, Xiuhua

    2015-03-01

    Neutral phytase is used as a feed additive for degradation of anti-nutritional phytate in aquatic feed industry. Site-directed mutagenesis of Bacillus amyloliquefaciens DSM 1061 phytase was performed with an aim to increase its activity. Mutation residues were chosen based on multiple sequence alignments and structure analysis of neutral phytsaes from different microorganisms. The mutation sites on surface (D148E, S197E and N156E) and around the active site (D52E) of phytase were selected. Analysis of the phytase variants showed that the specific activities of mutants D148E and S197E remarkably increased by about 35 and 13% over a temperature range of 40-75 °C at pH 7.0, respectively. The k cat of mutants D148E and S197E were 1.50 and 1.25 times than that of the wild-type phytase, respectively. Both D148E and S197E showed much higher thermostability than that of the wild-type phytase. However, mutants N156E and D52E led to significant loss of specific activity of the enzyme. Structural analysis revealed that these mutations may affect conformation of the active site of phytase. The present mutant phytases D148E and S197E with increased activities and thermostabilities have application potential as additives in aquaculture feed. PMID:25613522

  18. Bacterial Traits Involved in Colonization of Arabidopsis thaliana Roots by Bacillus amyloliquefaciens FZB42.

    Science.gov (United States)

    Dietel, Kristin; Beator, Barbara; Budiharjo, Anto; Fan, Ben; Borriss, Rainer

    2013-03-01

    Colonization studies previously performed with a green-fluorescent-protein, GFP, labeled derivative of Bacillus amyloliquefaciens FZB42 revealed that the bacterium behaved different in colonizing surfaces of plant roots of different species (Fan et al., 2012). In order to extend these studies and to elucidate which genes are crucial for root colonization, we applied targeted mutant strains to Arabidopsis seedlings. The fates of root colonization in mutant strains impaired in synthesis of alternative sigma factors, non-ribosomal synthesis of lipopeptides and polyketides, biofilm formation, swarming motility, and plant growth promoting activity were analyzed by confocal laser scanning microscopy. Whilst the wild-type strain heavily colonized surfaces of root tips and lateral roots, the mutant strains were impaired in their ability to colonize root tips and most of them were unable to colonize lateral roots. Ability to colonize plant roots is not only dependent on the ability to form biofilms or swarming motility. Six mutants, deficient in abrB-, sigH-, sigD-, nrfA-, yusV and RBAM017410, but not affected in biofilm formation, displayed significantly reduced root colonization. The nrfA- and yusV-mutant strains colonized border cells and, partly, root surfaces but did not colonize root tips or lateral roots.

  19. Improved poly-γ-glutamic acid production in Bacillus amyloliquefaciens by modular pathway engineering.

    Science.gov (United States)

    Feng, Jun; Gu, Yanyan; Quan, Yufen; Cao, Mingfeng; Gao, Weixia; Zhang, Wei; Wang, Shufang; Yang, Chao; Song, Cunjiang

    2015-11-01

    A Bacillus amyloliquefaciens strain with enhanced γ-PGA production was constructed by metabolically engineering its γ-PGA synthesis-related metabolic networks: by-products synthesis, γ-PGA degradation, glutamate precursor synthesis, γ-PGA synthesis and autoinducer synthesis. The genes involved in by-products synthesis were firstly deleted from the starting NK-1 strain. The obtained NK-E7 strain with deletions of the epsA-O (responsible for extracellular polysaccharide synthesis), sac (responsible for levan synthesis), lps (responsible for lipopolysaccharide synthesis) and pta (encoding phosphotransacetylase) genes, showed increased γ-PGA purity and slight increase of γ-PGA titer from 3.8 to 4.15 g/L. The γ-PGA degrading genes pgdS (encoding poly-gamma-glutamate depolymerase) and cwlO (encoding cell wall hydrolase) were further deleted. The obtained NK-E10 strain showed further increased γ-PGA production from 4.15 to 9.18 g/L. The autoinducer AI-2 synthetase gene luxS was deleted in NK-E10 strain and the resulting NK-E11 strain showed comparable γ-PGA titer to NK-E10 (from 9.18 to 9.54 g/L). In addition, we overexpressed the pgsBCA genes (encoding γ-PGA synthetase) in NK-E11 strain; however, the overexpression of these genes led to a decrease in γ-PGA production. Finally, the rocG gene (encoding glutamate dehydrogenase) and the glnA gene (glutamine synthetase) were repressed by the expression of synthetic small regulatory RNAs in NK-E11 strain. The rocG-repressed NK-anti-rocG strain exhibited the highest γ-PGA titer (11.04 g/L), which was 2.91-fold higher than that of the NK-1 strain. Fed-batch cultivation of the NK-anti-rocG strain resulted in a final γ-PGA titer of 20.3g/L, which was 5.34-fold higher than that of the NK-1 strain in shaking flasks. This work is the first report of a systematically metabolic engineering approach that significantly enhanced γ-PGA production in a B. amyloliquefaciens strain. The engineering strategies explored here are

  20. Improved poly-γ-glutamic acid production in Bacillus amyloliquefaciens by modular pathway engineering.

    Science.gov (United States)

    Feng, Jun; Gu, Yanyan; Quan, Yufen; Cao, Mingfeng; Gao, Weixia; Zhang, Wei; Wang, Shufang; Yang, Chao; Song, Cunjiang

    2015-11-01

    A Bacillus amyloliquefaciens strain with enhanced γ-PGA production was constructed by metabolically engineering its γ-PGA synthesis-related metabolic networks: by-products synthesis, γ-PGA degradation, glutamate precursor synthesis, γ-PGA synthesis and autoinducer synthesis. The genes involved in by-products synthesis were firstly deleted from the starting NK-1 strain. The obtained NK-E7 strain with deletions of the epsA-O (responsible for extracellular polysaccharide synthesis), sac (responsible for levan synthesis), lps (responsible for lipopolysaccharide synthesis) and pta (encoding phosphotransacetylase) genes, showed increased γ-PGA purity and slight increase of γ-PGA titer from 3.8 to 4.15 g/L. The γ-PGA degrading genes pgdS (encoding poly-gamma-glutamate depolymerase) and cwlO (encoding cell wall hydrolase) were further deleted. The obtained NK-E10 strain showed further increased γ-PGA production from 4.15 to 9.18 g/L. The autoinducer AI-2 synthetase gene luxS was deleted in NK-E10 strain and the resulting NK-E11 strain showed comparable γ-PGA titer to NK-E10 (from 9.18 to 9.54 g/L). In addition, we overexpressed the pgsBCA genes (encoding γ-PGA synthetase) in NK-E11 strain; however, the overexpression of these genes led to a decrease in γ-PGA production. Finally, the rocG gene (encoding glutamate dehydrogenase) and the glnA gene (glutamine synthetase) were repressed by the expression of synthetic small regulatory RNAs in NK-E11 strain. The rocG-repressed NK-anti-rocG strain exhibited the highest γ-PGA titer (11.04 g/L), which was 2.91-fold higher than that of the NK-1 strain. Fed-batch cultivation of the NK-anti-rocG strain resulted in a final γ-PGA titer of 20.3g/L, which was 5.34-fold higher than that of the NK-1 strain in shaking flasks. This work is the first report of a systematically metabolic engineering approach that significantly enhanced γ-PGA production in a B. amyloliquefaciens strain. The engineering strategies explored here are

  1. dRNA-Seq Reveals Genomewide TSSs and Noncoding RNAs of Plant Beneficial Rhizobacterium Bacillus amyloliquefaciens FZB42.

    Directory of Open Access Journals (Sweden)

    Ben Fan

    Full Text Available Bacillus amyloliquefaciens subsp. plantarum FZB42 is a representative of Gram-positive plant-growth-promoting rhizobacteria (PGPR that inhabit plant root environments. In order to better understand the molecular mechanisms of bacteria-plant symbiosis, we have systematically analyzed the primary transcriptome of strain FZB42 grown under rhizosphere-mimicking conditions using differential RNA sequencing (dRNA-seq. Our analysis revealed 4,877 transcription start sites for protein-coding genes, identified genes differentially expressed under different growth conditions, and corrected many previously mis-annotated genes. We also identified a large number of riboswitches and cis-encoded antisense RNAs, as well as trans-encoded small noncoding RNAs that may play important roles in the gene regulation of Bacillus. Overall, our analyses provided a landscape of Bacillus primary transcriptome and improved the knowledge of rhizobacteria-host interactions.

  2. Characterizing CMN1308, a Novel Strain of Bacillus amyloliquefaciens, for Potential Biological Control Application

    Directory of Open Access Journals (Sweden)

    Xuehua ZHANG

    2016-06-01

    Full Text Available Fungal diseases of plants continue to contribute to heavy crop losses in spite of the best control efforts of plant pathologists. Breeding for disease-resistant varieties and the application of synthetic chemical fungicides are the most widely accepted approaches in plant disease management. CMN1308 strain of Bacillus amyloliquefaciens was isolated from healthy Chinese chestnut fruit, which has antibiosis and induced resistance to the prevention mechanism of pathogenic bacterium after picking. In order to evaluate the antibiosis mechanism, CMN1308 was fostered with the method of confront culture. The antimicrobial components were also isolated from the culture of CMN1308, and their stability and antimicrobial activity was tested under different treatments such as temperature, pH and UV. The results showed that CMN1308 displays advantages in regard to spatial competition against the major pathogens of chestnut, Rhizopus stolonifer, Fusarium solani, Stachybotrys chartarum, Cryphonectria parasitica, Lasiodiplodia theobromae, Penicillium expansum and Aspergillus niger. Among this, CMN1308 had the best antimicrobial activity against P. expansum, with the inhibition zone diameter of 27.1 mm. The antimicrobial material isolated from CMN1308 culture showed a strong inhibition to the growth of P. expansum hyphal and also had a good stability to high temperature, alkali media and UV, but was sensitive to acidic conditions. Furthermore, CMN1308 increased the peroxidase, polyphenol oxidase activity and reduced the MDA content in chestnuts after infecting by pathogenic fungi. Thus, producing antibiotic compounds and inducible resistance are the main factors that may explain the antibacterial mechanism of CMN1308 on chestnut pathogenic. The results of this study might help to optimize the practical use of CMN1308 in the biological control of chestnut rot or other fruit rot infected by pathogenic fungi.

  3. Conclusion on the peer review of the pesticide risk assessment of the active substance Bacillus amyloliquefaciens subsp. plantarum strain D747

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2014-04-01

    Full Text Available The conclusions of the European Food Safety Authority (EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State Germany, for the pesticide active substance Bacillus amyloliquefaciens subsp. plantarum strain D747 are reported.  The context of the peer review was that required by Commission Regulation (EU No 188/2011.  The conclusions were reached on the basis of the evaluation of the representative uses of Bacillus amyloliquefaciens subsp. plantarum strain D747 as a fungicide on table and wine grapes. The reliable endpoints concluded as being appropriate for use in regulatory risk assessment, derived from the available studies and literature in the dossier peer reviewed, are presented.  Missing information identified as being required by the regulatory framework is listed.  The assessment of potential transfer of genetic material from Bacillus amyloliquefaciens subsp. plantarum strain D747 to other organisms cannot not be finalised.  The consumer and re-entry worker risk assessment cannot be finalised as data are missing on the levels of secondary metabolites/toxins produced by the organism on plants.  Furthermore, the risk assessment for non-target organisms and the groundwater exposure assessment from secondary metabolites/toxins could not be finalised.  As the soil exposure assessments could not be finalised, also the risk to soil-dwelling organisms from Bacillus amyloliquefaciens subsp. plantarum strain D747 could not be finalised.

  4. Draft Genome Sequence of Bacillus amyloliquefaciens Strain RHNK22, Isolated from Rhizosphere with Biosurfactant (Surfactin, Iturin, and Fengycin) and Antifungal Activity.

    Science.gov (United States)

    Narendra Kumar, Papathoti; Swapna, T H; Sathi Reddy, Koppula; Archana, K; Nageshwar, Lingampalli; Nalini, S; Khan, Mohamed Yahya; Hameeda, Bee

    2016-01-01

    Bacillus amyloliquefaciens strain RHNK22 isolated from groundnut rhizosphere showed direct and indirect plant growth-promoting traits along with biosurfactant activity and reduction in surface tension of water. Biosurfactants were identified as lipopeptides (surfactin, iturin, and fengycin) by molecular and biochemical analysis in our studies. PMID:26823600

  5. Draft Genome Sequence of Bacillus amyloliquefaciens Strain RHNK22, Isolated from Rhizosphere with Biosurfactant (Surfactin, Iturin, and Fengycin) and Antifungal Activity

    OpenAIRE

    Narendra Kumar, Papathoti; Swapna, T. H.; Sathi Reddy, Koppula; K. Archana; Nageshwar, Lingampalli; Nalini, S.; Khan, Mohamed Yahya; Hameeda, Bee

    2016-01-01

    Bacillus amyloliquefaciens strain RHNK22 isolated from groundnut rhizosphere showed direct and indirect plant growth-promoting traits along with biosurfactant activity and reduction in surface tension of water. Biosurfactants were identified as lipopeptides (surfactin, iturin, and fengycin) by molecular and biochemical analysis in our studies.

  6. Nutritional Value of Rice Bran Fermented by Bacillus amyloliquefaciens and Humic Substances and Its Utilization as a Feed Ingredient for Broiler Chickens

    OpenAIRE

    Supriyati; T Haryati; T Susanti; Susana, I. W. R.

    2015-01-01

    An experiment was conducted to increase the quality of rice bran by fermentation using Bacillus amyloliquefaciens and humic substances and its utilization as a feed ingredient for broiler chickens. The experiment was carried out in two steps. First, the fermentation process was done using a completely randomized design in factorial with 16 treatments: i) Dosage of B. amyloliquefaciens (2.108 cfu/g), 10 and 20 g/kg; ii) Graded levels of humic substances, 0, 100, 200, and 400 ppm; iii) Length o...

  7. Postharvest Biological Control of Blue Mold of Apple by Endophytic Bacillus amyloliquefaciens ES-2%植物内生菌Bacillus amyloliquefaciens ES-2菌株对苹果青霉病的抑制效果

    Institute of Scientific and Technical Information of China (English)

    孙力军; 王超男; 孙德坤; 吴士云; 孙永康

    2008-01-01

    本文主要研究了不同贮藏温度下植物内生菌Bacillus amyloliquefaciens ES-2菌株对苹果青霉病的抑制效果.ES-2菌株的各处理液在苹果果实和PDA培养基上对苹果青霉病菌均有抑制作用.较低的贮藏温度有利于拮抗菌对病菌的抑制效果;24h后接种病菌孢子的果实其病斑直径一般都高于48h后接种的果实.实验证明,ES-2菌株防治苹果青霉病的机理是由于ES-2产生的抗菌物质的作用.

  8. Bacillus amyloliquefaciens levansucrase-catalyzed the synthesis of fructooligosaccharides, oligolevan and levan in maple syrup-based reaction systems.

    Science.gov (United States)

    Li, Mengxi; Seo, Sooyoun; Karboune, Salwa

    2015-11-20

    Maple syrups with selected degree Brix (°Bx) (15, 30, 60) were investigated as reaction systems for levansucrase from Bacillus amyloliquefaciens. The enzymatic conversion of sucrose present in the maple syrup and the production of the transfructosylation products were assessed over a time course of 48h. At 30°C, the use of maple syrup 30°Bx led to the highest levansucrase activity (427.53μmol/mg protein/min), while maple syrup 66°Bx led to the highest converted sucrose concentration (1.53M). In maple syrup 30°Bx, oligolevans (1080%). In maple syrup 66°Bx, the most abundant products were oligolevans at 30°C and levans (DP≥30) at 8°C. The acceptor specificity study revealed the ability of B. amyloliquefaciens levansucrase to synthesize a variety of hetero-fructooligosaccharides (FOSs) in maple syrups 15°Bx and 30°Bx enriched with various disaccharides, with lactose being the preferred fructosyl acceptor. The current study is the first to investigate maple-syrup-based reaction systems for the synthesis of FOSs/oligolevans/levans. PMID:26344273

  9. Plant-Microbe Communication Enhances Auxin Biosynthesis by a Root-Associated Bacterium, Bacillus amyloliquefaciens SQR9.

    Science.gov (United States)

    Liu, Yunpeng; Chen, Lin; Zhang, Nan; Li, Zunfeng; Zhang, Guishan; Xu, Yu; Shen, Qirong; Zhang, Ruifu

    2016-04-01

    Mechanisms by which beneficial rhizobacteria promote plant growth include tryptophan-dependent indole-3-acetic acid (IAA) synthesis. The abundance of tryptophan in the rhizosphere, however, may influence the level of benefit provided by IAA-producing rhizobacteria. This study examined the cucumber-Bacillus amyloliquefaciens SQR9 system and found that SQR9, a bacterium previously shown to enhance the growth of cucumber, increased root secretion of tryptophan by three- to fourfold. Using a split-root system, SQR9 colonization of roots in one chamber not only increased tryptophan secretion from the noninoculated roots but also increased the expression of the cucumber tryptophan transport gene but not the anthranilate synthesis gene in those roots. The increased tryptophan in isolated rhizosphere exudates was sufficient to support increased IAA production by SQR9. Moreover, SQR9 colonization of roots in one chamber in the split-root system resulted in sufficient tryptophan production by the other roots to upregulate SQR9 IAA biosynthesis genes, including a 27-fold increase in the indole-3-acetonitrilase gene yhcX during subsequent colonization of those roots. Deletion of yhcX eliminated SQR9-mediated increases in root surface area, likely by reducing IAA-stimulated lateral root growth. This study demonstrates a chemical dialogue between B. amyloliquefaciens and cucumber in which this communication contributes to bacteria-mediated plant-growth enhancement.

  10. Suitable conditions for xylanases activities from Bacillus sp. GA2(1 and Bacillus sp. GA1(6 and their properties for agricultural residues hydrolysis

    Directory of Open Access Journals (Sweden)

    Sudathip Chantorn

    2016-04-01

    Full Text Available Bacillus sp. GA2(1 and Bacillus sp. GA1(6 were isolated from soybean field in Khon Kaen province, Thailand. Crude enzymes from both isolates showed the activities of cellulase, xylanase, and mannanase at 37°C for 24 h. The highest xylanase activities of Bacillus sp. GA2(1 and Bacillus sp. GA1(6 were 1.58±0.25 and 0.82±0.16 U/ml, respectively. The relative xylanase activities from both strains were more than 60% at pH 5.0 to 8.0. The optimum temperature of xylanases was 50°C in both strains. The residual xylanase activities from both strains were more than 70% at 60°C for 60 min. Five agricultural wastes (AWs, namely coffee residue, soybean meal, potato peel, sugarcane bagasse, and corn cobs, were used as substrates for hydrolysis properties. The highest reducing sugar content of 101±1.32 µg/ml was obtained from soybean meal hydrolysate produced by Bacillus sp. GA2(1 xylanase.

  11. INFLUENCE OF BACILLUS AMYLOLIQUEFACIENS SUBSP. PLANTARUM IMV B-7404 STRAIN EXOMETABOLITES ON PHENYLALANINE AMMONIA-LYASE ACTIVITY IN WINTER WHEAT SEEDLINGS.

    Science.gov (United States)

    Dragovoz, I V; Korzh, Yu V; Leonova, N O; Iliash, V M; Avdeeva, L V

    2015-01-01

    Influence of Bacillus amyloliquefaciens subsp. plantarum IMV B-7404 strain exometabolites on phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) activity in winter wheat seedlings has been studied. A significant increase of PAL activity at 4-6 hours after treatment of plant roots with Bacillus amyloliquefaciens subsp. plantarum IMVB-7404 strain exometabolites and in case of leaves infection with Bipolaris sorokiniana plant pathogen has been shown. It was established that PAL activity changed along with a decrease of the infected surface area of the leaves evidenced for the induction of response in winter wheat seedlings induced by IMV B-7404 strain exometabolites. It was concluded that the studied exponents could be used as model systems in the research of phytoimmunity induction mechanisms.

  12. Expression and secretion of Bacillus amyloliquefaciens alpha-amylase by using the yeast pheromone alpha-factor promoter and leader sequence in Saccharomyces cerevisiae.

    OpenAIRE

    Southgate, V J; Steyn, A J; Pretorius, I. S.; van Vuuren, H J

    1993-01-01

    Replacement of the regulatory and secretory signals of the alpha-amylase gene (AMY) from Bacillus amylolique-faciens with the complete yeast pheromone alpha-factor prepro region (MF alpha 1p) resulted in increased levels of extracellular alpha-amylase production in Saccharomyces cerevisiae. However, the removal of the (Glu-Ala)2 peptide from the MF alpha 1 spacer region (Lys-Arg-Glu-Ala-Glu-Ala) yielded decreased levels of extracellular alpha-amylase.

  13. Microbial interactions for enhancement of α-amylase production by Bacillus amyloliquefaciens 04BBA15 and Lactobacillus fermentum 04BBA19

    OpenAIRE

    Bertrand Tatsinkou Fossi; Frédéric Tavea; Lum Ayeoffe Fontem; Robert Ndjouenkeu; Samuel Wanji

    2014-01-01

    Interactions occurring between Saccharomyces cerevisiae and two thermostable α-amylase producing strains (Bacillus amyloliquefaciens 04BBA15 and Lactobacillus fermentum 04BBA19) were analyzed by comparing their growth patterns obtained in isolation with those obtained in mixture. The difference between the patterns was assessed using analysis of variance (ANOVA) in order to measure how much the growth of an organism was affected by other. The results showed two types of interactions in mixed ...

  14. Bacillus amyloliquefaciens TSBSO 3.8, a biosurfactant-producing strain with biotechnological potential for microbial enhanced oil recovery.

    Science.gov (United States)

    Alvarez, Vanessa Marques; Jurelevicius, Diogo; Marques, Joana Montezano; de Souza, Pamella Macedo; de Araújo, Livia Vieira; Barros, Thalita Gonçalves; de Souza, Rodrigo Octavio Mendonça Alves; Freire, Denise Maria Guimarães; Seldin, Lucy

    2015-12-01

    A screening for biosurfactant-producing bacteria was conducted with 217 strains that were isolated from environmental samples contaminated with crude oil and/or petroleum derivatives. Although 19 promising biosurfactant producers were detected, strain TSBSO 3.8, which was identified by molecular methods as Bacillus amyloliquefaciens, drew attention for its production of a high-activity compound that presented an emulsification activity of 63% and considerably decreased surface (28.5 mN/m) and interfacial (11.4 mN/m) tensions in Trypticase Soy Broth culture medium. TSBSO 3.8 growth and biosurfactant production were tested under different physical and chemical conditions to evaluate its biotechnological potential. Biosurfactant production occurred between 0.5% and 7% NaCl, at pH values varying from 6 to 9 and temperatures ranging from 28 to 50 °C. Moreover, biosurfactant properties remained the same after autoclaving at 121 °C for 15 min. The biosurfactant was also successful in a test to simulate microbial enhanced oil recovery (MEOR). Mass spectrometry analysis showed that the surface active compound was a surfactin, known as a powerful biosurfactant that is commonly produced by Bacillus species. The production of a high-efficiency biosurfactant, under some physical and chemical conditions that resemble those experienced in an oil production reservoir, such as high salinities and temperatures, makes TSBSO 3.8 an excellent candidate and creates good expectations for its application in MEOR. PMID:26350801

  15. Anti-methicillin Resistant Staphylococcus aureus Compound Isolation from Halophilic Bacillus amyloliquefaciens MHB1 and Determination of Its Mode of Action Using Electron Microscope and Flow Cytometry Analysis.

    Science.gov (United States)

    Jeyanthi, Venkadapathi; Velusamy, Palaniyandi

    2016-06-01

    The aim of this study was to purify, characterize and evaluate the antibacterial activity of bioactive compound against methicillin-resistant Staphylococcus aureus (MRSA). The anti-MRSA compound was produced by a halophilic bacterial strain designated as MHB1. The MHB1 strain exhibited 99 % similarity to Bacillus amyloliquefaciens based on 16S rRNA gene analysis. The culture conditions of Bacillus amyloliquefaciens MHB1 were optimized using nutritional and environmental parameters for enhanced anti-MRSA compound production. The pure bioactive compound was isolated using silica gel column chromatography and Semi-preparative High-performance liquid chromatography (Semi-preparative HPLC). The Thin layer chromatography, Fourier transform infrared spectroscopy and proton NMR ((1)H NMR) analysis indicated the phenolic nature of the compound. The molecular mass of the purified compound was 507 Da as revealed by Liquid chromatography-mass spectrometry (LC-MS) analysis. The compound inhibited the growth of MRSA with minimum inhibitory concentration (MIC) of 62.5 µg mL(-1). MRSA bacteria exposed to 4× MIC of the compound and the cell viability was determined using flow cytometric analysis. Scanning electron microscope and Transmission electron microscope analysis was used to determine the ultrastructural changes in bacteria. This is the first report on isolation of anti-MRSA compound from halophilic B. amyloliquefaciens MHB1 and could act as a promising biocontrol agent. PMID:27570306

  16. Effects of potential probiotic Bacillus amyloliquefaciens [corrected] FPTB16 on systemic and cutaneous mucosal immune responses and disease resistance of catla (Catla catla).

    Science.gov (United States)

    Das, Anushree; Nakhro, Khriezhato; Chowdhury, Supratim; Kamilya, Dibyendu

    2013-11-01

    Effects of dietary administration of Bacillus amyloliquefaciens FPTB16 on systemic and mucosal immunity and disease resistance of catla (Catla catla) against Edwardsiella tarda infection were evaluated in the present study. The laboratory maintained B. amyloliquefaciens was used to study antagonistic activity against fish pathogenic bacteria by agar well diffusion assay. Healthy catla were challenged by this bacterium for determination of its safety. For preparation of probiotic supplemented diet, the bacteria were added to the basal diet (control) at three different inclusion levels i.e., 1 × 10(9), 1 × 10(8) and 1 × 10(7) CFU/g diet. Fish (weight 25-30 g) were fed with these diets and various immune parameters and disease resistance study were conducted at 4 weeks and 8 weeks post-feeding. The bacterial antagonism study showed inhibition zone against E. tarda, Aeromonas hydrophila, Vibrio parahaemolyticus and V. harveyi. B. amyloliquefaciens was harmless to catla as neither mortalities nor morbidities were observed after the challenge. Study of different systemic and mucosal immunological parameters viz. superoxide anion production and nitric oxide production, myeloperoxidase content, lysozyme activity and total protein content showed significant enhancement (p Diet containing 10(8) and 10(9) CFU/g B. amyloliquefaciens significantly enhanced (p < 0.05) the resistance of catla against bacterial challenge at both time points. These results collectively suggest that B. amyloliquefaciens is a potential probiotic species and can be used in aquaculture to improve health status and disease resistance with an optimal dietary supplementation of 10(9) CFU/g.

  17. Study of the anti-sapstain fungus activity of Bacillus amyloliquefaciens CGMCC 5569 associated with Ginkgo biloba and identification of its active components.

    Science.gov (United States)

    Yuan, Bo; Wang, Zhe; Qin, Sheng; Zhao, Gui-Hua; Feng, You-Jian; Wei, Li-Hui; Jiang, Ji-Hong

    2012-06-01

    An endophytic bacterium, designated strain Bacillus amyloliquefaciens CGMCC 5569 was isolated from Chinese medicinal Ginkgo biloba collected from Xuzhou, China. Both the filtrate and the ethyl acetate extract of strain CGMCC 5569 showed growth inhibition activity against the sapstain fungi Lasiodiplodia rubropurpurea, L. crassispora, and L. theobromae obviously (>65%) based on the comparison of the length of zones on the petri dish. From the ethyl acetate extract of the filtrate, the antifungal compounds were obtained as a series of lipopeptides, which including series of fengycin, surfactin and bacillomycin. It showed strong growth inhibition activity in vitro against the L. rubropurpurea, L. crassispora and L. theobromae by about 70.22%, 69.53% and 78.76%, respectively. The strong anti-sapstain fungus activity indicated that the endophytic B. amyloliquefaciens CGMCC 5569 and its bioactive components might provide an alternative bio-resource for the bio-control of sapstain. PMID:22520222

  18. Purification and characterization of a new metallo-neutral protease for beer brewing from Bacillus amyloliquefaciens SYB-001.

    Science.gov (United States)

    Wang, Jinjing; Xu, Ailan; Wan, Yansong; Li, Qi

    2013-08-01

    The increased additive amount of adjuncts in the raw materials of Chinese beer requires the usage of protease to release more water-soluble proteins. Here, a metallo-neutral protease suited for brewing industry was purified from Bacillus amyloliquefaciens SYB-001. A 5.6-fold purification of the neutral protease was achieved with a 4-step procedure including ammonium sulfate precipitation, ion-exchange, hydrophobic interaction, and gel-filtration chromatography. The molecular mass of the enzyme was estimated to be 36.8 kDa. The protease was active and stable at a wide range of pH from 6.0-10.0 with an optimum at pH 7.0. The highest activity of the purified enzyme was found at 50 °C. The existence of manganese ion would specifically enhance the protease activity. Comparing with other commercial neutral proteases in China, adding the new neutral protease during mashing process would release more amino acids from wort such as aspartic acid, arginine, methione, and histidine, resulting in a better amino acid profile in wort. Moreover, the wort processed with the new neutral protease had a higher α-amino nitrogen concentration, which would ensure a vigorous yeast growth and better flavor. The study of the enzyme could lay a foundation for its industrial application and further research.

  19. The Crystal Structure of the YknZ Extracellular Domain of ABC Transporter YknWXYZ from Bacillus amyloliquefaciens.

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    Yongbin Xu

    Full Text Available Bacillus possesses the peptide toxin Sporulation-Delaying Protein (SDP, which can kill cells within a biofilm to support continued growth, thereby delaying the onset of biofilm sporulation. The four-component transporter YknWXYZ acts as a major SDP efflux pump to protect cells against the endogenous SDP toxin, for which YknYZ is a non-canonical ATP-binding cassette (ABC-type transporter. YknYZ consists of the following two components: (1 an individual protein (YknY and (2 a respective permease (YknZ. To date, the crystal structure, molecular function, and mechanism of action of the integral membrane protein YknZ remain to be elucidated. In this study, to characterize the structural and biochemical roles of YknZ in the functional assembly of YknWXYZ, we predicted and overexpressed the YknZ extracellular domain. We determined the crystal structure of B. amyloliquefaciens YknZ at a resolution of 2.0 Å. The structure revealed that the YknZ extracellular region exhibits significant structural similarity with the MacB periplasmic domain, which is a non-canonical ABC-type transporter in the tripartite macrolide-specific efflux pump in Gram-negative bacteria. We also found that the YknZ extracellular domain can directly bind to an extracellular component of YknX. This structural and biochemical study provides insights into the assembly of YknWXYZ, which may be relevant to understanding cannibalistic peptide toxin resistance in Bacillus and controlling bacterial growth.

  20. Purification and characterization of levansucrases from Bacillus amyloliquefaciens in intra- and extracellular forms useful for the synthesis of levan and fructooligosaccharides.

    Science.gov (United States)

    Tian, Feng; Inthanavong, Lotthida; Karboune, Salwa

    2011-01-01

    The intra- and extracellular levansucrase (LS) activities produced by Bacillus amyloliquefaciens were promoted by supplementing the sucrose medium with yeast and peptone as nitrogen sources. These activities were purified by polyethylene glycol (PEG) fractionation for the first time. PEGs of low molecular weight selectively fractionated the intracellular LS activity rather than the extracellular LS activity. Contrary to other LSs, B. amyloliquefaciens LSs exhibited high levan-forming activity over a wide range of sucrose concentrations. The optimum temperatures for the intra- (25-30 °C) and extracellular (40 °C) LS transfructosylation activities were lower than those for the hydrolytic activities (45-50 °C; 50 °C). In addition, the catalytic efficiency for the transfructosylation activity of intracellular LS was higher than that of extracellular LS. These differences between intra- and extracellular LSs reveal the occurrence of certain conformational changes to LS upon protein secretion and/or purification. This study is the first to highlight that B. amyloliquefaciens LSs synthesized a variety of FOSs from various saccharides, with lactose and maltose being the best fructosyl acceptors. PMID:21979064

  1. Nutritional Value of Rice Bran Fermented by Bacillus amyloliquefaciens and Humic Substances and Its Utilization as a Feed Ingredient for Broiler Chickens.

    Science.gov (United States)

    Supriyati; Haryati, T; Susanti, T; Susana, I W R

    2015-02-01

    An experiment was conducted to increase the quality of rice bran by fermentation using Bacillus amyloliquefaciens and humic substances and its utilization as a feed ingredient for broiler chickens. The experiment was carried out in two steps. First, the fermentation process was done using a completely randomized design in factorial with 16 treatments: i) Dosage of B. amyloliquefaciens (2.10(8) cfu/g), 10 and 20 g/kg; ii) Graded levels of humic substances, 0, 100, 200, and 400 ppm; iii) Length of fermentation, three and five days. The results showed that the fermentation significantly (price bran: 20 g/kg dosage of inoculums B. amyloliquefaciens, 100 ppm level of humic substances and three days fermentation period. The second step was a feeding trial to evaluate the fermented rice bran (FRB) as a feed ingredient for broiler chickens. Three hundred and seventy-five one-day-old broiler chicks were randomly assigned into five treatment diets. Arrangement of the diets as follows: 0%, 5%, 10%, 15%, and 20% level of FRB and the diets formulation based on equal amounts of energy and protein. The results showed that 15% inclusion of FRB in the diet provided the best bodyweight gain and feed conversion ratio (FCR) values. In conclusion, the nutrient content of rice bran improved after fermentation and the utilization of FRB as a feed ingredient for broiler chickens could be included up to 15% of the broiler diet. PMID:25557819

  2. Ultra high pressure homogenization (UHPH inactivation of Bacillus amyloliquefaciens spores in phosphate buffered saline (PBS and milk

    Directory of Open Access Journals (Sweden)

    Peng eDong

    2015-07-01

    Full Text Available Ultra high pressure homogenization (UHPH opens up new areas for dynamic high pressure assisted thermal sterilization of liquids. Bacillus amyloliquefaciens spores are resistant to high isostatic pressure and temperature and were suggested as potential surrogate for high pressure thermal sterilization validation. B. amyloliquefaciens spores suspended in PBS buffer (0.01 M, pH 7.0, low fat milk (1.5%, pH 6.7 and whole milk (3.5%, pH 6.7 at initial concentration of ~106 CFU/mL were subjected to UHPH treatments at 200, 300 and 350 MPa with an inlet temperature at ~80 °C. Thermal inactivation kinetics of B. amyloliquefaciens spores in PBS and milk were assessed with thin wall glass capillaries and modeled using mechanistic linear first order and Weibull models. The residence time during UHPH treatments was estimated to determine the contribution of temperature to spore inactivation by UHPH. No sublethal injury was detected after UHPH treatments using sodium chloride as selective component in the nutrient agar medium. The inactivation profiles of spores in PBS buffer and milk were compared and fat provided no clear protective effect for spores against treatments. Treatment at 200 MPa with valve temperatures lower than 125 °C caused no reduction of spores. A reduction of 3.5 log10 CFU/mL of B. amyloliquefaciens spores was achieved by treatment at 350 MPa with a valve temperature higher than 150 °C. The modeled thermal inactivation and observed inactivation during UHPH treatments suggest that temperature could be the main lethal effect driving inactivation.

  3. The impact of the pathogen Rhizoctonia solani and its beneficial counterpart Bacillus amyloliquefaciens on the indigenous lettuce microbiome.

    Science.gov (United States)

    Erlacher, Armin; Cardinale, Massimiliano; Grosch, Rita; Grube, Martin; Berg, Gabriele

    2014-01-01

    Lettuce belongs to the most commonly raw eaten food worldwide and its microbiome plays an important role for both human and plant health. Yet, little is known about the impact of potentially occurring pathogens and beneficial inoculants of the indigenous microorganisms associated with lettuce. To address this question we studied the impact of the phytopathogenic fungus Rhizoctonia solani and the biological control agent Bacillus amyloliquefaciens FZB42 on the indigenous rhizosphere and phyllosphere community of greenhouse-grown lettuce at two plant stages. The rhizosphere and phyllosphere gammaproteobacterial microbiomes of lettuce plants showed clear differences in their overall and core microbiome composition as well as in corresponding diversity indices. The rhizosphere was dominated by Xanthomonadaceae (48%) and Pseudomonadaceae (37%) with Rhodanobacter, Pseudoxanthomonas, Dokdonella, Luteimonas, Steroidobacter, Thermomonas as core inhabitants, while the dominating taxa associated to phyllosphere were Pseudomonadaceae (54%), Moraxellaceae (16%) and Enterobacteriaceae (25%) with Alkanindiges, Pantoea and a group of Enterobacteriaceae unclassified at genus level. The preferential occurrence of enterics in the phyllosphere was the most significant difference between both habitats. Additional enhancement of enterics on the phyllosphere was observed in bottom rot diseased lettuce plants, while Acinetobacter and Alkanindiges were identified as indicators of healthy plants. Interestingly, the microbial diversity was enhanced by treatment with both the pathogen, and the co-inoculated biological control agent. The highest impact and bacterial diversity was found by Rhizoctonia inoculation, but FZB42 lowered the impact of Rhizoctonia on the microbiome. This study shows that the indigenous microbiome shifts as a consequence to pathogen attack but FZB42 can compensate these effects, which supports their role as biocontrol agent and suggests a novel mode of action. PMID

  4. The impact of the pathogen Rhizoctonia solani and its beneficial counterpart Bacillus amyloliquefaciens on the indigenous lettuce microbiome

    Directory of Open Access Journals (Sweden)

    Armin eErlacher

    2014-04-01

    Full Text Available Lettuce belongs to the most commonly raw eaten food worldwide and its microbiome plays an important role for both human and plant health. Yet, little is known about the impact of potentially occurring pathogens and beneficial inoculants of the indigenous microorganisms associated with lettuce. To address this question we studied the impact of the phytopathogenic fungus Rhizoctonia solani and the biological control agent Bacillus amyloliquefaciens FZB42 on the indigenous rhizosphere and phyllosphere community of greenhouse-grown lettuce at two plant stages. The rhizosphere and phyllosphere gammaproteobacterial microbiomes of lettuce plants showed clear differences in their overall and core microbiome composition as well as in corresponding diversity indices. The rhizosphere was dominated by Xanthomonadaceae (48% and Pseudomonadaceae (37% with Rhodanobacter, Pseudoxanthomonas, Dokdonella, Luteimonas, Steroidobacter, Thermomonas as core inhabitants, while the dominating taxa associated to phyllosphere were Pseudomonadaceae (54%, Moraxellaceae (16% and Enterobacteriaceae (25% with Alkanindiges, Pantoea and a group of Enterobacteriaceae unclassified at genus level. The preferential occurrence of enterics in the phyllosphere was the most significant difference between both habitats. Additional enhancement of enterics on the phyllosphere was observed in bottom rot diseased lettuce plants, while Acinetobacter and Alkanindiges were identified as indicators of healthy plants. Interestingly, the microbial diversity was enhanced by treatment with both the pathogen, and the co-inoculated biological control agent. The highest impact and bacterial diversity was found by Rhizoctonia inoculation, but FZB42 lowered the impact of Rhizoctonia on the microbiome. This study shows that the indigenous microbiome shifts as a consequence to pathogen attack but FZB42 can compensate these effects, which supports their role as biocontrol agent and suggests a novel mode of

  5. The lipopeptide 6-2 produced by Bacillus amyloliquefaciens anti-CA has potent activity against the biofilm-forming organisms.

    Science.gov (United States)

    Song, Bo; Wang, Yu-Zhen; Wang, Guang-Yuan; Liu, Guang-Lei; Li, Wan-Zhong; Yan, Fang

    2016-07-15

    Both the whole cells and protoplasts of Pseudomonas aeruginosa PAO1 and Bacillus cereus, two biofilm-forming bacteria, were disrupted by the lipopeptide 6-2 produced by Bacillus amyloliquefaciens anti-CA. The lipopeptide 6-2 could also effectively inhibit the formation of biofilms and disperse pre-formed biofilms. Live/dead staining of the biofilms grown in the absence or presence of the lipopeptide 6-2 showed that more dead bacterial cells in the presence of the lipopeptide than those in the absence of the lipopeptide and biofilm formation was greatly reduced by the lipopeptide 6-2. Expression of the PslC gene related to exopolysaccharides in P. aeruginosa PAO1 was also inhibited. All these results demonstrated that the lipopeptide 6-2 produced by B. amyloliquefaciens anti-CA had a high activity against biofilm-forming bacteria. The lipopeptide 6-2 also killed the larvae of Balanus amphitrite and inhibit the germination of Laminaria japonica spore and growth of protozoa, all of which were the fouling organisms in marine environments. PMID:27184127

  6. Impact of different water activities (a w) adjusted by solutes on high pressure high temperature inactivation of Bacillus amyloliquefaciens spores.

    Science.gov (United States)

    Sevenich, Robert; Reineke, Kai; Hecht, Philipp; Fröhling, Antje; Rauh, Cornelia; Schlüter, Oliver; Knorr, Dietrich

    2015-01-01

    Much research has been conducted to comprehend the mechanisms of high pressure (HP) inactivation of spores in aqueous systems but for food model systems these information are scarce. In these systems spores can interact with ingredients which then could possibly lead to retarded or reduced inactivation, which can cause a problem for the sterilization process. The protective mechanism of a reduced a w-value is still unclear. HP processing might prove valuable to overcome protective effects of solutes and achieve shorter process times for sterilization under HP. To gain insight into the underlying mechanisms five a w-values (0.9, 0.92, 0.94, 0.96, 1) were adjusted with two different solutes (NaCl, sucrose). Solutions were inoculated with spores of Bacillus amyloliquefaciens and treated at 105, 110, and 115°C at 600 MPa. Further a thermal inactivation was conducted at the same temperatures for a comparison with the HP data. Afterward, the influence of HP high temperature treatment on the inactivation, the dipicolinic acid (DPA)-release and membrane constitution was assessed by plate count, HPLC and flow cytometry (FCM). The results show that during HP treatments sucrose and salt both have a protective effect, in which the influence of sucrose on the retarded inactivation is higher. The threshold water activities (a w), which is 0.94, here salt and sucrose have a significant influence on the inactivation. The comparison of thermal (105-115°C) and HP and high temperature (600 MPa, 105-115°C) treated samples showed that the time needed to achieve a 4-5 log10 inactivation is reduced from 45 (a w = 1) to 75 (a w = 0.9) min at 105°C to 3 (a w = 1) to 15 (a w = 0.9) minutes at 600 MPa and 105°C. The release of DPA is the rate limiting step of the inactivation and therefore monitoring the release is of great interest. The DPA-release is slowed down in high concentrated solutions (e.g., sucrose, salt) in comparison to a w 1. Since there is a difference in the way the

  7. Efficacy of protected sodium butyrate, a protected blend of essential oils, their combination, and Bacillus amyloliquefaciens spore suspension against artificially induced necrotic enteritis in broilers.

    Science.gov (United States)

    Jerzsele, A; Szeker, K; Csizinszky, R; Gere, E; Jakab, C; Mallo, J J; Galfi, P

    2012-04-01

    Necrotic enteritis caused by Clostridium perfringens leads to serious economical losses to the poultry industry. There is a growing need to find effective, nontoxic, antibiotic alternatives to prevent and cure the disease. In our study, the efficacy of protected sodium butyrate at 1.5 g/kg (BP70), a Bacillus amyloliquefaciens spore suspension with 10(9) cfu/g (BAL; Ecobiol), a protected blend of essential oils (1%) at 1.5 g/kg (EO), and a combination of sodium butyrate with essential oils (1%) protected with vegetable fat at 1.5 g/kg (BP70+EO; Natesse) was investigated in an artifical C. perfringens-infection model. Body weight gain, gross pathological and histopathological lesion scores, villus lengths, and villus length:crypt depth ratio was determined and compared with the control group. Broilers infected with C. perfringens and treated with essential oils or the combination of sodium butyrate and essential oils showed significantly better BW gain (P < 0.05), increased villus length and villus length:crypt depth ratio (P < 0.001), and decreased gross pathological and histopathological lesion scores (P < 0.05) compared with the control. Sodium butyrate alone and B. amyloliquefaciens spore suspension had no beneficial effects on the course of the disease in this study. According to our results, the protected combination of sodium butyrate and essential oils, as well as the protected essential oils, can be potential candidates for the prevention and treatment of necrotic enteritis in broiler chickens. PMID:22399722

  8. Microbial interactions for enhancement of α-amylase production by Bacillus amyloliquefaciens 04BBA15 and Lactobacillus fermentum 04BBA19

    Directory of Open Access Journals (Sweden)

    Bertrand Tatsinkou Fossi

    2014-12-01

    Full Text Available Interactions occurring between Saccharomyces cerevisiae and two thermostable α-amylase producing strains (Bacillus amyloliquefaciens 04BBA15 and Lactobacillus fermentum 04BBA19 were analyzed by comparing their growth patterns obtained in isolation with those obtained in mixture. The difference between the patterns was assessed using analysis of variance (ANOVA in order to measure how much the growth of an organism was affected by other. The results showed two types of interactions in mixed culture; commensalism between S. cerevisiae and B. amyloliquefaciens 04BBA15 and mutualism between S. cerevisiae and L. fermentum 04BBA19. In mixed culture, the α-amylase production increased significantly compared to that observed in monoculture (P < 0.05. Response surface optimization of fermentation parameters in mixed cultures (initial yeast to bacteria ratio 1.125, temperature 33.5 °C, pH 5.5 resulted in about 1.8 fold higher enzyme production than that observed in the unoptimized fermentation.

  9. Production of fibrinolytic enzyme from Bacillus amyloliquefaciens by fermentation of chickpeas, with the evaluation of the anticoagulant and antioxidant properties of chickpeas.

    Science.gov (United States)

    Wei, Xuetuan; Luo, Mingfang; Xu, Lin; Zhang, Yewei; Lin, Xing; Kong, Peng; Liu, Huizhou

    2011-04-27

    To develop safe and cheap thrombolytic agents, a fibrinolytic enzyme productive strain of LSSE-62 was isolated from Chinese soybean paste. This strain was identified as Bacillus amyloliquefaciens by 16S rDNA sequence analysis. Nucleotide and amino acid sequence analysis showed that this fibrinolytic enzyme was identical to subtilisin DJ-4. Chickpeas were used as the substrate for fibrinolytic enzyme production from B. amyloliquefaciens in solid-state fermentation. Under the optimized conditions (34 °C and 50% initial moisture content), the fibrinolytic activity of fermented chickpeas reached 39.28 fibrin degradation units (FU)/g. Additionally, the fermented chickpeas showed anticoagulant activity, and the purified anticoagulant component showed higher anticoagulant activity than heparin sodium. After fermentation, the total phenolic and total flavonoid contents increased by 222 and 71%, respectively, and then the antioxidant activities were improved significantly. This study provided a novel method for the preparation of multifunctional food of chickpeas or raw materials for the preparation of functional food additives and potential drugs.

  10. Production of alpha amylase from a randomly induced mutant strain of bacillus amyloliquefaciens and its application as a desizer in textile industry

    International Nuclear Information System (INIS)

    The present study is concerned with the improvement of Bacillus amyloliquefaciens strain UNG-16 for alpha amylase production. The bacterial culture was exposed to UV irradiation at 1.6X102 J/m2/S for 15-60 min. However, UV induced viables did not give improved alpha amylase production; therefore chemical mutation using ethyl methane sulphonate (EMS 50-300 mu l/ml) was undertaken for 10-60 min. The mutant B. amyloliquefaciens EMS-6 gave 102.78+-2.22 U/ml/min enzyme activity which was 1.4 fold higher than the parental strain. In stirred fermentor, the incubation period was reduced from 72 to 48 h after inoculation. The production of alpha amylase was found to be maximal when the 60% volume, 2.0 vvm air supply and 400 rpm agitation rate was maintained during the fermentation period. The incubation temperature (37 deg. C) and size of inoculum (8.0 %) were also optimized. A 100% desizing of grey fabric (or starch removal) was obtained with 200-250 enzyme units at pH 6.5 at 60 deg. C in 1 h. (author)

  11. Improving the quality of Laminaria japonica-based diet for Apostichopus japonicus through degradation of its algin content with Bacillus amyloliquefaciens WB1.

    Science.gov (United States)

    Wang, Xitao; Wang, Lili; Che, Jian; Li, Zhen; Zhang, Jiancheng; Li, Xiaoyu; Hu, Weiqing; Xu, Yongping

    2015-07-01

    Laminaria japonica feedstuff is used as a substitute for Sargassum thunbergii in the small-scale culturing of Apostichopus japonicus (sea cucumber) because of its abundant sources and low price in China. However, the difficulty associated with the degradation of algin by A. japonicus and, hence, its utilization have limited the practical value of L. japonica feedstuff in sea cucumber farming. In this study, A. japonicus individuals were fed with L. japonica feedstuff pretreated, via fermentation with the algin-degrading bacterial strain, Bacillus amyloliquefaciens WB1, and their growth performance, nonspecific immune responses, and resistance against Vibrio infection were then determined over a 60-day period. Growth performance of these individuals was similar to those fed with a commercial feedstuff made from S. thunbergii (mean weight gain of 5.79 versus 5.69 g on day 60), but was significantly (P < 0.05) increased compared to those fed with untreated L. japonica feedstuff (mean weight gain of 1.31 g). At the same time, they also showed significantly higher levels of amylase, protease, and alginate lyase activities than the other groups. These individuals and those fed with the commercial feedstuff or heat-inactivated but B. amyloliquefaciens WB1-treated L. japonicas feedstuff showed enhanced levels of activities for the immune enzymes nitric oxide synthase, lysozyme, peroxidase, and acid phosphatase, compared to those fed with nontreated L. japonica feedstuff. Furthermore, A. japonicus individuals fed with B. amyloliquefaciens WB1-treated L. japonica feedstuff exhibited greater resistance to disease following Vibrio splendidus challenge, as shown by the much lower cumulative symptom (10 %) compared to the rest, which showed as much as 73 % in the case of individuals fed with the untreated L. japonica feedstuff. Analysis of their intestinal tract revealed a much lower number of total Vibrio sp. These results demonstrated that L. japonica in which the algin

  12. Transposon Mutagenesis of the Plant-Associated Bacillus amyloliquefaciens ssp. plantarum FZB42 Revealed That the nfrA and RBAM17410 Genes Are Involved in Plant-Microbe-Interactions

    OpenAIRE

    Anto Budiharjo; Soumitra Paul Chowdhury; Kristin Dietel; Barbara Beator; Olga Dolgova; Ben Fan; Wilfrid Bleiss; Jörg Ziegler; Michael Schmid; Anton Hartmann; Rainer Borriss

    2014-01-01

    Bacillus amyloliquefaciens ssp. plantarum FZB42 represents the prototype of Gram-positive plant growth promoting and biocontrol bacteria. In this study, we applied transposon mutagenesis to generate a transposon library, which was screened for genes involved in multicellular behavior and biofilm formation on roots as a prerequisite of plant growth promoting activity. Transposon insertion sites were determined by rescue-cloning followed by DNA sequencing. As in B. subtilis, the global transcri...

  13. The Biological Characterization ofBacillus amyloliquefaciensLx-11%解淀粉芽胞杆菌Lx-11生物学特性研究

    Institute of Scientific and Technical Information of China (English)

    戴秀华; 张荣胜; 陈志谊

    2014-01-01

    In order to understand the mode of action ofBacillus amyloliquefaciens Lx-11, we studied its biological characteristics in respects of temperature, pH, carbon/nitrogen sources, trace elements, inorganic salt and growth curve. Results showed that 28℃, pH 7.0, sucrose, soybean powder, Gly, KH2PO3and NaCl were optimum for its growth. The optimal culture medium compositions of the orthogonal experiment were yeast extract 1 g/L, sucrose 5 g/L, tryptone 6 g/L, glycine 0.01 g/L and sodium chloride 0.15 g/L. Logarithmic growth was at the first 32 h.%本文从分泌代谢物种类、最佳碳源、氮源、无机盐、微量元素、pH 和温度方面研究了前期筛选获得的对水稻细菌性条斑病有良好防效的解淀粉芽胞杆菌Bacillus amyloliquefaciens Lx-11的生物学特性。试验结果表明,解淀粉芽胞杆菌Lx-11可产生蛋白酶、纤维素酶和嗜铁素;最适生长温度为28℃、最适pH为7.0、最佳碳源为蔗糖,最佳氮源为胰蛋白胨,微量元素甘氨酸(Gly)、谷氨酸(Glu)、VB2、VB6和肌醇均能促进Lx-11的生长,其中Gly促进作用明显;无机盐KH2PO3和NaCl能促进Lx-11的生长;生防菌Lx-11在32 h前处于对数生长期,32 h之后,菌体生长基本达到稳定。正交试验所得最优培养基组合为酵母膏1 g/L、蔗糖5 g/L、胰蛋白胨6 g/L、甘氨酸0.01 g/L和氯化钠0.15 g/L。

  14. Advance in Research on Biological Control of Postharvest Diseases of Fruits and Vegetables by Bacillus amyloliquefaciens%解淀粉芽孢杆菌防治果蔬采后病害研究进展

    Institute of Scientific and Technical Information of China (English)

    洪鹏; 安国栋; 胡美英; 王会冬

    2013-01-01

    综述了解淀粉芽孢杆菌在果蔬采后病害防治上的应用及研究进展,归纳了解淀粉芽孢杆菌的筛选途径和研究现状,总结了解淀粉芽孢杆菌的控病作用机制和提高解淀粉芽孢杆菌作用效果的方法;指出解淀粉芽孢杆菌用于果蔬保鲜存在的诸如防效不稳定和商业化困难等问题,并提出与低量化学药剂混用和运用分子生物学手段研究抑菌机理等建议;最后,认为以解淀粉芽孢杆菌为主要成分的生物农药具有广阔的应用前景.%The research advance of using Bacillus amyloliquefaciens to postharvest diseases of fruits and vegetables was reviewed, including the screening methods antagonists and situation of B.amyloliquefaciens. The mechanisms of the antagonist B. amyloliquefaciens against postharvest diseases of fruits and vegetables and improved ways of antagonistic microorganism were summarized. Moreover, the paper also presented the application of B. amyloliquefaciens agent and the existing problems such as instability of control effect and difficulty of commercialization, combined use of pesticides and using methods in molecular biology on bacteriostasis mechanism are propounded. Finally, the pesticides of B. amyloliquefaciens were considered as wide development prospect in the future.

  15. Biosynthesis of titanium dioxide nanoparticles using Bacillus amyloliquefaciens culture and enhancement of its photocatalytic activity for the degradation of a sulfonated textile dye Reactive Red 31.

    Science.gov (United States)

    Khan, Razia; Fulekar, M H

    2016-08-01

    The present study aims at exploiting Bacillus amyloliquefaciens for the biosynthesis of titanium dioxide nanoparticles and also investigates role of bacterial enzymes in the biosynthesis of titanium dioxide nanoparticles. Bacterial synthesized as well as metal doped titanium dioxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDAX). Amylase activity (43.37IU) in culture supernatant evinced a potential involvement of extracellular enzyme in TiO2 nanoparticle biosynthesis. Crystallite size of bio-synthesized nanoparticles was found to be in the range of 15.23-87.6nm. FTIR spectroscopy and native-PAGE (Polyacrylamide Gel Electrophoresis) clearly indicated involvement of alpha amylase in biosynthesis of TiO2 nanoparticles and in their stabilization. TEM micrographs of the synthesized titanium dioxide nanoparticles revealed the formation of spherical nanoparticles with a size range of 22.11-97.28nm. Photocatalytic degradation of Reactive Red 31 (RR31) dye was carried out using bio-synthesized TiO2 nanoparticles under UV radiation. Photocatalytic activity of synthesized nanoparticles was enhanced by Ag, La, Zn and Pt doping. Platinum doped TiO2 showed highest potential (90.98%) in RR31 degradation as compared to undoped (75.83%).

  16. Isolation and identification of the antagonistic strain DM-54 of Bacillus amyloliquefacien against Verticillium dahliae, and optimization of antifungal protein producing conditions

    Institute of Scientific and Technical Information of China (English)

    Ying ZHU; Shuna LI; Hongshui YUAN; Xiaojun GUO; Baocheng ZHU

    2009-01-01

    The strains capable of resistance against Verticillium dahliae Kleb were isolated and screened from the soils of cotton fields from several different provinces in China. A strain, coded DM-54, with a rather high antagonistic activity was obtained. Its morphological characteristics, physiological and biochemical properties and a 16 S rDNA sequence of this strain were further studied. The DM-54 strain was finally identified as a kind of Bacillus amyloliquefacien. Through a single factor experiment and an orthogonal experiment, the optimal shaking flask fermentation condition of strain DM-54 was found to be: media composed of 5% dextrin, 3% soy peptone, 0.02% MgSO4 0.01% CaCl2, initial pH 7.0 and 10% inoculum volume, media volume 30/250 (mL/mL), fermentation temperature at 32℃, rotating speed activity was distinguished to be elevated, at about 39.9%. Our research offers an effective means for the massive production of antagonistic proteins.

  17. Study of Biological Degradation of New Poly(Ether-Urethane-Urea)s Containing Cyclopeptide Moiety and PEG by Bacillus amyloliquefaciens Isolated from Soil.

    Science.gov (United States)

    Rafiemanzelat, Fatemeh; Jafari, Mahboobeh; Emtiazi, Giti

    2015-10-01

    The present work for the first time investigates the effect of Bacillus amyloliquefaciens, M3, on a new poly(ether-urethane-urea) (PEUU). PEUU was synthesized via reaction of 4,4'-methylenebis(4-phenylisocyanate) (MDI), L-leucine anhydride cyclopeptide (LACP) as a degradable monomer and polyethylene glycol with molecular weight of 1000 (PEG-1000). Biodegradation of the synthesized PEUU as the only source for carbon and nitrogen for M3 was studied. The co-metabolism biodegradation of the polymer by this organism was also investigated by adding mannitol or nutrient broth to the basic media. Biodegradation of the synthesized polymer was followed by SEM, FT-IR, TGA, and XRD techniques. It was shown that incubation of PEUU with M3 resulted in a 30-44 % reduction in polymer's weight after 1 month. This study indicates that the chemical structure of PEUU significantly changes after exposure to M3 due to hydrolytic and enzymatic degradation of polymer chains. The results of this work supports the idea that this poly(ether-urethane) is used as a sole carbon source by M3 and this bacterium has a good capability for degradation of poly(ether-urethane)s.

  18. Cotton fertilization using PGPR Bacillus amyloliquefaciens FZB42 and compost: Impact on insect density and cotton yield in North Benin, West Africa

    Directory of Open Access Journals (Sweden)

    Thiery B. Charles Alavo

    2015-12-01

    Full Text Available This work has compared the effects of the biofertilizer Bacillus amyloliquefaciens FZB42 with that of compost for cotton production. The population dynamics of pests and predators have been studied in order to check whether the use of both fertilization materials can contribute to pest management in cotton. Three treatments were considered: (i dressing of seeds in rhizobacteria suspension, (ii introduction of rhizobacterial suspension directly in the pocket, same time with the seeds, and (iii fertilization with compost. The study was carried out in northwest Benin (West Africa. Results showed that cotton aphids, Aphis gossypii, pink bollworm, Pectinophora gossypiella, leaf roller, Sylepta derogata, and cotton bugs, Dysdercus sp. are the major insect pests encountered in the experimental plots. Cotton bollworm, Helicoverpa armigera, was present but under the economic threshold. The coccinellid predators, Cheilomenes spp., occurred in the experimental plots and almost suppressed aphid proliferation. Other natural enemies such as chrysopids and ant species also occurred and probably contributed to maintain the cotton bollworm under the economic threshold. The treatment with seeds dressed with the rhizobacteria suspension yielded 39% more cotton compared to the compost fertilization. The use of both fertilization materials without application of chemicals can contribute to pest management in cotton.

  19. Biosynthesis of titanium dioxide nanoparticles using Bacillus amyloliquefaciens culture and enhancement of its photocatalytic activity for the degradation of a sulfonated textile dye Reactive Red 31.

    Science.gov (United States)

    Khan, Razia; Fulekar, M H

    2016-08-01

    The present study aims at exploiting Bacillus amyloliquefaciens for the biosynthesis of titanium dioxide nanoparticles and also investigates role of bacterial enzymes in the biosynthesis of titanium dioxide nanoparticles. Bacterial synthesized as well as metal doped titanium dioxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDAX). Amylase activity (43.37IU) in culture supernatant evinced a potential involvement of extracellular enzyme in TiO2 nanoparticle biosynthesis. Crystallite size of bio-synthesized nanoparticles was found to be in the range of 15.23-87.6nm. FTIR spectroscopy and native-PAGE (Polyacrylamide Gel Electrophoresis) clearly indicated involvement of alpha amylase in biosynthesis of TiO2 nanoparticles and in their stabilization. TEM micrographs of the synthesized titanium dioxide nanoparticles revealed the formation of spherical nanoparticles with a size range of 22.11-97.28nm. Photocatalytic degradation of Reactive Red 31 (RR31) dye was carried out using bio-synthesized TiO2 nanoparticles under UV radiation. Photocatalytic activity of synthesized nanoparticles was enhanced by Ag, La, Zn and Pt doping. Platinum doped TiO2 showed highest potential (90.98%) in RR31 degradation as compared to undoped (75.83%). PMID:27175828

  20. Effects of Bacillus amyloliquefaciens FZB42 on lettuce growth and health under pathogen pressure and its impact on the rhizosphere bacterial community.

    Directory of Open Access Journals (Sweden)

    Soumitra Paul Chowdhury

    Full Text Available The soil-borne pathogen Rhizoctonia solani is responsible for crop losses on a wide range of important crops worldwide. The lack of effective control strategies and the increasing demand for organically grown food has stimulated research on biological control. The aim of the present study was to evaluate the rhizosphere competence of the commercially available inoculant Bacillus amyloliquefaciens FZB42 on lettuce growth and health together with its impact on the indigenous rhizosphere bacterial community in field and pot experiments. Results of both experiments demonstrated that FZB42 is able to effectively colonize the rhizosphere (7.45 to 6.61 Log 10 CFU g(-1 root dry mass within the growth period of lettuce in the field. The disease severity (DS of bottom rot on lettuce was significantly reduced from severe symptoms with DS category 5 to slight symptom expression with DS category 3 on average through treatment of young plants with FZB42 before and after planting. The 16S rRNA gene based fingerprinting method terminal restriction fragment length polymorphism (T-RFLP showed that the treatment with FZB42 did not have a major impact on the indigenous rhizosphere bacterial community. However, the bacterial community showed a clear temporal shift. The results also indicated that the pathogen R. solani AG1-IB affects the rhizosphere microbial community after inoculation. Thus, we revealed that the inoculant FZB42 could establish itself successfully in the rhizosphere without showing any durable effect on the rhizosphere bacterial community.

  1. Purification and characterization of a naringinase from a newly isolated strain of Bacillus amyloliquefaciens 11568 suitable for the transformation of flavonoids.

    Science.gov (United States)

    Zhu, Yunping; Jia, Huiyong; Xi, Menglu; Xu, Liya; Wu, Shaoming; Li, Xiuting

    2017-01-01

    An intracellular naringinase from Bacillus amyloliquefaciens 11568 isolated from soil was purified, identified, and characterized. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the purified enzyme gave a single protein band corresponding to a molecular mass of 32kDa. The optimum pH and temperature for naringinase and its α-l-rhamnosidase and β-d-glucosidase activities were pH 7.5 and 45°C, respectively. The enzymes were stable below 45°C between pH 3.5 and 8.5. The Km and the Vmax of the isolated naringinase were 0.95mmol/L and 3847.3mmol/(L·min), respectively. The isolated naringinase was capable of hydrolyzing naringin, neohesperidin, and other glycosides. Additionally, a concentration of 4U/mL of the enzyme in citrus juice was sufficient to remove the naringin and alleviate the bitterness of the juice. These results provide an in-depth insight into the structure of the naringinase and the hydrolysis of naringin and other flavonoids. PMID:27507445

  2. Overproduction of Bacillus amyloliquefaciens extracellular glutamyl-endopeptidase as a result of ectopic multi-copy insertion of an efficiently-expressed mpr gene into the Bacillus subtilis chromosome

    Directory of Open Access Journals (Sweden)

    Yomantas Yurgis AV

    2011-08-01

    Full Text Available Abstract Background Plasmid-less, engineered Bacillus strains have several advantages over plasmid-carrier variants. Specifically, their stability and potential ecological safety make them of use in industrial applications. As a rule, however, it is necessary to incorporate many copies of a key gene into a chromosome to achieve strain performance that is comparable to that of cells carrying multiple copies of a recombinant plasmid. Results A plasmid-less B. subtilis JE852-based strain secreting glutamyl-specific protease (GSP-the protein product of the mpr gene from B. amyloliquefaciens was constructed that exhibits decreased levels of other extracellular proteases. Ten copies of an mprB.amy cassette in which the GSP gene was placed between the promoter of the B. amyloliquefaciens rplU-rpmA genes and the Rho-independent transcription terminator were ectopically inserted into designated (3 copies and random (7 copies points in the recipient chromosome. The resulting strain produced approximately 0.5 g/L of secreted GSP after bacterial cultivation in flasks with starch-containing media, and its performance was comparable to an analogous strain in which the mprB.amy cassette was carried on a multi-copy plasmid. Conclusion A novel strategy for ectopically integrating a cassette into multiple random locations in the B. subtilis chromosome was developed. This new method is based on the construction of DNA fragments in which the desired gene, marked by antibiotic resistance, is sandwiched between "front" and "back" portions of random chromosomal DNA restriction fragments. These fragments were subsequently inserted into the targeted sites of the chromosome using double-cross recombination. The construction of a marker-free strain was achieved by gene conversion between the integrated marked gene and a marker-less variant carried by plasmid DNA, which was later removed from the cells.

  3. Effects of volatile organic compounds produced by Bacillus amyloliquefaciens on the growth and virulence traits of tomato bacterial wilt pathogen Ralstonia solanacearum.

    Science.gov (United States)

    Raza, Waseem; Wang, Jichen; Wu, Yuncheng; Ling, Ning; Wei, Zhong; Huang, Qiwei; Shen, Qirong

    2016-09-01

    The production of volatile organic compounds (VOCs) by microbes is an important characteristic for their selection as biocontrol agents against plant pathogens. In this study, we identified the VOCs produced by the biocontrol strain Bacillus amyloliquefaciens T-5 and evaluated their impact on the growth and virulence traits of tomato bacterial wilt pathogen Ralstonia solanacearum. The results showed that the VOCs of strain T-5 significantly inhibited the growth of R. solanacearum in agar medium and in soil. In addition, VOCs significantly inhibited the motility traits, root colonization, biofilm formation, and production of antioxidant enzymes and exopolysaccharides by R. solanacearum. However, no effect of VOCs on the production of hydrolytic enzymes by R. solanacearum was observed. The strain T-5 produced VOCs, including benzenes, ketones, aldehydes, alkanes, acids, and one furan and naphthalene compound; among those, 13 VOCs showed 1-10 % antibacterial activity against R. solanacearum in their produced amounts by T-5; however, the consortium of all VOCs produced on agar medium, in sterilized soil, and in natural soil showed 75, 62, and 85 % growth inhibition of R. solanacearum, respectively. The real-time PCR analysis further confirmed the results when the expression of different virulence- and metabolism-related genes in R. solanacearum cells was decreased after exposure to the VOCs of strain T-5. The results of this study clearly revealed the significance of VOCs in the control of plant pathogens. This information would help to better comprehend the microbial interactions mediated by VOCs in nature and to develop safer strategies to control plant disease. PMID:27183998

  4. Co-expression of a Saccharomyces diastaticus glucoamylase-encoding gene and a Bacillus amyloliquefaciens alpha-amylase-encoding gene in Saccharomyces cerevisiae.

    Science.gov (United States)

    Steyn, A J; Pretorius, I S

    1991-04-01

    A glucoamylase-encoding gene (STA2) from Saccharomyces diastaticus and an alpha-amylase-encoding gene (AMY) from Bacillus amyloliquefaciens were cloned separately into a yeast-integrating shuttle vector (YIp5), generating recombinant plasmids pSP1 and pSP2, respectively. The STA2 and AMY genes were jointly cloned into YIp5, generating plasmid pSP3. Subsequently, the dominant selectable marker APH1, encoding resistance to Geneticin G418 (GtR), was cloned into pSP3, resulting in pSP4. For enhanced expression of GtR, the APH1 gene was fused to the GAL10 promoter and terminated by the URA3 terminator, resulting in pSP5. Plasmid pSP5 was converted to a circular minichromosome (pSP6) by the addition of the ARS1 and CEN4 sequences. Laboratory strains of Saccharomyces cerevisiae transformed with plasmids pSP1 through pSP6, stably produced and secreted glucoamylase and/or alpha-amylase. Brewers' and distillers' yeast transformed with pSP6 were also capable of secreting amylolytic enzymes. Yeast transformants containing pSP1, pSP2 and pSP3 assimilated soluble starch with an efficiency of 69%, 84% and 93%, respectively. The major starch hydrolysis products produced by crude amylolytic enzymes found in the culture broths of the pSP1-, pSP2- and pSP3-containing transformants, were glucose, glucose and maltose (1:1), and glucose and maltose (3:1), respectively. These results confirmed that co-expression of the STA2 and AMY genes synergistically enhanced starch degradation.

  5. Antagonistic mechanism of iturin A and plipastatin A from Bacillus amyloliquefaciens S76-3 from wheat spikes against Fusarium graminearum.

    Directory of Open Access Journals (Sweden)

    An-Dong Gong

    Full Text Available Controlling toxigenic Fusarium graminearum (FG is challenging. A bacterial strain (S76-3, identified as Bacillus amyloliquefaciens that was isolated from diseased wheat spikes in the field displayed strong antifungal activity against FG. Reverse-phase high performance liquid chromatography and electrospray ionization mass spectrometry analyses revealed that S76-3 produced three classes of cyclic lipopeptides including iturin, plipastatin and surfactin. Each class consisted of several different molecules. The iturin and plipastatin fractions strongly inhibited FG; the surfactin fractions did not. The most abundant compound that had antagonistic activity from the iturin fraction was iturin A (m/z 1043.35; the most abundant active compound from the plipastatin fraction was plipastatin A (m/z 1463.90. These compounds were analyzed with collision-induced dissociation mass spectrometry. The two purified compounds displayed strong fungicidal activity, completely killing conidial spores at the minimal inhibitory concentration range of 50 µg/ml (iturin A and 100 µg/ml (plipastatin A. Optical and fluorescence microscopy analyses revealed severe morphological changes in conidia and substantial distortions in FG hyphae treated with iturin A or plipastatin A. Iturin A caused leakage and/or inactivation of FG cellular contents and plipastatin A caused vacuolation. Time-lapse imaging of dynamic antagonistic processes illustrated that iturin A caused distortion and conglobation along hyphae and inhibited branch formation and growth, while plipastatin A caused conglobation in young hyphae and branch tips. Transmission electron microscopy analyses demonstrated that the cell walls of conidia and hyphae of iturin A and plipastatin A treated FG had large gaps and that their plasma membranes were severely damaged and separated from cell walls.

  6. Control of postharvest soft rot caused by Erwinia carotovora of vegetables by a strain of Bacillus amyloliquefaciens and its potential modes of action.

    Science.gov (United States)

    Zhao, Yancun; Li, Pengxia; Huang, Kaihong; Wang, Yuning; Hu, Huali; Sun, Ya

    2013-03-01

    Erwinia carotovora subsp. carotovora (Ecc), the causal agent of bacterial soft rot, is one of the destructive pathogens of postharvest vegetables. In this study, a bacterial isolate (BGP20) from the vegetable farm soil showed strong antagonistic activity against Ecc in vitro, and its twofold cell-free culture filtrate showed excellent biocontrol effect in controlling the postharvest bacterial soft rot of potatoes at 25 °C. The anti-Ecc metabolites produced by the isolate BGP20 had a high resistance to high temperature, UV-light and protease K. Based on the colonial morphology, cellular morphology, sporulation, and partial nucleotide sequences of 16S rRNA and gyrB gene, the isolate BGP20 was identified as Bacillus amyloliquefaciens subsp. plantarum. Further in vivo assays showed that the BGP20 cell culture was more effective in controlling the postharvest bacterial soft rot of green peppers and Chinese cabbages than its twofold cell-free culture filtrate. In contrast, the biocontrol effect and safety of the BGP20 cell culture were very poor on potatoes. In the wounds of potatoes treated with both the antagonist BGP20 and the pathogen Ecc, the viable count of Ecc was 31,746 times that of BGP20 at 48 h of incubation at 25 °C. But in the wounds of green peppers, the viable count of BGP20 increased 182.3 times within 48 h, and that of Ecc increased only 51.3 %. In addition, the treatment with both BGP20 and Ecc induced higher activity of phenylalanine ammonia-lyase (PAL) than others in potatoes. But the same treatment did not induce an increase of PAL activity in green peppers. In conclusion, the present study demonstrated that the isolate BGP20 is a promising candidate in biological control of postharvest bacterial soft rot of vegetables, but its main mode of action is different among various vegetables.

  7. 生防解淀粉芽胞杆菌(Bacillus amyloliquefaciens)最新研究进展%The Latest Advances in Bio-Control Bacillus amyloliquefaciens

    Institute of Scientific and Technical Information of China (English)

    李红晓; 张殿朋; 卢彩鸽; 赵洪新

    2016-01-01

    Bacillus amyloliquefaciens is a strain similar to B. subtilis,a beneficial microbe that can produce spore, Gram-positive,and possessing biocontrolling activity. During its metabolism it produces antibiotic substance,a varie-ty of antibiotic preparations or antibiotic extracts with broad antibiotic spectrum,non toxic,non harms,non residues, long effectiveness for a given period of time,and other advantages. It can be widely applied in keeping fruits and vegetables fresh,and in biocontrolling microbial pests during their growth and post-harvest. It is a very ideal biocon-trolling microbe with the most developing value. In this paper the studies,the current application of B. amyloliquefa-ciens were drawn and summarized from aspect of the antibiotic mechanism,the antibiotic gene component,the estab-lishment of genetic engineering strain,the development of resistance products,the controlling against microbial pests,and other aspects,and accordingly to provide references for its large-scale safety application in agricultural bio-engineering.%解淀粉芽胞杆菌(Bacillus amyloliquefaciens)是与枯草芽胞杆菌相似,可产芽胞、革兰阳性(G +)、具有生防活性的益生细菌。其代谢过程中产生的抗菌物质种类多、抗菌谱广,其抗菌制剂或抗菌提取物具有无毒、无害、无残留、抑菌时效长等优点,可广泛应用于果蔬保鲜、果蔬生长期及采后微生物病害的生物防治,是极具开发价值的生防菌。本文从抗菌机理、抗性基因组成、基因工程菌构建、抗性产品开发及对微生物病害防治等几个方面,对解淀粉芽胞杆菌的研究及应用现状进行了归纳和总结,为其在农业生物工程中的规模化安全应用提供参考。

  8. 生防菌解淀粉芽孢杆菌抗菌蛋白的研究进展%Research Advances of Antifungal Proteins Produced by Biocontrol Bacterium,Bacillus amyloliquefaciens

    Institute of Scientific and Technical Information of China (English)

    出晓铭; 林毅雄; 张珅; 严芬; 林河通

    2014-01-01

    Bacillus amyloliquefaciens is a kind of biocontrol bacterium which has great ability against fungi and bacteria,thereby it has high research values and potential for development in biological control of posthar-vest diseases of fruits and vegetables.The separation and purification of antifungal proteins produced by Bacil-lus amyloliquefaciens,the disease resistant mechanisms and the application of biocontrol of antifungal proteins were summarized.The future potential application in biocontrol of postharvest diseases of fruits and vegetables was also discussed.%生防解淀粉芽孢杆菌具有强烈抑制真菌和细菌的能力,在果蔬采后病害防治方面具有巨大的应用潜力。该文对解淀粉芽孢杆菌产生的抗菌蛋白、蛋白的分离纯化、抑菌机理和生防应用等方面进行了综述,并对其在果蔬采后病害防治应用前景进行了展望。

  9. The Optimization of Fermentation Condition in Flask forBacillus amyloliquefaciens LJ1%解淀粉芽孢杆菌LJ1摇瓶发酵条件优化

    Institute of Scientific and Technical Information of China (English)

    李娟; 夏凯丽; 王远宏; 董蕴琪; 郝蕾

    2015-01-01

    解淀粉芽孢杆菌(Bacillus amyloliquefaciens)LJ1是从天津土壤中分离筛选出的一株具有广谱抑菌效果的生防菌株,该实验旨在明确B. amyloliquefaciens LJ1的抑菌谱并通过优化发酵培养基和发酵条件提升其抑菌效果。通过对峙培养检测菌株LJ1对14种病原真菌的抑制效果;采用单因素试验、正交试验优化发酵培养基和摇瓶发酵条件;最后用孢子萌发法和盆栽试验验证优化后发酵液的抑菌效果。实验结果表明B. amyloliquefaciens LJ1对黄瓜灰霉病菌(Botrytis cinerea)、苹果炭疽病菌(Glomerella cingulata)、苹果腐烂病菌(Valsa ceratosperma)等11种病原真菌有抑制作用;优化后的摇瓶发酵条件为温度30℃、初始pH 5、转速200 r/min、装液量50 mL/250 mL;优化后的发酵培养基为马铃薯200 g,蔗糖10 g,黄豆粉20 g,MgCl2·6H2O 1.5 g,蒸馏水1000 mL。经发酵条件与培养基优化后,B. amyloliquefaciens LJ1发酵液对Botrytis cinerea孢子萌发的抑制率达99.7%,盆栽实验防效达51.08%。%Bacillus amyloliquefaciensstrainLJ1 isolated from the soil of Tianjin is biocontrol one with broad inhibition spectrum. This study aims to clarify the inhibition spectrum of strainB. amyloliquefaciens LJ1 and improve the antifungal activity by optimizing the medium composition and fermentation conditions. The confront culture was performed to test the antifungal activity of LJ1 on 14 phytopathogenic fungi. The medium composition and fermentation conditions were optimized by single-factor and orthogonal experiments. Finally, the inhibitory effect of optimized broth was tested by methods of spore germination and pot experiment. The results showed thatB. amyloliquefaciens LJ1 inhibited 11 tested fungal pathogens, i. e. ,Botrytis cinerea, Glomerella cingulata, andValsa ceratosperma. The optimal fermentation conditions were as temperature 30℃, initial pH5.0, rotation speed 200 r/min, and medium

  10. 海洋解淀粉芽孢杆菌GM-1菌株发酵液抗菌谱及稳定性测定%The Inhibitory Spectrum and Stability Determination of Marine Bacillus amyloliquefaciens GM-1 Strain

    Institute of Scientific and Technical Information of China (English)

    葛平华; 马桂珍; 付泓润; 王淑芳; 刘兆普

    2012-01-01

    [目的]研究海洋解淀粉芽孢杆菌(Bacillus amyloliquefaciens)菌株GM-1发酵液的抗菌谱及稳定性.[方法]以10种植物病原菌为供试菌,生长速率法测定GM-1菌株发酵液的抗菌谱;以油菜菌核病菌为指示菌,生长速率法测定发酵液在不同条件下的稳定性.[结果]GM-1菌株发酵液对供试的10种植物病原菌具有较好的抑制作用,抗菌范围较广,其中对葡萄白腐病菌(Coniella diplodiella)和小麦根腐病菌(Bipolaris sorokiniana)的抑菌率均达85%以上;其发酵液的抗菌作用有较好的热稳定性,在光照和紫外线照射下稳定性较好,在pH值6~8的条件下抗菌作用稳定,对蛋白酶不敏感.[结论]GM-1菌株具有广谱抗菌活性和较强的稳定性.%[Aims] Inhibitory spectrum and stability of Marine Bacillus amyloliquefaciens GM-1 strain fermentation broth were studied. [Methods] Growth rate method was used to measure inhibitory spectrum on 10 plant pathogens and to determine stability of B. amyloliquefaciens GM-1 strain on Sclerotinia sclerotiorum. [Results] GM-1 strain had better activity to 10 plant pathogens and its inhibitory rates to Coniella diplodiella and Bipolaris sorokiniana was both more than 85%. It was stable to heat, light and ultraviolet rays. It was steady at pH 6-8 and insensitive to protease. [Conclusions] GM-1 strain has broad antimicrobial spectrum and strong stability.

  11. Antagonistic effects of Bacillus subtilis subsp. subtilis and B. amyloliquefaciens against Macrophomina phaseolina: SEM study of fungal changes and UV-MALDI-TOF MS analysis of their bioactive compounds.

    Science.gov (United States)

    Torres, M J; Brandan, C Pérez; Petroselli, G; Erra-Balsells, R; Audisio, M C

    2016-01-01

    The antifungal effect of Bacillus subtilis subsp. subtilis PGPMori7 and Bacillus amyloliquefaciens PGPBacCA1 was evaluated against Macrophomina phaseolina (Tassi) Goid. Cell suspension (CS), cell-free supernatant (CFS) and the lipopeptide fraction (LF) of PGPMori7 and PGPBacCA1 were screened against three different M. phaseolina strains. CS exhibited the highest inhibitory effect (around 50%) when compared to those of CFS and LF, regardless of the fungal strain studied. The synthesis of lipopeptides was studied by UV-MALDI TOF. Chemical analysis of Bacillus metabolite synthesis revealed that surfactin and iturin were mainly produced in liquid medium. Potential fengycin was also co-produced when both Bacillus were cultivated in solid medium. In co-culture assays, the bacterial colony-fungal mycelium interface at the inhibition zone was evaluated by both scanning electron microscopy (SEM) and UV-MALDI TOF, the former to determine the structural changes on M. phaseolina cells and the latter to identify the main bioactive molecules involved in the inhibitory effect. PGPBacCA1 produced surfactin, iturin and fengycin in the inhibition zone while PGPMori7 only produced these metabolites within its colony and not in the narrow inhibition zone. Interestingly, SEM revealed that PGPBacCA1 induced damage in M. phaseolina sclerotia, generating a fungicidal effect as no growth was observed when normal growth conditions were reestablished. In turn, PGPMori7 inhibited the growth of the Macrophomina mycelium without fungal injury, resulting only in a fungistatic activity. From these results, it was determined that the two bacilli significantly inhibited the growth of an important phytopathogenic fungus by at least two different mechanisms: lipopeptide synthesis and competition among microorganisms.

  12. Antagonistic effects of Bacillus subtilis subsp. subtilis and B. amyloliquefaciens against Macrophomina phaseolina: SEM study of fungal changes and UV-MALDI-TOF MS analysis of their bioactive compounds.

    Science.gov (United States)

    Torres, M J; Brandan, C Pérez; Petroselli, G; Erra-Balsells, R; Audisio, M C

    2016-01-01

    The antifungal effect of Bacillus subtilis subsp. subtilis PGPMori7 and Bacillus amyloliquefaciens PGPBacCA1 was evaluated against Macrophomina phaseolina (Tassi) Goid. Cell suspension (CS), cell-free supernatant (CFS) and the lipopeptide fraction (LF) of PGPMori7 and PGPBacCA1 were screened against three different M. phaseolina strains. CS exhibited the highest inhibitory effect (around 50%) when compared to those of CFS and LF, regardless of the fungal strain studied. The synthesis of lipopeptides was studied by UV-MALDI TOF. Chemical analysis of Bacillus metabolite synthesis revealed that surfactin and iturin were mainly produced in liquid medium. Potential fengycin was also co-produced when both Bacillus were cultivated in solid medium. In co-culture assays, the bacterial colony-fungal mycelium interface at the inhibition zone was evaluated by both scanning electron microscopy (SEM) and UV-MALDI TOF, the former to determine the structural changes on M. phaseolina cells and the latter to identify the main bioactive molecules involved in the inhibitory effect. PGPBacCA1 produced surfactin, iturin and fengycin in the inhibition zone while PGPMori7 only produced these metabolites within its colony and not in the narrow inhibition zone. Interestingly, SEM revealed that PGPBacCA1 induced damage in M. phaseolina sclerotia, generating a fungicidal effect as no growth was observed when normal growth conditions were reestablished. In turn, PGPMori7 inhibited the growth of the Macrophomina mycelium without fungal injury, resulting only in a fungistatic activity. From these results, it was determined that the two bacilli significantly inhibited the growth of an important phytopathogenic fungus by at least two different mechanisms: lipopeptide synthesis and competition among microorganisms. PMID:26686611

  13. Collagen-like proteins (ClpA, ClpB, ClpC, and ClpD are required for biofilm formation and adhesion to plant roots by Bacillus amyloliquefaciens FZB42.

    Directory of Open Access Journals (Sweden)

    Xia Zhao

    Full Text Available The genes of collagen-like proteins (CLPs have been identified in a broad range of bacteria, including some human pathogens. They are important for biofilm formation and bacterial adhesion to host cells in some human pathogenic bacteria, including several Bacillus spp. strains. Interestingly, some bacterial CLP-encoding genes (clps have also been found in non-human pathogenic strains such as B. cereus and B. amyloliquefaciens, which are types of plant-growth promoting rhizobacteria (PGPR. In this study, we investigated a putative cluster of clps in B. amyloliquefaciens strain FZB42 and a collagen-related structural motif containing glycine-X-threonine repeats was found in the genes RBAM_007740, RBAM_007750, RBAM_007760, and RBAM_007770. Interestingly, biofilm formation was disrupted when these genes were inactivated separately. Scanning electron microscopy and hydrophobicity value detection were used to assess the bacterial cell shape morphology and cell surface architecture of clps mutant cells. The results showed that the CLPs appeared to have roles in bacterial autoaggregation, as well as adherence to the surface of abiotic materials and the roots of Arabidopsis thaliana. Thus, we suggest that the CLPs located in the outer layer of the bacterial cell (including the cell wall, outer membrane, flagella, or other associated structures play important roles in biofilm formation and bacteria-plant interactions. This is the first study to analyze the function of a collagen-like motif-containing protein in a PGPR bacterium. Knocking out each clp gene produced distinctive morphological phenotypes, which demonstrated that each product may play specific roles in biofilm formation. Our in silico analysis suggested that these four tandemly ranked genes might not belong to an operon, but further studies are required at the molecular level to test this hypothesis. These results provide insights into the functions of clps during interactions between bacteria

  14. Collagen-like proteins (ClpA, ClpB, ClpC, and ClpD) are required for biofilm formation and adhesion to plant roots by Bacillus amyloliquefaciens FZB42.

    Science.gov (United States)

    Zhao, Xia; Wang, Yun; Shang, Qianhan; Li, Yuyao; Hao, Haiting; Zhang, Yubao; Guo, Zhihong; Yang, Guo; Xie, Zhongkui; Wang, Ruoyu

    2015-01-01

    The genes of collagen-like proteins (CLPs) have been identified in a broad range of bacteria, including some human pathogens. They are important for biofilm formation and bacterial adhesion to host cells in some human pathogenic bacteria, including several Bacillus spp. strains. Interestingly, some bacterial CLP-encoding genes (clps) have also been found in non-human pathogenic strains such as B. cereus and B. amyloliquefaciens, which are types of plant-growth promoting rhizobacteria (PGPR). In this study, we investigated a putative cluster of clps in B. amyloliquefaciens strain FZB42 and a collagen-related structural motif containing glycine-X-threonine repeats was found in the genes RBAM_007740, RBAM_007750, RBAM_007760, and RBAM_007770. Interestingly, biofilm formation was disrupted when these genes were inactivated separately. Scanning electron microscopy and hydrophobicity value detection were used to assess the bacterial cell shape morphology and cell surface architecture of clps mutant cells. The results showed that the CLPs appeared to have roles in bacterial autoaggregation, as well as adherence to the surface of abiotic materials and the roots of Arabidopsis thaliana. Thus, we suggest that the CLPs located in the outer layer of the bacterial cell (including the cell wall, outer membrane, flagella, or other associated structures) play important roles in biofilm formation and bacteria-plant interactions. This is the first study to analyze the function of a collagen-like motif-containing protein in a PGPR bacterium. Knocking out each clp gene produced distinctive morphological phenotypes, which demonstrated that each product may play specific roles in biofilm formation. Our in silico analysis suggested that these four tandemly ranked genes might not belong to an operon, but further studies are required at the molecular level to test this hypothesis. These results provide insights into the functions of clps during interactions between bacteria and plants.

  15. Synthesis and processing in Escherichia coli of human leucocyte interferon fused with the signal sequence of Bacillus amyloliquefaciens a-amylase

    International Nuclear Information System (INIS)

    Earlier, the authors reported cloning of the alpha-amylase gene of B. amyloliquefaciens in B. subtilis and E. coli. Currently, the authors report results on the expression of the hybrid gene consisting of the DNA fragment coding for the leader part of B. amyloliquefaciens alpha-amylase and the structural part of the human interferon alpha-2 in E. coli cells. This gene contains an additional methionine codon at the 5'-terminal, which codes for the interferon structure (without its own signal peptide). The interferon gene was inserted into plasmid /sub p/TG 278 at the cleavage site of EcoRI. The structure of the plasmid thus obtained the signal peptide of amylase, five amino acids (Val-Gly-Glu-Phe-Met), and the structural part of the interferon. The E. coli C600 cells carrying plasmid pTGA6 were used to study interferon secretions. The interferon activity was determined radioimmunologically with the use of monoclonal anti-bodies NK2

  16. Resistance to antimicrobials and acid and bile tolerance of Bacillus spp isolated from Bikalga, fermented seeds of Hibiscus sabdariffa

    DEFF Research Database (Denmark)

    Compaore, Clarisse S.; Jensen, Lars Bogø; Diawara, Brehima;

    2013-01-01

    In the aim of selecting starter cultures, thirteen species of Bacillus spp. including six Bacillus subtilis ssp. subtilis, four Bacillus licheniformis and three Bacillus amyloliquefaciens ssp. plantarum isolated from traditional Bikalga were investigated. The study included, for all isolates, gen...

  17. Research of Fermentation Observation and Preservative of Bacillus amyloliquefaciens Lx-11%解淀粉芽胞杆菌Lx-11发酵培养和液体菌剂贮存研究

    Institute of Scientific and Technical Information of China (English)

    张荣胜; 戴秀华; 王晓宇; 罗楚平; 陈志谊

    2014-01-01

    To screen preservatives for long-term preservation of Bacillus amyloliquefaciens Lx-11 fermentation broth, this paper discussed five different preservatives inhibition of B. amyloliquefaciens Lx-11. Adding different concentrations of preservatives and assaying bacteria concentration by dilution plate method, our data showed that five different preservatives had inhibitory effect on fermentation broth at different level. They could be ranked in decreasing order of antibacterial activity as follows: methyl paraben=sodium diacetate>dehydrogenation acid>sodium benzoate>potassium sorbate. Compared with sodium benzoate in optimum pH range, when adding 1‰concentration of potassium sorbate and the pH values at 5.5-6.0, potassium sorbate had least effect on B. amyloliquefaciens Lx-11. In dynamic observation of 15 t tank bacteria fermentation process, we observed that the strain after fermentation 4 h reached the logarithmic growth phase, beginning to form spores around 16 h, and more than 90%formed spores after 18 h. Added 1‰potassium sorbate in fermentation broth, and adjusted pH value to around 6.0, after placing 180 d, the amount of bacteria was significantly higher than that without adding potassium sorbate treatment, which were 6.3×109 and 3.5×108 cfu/mL, respectively.%为了筛选芽胞杆菌发酵菌液Lx-11长期保存的防腐剂,本文探讨了5种化学防腐剂对解淀粉芽胞杆菌Lx-11的抑制作用。通过比较添加不同浓度防腐剂对发酵液菌含量的影响,试验结果表明,5种防腐剂对发酵液菌含量的抑制作用大小的顺序为尼泊金甲酯=双乙酸钠>脱氢乙酸>苯甲酸钠>山梨酸钾;进一步对山梨酸钾和苯甲酸钠在最适pH范围内用量比较研究,表明山梨酸钾添加量在1‰时,pH值在5.5~6.0时,对解淀粉芽胞杆菌Lx-11菌含量影响最小。通过对15吨罐体中发酵过程Lx-11菌液菌体性状和数量动态的观察,玻片检测表

  18. High-level Expression of Acid-stable α-amylase Gene of Bacillus amyloliquefaciens in Bacillus subtilis WB600%酸性α-淀粉酶基因在枯草芽孢杆菌中的高效表达

    Institute of Scientific and Technical Information of China (English)

    王彩澜; 刘新育; 李学琴; 刘亮伟; 陈红歌

    2012-01-01

    Acid-stable α-amylase is widely used in fermentation industry. In order to highly express acid-stable or-amylase gene, a recombinant vector containing no signal peptide of acid-stable or-amylase gene from Bacillus amyloliquefaciens was constructed followed by transformation into Bacillus subtilis WB6oo host. The highest activity of recombinant acid-stable α-amylase was 1230 U/mL under the condition as follows: OD600 of the initial bacteria was 0.8 and final concentration of IPTG was 0.9 mmol/L, and the cell suspension was cultured for 6 hours after addition of IPTG. As the recombinant Bacillus subtilis WB600 secreted ylase, it showed obvious advantages in amylase production. few other proteins except the targeted acid-stableα-am-ylase, it showed obvious advantages in amylase production.%酸性α-淀粉酶是发酵行业用量最大的酶类,为了实现酸性α-淀粉酶基因的高效表达,将本实验室已经克隆得到的去信号肽的酸性α-淀粉酶基因在枯草芽孢杆菌WB600宿主中进行表达,成功的构建了表达菌株pHT43-amy/WB600。在初始菌浓度OD600为0.8时加入终浓度为0.9mmol/L的IPTG,诱导6h的条件下测得酶活力为1230U/mL,又由于宿主菌WB600外分泌蛋白较少,因此具有明显的生产优势。

  19. 解淀粉芽孢杆菌BI2产抑菌物质的新型种衣剂的研制%A Novel Seed Coating Formula with Antifungal Substances Produced by Bacillus amyloliquefaciens BI2

    Institute of Scientific and Technical Information of China (English)

    王亚军; 李昆; 王德培

    2015-01-01

    The antifungal substances produced from Bacillus amyloliquefaciens BI2,were for the first time used asactive ingredients in seed coating. The fermented broth containing antifungal substances was ultrafiltered and freeze-dried to form lyophilized powder,and then mixed with composite film-forming agent solution. Finally,peanut seeds were coated with this kind of seed coating containing antifungal substances. The results showed that the best volume ratio of 4%, polyvinyl alco-hol(PVA)to 1.5%, sodium carboxymethyl cellulose(CMC-Na)was 5:1,which is the best film former recipe in seed coating,and it has no significant effect on seed germination potential and germination rate. The pH stability andthermal stability of the lyophilized powder of the fermentated broth containing antifungal substances are good. The MIC of the pow-der to inhibitAspergillus flavus spore germination is 1.92,mg/mL. When the content of that powder in the film former reaches 4,mg/mL,A. flavuswas completely inhibited.%将解淀粉芽孢杆菌BI2发酵所产抑菌物质作为新型种衣剂的有效成分与研制的复合型成膜剂溶液混合,制成可抑制黄曲霉孢子萌发的花生种子包衣.结果表明,选用 4%,聚乙烯醇(PVA)与 1.5%,羧甲基纤维素钠(CMC-Na)以体积比 5:1 混合作为种子包衣最佳成膜剂配方,经过包衣后对花生种子的发芽势和发芽率没有显著影响.含有抑菌物质的发酵液冻干粉的 pH 稳定性和热稳定性均较好.发酵液冻干粉抑制黄曲霉孢子萌发的最小质量浓度为1.92,mg/mL.在与花生种子混合时,发酵液冻干粉在成膜剂中的含量达到4,mg/mL时,黄曲霉完全被抑制.

  20. Effect of bacillus amyloliquefaciens fermentation liquid on different types of peppers for biological control of postharvest A. alternate%解淀粉芽孢杆菌发酵液处理提高辣椒采后品质

    Institute of Scientific and Technical Information of China (English)

    蔡文韬; 夏菠; 夏延斌; 易有金; 王宇婷

    2013-01-01

    In order to understand the fresh-keeping effect of bacillus amylo-liquefaciens strain-L fermented liquid on the postharvest pepper, the different pepper varieties (the green pepper and red chilli) were treated with fermented filtrated liquor of bacillus amylo-liquefaciens isolated from chilli bell peppers pulp to study the preserve effects of peppers. The results indicated that the strain-L fermentation medium over a certain concentration had a good antibacterial effect on pepper pathogenic fungi (A.alternate) with the invitro tests. The invivo test results showed that even though the fresh-keeping effect of fermentation liquid was not as good as fresh-keeping effect of preservative liquid, but significantly better than the sterile water group. Comparing the different varieties of peppers, fresh-keeping effect of fermentation liquid on red chilli was better than that of green pepper, and the inhibition effect of invivo decreased compared with invitro inhibition effect. For the damage inoculation, strain-L fermentation medium has obvious antibacterial effect on the green pepper and red chilli, the decay rate of green pepper declined by 51.87% compared with sterile water treatment. The decay rate of the red chilli declined by 58.54%compared with sterile water. The preservation effect of strain-L fermentation medium on different varieties of pepper had significant difference during 24 d storage period by noninvasive inoculation. The results showed that the strain-L fermented liquid treatment can obviously decrease the decay rate of postharvest chili in the storage period, which was obviously superior to the sterile water group. After 24 d storage, the decay rates of green peppers treated with fermentation medium and preservation liquid were 37.5%, 32.50%respectively, decreased by 35%and 40%respectively compared to sterile water group. The decay rate of red chilli treated with fermentation medium and preservation liquid were 29.63%, 24.14%respectively, decreased by 34

  1. Biocontrol Characteristics of Bacillus Species in Suppressing Stem Rot of Grafted Cactus Caused by Bipolaris cactivora

    Directory of Open Access Journals (Sweden)

    Sooil Bae

    2013-03-01

    Full Text Available One of the most important limiting factors for the production of the grafted cactus in Korea is the qualitative and quantitative yield loss derived from stem rots especially caused by Bipolaris cactivora. This study is aimed to develop microbial control agents useful for the control of the bipolaris stem rot. Two bacteria (GA1-23 and GA4-4 selected out of 943 microbial isolates because of their strong antibiotic activity against B. cactivora were identified as Bacillus subtilis and B. amyloliquefaciens, respectively, by the cultural characteristics, Biolog program and 16S rRNA sequencing analyses. Both bacterial isolates significantly inhibited the conidial germination and mycelial growth of the pathogen with no significant difference between the two, of which the inhibitory efficacies varied depending on the cultural conditions such as temperature, nutritional compositions and concentrations. Light and electron microscopy of the pathogen treated with the bacterial isolates showed the inhibition of spore germination with initial malformation of germ tubes and later formation of circle-like vesicles with no hyphal growth and hyphal disruption sometimes accompanied by hyphal swellings and shrinkages adjacent to the bacteria, suggesting their antibiotic mode of antagonistic activity. Control efficacy of B. subtilis GA1-23 and B. amyloliquefaciens GA4-4 on the cactus stem rot were not as high as but comparable to that of fungicide difenoconazole when they were treated simultaneously at the time of pathogen inoculation. All of these results suggest the two bacterial isolates have a good potential to be developed as biocontrol agents for the bipolaris stem rot of the grafted cactus.

  2. Computing Method of Specific Resistances of Constant Pressure Filtrating Fermented Broth Based on MATLAB---Taking Bacillus amyloliquefaciens Q -426 as an Example%基于MATLAB的发酵液恒压过滤比阻计算方法--以解淀粉芽孢杆菌Q-426发酵液为例

    Institute of Scientific and Technical Information of China (English)

    刘俏; 刘涛; 杨薇

    2015-01-01

    介绍了用MATLAB的Curve Fitting Toolbox计算解淀粉芽孢杆菌Q-426发酵液恒压过滤比阻的方法。通过在图形界面下导入恒压过滤实验数据及平滑处理、采用平滑样条拟合数据以及数值微分等操作,确定了解淀粉芽孢杆菌Q-426发酵液恒压过滤的滤饼比阻。研究表明,该方法运行可靠,无需编程,易于掌握。与传统计算方法相比,操作更为便捷,强有力的图形界面也使计算变得更加简单而直观。%This paper presents a method to determine the cake specific resistances( CSR) for con-stant pressure filtrating fermented broth of Bacillus amyloliquefaciens Q–426 using MATLAB’ s Curve Fitting Toolbox. The acquired data was imported and smoothed via the graphical user in-terface ( GUI) . Smoothing spline was used to produce smooth curves to fit to the data, and the CSR was calculated by numerical differentiation. The study showed that the calculated results are accurate and reliable. Compared with the traditional calculations, this method provides visu-alized results, and the GUI simplifies the calculation and makes it intuitive. It can be easily mastered for those who are not adept programmers.

  3. 利用cDNA-AFLP分析内生解淀粉芽胞杆菌Fy11诱导辣椒差异表达基因%cDNA-AFLP Analysis of Differential Gene Expression in Pepper Inoculated with Endophytic Bacillus amyloliquefaciens Fy11

    Institute of Scientific and Technical Information of China (English)

    杨瑞先; 范晓静; 邱思鑫; 蔡学清; 胡方平

    2013-01-01

    [目的]分析内生解淀粉芽胞杆菌(Bacillus amyloliquefaciens)Fy11诱导辣椒(Capsicum annuum)幼苗差异表达基因,了解辣椒与内生芽胞杆菌互作的分子机制.[方法]利用cDNA-AFLP技术,采用256对引物,分析辣椒幼苗接种内生解淀粉芽胞杆菌Fy11后5个时间点的基因表达谱;利用qRT-PCR分析差异基因表达模式,验证cDNA-AFLP表达谱.[结果]256对引物共产生18620个转录本(TDF),筛选获得353条差异表达条带,占扩增条带总数的1.89%.经克隆、测序分析,最终获得257个差异TDF,聚类分析得到229个独立基因(EST,unigenes),其中144个基因上调表达,85个基因下调表达.经Blastx比对和功能分类分析,其中65条EST(28.38%)未找到同源性匹配,8条(3.49%)与未知功能蛋白同源性较高.其余156条EST主要涉及基础代谢基因(10.92%);与能量和抗病与防御类相关基因,各占8.73%;信号转导基因占7.42%;转运子或转座子基因占6.99%;与细胞结构相关基因占6.55%;参与转录调控基因占5.68%;细胞生长类基因占3.93%;参与蛋白质运输和储存有8个基因,占3.49%;蛋白质合成类基因占2.18%;次生代谢类和胞间运输类基因,其数量相对较少,各占1.75%.选取与抗病防御、转录调控及信号转导类等相关的10个差异基因,qRT-PCR分析结果显示其表达模式符合cDNA-AFLP表达谱.[结论]内生细菌与植物互作的分子机制涉及植物多方面生理生化反应,包括抗病防御、转录调控、蛋白质代谢、信号转导、以及非生物胁迫等多种途径相关基因的协同控制.%[Objective] The objective of this study is to analyze extensive transcription profiling of pepper seedlings inoculated with an endophytic bacterial strain,Bacillus amyloliquefaciens Fyl l,and elucidate the molecular mechanism of endophytic Bacillus and plant interaction.[Method] cDNA-AFLP technique was used to conduct transcription profiling of

  4. Effects of Different Nitrogen and Carbon Sources on the Production of Antifungal Lipopeptides from Bacillus amyloliquefaciens Q-426%氮源和碳源对解淀粉芽孢杆菌Q-426抗菌脂肽合成的影响

    Institute of Scientific and Technical Information of China (English)

    赵朋超; 权春善; 金黎明; 王丽娜; 范圣第

    2012-01-01

    微生物来源的环状脂肽在生物农药以及医学领域极具应用潜力.通过测量抑菌活性并利用反相高效液相色谱( RP-HPLC),液相质谱联用(HPLC-MS)和串联质谱(MS/MS)技术检测抗菌脂肽组分的变化研究了氮(N)源、碳(C)源和培养基中的初始pH值对解淀粉芽孢杆菌Q-426菌株中抗菌脂肽bacillomycin D和fengycins合成的影响,从而为进一步研究它们生物合成的基因调控以及更有目的性提高产量提供理论依据.结果表明:L-组氨酸、L-赖氨酸、甘油、山梨醇以及培养基中的[OH]-均能促进脂肽bacillomycin D的合成,但它们在该实验菌株抗菌脂肽bacillomycin D合成途径中的调控靶点有所不同.%Cyclic lipopeptides, which are produced by several types of microorganisms, will have great potential in the agricultural and biomedical field with their unusual antibacterial, antifungal and antiviral activities. To provide a theoretical basis for investigating the gene regulation of antifungal lipopeptides and enhancing their yield more effectively in the next step, effects of three factors ( nitrogen sources, carbon sources and initial pH in the medium) on the production of bacillomycin D and fengycins from Bacillus amyloliquefaciens Q-426 were analyzed by measurement of antifungal activities against Curvularia lunata ( Walk) Boed, reverse-phase high performance liquid chromatography ( RP-HPLC ) , HPLC-mass spectrometry ( MS) and MS/MS. Finally, the results were screened as follows; L-histine, L-lysine, glycerol, sorbitol and [ OH ]" in the medium could promote the accumulation of bacillomycin D, but less effective to that of fengycins. However, further analysis of RP-HPLC spectrum revealed the three factors above played different roles in the pathway of bacillomycin D biosynthesis from strain Q-426.

  5. Дослідження пробіотичних властивостей штамів Bacillus sp. 1.1. та B. amyloliquefaciens УКМ В-5113

    Directory of Open Access Journals (Sweden)

    Владислав Олександрович Мілян

    2014-12-01

    Full Text Available Проведено дослідження пробіотичних властивостей, виділенних з навколишнього середовища штамів Bacillus sp. 1.1. та B. amyloliquefaciens УКМ В-5113. Встановлено їх морфологічні та фізіолого-біохімічні ознаки, досліджено та встановлено високу та середню антагоністичну активність щодо музейних та актуальних штамів умовно патогенних мікроорганізмів. Показана стійкість до низьких та високих значень рН та різних концентрацій жовчних кислот.

  6. 解淀粉芽孢杆菌ES-2对肉鸡屠宰性能和肉品质及肌肉抗氧化能力的影响%Effect of Bacillus amyloliquefaciens ES-2 on carcass characteristics,meat quality and antioxidative status of broilers

    Institute of Scientific and Technical Information of China (English)

    杨敏馨; 寇涛; 李悦; 张昊; 金顺顺; 苏越; 张莉莉; 王恬

    2016-01-01

    [目的]研究日粮中添加解淀粉芽孢杆菌ES-2(BAP)对肉鸡屠宰性能、肉品质及肌肉抗氧化能力的影响.[方法]选用1日龄AA(Arbor Acres)肉鸡600只,随机分成5组:对照组、抗生素组、试验Ⅰ、试验Ⅱ和试验Ⅲ组.对照组饲喂基础日粮;抗生素组添加45 mg· kg-金霉素;试验Ⅰ、Ⅱ和Ⅲ组分别添加200、500和1 000 mg·kg-1的BAP,每组6个重复,试验期42 d.[结果]与对照组相比,500和1 000 mg· kg-1的BAP可显著提高肉鸡胸肌率,且500 mg· kg-1的BAP可显著降低腹脂率(P<0.05).BAP主要影响胸肌的肉品质,500和1 000 mg· kg-1剂量组宰后24 h胸肌的pH值较对照组显著提高(P<0.05);日粮中添加抗生素及500 mg·kg-的BAP均能显著降低胸肌压力损失(P<0.05).500和1 000 mg· kg-1剂量组及抗生素组胸肌总超氧化物歧化酶(T-SOD)活性较对照组显著提高(P<0.05).另外,日粮中添加500和1 000 mg·kg-1的BAP可显著提高胸肌总抗氧化能力(T-AOC)水平,其中500 mg· kg-1剂量组胸肌T-AOC水平要显著高于200 mg·kg-1剂量组;500mg· kg-1剂量组及抗生素组肉鸡腿肌T-AOC水平较对照组显著提高(P<0.05).[结论]日粮中添加500和1 000 mg·kg-1的解淀粉芽孢杆菌ES-2均可在一定程度提高肉鸡屠宰性能,增强胸肌宰后24 h的pH值,提高肌肉T-AOC水平和T-SOD活力,增强宰后肌肉的抗氧化能力,且以添加500 mg· kg-1的解淀粉芽孢杆菌ES-2剂量效果较好.解淀粉芽孢杆菌ES-2替代抗生素在肉鸡饲粮中应用具有可行性.%[Objectives] The study was conducted to evaluate the effect of Bacillus amyloliquefaciens ES-2(BAP)on carcass characteristics,meat quality and antioxidative status of broilers.[Methods] A total of 600 one-day-age broilers(Arbor Acres)were randomly assigned to five groups with 6 replicates.The control group were fed a basal diet without any probiotic and the antibiotic groups were fed the basic diet supplemented with 45 nmg· kg-1

  7. Resistance to antimicrobials and acid and bile tolerance of Bacillus spp isolated from Bikalga, fermented seeds of Hibiscus sabdariffa

    OpenAIRE

    Compaore, Clarisse S.; Jensen, Lars Bogø; Diawara, Brehima; Ouedraogo, Georges A.; Jakobsen, Mogens; Ouoba, Labia I. I.

    2013-01-01

    In the aim of selecting starter cultures, thirteen species of Bacillus spp. including six Bacillus subtilis ssp. subtilis, four Bacillus licheniformis and three Bacillus amyloliquefaciens ssp. plantarum isolated from traditional Bikalga were investigated. The study included, for all isolates, genes, determination of minimal inhibitory concentration (MIC) for 24 antimicrobials and detection of resistance by PCR using specific primers. The isolates were also examined for their resistance to pH ...

  8. Protein Profiling Reveals Novel Proteins in Pollen and Pistil of W22 (ga1; Ga1 in Maize

    Directory of Open Access Journals (Sweden)

    Jin Yu

    2014-05-01

    Full Text Available Gametophytic factors mediate pollen-pistil interactions in maize (Zea mays L. and play active roles in limiting gene flow among maize populations and between maize and teosinte. This study was carried out to identify proteins and investigate the mechanism of gametophytic factors using protein analysis. W22 (ga1; which did not carry a gametophytic factor and W22 (Ga1, a near iso-genic line, were used for the proteome investigation. SDS-PAGE was executed to investigate proteins in the pollen and pistil of W22 (ga1 and W22 (Ga1. A total of 44 differentially expressed proteins were identified in the pollen and pistil on SDS-PAGE using LTQ-FTICR MS. Among the 44 proteins, a total of 24 proteins were identified in the pollen of W22 (ga1 and W22 (Ga1 whereas 20 differentially expressed proteins were identified from the pistil of W22 (ga1 and W22 (Ga1. However, in pollen, 2 proteins were identified only in the W22 (ga1 and 12 proteins only in the W22 (Ga1 whereas 10 proteins were confirmed from the both of W22 (ga1 and W22 (Ga1. In contrary, 10 proteins were appeared only in the pistil of W22 (ga1 and 7 proteins from W22 (Ga1 while 3 proteins confirmed in the both of W22 (ga1 and W22 (Ga1. Moreover, the identified proteins were generally involved in hydrolase activity, nucleic acid binding and nucleotide binding. These results help to reveal the mechanism of gametophytic factors and provide a valuable clue for the pollen and pistil research in maize.

  9. Complete Genome Sequence of the Endophytic Biocontrol Strain Bacillus velezensis CC09

    Science.gov (United States)

    Cai, Xunchao; Kang, Xingxing; Xi, Huan

    2016-01-01

    Bacillus velezensis is a heterotypic synonym of B. methylotrophicus, B. amyloliquefaciens subsp. plantarum, and Bacillus oryzicola, and has been used to control plant fungal diseases. In order to fully understand the genetic basis of antimicrobial capacities, we did a complete genome sequencing of the endophytic B. velezensis strain CC09. Genes tightly associated with biocontrol ability, including nonribosomal peptide synthetases, polyketide synthetases, iron acquisition, colonization, and volatile organic compound synthesis were identified in the genome. PMID:27688342

  10. Complete Genome Sequence of the Endophytic Biocontrol Strain Bacillus velezensis CC09.

    Science.gov (United States)

    Cai, Xunchao; Kang, Xingxing; Xi, Huan; Liu, Changhong; Xue, Yarong

    2016-01-01

    Bacillus velezensis is a heterotypic synonym of B. methylotrophicus, B. amyloliquefaciens subsp. plantarum, and Bacillus oryzicola, and has been used to control plant fungal diseases. In order to fully understand the genetic basis of antimicrobial capacities, we did a complete genome sequencing of the endophytic B. velezensis strain CC09. Genes tightly associated with biocontrol ability, including nonribosomal peptide synthetases, polyketide synthetases, iron acquisition, colonization, and volatile organic compound synthesis were identified in the genome. PMID:27688342

  11. Analysis of myo-inositol hexakisphosphate hydrolysis by Bacillus phytase

    DEFF Research Database (Denmark)

    Kerovuo, J.; Rouvinen, J.; Hatzack, Frank-Andreas

    2000-01-01

    Phytic acid (myo-inositol hexakisphosphate, InsP(6)) hydrolysis by Bacillus phytase (PhyC) was studied. The enzyme hydrolyses only three phosphates from phytic acid. Moreover, the enzyme seems to prefer the hydrolysis of every second phosphate over that of adjacent ones. Furthermore, it is very...... a reaction mechanism different from that of other phytases. By combining the data presented in this study with (1) structural information obtained from the crystal structure of Bacillus amyloliquefaciens phytase [Ha, Oh, Shin, Kim, Oh, Kim, Choi and Oh (2000) Nat. Struct. Biol. 7, 147-153], and (2) computer...

  12. Control of Anthracnose Caused by Colletotrichum musae on Curcuma alismatifolia Gagnep. Using Antagonistic Bacillus spp.

    Directory of Open Access Journals (Sweden)

    Supuk Mahadtanapuk

    2007-01-01

    Full Text Available Over 400 bacterial strains, isolated from leaf surfaces of Curcuma alismatifolia Gagnep. and hot springs in the Chiang Mai province of northern Thailand, were screened in vitro for antagonistic activity against Colletotrichum musae, an anthracnose fungus. Three isolates provided greater than 75% growth inhibition of the fungus in vitro and were identified as Bacillus licheniformis, B. amyloliquefaciens and B. subtilis. Using in planta tests, B. amyloliquefaciens and B. subtilis were shown to efficiently colonize the curcuma bracts, provide a statistically significant growth suppression of C. musae over that of B. licheniformis, and all three isolates could provide 100% inhibition of conidial fungal germination. When B. licheniformis was co-inoculated in combination with either of the other two bacteria, the ability of B. amyloliquefaciens and B. subtilis to suppress the fungal disease was dramatically reduced. Both B. amyloliquefaciens and B. subtilis were found to contain an isoform of iturin A with antifungal activity against C. musae. As a preventative measure to control the spread of C. musae and reduce the severity of fungal infections, B. amyloliquefaciens could be used to inoculate curcuma flowers cost effectively and reduce the need for the toxic synthetic fungicides currently in use.

  13. Isolation and characterization of antagonistic Bacillus strains capable to degrade ethylenethiourea.

    Science.gov (United States)

    Vágvölgyi, Csaba; Sajben-Nagy, Enikő; Bóka, Bettina; Vörös, Mónika; Berki, Adrienn; Palágyi, Andrea; Krisch, Judit; Skrbić, Biljana; Durišić-Mladenović, N; Manczinger, László

    2013-03-01

    In this study, more than 150 bacteria showing antagonistic properties against bacterial and fungal pathogens of the tomato plant were isolated and characterized. The most efficient agents against these phytopathogenic microorganisms belong to the genus Bacillus: the best biocontrol isolates were representatives of Bacillus subtilis, B. mojavensis and B. amyloliquefaciens species. They intensively produced fengycin or/and surfactin depsipeptide antibiotics and also proved to be excellent protease secretors. It was proved, that the selected strains were able to use ethylenethiourea (ETU) as sole nitrogen source. These antagonistic and ETU-degrading Bacillus strains can be applied as biocontrol and also as bioremediation agents. PMID:23143288

  14. Computational based functional analysis of Bacillus phytases.

    Science.gov (United States)

    Verma, Anukriti; Singh, Vinay Kumar; Gaur, Smriti

    2016-02-01

    Phytase is an enzyme which catalyzes the total hydrolysis of phytate to less phosphorylated myo-inositol derivatives and inorganic phosphate and digests the undigestable phytate part present in seeds and grains and therefore provides digestible phosphorus, calcium and other mineral nutrients. Phytases are frequently added to the feed of monogastric animals so that bioavailability of phytic acid-bound phosphate increases, ultimately enhancing the nutritional value of diets. The Bacillus phytase is very suitable to be used in animal feed because of its optimum pH with excellent thermal stability. Present study is aimed to perform an in silico comparative characterization and functional analysis of phytases from Bacillus amyloliquefaciens to explore physico-chemical properties using various bio-computational tools. All proteins are acidic and thermostable and can be used as suitable candidates in the feed industry. PMID:26672917

  15. Biocontrol and Plant Growth Promotion Characterization of Bacillus Species Isolated from Calendula officinalis Rhizosphere.

    Science.gov (United States)

    Ait Kaki, Asma; Kacem Chaouche, Noreddine; Dehimat, Laid; Milet, Asma; Youcef-Ali, Mounia; Ongena, Marc; Thonart, Philippe

    2013-12-01

    The phenotypic and genotypic diversity of the plant growth promoting Bacillus genus have been widely investigated in the rhizosphere of various agricultural crops. However, to our knowledge this is the first report on the Bacillus species isolated from the rhizosphere of Calendula officinalis. 15 % of the isolated bacteria were screened for their important antifungal activity against Fusarium oxysporum, Botrytis cinerea, Aspergillus niger, Cladosporium cucumerinium and Alternaria alternata. The bacteria identification based on 16S r-RNA and gyrase-A genes analysis, revealed strains closely related to Bacillus amyloliquefaciens, B. velezensis, B. subtilis sub sp spizezenii and Paenibacillus polymyxa species. The electro-spray mass spectrometry coupled to liquid chromatography (ESI-LC MS) analysis showed that most of the Bacillus isolates produced the three lipopeptides families. However, the P. polymyxa (18SRTS) didn't produce any type of lipopeptides. All the tested Bacillus isolates produced cellulase but the protease activity was observed only in the B. amyloliquefaciens species (9SRTS). The Salkowsky colorimetric test showed that the screened bacteria synthesized 6-52 μg/ml of indole 3 acetic acid. These bacteria produced siderophores with more than 10 mm wide orange zones on chromazurol S. The greenhouse experiment using a naturally infested soil with Sclerotonia sclerotiorum showed that the B. amyloliquefaciens (9SRTS) had no significant (P > 0.05) effect on the pre-germination of the chickpea seeds. However, it increased the size of the chickpea plants and reduced the stem rot disease (P officinalis and other crop systems. PMID:24426149

  16. Novel routes for improving biocontrol activity of Bacillus based bioinoculants

    Directory of Open Access Journals (Sweden)

    Liming eWu

    2015-12-01

    Full Text Available Biocontrol formulations prepared from plant-growth-promoting bacteria are increasingly applied in sustainable agriculture. Especially inoculants prepared from endospore-forming Bacillus strains have been proven as efficient and environmental-friendly alternative to chemical pesticides due to their long shelf life, which is comparable with that of agrochemicals. However, these formulations of the first generation are sometimes hampered in their action and do not fulfill in each case the expectations of the appliers. In this review we use the well-known plant-associated Bacillus amyloliquefaciens type strain FZB42 as example for the successful application of different techniques offered today by comparative, evolutionary and functional genomics, site-directed mutagenesis and strain construction including marker removal, for paving the way for preparing a novel generation of biocontrol agents.

  17. 77 FR 745 - Bacillus Amyloliquefaciens Strain D747; Exemption From the Requirement of a Tolerance

    Science.gov (United States)

    2012-01-06

    ... commodities when used in accordance with good agricultural practices. Certis USA LLC submitted a petition to... used in accordance with good agricultural practices. BILLING CODE 6560-50-P ... apply to me? You may be potentially affected by this action if you are an agricultural ] producer,...

  18. Monolithic white LED based on AlxGa1-x N/InyGa1-yN DBR resonant-cavity

    Institute of Scientific and Technical Information of China (English)

    Chen Yu; Huang Lirong; Zhu Shanshan

    2009-01-01

    A monolithic white light-emitting diode (LED) with blue and yellow light active regions has been de-signed and studied. With the AlxGa1-xN/InyGa1-yN distributed Bragg reflector (DBR) resonant-cavity, the extraction efficiency and power of the yellow light are enhanced so that high quality white light can be obtained.

  19. Properties of AlyGa1-yN/AlxGa1-xN/AlN/GaN Double-Barrier High Electron Mobility Transistor Structure

    Institute of Scientific and Technical Information of China (English)

    GUO Lun-Chun; WANG Xiao-Liang; XIAO Hong-Ling; RAN Jun-Xue; Wang Cui-Mei; MA Zhi-Yong; LUO Wei-Jun; WANG Zhan-Guo

    2009-01-01

    Electrical properties of AlyGa1-yN/AlxGa1-xN/AIN/GaN structure are investigated by solving coupled Schrodinger and Poisson equation self-consistently. Our calculations show that the two-dimensional electron gas (2DEG) den-sity will decrease with the thickness of the second barrier (AlyGa1-yN) once the AIN content of the second barrier is smaller than a critical value yc, and will increase with the thickness of the second barrier (AlyGa1-yN) when the critical AIN content of the second barrier yc is exceeded. Our calculations also show that the critical AlN content of the second barrier yc will increase with the AlN content and the thickness of the first barrier layer (AlxGa1-xN).

  20. Production and Characterization of Keratinolytic Protease from New Wool-Degrading Bacillus Species Isolated from Egyptian Ecosystem

    Directory of Open Access Journals (Sweden)

    Mohamed A. Hassan

    2013-01-01

    Full Text Available Novel keratin-degrading bacteria were isolated from sand soil samples collected from Minia Governorate, Egypt. In this study, the isolates were identified as Bacillus amyloliquefaciens MA20 and Bacillus subtilis MA21 based on morphological and biochemical characteristics as well as 16S rRNA gene sequencing. B. amyloliquefaciens MA20 and B. subtilis MA21 produced alkaline keratinolytic serine protease when cultivated in mineral medium containing 1% of wool straight off sheep as sole carbon and nitrogen source. The two strains were observed to degrade wool completely to powder at pH 7 and 37°C within 5 days. Under these conditions the maximum activity of proteases produced by B. amyloliquefaciens MA20 and B. subtilis MA21 was 922 and 814 U/ml, respectively. The proteases exhibited optimum temperature and pH at 60°C and 9, respectively. However, the keratinolytic proteases were stable in broad range of temperature and pH values towards casein Hammerstein. Furthermore the protease inhibitor studies indicated that the produced proteases belong to serine protease because of their sensitivity to PMSF while they were inhibited partially in presence of EDTA. The two proteases are stable in most of the used organic solvents and enhanced by metals suggesting their potential use in biotechnological applications such as wool industry.

  1. Resonant tunneling transport in AlzGa1−zN/InxGa1−xN/AlzGa1−zN/InyGa1−yN quantum structures

    International Nuclear Information System (INIS)

    We present a room temperature simulation of the vertical electron transport in the pseudomorphic quantum stack Al0.5G0.5N/InxGa1−xN/Al0.5G0.5N/In0.1Ga0.9N/GaN, which is designed with a 6 nm thick lateral In0.1Ga0.9N/GaN n-type corrected spacer. Using the transfer matrix formalism, we investigate the effects of the conduction band discontinuities and internal field on the transmission coefficient and the current-voltage characteristics by varying the indium contents in the central quantum well. We demonstrate that an optimal design in terms of compositions, thicknesses, and doping of the studied resonant tunneling structure may allow a peak-to-valley ratio as high as 882 @1.1–1.3 V. (paper)

  2. Bacillus vanillea sp. nov., Isolated from the Cured Vanilla Bean.

    Science.gov (United States)

    Chen, Yong-gan; Gu, Feng-lin; Li, Ji-hua; Xu, Fei; He, Shu-zhen; Fang, Yi-ming

    2015-02-01

    A Gram-positive bacterium, designated strain XY18(T), was isolated from a cured vanilla bean in Hainan province, China. Cells were rod-shaped, endospore producing, and peritrichous flagella. Strain XY18(T) grew at salinities of 0-8 % (w/v) NaCl (optimally 1-4 %), pH 4.0-8.0 (optimally 5.0-7.0 %) and temperature range 20-45 °C (optimally 28-35 °C). The predominant menaquinone was MK-7. The major cellular fatty acids were anteiso-C15:0, iso-C15:0, anteiso-C17:0, and iso-C17:0. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain XY18(T) was a member of the genus Bacillus, and closely related to B. amyloliquefaciens NBRC 15535(T) and B. siamensis PD-A10(T), with 99.1 and 99.2 % sequence similarity, respectively. However, the DNA-DNA hybridization value between strain XY18(T) and B. amyloliquefaciens NBRC 15535(T) was 35.7 %. The genomic DNA G+C content of strain XY18(T) was 46.4 mol%, significantly differed from B. siamensis PD-A10(T) (41.4 %), which was higher than the range of 4 % indicative of species. On the basis of polyphasic taxonomic study, including phenotypic features, chemotaxonomy, and phylogenetic analyses, strain XY18(T) represents a novel species within the genus Bacillus, for which the name Bacillus vanillea sp. nov. is proposed. The type strain is XY18(T) (=CGMCC 8629 = NCCB 100507).

  3. Bacillus vanillea sp. nov., Isolated from the Cured Vanilla Bean.

    Science.gov (United States)

    Chen, Yong-gan; Gu, Feng-lin; Li, Ji-hua; Xu, Fei; He, Shu-zhen; Fang, Yi-ming

    2015-02-01

    A Gram-positive bacterium, designated strain XY18(T), was isolated from a cured vanilla bean in Hainan province, China. Cells were rod-shaped, endospore producing, and peritrichous flagella. Strain XY18(T) grew at salinities of 0-8 % (w/v) NaCl (optimally 1-4 %), pH 4.0-8.0 (optimally 5.0-7.0 %) and temperature range 20-45 °C (optimally 28-35 °C). The predominant menaquinone was MK-7. The major cellular fatty acids were anteiso-C15:0, iso-C15:0, anteiso-C17:0, and iso-C17:0. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain XY18(T) was a member of the genus Bacillus, and closely related to B. amyloliquefaciens NBRC 15535(T) and B. siamensis PD-A10(T), with 99.1 and 99.2 % sequence similarity, respectively. However, the DNA-DNA hybridization value between strain XY18(T) and B. amyloliquefaciens NBRC 15535(T) was 35.7 %. The genomic DNA G+C content of strain XY18(T) was 46.4 mol%, significantly differed from B. siamensis PD-A10(T) (41.4 %), which was higher than the range of 4 % indicative of species. On the basis of polyphasic taxonomic study, including phenotypic features, chemotaxonomy, and phylogenetic analyses, strain XY18(T) represents a novel species within the genus Bacillus, for which the name Bacillus vanillea sp. nov. is proposed. The type strain is XY18(T) (=CGMCC 8629 = NCCB 100507). PMID:25292250

  4. Phylogeny of marine Bacillus isolates from the Gulf of Mexico

    Science.gov (United States)

    Siefert, J. L.; Larios-Sanz, M.; Nakamura, L. K.; Slepecky, R. A.; Paul, J. H.; Moore, E. R.; Fox, G. E.; Jurtshuk, P. Jr

    2000-01-01

    The phylogeny of 11 pigmented, aerobic, spore-forming isolates from marine sources was studied. Forty-two biochemical characteristics were examined, and a 16S rDNA sequence was obtained for each isolate. In a phylogenetic tree based on 16S sequencing, four isolates (NRRL B-14850, NRRL B-14904, NRRL B-14907, and NRRL B-14908) clustered with B. subtilis and related organisms; NRRL B-14907 was closely related to B. amyloliquefaciens. NRRL B-14907 and NRRL B-14908 were phenotypically similar to B. amyloliquefaciens and B. pumilus, respectively. Three strains (NRRL B-14906, NRRL B-14910, and NRRL B-14911) clustered in a clade that included B. firmus, B. lentus, and B. megaterium. NRRL B-14910 was closely related phenotypically and phylogenetically to B. megaterium. NRRL B-14905 clustered with the mesophilic round spore-producing species, B. fusiformis and B. sphaericus; the isolate was more closely related to B. fusiformis. NRRL B-14905 displayed characteristics typical of the B. sphaericus-like organisms. NRRL B-14909 and NRRL B-14912 clustered with the Paenibacillus species and displayed characteristics typical of the genus. Only NRRL B-14851, an unusually thin rod that forms very small spores, may represent a new Bacillus species.

  5. High-temperature characteristics of AixGa1-xN/GaN Schottky diodes

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaoling; Li Fei; Lv Changzhi; Xie Xuesong; Li Ying; Mohammad S N

    2009-01-01

    High-temperature characteristics of the metal/AlxGa1_xN/GaN M/S/S (M/S/S) diodes have been studied with current-voltage (I-V) and capacitance-voltage (C-V) measurements at high temperatures. Due to the presence of the piezoelectric polarization field and a quantum well at the AIxGa1_xN/GaN interface, the AIxGa1_xN/GaNdiodes show properties distinctly different from those of the AIxGa1_xN diodes. For the AIxGa1_xN/GaN diodes, an increase in temperature accompanies an increase in barrier height and a decrease in ideality factor, while the AIxGa1_xN diodes are opposite. Furthermore, at room temperature, both reverse leakage current and reverse break-down voltage are superior for the AIxGa1_xN/GaN diodes to those for the AIxGa1_xN diodes.

  6. Room-temperature ferromagnetic semiconductor MnxGa1-xSb

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Ferromagnetic semiconductor MnxGa1-xSb single crystals were fabricated by Mn-ions implantation, deposition, and the post annealing. Magnetic hysteresis-loops in the MnxGa1-xSb single crystals were obtained at room temperature (300 K). The structure of the ferromagnetic semiconductor MnxGa1-xSb single crystal was analyzed by X- ray diffraction. The distribution of carrier concentrations in MnxGa1-xSb was investigated by electrochemical capacitance-voltage profiler. The content of Mn in MnxGa1-xSb varied gradually from x = 0.09 near the surface to x = 0 in the wafer inner analyzed by X-ray diffraction. Electrochemical capacitance-voltage profiler reveals that the concentration of p-type carriers in MnxGa1-xSb is as high as 1×1021 cm-3, indicating that most of the Mn atoms in MnxGa1-xSb take the site of Ga, and play a role of acceptors.

  7. First-Principles Calculations Of Electronic Structures of New Ⅲ-Ⅴ Semiconductors: BxGa1-x As and Tlx Ga1-x As alloys

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jing; REN Xiao-Min; HUANG Yong-Qing; WANG Qi; HUANG Hui

    2008-01-01

    We investigate the electronic structures of new semiconductor alloys BxGa1-x As and Tlx Ga1-x As, employing first-principles calculations within the density-functional theory and the generalized gradient approximation.The calculation results indicate that alloying a small Tl content with GaAs will produce larger modifications of the band structures compared to B. A careful investigation of the internal lattice structure relaxation shows that significant bond-length relaxations takes place in both the alloys, and it turns out that difference between the band-gap bowing behaviours for B and Tl stems from the different impact of atomic relaxation on the electronic structure. The relaxed structure yields electronic-structure results, which are in good agreement with the experimental data. Finally, a comparison of formation enthalpies indicates that the production Tlx Ga1-x As with Tl concentration of at least 8% is possible.

  8. Surface States in the AlxGa1-xN Barrier in AlxGa1-xN/GaN Heterosturctures

    Institute of Scientific and Technical Information of China (English)

    刘杰; 沈波; 王茂俊; 周玉刚; 陈敦军; 张荣; 施毅; 郑有炓

    2004-01-01

    Frequency-dependent capacitance-voltage (C-V) measurements have been performed on modulation-doped Al0.22Ga0.78N/GaN heterostructures to investigate the characteristics of the surface states in the Alx Ga1-xN barrier.Numerical fittings based on the experimental data indicate that there are surface states with high density locating on the AlxGa1-xN barrier. The density of the surface states is about 1012 cm-2 eV-1, and the time constant is about 1 μs. It is found that an insulating layer (Si3N4) between the metal contact and the surface of AlxGa1-xN can passivate the surface states effectively.

  9. Different temperature dependence of carrier transport properties between Alx Ga1-xN/InyGa1-yN/GaN and AlxGa1-xN/GaN heterostructures

    Institute of Scientific and Technical Information of China (English)

    Song Jie; Xu Fu-Jun; Huang Cheng-Cheng; Lin Fang; Wang Xin-Qiang; Yang Zhi-Jian; Shen Bo

    2011-01-01

    The temperature dependence of carrier transport properties of AlxGai-xN/InyGa1-yN/GaN and AlxGa1-xN/GaN heterostructures has been investigated. It is shown that the Hall mobility in Al0.25Ga0.75N/In0.03Ga0.97N/GaN heterostructures is higher than that in Al0.25Ga0.75N/GaN heterostructures at temperatures above 500 K, even the mobility in the former is much lower than that in the latter at 300 K. More importantly, the electron sheet density in Al0.25Ga0.75N/In0.03Ga0.97N/GaN heterostructures decreases slightly,whereas the electron sheet density in Al0.25Ga0.75N/GaN heterostructures gradually increases with increasing temperature above 500 K. It is believed that an electron depletion layer is formed due to the negative polarization charges at the InyGa1-yN/GaN heterointerface induced by the compressive strain in the InyGa1-yN channel, which effectively suppresses the parallel conductivity originating from the thermal excitation in the underlying GaN layer at high temperatures.

  10. Bacillus anthracis

    OpenAIRE

    2003-01-01

    The events of 11 September 2001 and the subsequent anthrax outbreaks have shown that the West needs to be prepared for an increasing number of terrorist attacks, which may include the use of biological warfare. Bacillus anthracis has long been considered a potential biological warfare agent, and this review will discuss the history of its use as such. It will also cover the biology of this organism and the clinical features of the three disease forms that it can produce: cutaneous, gastrointe...

  11. Bacillus anthracis

    OpenAIRE

    BOSERET, GÉRALDINE; Linden, Annick; Mainil, Jacques

    2002-01-01

    The literature describes several methods for detection of Bacillus anthracis based on application of specific bacteriophages. The following methods of pahoinpitely are used to identify the causative agent of anthrax: the reaction of bacteriophage titer growth (RBTG), the reaction of phage adsorption (RPA), fagoterapii method (FTM) and fluorescentserological method (FSM). The essence of RBTG consists in the following: if there is the researchform of bacteria presents in the test material, then...

  12. Phase stability and the arsenic vacancy defect in InxGa1−xAs

    KAUST Repository

    Murphy, S. T.

    2011-11-18

    The introduction of defects, such as vacancies, into InxGa1−xAs can have a dramatic impact on the physical and electronic properties of the material. Here we employ ab initio simulations of quasirandom supercells to investigate the structure of InxGa1−xAs and then examine the energy and volume changes associated with the introduction of an arsenic vacancy defect. We predict that both defect energies and volumes for intermediate compositions of InxGa1−xAs differ significantly from what would be expected by assuming a simple linear interpolation of the end member defect energies/volumes.

  13. Optimization of Amylase Production from B. amyloliquefaciens (MTCC 1270) Using Solid State Fermentation

    OpenAIRE

    Koel Saha; Sujan Maity; Sudeshna Roy; Koustav Pahan; Rishija Pathak; Susmita Majumdar; Suvroma Gupta

    2014-01-01

    Demand for microbial amylase production persists because of its immense importance in wide spectrum industries. The present work has been initiated with a goal of optimization of solid state fermentation condition for amylase using agroindustrial waste and microbial strain like B. amyloliquefaciens (MTCC 1270). In an aim to improve the productivity of amylase, fermentation has been carried out in the presence of calcium (Ca+2), Nitrate (NO3 −), and chloride ions (Cl−) as well as in the presen...

  14. Antifungal Activity of Selected Indigenous Pseudomonas and Bacillus from the Soybean Rhizosphere

    Directory of Open Access Journals (Sweden)

    A. F. García

    2009-01-01

    Full Text Available The purpose of this study was to isolate and select indigenous soil Pseudomonas and Bacillus bacteria capable of developing multiple mechanisms of action related to the biocontrol of phytopathogenic fungi affecting soybean crops. The screening procedure consisted of antagonism tests against a panel of phytopathogenic fungi, taxonomic identification, detection by PCR of several genes related to antifungal activity, in vitro detection of the antifungal products, and root colonization assays. Two isolates, identified and designated as Pseudomonas fluorescens BNM296 and Bacillus amyloliquefaciens BNM340, were selected for further studies. These isolates protected plants against the damping-off caused by Pythium ultimum and were able to increase the seedling emergence rate after inoculation of soybean seeds with each bacterium. Also, the shoot nitrogen content was higher in plants when seeds were inoculated with BNM296. The polyphasic approach of this work allowed us to select two indigenous bacterial strains that promoted the early development of soybean plants.

  15. Antifungal activity of selected indigenous pseudomonas and bacillus from the soybean rhizosphere.

    Science.gov (United States)

    León, M; Yaryura, P M; Montecchia, M S; Hernández, A I; Correa, O S; Pucheu, N L; Kerber, N L; García, A F

    2009-01-01

    The purpose of this study was to isolate and select indigenous soil Pseudomonas and Bacillus bacteria capable of developing multiple mechanisms of action related to the biocontrol of phytopathogenic fungi affecting soybean crops. The screening procedure consisted of antagonism tests against a panel of phytopathogenic fungi, taxonomic identification, detection by PCR of several genes related to antifungal activity, in vitro detection of the antifungal products, and root colonization assays. Two isolates, identified and designated as Pseudomonas fluorescens BNM296 and Bacillus amyloliquefaciens BNM340, were selected for further studies. These isolates protected plants against the damping-off caused by Pythium ultimum and were able to increase the seedling emergence rate after inoculation of soybean seeds with each bacterium. Also, the shoot nitrogen content was higher in plants when seeds were inoculated with BNM296. The polyphasic approach of this work allowed us to select two indigenous bacterial strains that promoted the early development of soybean plants. PMID:20016811

  16. The band structures of BSb and BxGa1-xSb alloys

    Institute of Scientific and Technical Information of China (English)

    XIONG DePing; ZHOU ShouLi; WANG Qi; LUO Li; HUANG YongQing; REN XiaoMin

    2009-01-01

    The band structures of BSb and BxGa1-xSb alloys are studied using first-principles calculations in the generalized gradient approximation. By SQS-8 supercells to model a random alloy, the direct transition energy-gap (Γ15v-Γ1c) bowing of 3.0 eV is obtained for BxGa1-xSb alloys in x=0-50%, in x=0-11% the energy-gap is the band-gap and increases by 7 meV/%B with boron composition increasing; by SQS-16 supercells the bowing parameter is about 1.9 eV in x= 0-12.5%. The formation enthalpies of mixing, ΔH,are calculated for BxGa1-xAs and BxGa1-xSb alloys. A comparison of enthalpies indicates that BxGa1-xSb films with boron composition of 7% may be possible.

  17. The band structures of BSb and BxGa1-xSb alloys

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The band structures of BSb and BxGa1-xSb alloys are studied using first-principles calculations in the generalized gradient approximation. By SQS-8 supercells to model a random alloy, the direct transition energy-gap (Γ15v- Γ1c) bowing of 3.0 eV is obtained for BxGa1-xSb alloys in x = 0-50%, in x = 0-11% the energy-gap is the band-gap and increases by 7 meV/%B with boron composition increasing; by SQS-16 supercells the bowing parameter is about 1.9 eV in x = 0-12.5%. The formation enthalpies of mixing, ΔH, are calculated for BxGa1-xAs and BxGa1-xSb alloys. A comparison of enthalpies indicates that BxGa1-xSb films with boron composition of 7% may be possible.

  18. Strain gauges of GaSb-FeGa1.3 eutectic composites

    OpenAIRE

    Aliyev, M.I.; Khalilova, A. A.; Arasly, D. H.; Rahimov, R. N.; Tanoğlu, Metin; ÖZYÜZER, Lütfi

    2004-01-01

    A needle-shaped metallic FeGa1.3 phase oriented in a specific direction and uniformly distributed within a GaSb matrix was grown by a vertical Bridgman method. Strain-gauge characteristics, such as strain-sensitivity coefficient (S), temperature coefficient of strain sensitivity (TCS) and temperature coefficient of resistance, of GaSb and GaSb-FeGa1.3 eutectic alloy have been investigated in the range of 200 to 400 K under deformation up to strains of 1.3 × 10-3. The value of S of the GaSb-Fe...

  19. Electronic structures of GaAs/Al x Ga1-x As quantum double rings

    OpenAIRE

    Li Shu-Shen; Xia Jian-Bai

    2006-01-01

    AbstractIn the framework of effective mass envelope function theory, the electronic structures of GaAs/AlxGa1-xAs quantum double rings (QDRs) are studied. Our model can be used to calculate the electronic structures of quantum wells, wires, dots, and the single ring. In calculations, the effects due to the different effective masses of electrons and holes in GaAs and AlxGa1-xAs and the valence band mixing are considered. The energy levels of electrons and holes are calculated for different sh...

  20. EXOPOLYSACCHARIDE PRODUCTION BY DROUGHT TOLERANT BACILLUS SPP. AND EFFECT ON SOIL AGGREGATION UNDER DROUGHT STRESS

    Directory of Open Access Journals (Sweden)

    Sandhya Vardharajula

    2014-08-01

    Full Text Available Exopolysaccharides (EPS of microbial origin with novel functionality, reproducible physico-chemical properties, are important class of polymeric materials. EPS are believed to protect bacterial cells from dessication, produce biofilms, thus enhancing the cells chances of bacterial colonizing special ecological niches. In rhizosphere, EPS are known to be useful to improve the moisture-holding capacity. Three Bacillus spp. strains identified by 16s rDNA sequence analysis as B. amyloliquefaciens strain HYD-B17; B. licheniformis strain HYTAPB18; B. subtilis strain RMPB44 were studied for the ability to tolerate matric stress and produce EPS under different water potentials. EPS production in all the three Bacillus spp strains increased with increasing water stress indicating correlation between drought stress tolerance and EPS production. Among the isolates, strain HYD-17 showed highest production of EPS. The exopolysaccharide composition of the three strains was further analyzed by HPLC. Drought stress influenced the ratio of sugars in EPS and glucose was found as major sugar in strains HYTAPB18 and RMPB44 whereas raffinose was major sugar found in strain HYD-B17. Inoculation of EPS producing Bacillus spp. strains in soil resulted in good soil aggregation under drought stress conditions at different incubation periods. This study shows that exposure to water stress conditions affects the composition and ratios of sugars in EPS produced by Bacillus spp. strains HYD-B17, HYTAPB18 and RMPB44 influencing abiotic stress tolerance of the microorganisms.

  1. Characterization of antagonistic-potential of two Bacillus strains and their biocontrol activity against Rhizoctonia solani in tomato.

    Science.gov (United States)

    Solanki, Manoj Kumar; Singh, Rajesh Kumar; Srivastava, Supriya; Kumar, Sudheer; Kashyap, Prem Lal; Srivastava, Alok K

    2015-01-01

    To investigate the biocontrol mechanism of two antagonistic Bacillus strains (Bacillus subtilis MB14 and Bacillus amyloliquefaciens MB101), three in vitro antagonism assays were screened and the results were concluded that both strains inhibited Rhizoctonia solani growth in a similar manner by dual culture assay, but the maximum percent of inhibition only resulted with MB101 by volatile and diffusible metabolite assays. Moreover, cell free supernatant (CFS) of MB101 also showed significant (p > 0.05) growth inhibition as compared to MB14, when 10 and 20% CFS mix with the growth medium of R. solani. After in vitro-validation, both strains were evaluated under greenhouse and the results concluded that strain MB101 had significant biocontrol potential as compared to MB14. Strain MB101 was enhanced the plant height, biomass and chlorophyll content of tomato plant through a higher degree of root colonization. In field trials, strain MB101 showed higher lessening in root rot symptoms with significant fruit yield as compare to strain MB14 and infected control. Next to the field study, the presence of four antibiotic genes (srfAA, fenD, ituC, and bmyB) also concluded the antifungal nature of both Bacillus strains. Phylogenetic analysis of protein sequences revealed a close relatedness of three genes (srfAA, fenD, and ituC) with earlier reported sequences of B. subtilis and B. amyloliquefaciens. However, bmyB showed heterogeneity in among both strains (MB14 and MB101) and it may be concluded that higher degree of antagonism, root colonization and different antibiotic producing genes may play an important role in biocontrol mechanism of strain MB101. PMID:24277414

  2. Exciton dynamics in GaAs/AlxGa1-xAs quantum wells

    DEFF Research Database (Denmark)

    Litvinenko, K.; Birkedal, Dan; Lyssenko, V. G.;

    1999-01-01

    The changes induced in the optical absorption spectrum of a GaAs/AlxGa1-xAs multiple quantum well due to a photoexcited carrier distribution are reexamined. We use a femtosecond pump-probe technique to excite excitons and free electron-hole pairs. We find that for densities up to 10(11) cm(-2...

  3. Antioxidant and Neuroprotective Effects of Doenjang Prepared with Rhizopus, Pichia, and Bacillus

    Science.gov (United States)

    Kang, Su Jin; Seo, Ji Yeon; Cho, Kye Man; Lee, Chang Kwon; Kim, Jeong Hwan; Kim, Jong-Sang

    2016-01-01

    A new type of doenjang was manufactured by mixing soaked soybean, koji (Rhizopus oryzae), cheonggukjang (Bacillus amyloliquefaciens MJ1-4 and B. amyloliquefaciens EMD17), and Pichia farinosa SY80 as a yeast, salt, and water, followed by fermentation with koji that was made by fermenting whole wheat with R. oryzae. The mixed culture doenjang was designed to have a more palatable flavor and stronger biological activities than the conventional product. The extract of mixed culture doenjang showed higher antioxidant activity than the commercial doenjang as evaluated by the ferric reducing antioxidant power assay although it was not significantly different from the commercial product in 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activities. Further, the mixed culture doenjang reduced intracellular reactive oxygen species levels and protected cells from glutamate-induced cytotoxicity more efficiently in human hippocampal HT22 neuroblastoma cells than the commercial doenjang. In conclusion, a newly-developed mixed culture doenjang had a strong antioxidant activity in vitro and cultured cell model systems, exhibited a potential to prevent oxidative stress-associated disorders although animal and clinical studies are needed to confirm its in vivo efficacy. PMID:27752498

  4. Effect of tin oxide nanoparticle binding on the structure and activity of α-amylase from Bacillus amyloliquefaciens

    Science.gov (United States)

    Jahir Khan, Mohammad; Qayyum, Shariq; Alam, Fahad; Husain, Qayyum

    2011-11-01

    Proteins adsorbed on nanoparticles (NPs) are being used in biotechnology, biosensors and drug delivery. However, understanding the effect of NPs on the structure of proteins is still in a nascent state. In the present paper tin oxide (SnO2) NPs were synthesized by the reaction of SnCl4·5H2O in methanol via the sol-gel method and characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The binding of these SnO2-NPs with α-amylase was investigated by using UV-vis, fluorescence and circular dichroism (CD) spectroscopic techniques. A strong quenching of tryptophan fluorescence intensity in α-amylase was observed due to formation of a ground state complex with SnO2-NPs. Far-UV CD spectra showed that the secondary structure of α-amylase was changed in the presence of NPs. The Michaelis-Menten constant (Km), was found to be 26.96 and 28.45 mg ml - 1, while Vmax was 4.173 and 3.116 mg ml - 1 min - 1 for free and NP-bound enzyme, respectively.

  5. Effect of tin oxide nanoparticle binding on the structure and activity of α-amylase from Bacillus amyloliquefaciens

    International Nuclear Information System (INIS)

    Proteins adsorbed on nanoparticles (NPs) are being used in biotechnology, biosensors and drug delivery. However, understanding the effect of NPs on the structure of proteins is still in a nascent state. In the present paper tin oxide (SnO2) NPs were synthesized by the reaction of SnCl4·5H2O in methanol via the sol–gel method and characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The binding of these SnO2–NPs with α-amylase was investigated by using UV–vis, fluorescence and circular dichroism (CD) spectroscopic techniques. A strong quenching of tryptophan fluorescence intensity in α-amylase was observed due to formation of a ground state complex with SnO2–NPs. Far-UV CD spectra showed that the secondary structure of α-amylase was changed in the presence of NPs. The Michaelis–Menten constant (Km), was found to be 26.96 and 28.45 mg ml−1, while Vmax was 4.173 and 3.116 mg ml−1 min−1 for free and NP-bound enzyme, respectively.

  6. Infrared probe of the insulator-to-metal transition in Ga1-xMnxAs and Ga1-xBexAs

    Science.gov (United States)

    Chapler, B. C.; Myers, R. C.; Mack, S.; Frenzel, A.; Pursley, B. C.; Burch, K. S.; Singley, E. J.; Dattelbaum, A. M.; Samarth, N.; Awschalom, D. D.; Basov, D. N.

    2011-08-01

    We report infrared studies of the insulator-to-metal transition (IMT) in GaAs doped with either magnetic (Mn) or nonmagnetic acceptors (Be). We observe a resonance with a natural assignment to impurity states in the insulating regime of Ga1-xMnxAs, which persists across the IMT to the highest doping (16%). Beyond the IMT boundary, behavior combining insulating and metallic trends also persists to the highest Mn doping. Be-doped samples, however, display conventional metallicity just above the critical IMT concentration, with features indicative of transport within the host valence band.

  7. Über die Molekularstrahlepitaxie von InxGa1-xN Heterostrukturen und deren optische Charakterisierung

    OpenAIRE

    Graber, Andreas

    2000-01-01

    In der vorliegenden Dissertation wurden grundlegende Eigenschaften der InxGa1-xN Molekularstrahlepitaxie und der damit hergestellten Proben untersucht. Es wurden sowohl Si -dotierte als auch undotierte InxGa1-xN Schichten mit einem In Gehalt xIn

  8. Raman Scattering Study of InxGa1-xN Alloys with Low Indium Compositions

    Institute of Scientific and Technical Information of China (English)

    TENG Long; ZHENG You-Dou; ZHANG Rong; XIE Zi-Li; TAO Tao; ZHANG Zhao; LI Ye-Cao; LIU Bin; CHEN Peng; HAN Ping

    2012-01-01

    InxGa1-xN alloys with low indium composition x in the range 0.13 ≤ x ≤ 0.23 are systematically studied mainly based on a Raman scattering technique.Scanning electron microscopy and x-ray diffraction results show that our samples can be divided into two groups:pseudomorphic (0.13 ≤ x ≤ 0.16) and relaxed (0.18 ≤ x ≤ 0.23).The prominent enhancement of A1 longitudinal-optical (LO) mode is found with 325nm laser excitation.For pseudomorphic samples,the frequencies of A1 (LO) phonons agree well with the theoretical predictions,which verifies that the samples are fully strained.For relaxed Inx Ga1-xN samples,a linear dependence of the A1 (LO) mode frequency is obtained:Ωo(x) =(740.8 ± 3.3) - (143.1 ± 16.0)x,which is the evidence of one-mode behavior in InxGa1-xN ternary alloys.Residual strains in these partially relaxed samples are also evaluated.%InxGa1-xN alloys with low indium composition x in the range 0.13≤x ≤0.23 are systematically studied mainly based on a Raman scattering technique. Scanning electron microscopy and x-ray diffraction results show that our samples can be divided into two groups: pseudomorphic (0.13 ≤ x ≤ 0.16) and relaxed (0.18 ≤ x ≤ 0.23). The prominent enhancement of A1 longitudinal-optical (LO) mode is found with 325 nm laser excitation. For pseudomorphic samples, the frequencies of A1 (LO) phonons agree well with the theoretical predictions, which verifies that the samples are fully strained. For relaxed Inx Ga1-XN samples, a linear dependence of the A1 (LO) mode frequency is obtained:Ω0(x) = (740.8 ± 3.3) - (143.1 ± 16.0)x, which is the evidence of one-mode behavior in InxGa1-xN ternary alloys. Residual strains in these partially relaxed samples are also evaluated.

  9. Diversity of bacteria of the genus Bacillus on board of international space station.

    Science.gov (United States)

    Alekhova, T A; Zakharchuk, L M; Tatarinova, N Yu; Kadnikov, V V; Mardanov, A V; Ravin, N V; Skryabin, K G

    2015-01-01

    From swabs of surfaces of equipment and air samples of the Russian segment of the International Space Station, nine strains of spore-forming bacteria of the genus Bacillus belonging to the species B. pumilus, B. licheniformis, B. subtilis, B. megaterium, and B. amyloliquefaciens were isolated. The last species of bacilli on the equipment of RS ISS was detected for the first time. For these species of bacilli, there are known strains that can be opportunistic to humans, and their metabolites can cause biodegradation of equipment and materials. B. pumilus found on ISS belongs to the group of bacteria that exhibits a particularly high resistance to adverse environmental conditions, such as dehydration, ultraviolet and gamma radiation, and chemical disinfection.

  10. Characterization of Bacillus spp. strains for use as probiotic additives in pig feed

    DEFF Research Database (Denmark)

    Larsen, Nadja; Thorsen, Line; Kpikpi, Elmer Nayra;

    2014-01-01

    for use as probiotic additives in pig feed. A total of 245 bacterial isolates derived from African fermented food, feces and soil were identified by 16S rRNA gene sequencing and screened for antimicrobial activity and growth in the presence of antibiotics, bile salts and at pH 4.0. Thirty-three Bacillus...... investigated for their activity against the pathogenic bacteria, antibiotic susceptibility, sporulation rates, biofilm formation and production of glycosyl hydrolytic enzymes. Additionally, ten selected isolates were assessed for heat resistance of spores and the effect on porcine epithelial cells IPEC-J2....... Isolates of B. amyloliquefaciens, B. subtilis and B. mojavensis, showed the best overall characteristics and, therefore, potential for usage as probiotic additives in feed. A large number of taxonomically diverse strains made it possible to reveal species and subspecies-specific trends, contributing to our...

  11. Diversity of bacteria of the genus Bacillus on board of international space station.

    Science.gov (United States)

    Alekhova, T A; Zakharchuk, L M; Tatarinova, N Yu; Kadnikov, V V; Mardanov, A V; Ravin, N V; Skryabin, K G

    2015-01-01

    From swabs of surfaces of equipment and air samples of the Russian segment of the International Space Station, nine strains of spore-forming bacteria of the genus Bacillus belonging to the species B. pumilus, B. licheniformis, B. subtilis, B. megaterium, and B. amyloliquefaciens were isolated. The last species of bacilli on the equipment of RS ISS was detected for the first time. For these species of bacilli, there are known strains that can be opportunistic to humans, and their metabolites can cause biodegradation of equipment and materials. B. pumilus found on ISS belongs to the group of bacteria that exhibits a particularly high resistance to adverse environmental conditions, such as dehydration, ultraviolet and gamma radiation, and chemical disinfection. PMID:26728721

  12. Electronic structures of GaAs/AlxGa1-xAs quantum double rings

    Directory of Open Access Journals (Sweden)

    Li Shu-Shen

    2006-01-01

    Full Text Available AbstractIn the framework of effective mass envelope function theory, the electronic structures of GaAs/AlxGa1-xAs quantum double rings (QDRs are studied. Our model can be used to calculate the electronic structures of quantum wells, wires, dots, and the single ring. In calculations, the effects due to the different effective masses of electrons and holes in GaAs and AlxGa1-xAs and the valence band mixing are considered. The energy levels of electrons and holes are calculated for different shapes of QDRs. The calculated results are useful in designing and fabricating the interrelated photoelectric devices. The single electron states presented here are useful for the study of the electron correlations and the effects of magnetic fields in QDRs.

  13. High-Gain AlxGa1-xAs/GaAs Transistors For Neural Networks

    Science.gov (United States)

    Kim, Jae-Hoon; Lin, Steven H.

    1991-01-01

    High-gain AlxGa1-xAs/GaAs npn double heterojunction bipolar transistors developed for use as phototransistors in optoelectronic integrated circuits, especially in artificial neural networks. Transistors perform both photodetection and saturating-amplification functions of neurons. Good candidates for such application because structurally compatible with laser diodes and light-emitting diodes, detect light, and provide high current gain needed to compensate for losses in holographic optical elements.

  14. First-principles investigation of BAs and BxGa1-xAs alloys

    Institute of Scientific and Technical Information of China (English)

    Xiong De-Ping; Zhou Shou-Li; Wang Qi; Ren Xiao-Min

    2008-01-01

    Using first-principles calculations in the generalized gradient approximation, the electronic properties of BAs and BxGa1-xAs alloys are studied. At the Brillouin-zone centre, the lowest conduction band is the three-degenerate p-like Γ15c state rather than s-like Γ1c state, and the conduction band minimum (CBM) is along the △ line between the Γ and X points-at approximately 11/14(1,0,0)2π/a. With boron content at 0%-18.75%, BxGa1-xAs alloys have a small (2.6 eV) and relatively composition-independent band-gap bowing parameter, the band-gap increases monotonically by ~18meV/B% with increasing boron content. In addition, the formation enthalpies of mixing for BxGa1-xAs alloys with boron content at 6.25% and 12.5% are calculated, and the large formation enthalpies may explain the difficulty in alloying boron to GaAs.

  15. Ferromagnetism and infrared electrodynamics of Ga1-xMnxAs

    Science.gov (United States)

    Chapler, B. C.; Mack, S.; Myers, R. C.; Frenzel, A.; Pursley, B. C.; Burch, K. S.; Dattelbaum, A. M.; Samarth, N.; Awschalom, D. D.; Basov, D. N.

    2013-05-01

    We report on the magnetic and the electronic properties of the prototype dilute magnetic semiconductor Ga1-xMnxAs using infrared (IR) spectroscopy. Trends in the ferromagnetic transition temperature TC with respect to the IR spectral weight are examined using a sum-rule analysis of IR conductivity spectra. We find nonmonotonic behavior of trends in TC with the spectral weight to effective Mn ratio, which suggest a strong double-exchange component to the FM mechanism, and highlights the important role of impurity states and localization at the Fermi level. Spectroscopic features of the IR conductivity are tracked as they evolve with temperature, doping, annealing, As-antisite compensation, and are found only to be consistent with a Mn-induced IB scenario. Furthermore, our detailed exploration of these spectral features demonstrates that seemingly conflicting trends reported in the literature regarding a broad mid-IR resonance with respect to carrier density in Ga1-xMnxAs are in fact not contradictory. Our study thus provides a consistent experimental picture of the magnetic and electronic properties of Ga1-xMnxAs.

  16. Phonon deformation potentials of the E2(high) phonon mode of AlxGa1-xN

    International Nuclear Information System (INIS)

    Micro-Raman spectroscopy was applied to study the E2(high) phonon deformation potentials in AlxGa1-xN material, which are required to convert phonon frequency shifts into stress values. AlxGa1-xN layers were grown by molecular beam epitaxy directly on (111)-oriented Si substrates. Mechanical bending was applied to introduce biaxial stress in the AlxGa1-xN layers and Raman shifts were measured as a function of the applied deformation. The Si phonon mode provided a reference for the applied stress and allowed determination of phonon deformation potential values for AlxGa1-xN. Deformation potentials of the GaN- and AlN-like E2(high) phonon mode of AlGaN alloys were found to be similar to the corresponding values of binary compounds

  17. InGa1−N fibres grown on Au/SiO2 by chemical vapour deposition

    Indian Academy of Sciences (India)

    A Ramos-Carrazco; R García; M Barboza-Flores; R Rangel

    2014-12-01

    The growth of InGa1−N films ( = 0.1 and = 0.2) on a thin gold layer (Au/SiO2) by chemical vapour deposition (CVD) at 650 °C is reported. As a novelty, the use of a Ga–In metallic alloy to improve the indium incorporation in the InGa1−N is proposed. The results of high quality InGa1−N films with a thickness of three micrometres and the formation of microfibres on the surface are presented. A morphological comparison between the InGa1−N and GaN films is shown as a function of the indium incorporation. The highest crystalline InGa1−N films structure was obtained with an indium composition of = 0.20. Also, the preferential growth on the (002) plane over In0.2Ga0.8N was observed by means of X-ray diffraction. The thermoluminescence (TL) of the InGa1−N films after beta radiation exposure was measured indicating the presence of charge trapping levels responsible for a broad TL glow curve with a maximum intensity around 150 °C. The TL intensity was found to depend on composition being higher for = 0.1 and increases as radiation dose increases.

  18. Al Incorporation at All Growth Stages of Al x Ga1- x N Epilayers Using SiN Treatment

    Science.gov (United States)

    Benzarti, Z.; Halidou, I.; Touré, A.; El Jani, B.

    2016-02-01

    Al compositional distribution of Al x Ga1- x N epilayers grown on SiN-treated sapphire substrate by atmospheric pressure metalorganic vapor phase epitaxy is investigated. The growth process was interrupted at various stages allowing a systematic study of Al x Ga1- x N epilayers during the smoothing process. A transition from three-dimensional (3D) to two-dimensional (2D) growth mode is revealed by in situ laser reflectometry (λ = 632.8 nm) as well as by atomic force microscopic images. Then, ion mass spectrometry analysis was performed to obtain the solid Al composition ( x) profile as well as by photoluminescence measurements. Moreover, the in situ reflectivity signal is simulated; thereby Al x Ga1- x N growth rate is derived and compared with that of GaN layer in order to study the effect of the aluminum incorporation on the growth mechanism. It is worth emphasising that the growth mode of Al x Ga1- x N layers is dictated by SiN treatment, which influences the Al compositional distribution. Electron mobility and refractive index against the thickness of Al x Ga1- x N layers have similar trends, which confirm a competitive mechanism between growth mode and Al incorporation. Therefore, the correlation between the Al composition and morphological, optical, and electrical properties of Al x Ga1- x N layers is established.

  19. Phonon bottleneck in GaAs/AlxGa1−xAs quantum dots

    Directory of Open Access Journals (Sweden)

    Y. C. Chang

    2015-06-01

    Full Text Available We report low-temperature photoluminescence measurements on highly-uniform GaAs/AlxGa1−xAs quantum dots grown by droplet epitaxy. Recombination between confined electrons and holes bound to carbon acceptors in the dots allow us to determine the energies of the confined states in the system, as confirmed by effective mass calculations. The presence of acceptor-bound holes in the quantum dots gives rise to a striking observation of the phonon-bottleneck effect.

  20. Coherent dynamics of interwell excitons in GaAs/AlxGa1-xAs superlattices

    DEFF Research Database (Denmark)

    Mizeikis, V.; Birkedal, Dan; Langbein, Wolfgang Werner;

    1997-01-01

    Coherent exciton dynamics in a GaAs/AlxGa1-xAs narrow-miniband superlattice is studied by spectrally resolved transient four-wave mixing. Coherent optical properties of the investigated structure are found to be strongly affected by the existence of two different heavy-hole excitonic states. One...... of them, the Is heavy-hole exciton, is almost identical to the same state in noninteracting quantum wells, while the other, the heavy-hole interwell exciton, is composed of an electron and a heavy hole in adjacent wells. The interwell exciton leads to a resonant enhancement in the four-wave mixing spectra...

  1. TDDFT calculations for excitation spectra of $In_xGa_{1-x}As$ alloys

    CERN Document Server

    Ning, Zhenhua; Chang, Yia-Chung

    2014-01-01

    We adopted the TDDFT theory and the cluster averaging method to compute the spectra of $\\rm In_xGa_{1-x}As$ with arbitrary concentration $x$. We find great agreement between theoretical and experimental data. The success of this method is mainly because that we approximate the transition matrix elements by the LDA p-matrix elements via meta-generalized gradient approximation(mGGA) which includes the singularity of the type $f_{XC,00}(\\mathbf{q})\\sim 1/q^2 $ as $q\\rightarrow 0$. Thus, Our studies provide some insight into the theoretical calculation of optical spectra of semiconductor alloys.

  2. Evaluation and Selection of Bacillus Species Based on Enzyme Production, Antimicrobial Activity, and Biofilm Synthesis as Direct-Fed Microbial Candidates for Poultry

    Science.gov (United States)

    Latorre, Juan D.; Hernandez-Velasco, Xochitl; Wolfenden, Ross E.; Vicente, Jose L.; Wolfenden, Amanda D.; Menconi, Anita; Bielke, Lisa R.; Hargis, Billy M.; Tellez, Guillermo

    2016-01-01

    Social concern about misuse of antibiotics as growth promoters (AGP) and generation of multidrug-resistant bacteria have restricted the dietary inclusion of antibiotics in livestock feed in several countries. Direct-fed microbials (DFM) are one of the multiple alternatives commonly evaluated as substitutes of AGP. Sporeformer bacteria from the genus Bacillus have been extensively investigated because of their extraordinary properties to form highly resistant endospores, produce antimicrobial compounds, and synthesize different exogenous enzymes. The purpose of the present study was to evaluate and select Bacillus spp. from environmental and poultry sources as DFM candidates, considering their enzyme production profile, biofilm synthesis capacity, and pathogen-inhibition activity. Thirty-one Bacillus isolates were screened for in vitro relative enzyme activity of amylase, protease, lipase, and phytase using a selective media for each enzyme, with 3/31 strains selected as superior enzyme producers. These three isolates were identified as Bacillus subtilis (1/3), and Bacillus amyloliquefaciens (2/3), based on biochemical tests and 16S rRNA sequence analysis. For evaluation of biofilm synthesis, the generation of an adherent crystal violet-stained ring was determined in polypropylene tubes, resulting in 11/31 strains showing a strong biofilm formation. Moreover, all Bacillus strains were evaluated for growth inhibition activity against Salmonella enterica serovar Enteritidis (26/31), Escherichia coli (28/31), and Clostridioides difficile (29/31). Additionally, in previous in vitro and in vivo studies, these selected Bacillus strains have shown to be resistant to different biochemical conditions of the gastrointestinal tract of poultry. Results of the present study suggest that the selection and consumption of Bacillus-DFM, producing a variable set of enzymes and antimicrobial compounds, may contribute to enhanced performance through improving nutrient digestibility

  3. Emergence of half-metallic ferromagnetism in Ga1- x Cr x As

    Science.gov (United States)

    Rani, Anita; Kumar, Ranjan

    2016-08-01

    We have studied the structural, electronic and half-metallic ferromagnetic properties of Ga1- x Cr x As compounds at dopant concentrations x = 0.25, 0.125 and 0.0625. First principle calculations based on density functional theories as implemented in SIESTA code using LDA + U (local density approximation + U) as exchange correlation potential have been used to study the properties of these compounds. Here, U is the Hubbard's parameter. The calculated results predict that Cr-doped GaAs diluted magnetic semiconductors exhibit half-metallic properties at different concentrations, in which Cr atoms form deep levels in forbidden energy gap. The results also predict that with increase of fraction of Cr atoms, half-metallic energy band gap of Ga1- x Cr x As decreases. Total magnetic moment of these compounds is due to Cr states, and also p-d hybridization between Ga-p and Cr-d induces small magnetic moment on nonmagnetic atoms (Ga and As) for all concentrations.

  4. Observations of flow in Inx Ga1-xAs multilayers

    Science.gov (United States)

    Korte, S.; McLaughlin, K. K.; Farrer, I.; Clegg, W. J.

    2008-08-01

    Work elsewhere has shown that the hardnesses of coherent InxGa1-xAs multilayer structures in which the misfit stresses are controlled by varying the indium content in each layer are influenced by the thicknesses and the coherency strains in the layers. These results have been interpreted in terms of the length-scale for flow being greater than the layer thickness and associated with deformation size effects. However, nanoindentation of InxGa1-x As suggests an influence of the flow stress of the individual layers on the overall multilayer flow stress. Consequently, initiation of flow in the weaker layer is expected. A deformed multilayer has been characterized by measurement of the lattice rotations measured from energy-filtered convergent beam electron diffraction (CBED) patterns recorded in scanning transmission electron microscopy (STEM) mode. Based on the movement of Kikuchi lines as a result of rotations of the lattice the local orientation of the crystal can be extracted, allowing the local orientations to be estimated. The small probe-size in CBED of ~1 nm used here ensures the region sampled is smaller than the thickness of the individual layers. These measurements have been used to construct a map of the axes of rotation in the lattice which demonstrates the ability to distinguish the individual layers.

  5. Mapping by interspecies transformation experiments of several ribosomal protein genes near the replication origin of Bacillus subtilis chromosome.

    Science.gov (United States)

    Osawa, S; Tokui, A; Saito, H

    1978-08-17

    Bacillus subtilis 168 was transformed with DNAs from B. amyloliquefaciens K or B. licheniformis IAM 11054. These two species show a considerable difference in ribosomal proteins from B. subtilis. Analyses of the transformants indicated that the genes for 16 proteins, S3, S5, S8, S12, S17, S19, BL1, BL5, BL6, BL8, BL14, BL16, BL17, BL22, BL23 and BL25 are located in the cysA-str-spc region on B. subtilis chromosome. The genes for 10 proteins, S4, S6, S13, S16, S20, BL15, BL18, BL20, BL24 and BL28 could not be found in this region in the present experiments.

  6. Study of the relationship between the crystal structure of nanolayers and electrical properties in AlxGa1−xAs/InyGa1−yAs pseudobinary heterostructures by double-crystal X-ray diffraction

    International Nuclear Information System (INIS)

    The structural parameters of individual layers of samples of a AlxGa1−xAs/InyGa1−yAs/GaAs pseudomorphic heterostructure have been determined by double-crystal X-ray diffraction. A relationship of the technological parameters of fabrication of heterostructures with their structural and electrical properties is established. The increase in the mobility of the 2D electron gas in the samples under study, caused by the increase in the growth temperature of the AlxGa1−xAs spacer layer and the decrease in the time of silicon δ doping from the two sides of the quantum well, correlates well with the degree of the sample structural quality.

  7. Biocontrol of geosmin-producing Streptomyces spp. by two Bacillus strains from Chinese liquor.

    Science.gov (United States)

    Zhi, Yan; Wu, Qun; Du, Hai; Xu, Yan

    2016-08-16

    Streptomyces spp. producing geosmin have been regarded as the most frequent and serious microbial contamination causing earthy off-flavor in Chinese liquor. It is therefore necessary to control the Streptomyces community during liquor fermentation. Biological control, using the native microbiota present in liquor making, appears to be a better solution than chemical methods. The objective of this study was to isolate native microbiota antagonistic toward Streptomyces spp. and then to evaluate the possible action mode of the antagonists. Fourteen Bacillus strains isolated from different Daqu (the fermentation starter) showed antagonistic activity against Streptomyces sampsonii, which is one of the dominant geosmin producers. Bacillus subtilis 2-16 and Bacillus amyloliquefaciens 1-45 from Maotai Daqu significantly inhibited the growth of S. sampsonii by 57.8% and 84.3% respectively, and effectively prevented the geosmin production in the simulated fermentation experiments (inoculation ratio 1:1). To probe the biocontrol mode, the ability of strain 2-16 and 1-45 to produce antimicrobial metabolites and to reduce geosmin in the fermentation system was investigated. Antimicrobial substances were identified as lipopeptides by ultra-performance liquid chromatography tandem electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI/Q-TOF MS) and in vitro antibiotic assay. In addition, strains 2-16 and 1-45 were able to remove 45% and 15% of the geosmin respectively in the simulated solid-state fermentation. This study highlighted the potential of biocontrol, and how the use of native Bacillus species in Daqu could provide an eco-friendly method to prevent growth of Streptomyces spp. and geosmin contamination in Chinese liquor fermentation.

  8. Spectroscopic Characterization of GaAs and AlxGa1 – xAs / AlyGa1 – yAs Quantum Well Heterostructures

    Directory of Open Access Journals (Sweden)

    Mirgender Kumar

    2013-07-01

    Full Text Available This work presents the results of the characterization of GaAs and AlxGa1 – xAs / AlyGa1 – yAs quantum well hetero-structures growth by MOVPE system. The main goal is to explore the ability of characterization techniques for multilayer structures like quantum wells. The characterization was performed using photoreflectance spectroscopy, surface photovoltaic spectroscopy and X-ray diffraction. The experimental results are verified by numerical simulation.

  9. Structural and optical characteristics of AlxGa1-xN/AlN superlattice

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    AlN/Al0.3Ga0.7N superlattices were grown on (0001) sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The superlattice period varies from 6 to 30. The layer thickness of different period stack was designed. GaN or AlGaN template was employed for growing AlN/AlGaN superlattices. Reflectivity, SEM, AFM and XRD data of the AlxGa1-xN/AlN superlattices are presented. It is found that the templates used have an intensive impact on surface roughness and interfacial properties of following AlN/AlGaN superlattices. The result of atomic force microscopy indicates that AlN/AlGaN superlattices grown on GaN template exhibit quasi-two-dimensional growth mode. The resulting superlattice has a smooth surface morphology and distinct interface. No crack is observed in the area of a 2-inch wafer.

  10. Dynamics of relaxation and trapping of excitons in AlxGa1-xAs films

    International Nuclear Information System (INIS)

    Carrier relaxation in high quality AlxGa1-xAs (x up to 5%) epilayers has been investigated by means of time resolved photoluminescence. The time for the excitonic PL to reach the maximum intensity shows a non-monotonic behaviour with increasing excitation density, which is attributed to the competition between exciton localization and carrier-carrier scattering. The increase of the Al content enhances the alloy scattering and increases the number of localization sites, moderately accelerating the dynamics. A four-level rate equation model qualitatively describes the influence of trapping in the exciton dynamics at low excitation densities. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Bond length variation in Ga1-xInxAs crystals from the Tersoff potential

    Science.gov (United States)

    Titantah, J. T.; Lamoen, D.; Schowalter, M.; Rosenauer, A.

    2007-06-01

    In this work we show that a reparametrized Tersoff potential accurately reproduces the bond length variations observed in ternary Ga1-xInxAs mixed crystals. The reparametrization is based on accurate first-principles electronic structure calculations. Previous parametrizations of the Tersoff potential for GaAs and InAs structures, although they accurately reproduce the properties of the zinc-blende GaAs and InAs crystals, are shown to be unable to reproduce the bond length variations in these mixed crystals. In addition to correcting the bond length inconsistencies, the new set of parameters is also shown to yield the elastic constants of GaAs and InAs that agree fairly well with measurements and to reproduce accurately their respective melting temperature.

  12. Fe x Ga1- x BO3 single crystals: synthesis and characterization

    Science.gov (United States)

    Yagupov, S.; Strugatsky, M.; Seleznyova, K.; Maksimova, E.; Nauhatsky, I.; Yagupov, V.; Milyukova, E.; Kliava, J.

    2015-10-01

    A series of Fe x Ga1- x BO3 single crystals in the concentration range 0 ≤ x ≤ 1 has been synthesized by solution in the melt method. In order to determine optimal crystallization regimes, two settings have been worked out and applied in the present study: the first one, for precise differential thermal analysis and the second one, for the probe method. X-ray fluorescence and X-ray diffraction analysis have allowed accurate determination of iron contents and lattice parameters for synthesized crystals with different x. Computer-assisted EPR studies of Fe3+ have revealed a high perfection of the crystals: low degree of disorder and the absence of twinning.

  13. Origin of background electron concentration in InxGa1-xN alloys

    Science.gov (United States)

    Pantha, B. N.; Wang, H.; Khan, N.; Lin, J. Y.; Jiang, H. X.

    2011-08-01

    The origin of high background electron concentration (n) in InxGa1-xN alloys has been investigated. A shallow donor was identified as having an energy level (ED1) that decreases with x (ED1 = 16 meV at x = 0 and ED1 = 0 eV at x ˜ 0.5) and that crossover the conduction band at x ˜ 0.5. This shallow donor is believed to be the most probable cause of high n in InGaN. This understanding is consistent with the fact that n increases sharply with an increase in x and becomes constant for x > 0.5. A continuous reduction in n was obtained by increasing the V/III ratio during the epilayer growth, suggesting that nitrogen vacancy-related impurities are a potential cause of the shallow donors and high background electron concentration in InGaN.

  14. Microstructure of InxGa1−xN nanorods grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Transmission electron microscopy is used to examine the structure and composition of InxGa1−xN nanorods grown by plasma-assisted molecular beam epitaxy. The results confirm a core–shell structure with an In-rich core and In-poor shell resulting from axial and lateral growth sectors respectively. Atomic resolution mapping by energy-dispersive x-ray microanalysis and high angle annular dark field imaging show that both the core and the shell are decomposed into Ga-rich and In-rich platelets parallel to their respective growth surfaces. It is argued that platelet formation occurs at the surfaces, through the lateral expansion of surface steps. Studies of nanorods with graded composition show that decomposition ceases for x ≥ 0.8 and the ratio of growth rates, shell:core, decreases with increasing In concentration. (paper)

  15. MOCVD Growth and Characterization of Epitaxial AlxGa1-xN Films

    Institute of Scientific and Technical Information of China (English)

    LI Liang; GONG Hai-Mei; ZHENG You-Dou; ZHANG Rong; XIE Zi-Li; ZHANG Yu; XIU Xiang-Qian; LIU Bin; CHEN Lin; YU Hui-Qiang; HAN Ping

    2007-01-01

    We study the growth of AlxGa1-x N epilayers on (0001) sapphire by low-pressure MOCVD, using a low-temperature A1N buffer. By varying the input now rates of trimethylgallium (TMGa),e obtain crack-free AlGaN films in the whole range of composition. A linear relationship between gas and solid Al content is observed. The structural properties of the layers (x = 0 - 1) are investigated by x-ray diffraction, atomic force microscopy (AFM) and scanning electron microscopy (SEM).It is found that a two-direction growth appears along the c-axis and the (10(1)1) directions for x≥0.45.From the results of Raman spectroscopy, we suggest that the compressive stain and the lack of mobility of Al adatoms can induce the formation of (1011) grains.

  16. Structural and optical characteristics of AlxGa1-xN/AIN superlattice

    Institute of Scientific and Technical Information of China (English)

    XIE ZiLi; SHI Yi; ZHENG YouDou; ZHANG Rong; JIANG RuoLian; LIU Bin; GONG HaiMei; XIU XiangQian; CHEN Peng; LU Hai; HAN Ping

    2009-01-01

    AIN/Al0.3Ga0.7N superlattices were grown on (0001) sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The superlattice period varies from 6 to 30. The layer thickness of different period stack was designed. GaN or AiGaN template was employed for growing AIN/AIGaN superlattices. Re-flectivity, SEM, AFM and XRD data of the AlxGa1-xN/AIN superlattices are presented. It is found that the templates used have an intensive impact on surface roughness and interfacial properties of following AIN/AIGaN superlattices. The result of atomic force microscopy indicates that AIN/AIGaN superlattices grown on GaN template exhibit quasi-two-dimensional growth mode. The resulting superlattice has a smooth surface morphology and distinct interface. No crack is observed in the area of a 2-inch wafer.

  17. Detection Wavelength of Strained Inx Ga1-x As/GaAs Very-Long-Wavelength Quantum Well Infrared Photodetectors

    Institute of Scientific and Technical Information of China (English)

    XIONG Da-Yuan; LI Ning; LI Zhi-Feng; ZHEN Hong-Lou; LU Wei

    2007-01-01

    Detection wavelength is one of the key performance indices of infrared photodetectors. We study the character of detection wavelength of the strained InxGa1-xAs/GaAs very-long-wavelength (>12μm) quantum well infrared photodetectors (VLW-QWIPs) characterized by the photoluminescence (PL) and photocurrent (PC) measurements. Based on the theoretical calculation and experimental data, we have built a practical model for the InxGa1-xAs/GaAs strained VLW-QWIPs, from which the interband transitions, intersubband transition and peak detection wavelength can be determined. Afterwards, the dependences of detection wavelength and device operation mode on the In mole fraction and InxGa1-xAs well width are presented, which will be helpful for device design and optimization.

  18. X-ray Reciprocal Space Mapping of Graded Al x Ga1 - x N Films and Nanowires.

    Science.gov (United States)

    Stanchu, Hryhorii V; Kuchuk, Andrian V; Kladko, Vasyl P; Ware, Morgan E; Mazur, Yuriy I; Zytkiewicz, Zbigniew R; Belyaev, Alexander E; Salamo, Gregory J

    2016-12-01

    The depth distribution of strain and composition in graded Al x Ga1 - x N films and nanowires (NWs) are studied theoretically using the kinematical theory of X-ray diffraction. By calculating [Formula: see text] reciprocal space maps (RSMs), we demonstrate significant differences in the intensity distributions from graded Al x Ga1 - x N films and NWs. We attribute these differences to relaxation of the substrate-induced strain on the NWs free side walls. Finally, we demonstrate that the developed X-ray reciprocal space map model allows for reliable depth profiles of strain and Al composition determination in both Al x Ga1 - x N films and NWs.

  19. X-ray Reciprocal Space Mapping of Graded Al x Ga1 - x N Films and Nanowires.

    Science.gov (United States)

    Stanchu, Hryhorii V; Kuchuk, Andrian V; Kladko, Vasyl P; Ware, Morgan E; Mazur, Yuriy I; Zytkiewicz, Zbigniew R; Belyaev, Alexander E; Salamo, Gregory J

    2016-12-01

    The depth distribution of strain and composition in graded Al x Ga1 - x N films and nanowires (NWs) are studied theoretically using the kinematical theory of X-ray diffraction. By calculating [Formula: see text] reciprocal space maps (RSMs), we demonstrate significant differences in the intensity distributions from graded Al x Ga1 - x N films and NWs. We attribute these differences to relaxation of the substrate-induced strain on the NWs free side walls. Finally, we demonstrate that the developed X-ray reciprocal space map model allows for reliable depth profiles of strain and Al composition determination in both Al x Ga1 - x N films and NWs. PMID:26860714

  20. Effects of varying indium composition on the thermoelectric properties of In x Ga1- x Sb ternary alloys

    Science.gov (United States)

    Nirmal Kumar, V.; Arivanandan, M.; Koyoma, T.; Udono, H.; Inatomi, Y.; Hayakawa, Y.

    2016-10-01

    In x Ga1- x Sb ( x = 0-1), a III-V ternary alloy, was grown by melt solidification process. The effects of varying indium composition on the thermoelectric properties of In x Ga1- x Sb polycrystals were studied for the first time. The segregations of indium and gallium elements were observed in the grown crystals, and the defects present in crystals were revealed by etching process. Room-temperature Raman measurement revealed that the dominant optical modes of phonon vibrations in InSb and GaSb binaries were suppressed in In x Ga1- x Sb ternaries. The in-phase vibrations of acoustic mode phonons were scattered more effectively in In x Ga1- x Sb by the present defects, and the relative value of lattice thermal conductivity was reduced. Thus, the thermal conductivity of InSb and GaSb binaries was drastically reduced in In x Ga1- x Sb by alloy scattering. InSb indicated the highest ZT 0.51 because of its higher power factor 70 µW/cmK2. Next to InSb, In0.8Ga0.2Sb had higher ZT value of 0.29 at 600 K among the In x Ga1- x Sb ternaries. The ZT of In0.8Ga0.2Sb was increased about 30 times than that of GaSb by the increase of power factor as well as the decrease of thermal conductivity.

  1. Computational Investigation of InxGa1-xN/InN Quantum-Dot Intermediate-Band Solar Cell

    Institute of Scientific and Technical Information of China (English)

    DENG Qing-Wen; WANG Zhan-Guo; HOU Xun; WANG Xiao-Liang; YANG Cui-Bai; XIAO Hong-Ling; WANG Cui-Mei; YIN Hai-Bo; HOU Qi-Feng; BI Yang; LI Jin-Min

    2011-01-01

    An InxGa1-xN/InN quantum-dot intermediate-band solar cell is calculated by means of solving the Schrodinger equation according to the Kronig-Penney model. Based on particular assumptions, the power conversion efficiency is worked out. The results reveal that the InxGa1-xN/InN quantum-dot intermediate-band solar cell manifests much larger power conversion efficiency than that of p-n junction solar cells, and the power conversion efficiency strongly depends on the size of the quantum dot and the interdot distance.

  2. Isolation, screening and identifi cation of Bacillus spp. as direct-fed microbial candidates for aflatoxin B1 biodegradation

    Institute of Scientific and Technical Information of China (English)

    Rosario; Galarza-Seeber; Juan; David; Latorre; Xochitl; Hernandez-Velasco; Amanda; Drake; Wolfenden; Lisa; Renee; Bielke; Anita; Menconi; Billy; Marshall; Hargis; Guillermo; Tellez

    2015-01-01

    Objective: To evaluate the ability of Bacillus spp. as direct-fed microbials(DFM) to biodegrade al atoxin B1(AFB1) by using an in vitro digestive model simulating in vivo conditions.Methods: Sixty-nine Bacillus isolates were obtained from intestines, and soil samples were screened by using a selective media method against 0.25 and 1.00 μg/m L of AFB1 in modii ed Czapek-Dox medium. Plates were incubated at 37 °C and observed every two days for two weeks. Physiological properties of the three Bacillus spp. candidates were characterized biochemically and by 16 S r RNA sequence analyzes for identii cation. Tolerance to acidic p H, osmotic concentrations of Na Cl, bile salts were tested, and antimicrobial sensitivity proi les were also determined. Bacillus candidates were individually sporulated by using a solid fermentation method and combined. Spores were incorporated into 1 of 3 experimental feed groups: 1) Negative control group, with unmedicated starter broiler feed without AFB1; 2) Positive control group, with negative control feed contaminated with 0.01% AFB1; 3) DFM treated group, with positive control feed supplemented with 109 spores/g. After digestion time(3:15 h), supernatants and digesta were collected for high-performance liquid chromatography l uorescence detection analysis by triplicate.Results: Three out of those sixty-nine DFM candidates showed ability to biodegrade AFB1 in vitro based on growth as well as reduction of l uorescence and area of clearance around each colony in modii ed Czapek-Dox medium which was clearly visible under day light after 48 h of evaluation. Analysis of 16S-DNA identii ed the strains as Bacillus amyloliquefaciens, Bacillus megaterium and Bacillus subtilis. The three Bacillus strains were tolerant to acidic conditions(p H 2.0), tolerant to a high osmotic pressure(Na Cl at 6.5%), and were able to tolerate 0.037% bile salts after 24 h of incubation. No signii cant dif erences(P > 0.05) were observed in the concentrations of

  3. Isolation, screening and identification of Bacillus spp. as direct-fed microbial candidates for aflatoxin B1 biodegradation

    Institute of Scientific and Technical Information of China (English)

    Rosario Galarza-Seeber; Juan David Latorre; Xochitl Hernandez-Velasco; Amanda Drake Wolfenden; Lisa Renee Bielke; Anita Menconi; Billy Marshall Hargis; Guillermo Tellez

    2015-01-01

    To evaluate the ability of Bacillus spp. as direct-fed microbials (DFM) to biodegrade aflatoxin B1 (AFB1) by using an in vitro digestive model simulating in vivo conditions. Methods: Sixty-nine Bacillus isolates were obtained from intestines, and soil samples were screened by using a selective media method against 0.25 and 1.00 µg/mL of AFB1 in modified Czapek-Dox medium. Plates were incubated at 37 °C and observed every two days for two weeks. Physiological properties of the three Bacillus spp. candidates were characterized biochemically and by 16S rRNA sequence analyzes for identification. Tolerance to acidic pH, osmotic concentrations of NaCl, bile salts were tested, and antimicrobial sensitivity profiles were also determined. Bacillus candidates were individually sporulated by using a solid fermentation method and combined. Spores were incorporated into 1 of 3 experimental feed groups: 1) Negative control group, with unmedicated starter broiler feed without AFB1; 2) Positive control group, with negative control feed contaminated with 0.01% AFB1; 3) DFM treated group, with positive control feed supplemented with 109 spores/g. After digestion time (3:15 h), supernatants and digesta were collected for high-performance liquid chromatography fluorescence detection analysis by triplicate. Results: Three out of those sixty-nine DFM candidates showed ability to biodegrade AFB1 in vitro based on growth as well as reduction of fluorescence and area of clearance around each colony in modified Czapek-Dox medium which was clearly visible under day light after 48 h of evaluation. Analysis of 16S-DNA identified the strains as Bacillus amyloliquefaciens, Bacillus megaterium and Bacillus subtilis. The three Bacillus strains were tolerant to acidic conditions (pH 2.0), tolerant to a high osmotic pressure (NaCl at 6.5%), and were able to tolerate 0.037%bile salts after 24 h of incubation. No significant differences (P > 0.05) were observed in the concentrations of AFB1 in

  4. Inactivation of Spores of Bacillus anthracis Sterne, Bacillus cereus, and Bacillus thuringiensis subsp. israelensis by Chlorination

    OpenAIRE

    Rice, E W; Adcock, N. J.; Sivaganesan, M; Rose, L. J.

    2005-01-01

    Three species of Bacillus were evaluated as potential surrogates for Bacillus anthracis for determining the sporicidal activity of chlorination as commonly used in drinking water treatment. Spores of Bacillus thuringiensis subsp. israelensis were found to be an appropriate surrogate for spores of B. anthracis for use in chlorine inactivation studies.

  5. Study of Dislocation-Ordered In(x)Ga(1-x)As/GaAs Quantum Dots

    Science.gov (United States)

    Leon, Rose

    2003-01-01

    A report describes an experimental study of dislocation-induced spatial ordering of quantum dots (QDs) comprising nanometer-sized In(x)Ga(1-x)As islands surrounded by GaAs. Metastable heteroepitaxial structures were grown by molecular-beam epitaxy of In(x)Ga(1-x)As onto n+ GaAs and semi-insulating GaAs substrates. Then the structures were relaxed during a post-growth annealing/self-organizing process leading to the formation of surface undulations that acted as preferential sites for the nucleation of QDs. Structural effects of annealing times and temperatures on the strain-relaxed In(x)Ga(1-x)As/GaAs and the subsequent spatial ordering of the QDs were analyzed by atomic-force microscopy and transmission electron microscopy. Continuous-wave spectral and time-resolved photoluminescence (PL) measurements were performed to study the effects, upon optical properties, of increased QD positional ordering, increased QD uniformity, and proximity of QDs to arrays of dislocations. PL spectral peaks of ordered QD structures formed on strain-relaxed In(x)Ga(1-x)As/GaAs layers were found to be narrower than those of structures not so formed and ordered. Rise and decay times of time-resolved PL were found to be lower at lower temperatures -- apparently as a consequence of decreased carrier-transport times within the barriers surrounding the QDs.

  6. Anticrossing Gap between Pairs of the Subbands in AlxGa1-xN/GaN Double Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    LEI Shuang-Ying; SHEN Bo; ZHANG Guo-Yi

    2006-01-01

    @@ Dependences of anticrossing gaps between pairs of subbands in Alx Ga1-x N/GaN double quantum wells (DQWs) on the width and the Al composition of the central barrier of the DQWs and on the well width of the DQWs have been investigated by solving the Schrodinger and Poisson equations self-consistently.

  7. Ion-implantation-induced amorphization of InxGa1-xP alloys as functions of stoichiometry and temperature

    Science.gov (United States)

    Hussain, Z. S.; Wendler, E.; Wesch, W.; Schnohr, C. S.; Ridgway, M. C.

    2016-05-01

    Rutherford Backscattering Spectrometry/Channeling and Extended X-ray Absorption Fine Structure measurements have been combined to investigate the amorphization of InxGa1-xP alloys at 15 and 300 K for selected stoichiometries representative of the entire stoichiometric range. The amorphization kinetics differs considerably for the two temperatures: at 15 K, the amorphization kinetics of InxGa1-xP is intermediate between the two binary extremes while at 300 K, InxGa1-xP is more easily amorphized than both InP and GaP. Direct impact and stimulated amorphization both contribute to the amorphization process at 15 K. Dynamic annealing via thermally induced Frenkel pair recombination reduces the influence of direct impact amorphization at 300 K such that the stimulated amorphization is dominant. At this temperature, stimulated amorphization in ternary InxGa1-xP alloys is supported by the structural disorder inherent from the bimodal bond length distribution.

  8. Comparison of Bacillus thuringiensis and Bacillus cereus

    International Nuclear Information System (INIS)

    Bacillus cereus and Bacillus thuringiensis are closely related, spore forming soil bacteria. B. thuringiensis produces insecticidal crystal proteins during sporulation and these toxins are the most important biopesticides in the world today. Genomes of the B. thuringiensis and B. cereus strains were analysed by pulsed field gel electrophoresis after treatment of the DNA with the restriction enzyme NotI. The NotI fingerprint patterns varied both within the B. thuringiensis and the B. cereus strains. The size of the fragments varied between 15 and 1350 kb. When physical maps of the B. thuringiensis and B. cereus strains were compared, B. thuringiensis appeared to be as closely related to B. cereus as the B. cereus strains were to each other. Nine out of 12 B. thuringiensis strains and 18 out of 25 B. cereus strains produced enterotoxins. The close relationship between B. thuringiensis and B. cereus should be taken into consideration when B. thuringiensis is used as a biopesticide. (author). 10 refs, 4 figs, 1 tab

  9. MBE Grown In x Ga1- x N Thin Films with Bright Visible Emission Centered at 550 nm

    Science.gov (United States)

    Dasari, K.; Thapa, B.; Wang, J.; Wright, J.; Kaya, S.; Jadwisienczak, W. M.; Palai, R.

    2016-04-01

    The In x Ga1- x N thin films with indium content of x = 14-18 at.% were successfully grown by using molecular beam epitaxy (MBE) at high growth temperatures from 650°C to 800°C. In situ reflection high-energy electron diffraction (RHEED) of the In x Ga1- x N films confirmed the Stranski-Krastanov growth mode. X-ray diffraction (XRD) of the films confirmed their highly crystalline nature having c-axis orientation with a small fraction of secondary InN phase admixture. High-resolution cross-sectional scanning electron microscopy images showed two-dimensional epilayers growth with thickness of about ˜260 nm. The high growth temperature of In x Ga1- x N epilayers is found to be favorable to facilitate more GaN phase than InN phase. All the fundamental electronic states of In, Ga, and N were identified by x-ray photoelectron spectroscopy (XPS) and the indium composition has been calculated from the obtained XPS spectra with CASAXPS software. The composition calculations from XRD, XPS and photoluminescence closely match each other. The biaxial strain has been calculated and found to be increasing with the In content. Growing In x Ga1- x N at high temperatures resulted in the reduction in stress/strain which affects the radiative electron-hole pair recombination. The In x Ga1- x N film with lesser strain showed a brighter and stronger green emission than films with the larger built-in strain. A weak S-shaped near band edge emission profile confirms the relatively homogeneous distribution of indium.

  10. Characterization of Bacillus cereus

    NARCIS (Netherlands)

    Wijnands LM; Dufrenne JB; Leusden FM; MGB

    2002-01-01

    Bacillus cereus is a ubiquitary microorganism that may cause food borne disease. Pathogenicity, however, depends on various characteristics such as the ability to form (entero)-toxin(s) that can not be detected by microbiological methods. Further characterization of pathogenic properties is not only

  11. Biodiversity in Bacillus cereus

    NARCIS (Netherlands)

    Pielaat A; Fricker M; Nauta MJ; Leusden FM van; MGB

    2006-01-01

    Experiments have been performed by different partners to identify variability in properties of Bacillus cereus strains that contribute to the extent of their virulence as part of an EU project. To this end, 100 B. cereus strains were selected and screened for biological properties, such as toxin pro

  12. Essential Bacillus subtilis genes

    DEFF Research Database (Denmark)

    Kobayashi, K.; Ehrlich, S.D.; Albertini, A.;

    2003-01-01

    To estimate the minimal gene set required to sustain bacterial life in nutritious conditions, we carried out a systematic inactivation of Bacillus subtilis genes. Among approximate to4,100 genes of the organism, only 192 were shown to be indispensable by this or previous work. Another 79 genes we...

  13. Structure and strain relaxation effects of defects in InxGa1-xN epilayers

    Science.gov (United States)

    Rhode, S. L.; Fu, W. Y.; Moram, M. A.; Massabuau, F. C.-P.; Kappers, M. J.; McAleese, C.; Oehler, F.; Humphreys, C. J.; Dusane, R. O.; Sahonta, S.-L.

    2014-09-01

    The formation of trench defects is observed in 160 nm-thick InxGa1-xN epilayers with x ≤ 0.20, grown on GaN on (0001) sapphire substrates using metalorganic vapour phase epitaxy. The trench defect density increases with increasing indium content, and high resolution transmission electron microscopy shows an identical structure to those observed previously in InGaN quantum wells, comprising meandering stacking mismatch boundaries connected to an I1-type basal plane stacking fault. These defects do not appear to relieve in-plane compressive strain. Other horizontal sub-interface defects are also observed within the GaN pseudosubstrate layer of these samples and are found to be pre-existing threading dislocations which form half-loops by bending into the basal plane, and not basal plane stacking faults, as previously reported by other groups. The origins of these defects are discussed and are likely to originate from a combination of the small in-plane misorientation of the sapphire substrate and the thermal mismatch strain between the GaN and InGaN layers grown at different temperatures.

  14. Phonon-drag magnetothermopower oscillations in GaAs/AsxGa1-xAs heterojunctions

    Science.gov (United States)

    Fromhold, T. M.; Butcher, P. N.; Qin, G.; Mulimani, B. G.; Oxley, J. P.; Gallagher, B. L.

    1993-08-01

    The tensor M--> which determines the heat flux U=M-->E in a weak electric field E is calculated for a two-dimensional electron gas in a perpendicular magnetic field B. The dominant phonon-drag contribution is calculated using Boltzmann transport, allowing for the two-dimensional (2D) character of the electron gas. The Landau levels are taken to have Gaussian line shapes with the rms level width γ=CB1/2 where C is the only adjustable parameter. Setting C=0.5 meV T-1/2 gives good agreement with new experimental values of Myx obtained for GaAs/AlxGa1-xAs heterojunctions when B varies between 2 and 10 T and the temperature varies between 1 and 5 K. Myx is negative and contains strong magneto-oscillations in phase with the density of states at the Fermi level. The model also predicts Mxx=0, whereas experiment gives peak values of ||Mxx|| up to 60% of those of ||Myx||. We demonstrate that setting Mxx=0 in the calculation has little effect on the predicted thermopower component Sxx but yields poor approximations to the experimental values of Syx.

  15. Maintenance metabolism and carbon fluxes in Bacillus species

    Directory of Open Access Journals (Sweden)

    Decasper Seraina

    2008-06-01

    Full Text Available Abstract Background Selection of an appropriate host organism is crucial for the economic success of biotechnological processes. A generally important selection criterion is a low maintenance energy metabolism to reduce non-productive consumption of substrate. We here investigated, whether various bacilli that are closely related to Bacillus subtilis are potential riboflavin production hosts with low maintenance metabolism. Results While B. subtilis exhibited indeed the highest maintenance energy coefficient, B. licheniformis and B. amyloliquefaciens exhibited only statistically insignificantly reduced maintenance metabolism. Both B. pumilus and B. subtilis (natto exhibited irregular growth patterns under glucose limitation such that the maintenance metabolism could not be determined. The sole exception with significantly reduced maintenance energy requirements was the B. licheniformis strain T380B. The frequently used spo0A mutation significantly increased the maintenance metabolism of B. subtilis. At the level of 13C-detected intracellular fluxes, all investigated bacilli exhibited a significant flux through the pentose phosphate pathway, a prerequisite for efficient riboflavin production. Different from all other species, B. subtilis featured high respiratory tricarboxylic acid cycle fluxes in batch and chemostat cultures. In particular under glucose-limited conditions, this led to significant excess formation of NADPH of B. subtilis, while anabolic consumption was rather balanced with catabolic NADPH formation in the other bacilli. Conclusion Despite its successful commercial production of riboflavin, B. subtilis does not seem to be the optimal cell factory from a bioenergetic point of view. The best choice of the investigated strains is the sporulation-deficient B. licheniformis T380B strain. Beside a low maintenance energy coefficient, this strain grows robustly under different conditions and exhibits only moderate acetate overflow, hence

  16. Taxonomy Icon Data: Bacillus subtilis [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available g Bacillus_subtilis_S.png Bacillus_subtilis_NS.png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Bacillus...+subtilis&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Bacillus+subtilis&t=NL http://biosciencedbc.jp/taxonomy..._icon/icon.cgi?i=Bacillus+subtilis&t=S http://biosciencedbc.jp/taxonomy..._icon/icon.cgi?i=Bacillus+subtilis&t=NS http://togodb.biosciencedbc.jp/togodb/view/taxonomy_icon_comment_en?species_id=214 ...

  17. Cyclic Lipopeptide Biosynthetic Genes and Products, and Inhibitory Activity of Plant-Associated Bacillus against Phytopathogenic Bacteria.

    Directory of Open Access Journals (Sweden)

    Isabel Mora

    Full Text Available The antibacterial activity against bacterial plant pathogens and its relationships with the presence of the cyclic lipopeptide (cLP biosynthetic genes ituC (iturin, bmyB (bacillomycin, fenD (fengycin and srfAA (surfactin, and their corresponding antimicrobial peptide products have been studied in a collection of 64 strains of Bacillus spp. isolated from plant environments. The most frequent antimicrobial peptide (AMP genes were bmyB, srfAA and fenD (34-50% of isolates. Most isolates (98.4% produced surfactin isoforms, 90.6% iturins and 79.7% fengycins. The antibacterial activity was very frequent and generally intense among the collection of strains because 75% of the isolates were active against at least 6 of the 8 bacterial plant pathogens tested. Hierarchical and correspondence analysis confirmed the presence of two clearly differentiated groups. One group consisted of Bacillus strains that showed a strong antibacterial activity, presented several cLPs genes and produced several isoforms of cLPs simultaneously, mainly composed of B. subtilis and B. amyloliquefaciens, although the last one was exclusive to this group. Another group was characterized by strains with very low or none antibacterial activity, that showed one or none of the cLP genes and produced a few or none of the corresponding cLPs, and was the most heterogenous group including B. subtilis, B. licheniformis, B. megaterium, B. pumilus, B. cereus and B. thuringiensis, although the last two were exclusive to this group. This work demonstrated that the antagonistic capacity of plant-associated Bacillus against plant pathogenic bacteria is related to the presence of cLP genes and to the production of the corresponding cLPs, and it is mainly associated to the species B. subtilis and B. amyloliquefaciens. Our findings would help to increase the yield and efficiency of screening methods to obtain candidate strains to biocontrol agents with a mechanism of action relaying on the

  18. Cyclic Lipopeptide Biosynthetic Genes and Products, and Inhibitory Activity of Plant-Associated Bacillus against Phytopathogenic Bacteria.

    Science.gov (United States)

    Mora, Isabel; Cabrefiga, Jordi; Montesinos, Emilio

    2015-01-01

    The antibacterial activity against bacterial plant pathogens and its relationships with the presence of the cyclic lipopeptide (cLP) biosynthetic genes ituC (iturin), bmyB (bacillomycin), fenD (fengycin) and srfAA (surfactin), and their corresponding antimicrobial peptide products have been studied in a collection of 64 strains of Bacillus spp. isolated from plant environments. The most frequent antimicrobial peptide (AMP) genes were bmyB, srfAA and fenD (34-50% of isolates). Most isolates (98.4%) produced surfactin isoforms, 90.6% iturins and 79.7% fengycins. The antibacterial activity was very frequent and generally intense among the collection of strains because 75% of the isolates were active against at least 6 of the 8 bacterial plant pathogens tested. Hierarchical and correspondence analysis confirmed the presence of two clearly differentiated groups. One group consisted of Bacillus strains that showed a strong antibacterial activity, presented several cLPs genes and produced several isoforms of cLPs simultaneously, mainly composed of B. subtilis and B. amyloliquefaciens, although the last one was exclusive to this group. Another group was characterized by strains with very low or none antibacterial activity, that showed one or none of the cLP genes and produced a few or none of the corresponding cLPs, and was the most heterogenous group including B. subtilis, B. licheniformis, B. megaterium, B. pumilus, B. cereus and B. thuringiensis, although the last two were exclusive to this group. This work demonstrated that the antagonistic capacity of plant-associated Bacillus against plant pathogenic bacteria is related to the presence of cLP genes and to the production of the corresponding cLPs, and it is mainly associated to the species B. subtilis and B. amyloliquefaciens. Our findings would help to increase the yield and efficiency of screening methods to obtain candidate strains to biocontrol agents with a mechanism of action relaying on the production of

  19. Photoelectric behaviour of lattice-matched GaAs/Alx Ga1-xAs quantum well electrodes

    Institute of Scientific and Technical Information of China (English)

    刘尧; 肖绪瑞; 曾一平; 闫春辉; 郑海群; 孙殿照

    1997-01-01

    The photoelectric properties of the lattice-matched GaAs/AlxGa1-xAs quantum well electrodes and the influence of the electrode structure such as well width, the thickness of outer barrier and the number of period were studied in a nonaqueous electrolyte. A new kind of structure of multiple quantum well electrode with varied well width, possessing the quantum yield three times that of GaAs bulk materials, was designed and fabricated.

  20. Pressure and doping dependent elastic and thermodynamical properties of Ga1-xInxP mixed valent compounds

    International Nuclear Information System (INIS)

    Using a phenomenological lattice model incorporating the long-range Coulomb and charge transfer caused by the deformation of the electron shells of the overlapping ions and the Hafemeister and Flygare type short-range overlap repulsion extended upto the second neighbor ions and the van der Waals (vdW) interaction, we present a comprehensive study to understand the effects of pressure on the elastic behavior as ductility (brittleness) and thermodynamical properties of Ga1-xInxP. Estimated phase-transition pressure and the vast volume discontinuity in pressure-volume phase diagram confirm the structural phase transition from zinc blende (B3) to rock salt (B1) phase. From the elastic constants the Poisson's ratio ν, the ratio RS/B of S (Voigt averaged shear modulus) over B (bulk modulus), elastic wave velocity, average wave velocity and thermodynamical property Debye temperature is calculated. The Poisson's ratio ν and the ratio RS/B allows one to conclude that Ga1-xInxP is brittle in zinc blende (B3) and ductile nature is inferred in sodium chloride (B1) phase. To our knowledge this is the first quantitative theoretical prediction of the doping and pressure dependent elastic properties for mixed valent Ga1-xInxP compounds and still awaits experimental confirmations.

  1. Optimization of growth parameters for MOVPE-grown GaSb and Ga1−xInxSb

    International Nuclear Information System (INIS)

    The triethylgallium/trimethylantimony (TEGa/TMSb) precursor combination was used for the metal-organic vapour phase epitaxial growth of GaSb at a growth temperature of 520 °C at atmospheric pressure. Trimethylindium was added in the case of Ga1−xInxSb growth. The effects of group V flux to group III flux ratio (V/III ratio) on the crystallinity and optical properties of GaSb layers are reported. It has been observed from the crystalline quality and optical properties that nominal V/III ratios of values greater than unity are required for GaSb epitaxial layers grown at this temperature. It has also been shown that Ga1−xInxSb can be grown using TEGa as a source of gallium species at atmospheric pressure. The relationship between Ga1−xInxSb vapour composition and solid composition has been studied at a V/III ratio of 0.78.

  2. Fluorescent Amplified Fragment Length Polymorphism Analysis of Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis Isolates

    OpenAIRE

    Hill, Karen K.; Ticknor, Lawrence O.; Okinaka, Richard T.; Asay, Michelle; Blair, Heather; Bliss, Katherine A.; Laker, Mariam; Pardington, Paige E.; Richardson, Amber P.; Tonks, Melinda; Beecher, Douglas J.; Kemp, John D.; Kolstø, Anne-Brit; Wong, Amy C. Lee; Keim, Paul

    2004-01-01

    DNA from over 300 Bacillus thuringiensis, Bacillus cereus, and Bacillus anthracis isolates was analyzed by fluorescent amplified fragment length polymorphism (AFLP). B. thuringiensis and B. cereus isolates were from diverse sources and locations, including soil, clinical isolates and food products causing diarrheal and emetic outbreaks, and type strains from the American Type Culture Collection, and over 200 B. thuringiensis isolates representing 36 serovars or subspecies were from the U.S. D...

  3. Bacillus oryzicola sp. nov., an Endophytic Bacterium Isolated from the Roots of Rice with Antimicrobial, Plant Growth Promoting, and Systemic Resistance Inducing Activities in Rice

    Directory of Open Access Journals (Sweden)

    Eu Jin Chung

    2015-06-01

    Full Text Available Biological control of major rice diseases has been attempted in several rice-growing countries in Asia during the last few decades and its application using antagonistic bacteria has proved to be somewhat successful for controlling various fungal diseases in field trials. Two novel endophytic Bacillus species, designated strains YC7007 and YC7010T, with anti-microbial, plant growth-promoting, and systemic resistance-inducing activities were isolated from the roots of rice in paddy fields at Jinju, Korea, and their multifunctional activities were analyzed. Strain YC7007 inhibited mycelial growth of major rice fungal pathogens strongly in vitro. Bacterial blight and panicle blight caused by Xanthomonas oryzae pv. oryzae (KACC 10208 and Burkholderia glumae (KACC 44022, respectively, were also suppressed effectively by drenching a bacterial suspension (10⁷ cfu/ml of strain YC7007 on the rhizosphere of rice. Additionally, strain YC7007 promoted the growth of rice seedlings with higher germination rates and more tillers than the untreated control. The taxonomic position of the strains was also investigated. Phylogenetic analyses based on 16S rRNA gene sequences indicated that both strains belong to the genus Bacillus, with high similarity to the closely related strains, Bacillus siamensis KACC 15859T (99.67%, Bacillus methylotrophicus KACC 13105T (99.65%, Bacillus amyloliquefaciens subsp. plantarum KACC 17177T (99.60%, and Bacillus tequilensis KACC 15944T (99.45%. The DNA-DNA relatedness value between strain YC7010T and the most closely related strain, B. siamensis KACC 15859T was 50.4±3.5%, but it was 91.5±11.0% between two strains YC7007 and YC7010T, indicating the same species. The major fatty acids of two strains were anteiso-C15:0 and iso C15:0. Both strains contained MK-7 as a major respiratory quinone system. The G+C contents of the genomic DNA of two strains were 50.5 mol% and 51.2 mol%, respectively. Based on these polyphasic studies, the

  4. Genome analysis shows Bacillus axarquiensis is not a later heterotypic synonym of Bacillus mojavensis; reclassification of Bacillus malacitensis and Brevibacterium halotolerans as heterotypic synonyms of Bacillus axarquiensis.

    Science.gov (United States)

    Dunlap, Christopher A; Bowman, Michael J; Schisler, David A; Rooney, Alejandro P

    2016-06-01

    Bacillus axarquiensis and Bacillus malacitensis were previously reported to be later heterotypic synonyms of Bacillus mojavensis, based primarily on DNA-DNA relatedness values. We have sequenced draft genomes of Bacillus axarquiensis NRRL B-41617T and Bacillus malacitensis NRRL B-41618T. Comparative genomics and DNA-DNA relatedness calculations showed that while Bacillus axarquiensis and Bacillus malacitensis are synonymous with each other, they are not synonymous with Bacillus mojavensis. In addition, a draft genome was completed for Brevibacterium halotolerans, a strain long suspected of being a Bacillus subtilis group member based on 16S rRNA similarities (99.8 % with Bacillus mojavensis). Comparative genomics and DNA-DNA relatedness calculations showed that Brevibacterium halotolerans is synonymous with Bacillus axarquiensis and Bacillus malacitensis. The pairwise in silico DNA-DNA hybridization values calculated in comparisons between the three conspecific strains were all greater than 92 %, which is well above the standard species threshold of 70 %. While the pairwise in silico DNA-DNA hybridization values calculated in comparisons of the three conspecific strains with Bacillus mojavensis were all less than 65 %. The combined results of our genotype and phenotype studies showed that Bacillus axarquiensis, Bacillus malacitensis and Brevibacterium halotolerans are conspecific and distinct from Bacillus mojavensis. Because the valid publication of the name Bacillus axarquiensis predates the publication of the name Bacillus malacitensis, we propose that Bacillus malacitensis be reclassified as a synonym of Bacillus axarquiensis. In addition, we propose to reclassify Brevibacterium halotolerans as a synonym of Bacillus axarquiensis. An amended description of Bacillus axarquiensis is provided.

  5. Genome analysis shows Bacillus axarquiensis is not a later heterotypic synonym of Bacillus mojavensis; reclassification of Bacillus malacitensis and Brevibacterium halotolerans as heterotypic synonyms of Bacillus axarquiensis.

    Science.gov (United States)

    Dunlap, Christopher A; Bowman, Michael J; Schisler, David A; Rooney, Alejandro P

    2016-06-01

    Bacillus axarquiensis and Bacillus malacitensis were previously reported to be later heterotypic synonyms of Bacillus mojavensis, based primarily on DNA-DNA relatedness values. We have sequenced draft genomes of Bacillus axarquiensis NRRL B-41617T and Bacillus malacitensis NRRL B-41618T. Comparative genomics and DNA-DNA relatedness calculations showed that while Bacillus axarquiensis and Bacillus malacitensis are synonymous with each other, they are not synonymous with Bacillus mojavensis. In addition, a draft genome was completed for Brevibacterium halotolerans, a strain long suspected of being a Bacillus subtilis group member based on 16S rRNA similarities (99.8 % with Bacillus mojavensis). Comparative genomics and DNA-DNA relatedness calculations showed that Brevibacterium halotolerans is synonymous with Bacillus axarquiensis and Bacillus malacitensis. The pairwise in silico DNA-DNA hybridization values calculated in comparisons between the three conspecific strains were all greater than 92 %, which is well above the standard species threshold of 70 %. While the pairwise in silico DNA-DNA hybridization values calculated in comparisons of the three conspecific strains with Bacillus mojavensis were all less than 65 %. The combined results of our genotype and phenotype studies showed that Bacillus axarquiensis, Bacillus malacitensis and Brevibacterium halotolerans are conspecific and distinct from Bacillus mojavensis. Because the valid publication of the name Bacillus axarquiensis predates the publication of the name Bacillus malacitensis, we propose that Bacillus malacitensis be reclassified as a synonym of Bacillus axarquiensis. In addition, we propose to reclassify Brevibacterium halotolerans as a synonym of Bacillus axarquiensis. An amended description of Bacillus axarquiensis is provided. PMID:27030978

  6. Species of Staphylococcus and Bacillus isolated from traditional sausages as producers of biogenic amines.

    Directory of Open Access Journals (Sweden)

    Roberto eBermúdez

    2012-04-01

    Full Text Available Histidine, lysine, ornithine and tyrosine decarboxylase activities were tested in 38 strains of Staphylococcus (15 of Staph. equorum, 11 of Staph. epidermidis, 7 of Staph. saprophyticus, and 5 of Staph. pasteuri and 19 strains of Bacillus (13 of B. subtilis and 6 of B. amyloliquefaciens isolated from two Spanish traditional sausage varieties.The four decarboxylase activities were present in most of the strains studied, but some variability was observed between strains within each microbial species.Accumulation of putrescine and cadaverine was assessed in the culture media of the strains that displayed ornithine and lysine decarboxylase activities. The aminogenic potential of the strains was low, with amounts accumulated lower than 25 mg/L for the putrescine and than 5 mg/L for the cadaverine, with the exception of a strain of Staph. equorum that produced 1415 mg/L of putrescine, and of a strain of Staph. epidermidis that accumulated 977 mg/L of putrescine and 36 mg/L of cadaverine.

  7. 闪锌矿Ga1-xCrxN铁磁性的密度泛函理论%Ferromagnetism in cubic Ga1-xCrxN by density functional calculations

    Institute of Scientific and Technical Information of China (English)

    熊志华; 孙振辉; 彭建飞; 李冬梅; 万齐欣; 刘国栋; 汪胜前; 施思齐

    2009-01-01

    We report the results of a theoretical study of magnetic coupling between Cr atoms doped in cu-bic GaN. The calculations are within the framework of density functional theory. By varying the concen-tration of doped Cr atoms and the sites they occupy,the electronic structure and magnetic properties of Cr - doped cubic GaN are calculated. It is found that the ferromagnetic phase of Ga1-xCrx N is energetically the most preferable state irrespective of the concentration and site occupation of the Cr atom. Cr atoms cluster around N and couple ferromagnetically,while the neighboring N atom is antiferromagnetically cou-pled to the Cr spin in the zinc blende Ga1-xCrx N. The origin of the ferromagnetism in the Cr -doped cu-bic GaN can be understood by double - exchange mechanism. The calculated results are consistent with the recent experimental discovery of ferromagnetism in Cr - doped GaN single cubic phase.%采用基于密度泛函的第一性原理方法计算了闪锌矿GaN掺Cr的电子结构和磁性.考虑不同掺杂浓度和位置,计算结果表明,Ga1-xCrxN呈现铁磁基态,Cr原子间是铁磁性耦合并团簇于N原子,Cr原子与最近邻N原子为反铁磁性耦合.我们采用双交换机制解释了磁性来源和机制.计算结果和最近闪锌矿GaN掺Cr的实验结果吻合.

  8. The usage of rice straw as a major substrate for the production of surfactin by Bacillus amyloliquefaciens XZ-173 in solid-state fermentation.

    Science.gov (United States)

    Zhu, Zhen; Zhang, Fengge; Wei, Zhong; Ran, Wei; Shen, Qirong

    2013-09-30

    Agro-industrial byproducts, especially rice straw, are potential resources. This work was aimed to utilize raw materials to produce value-added biosurfactant in solid-state fermentation (SSF). Rice straw and soybean flour were found efficient and selected as major substrates for surfactin production. The results of Plackett-Burman design indicated that glycerol, water content, inoculum size and temperature were the significant variables identified in the screen of nine total variables. The optimum values for the four significant variables were determined by the Box-Behnken design. The optimal surfactin production was obtained when the medium contained 5 g soybean flour, 4 g rice straw, 2% (w/w) maltose and 2.65% (w/w) glycerol, pH 7.0. The ideal growth conditions for surfactin production consisted of a moisture content of 62.8% (v/w) and growth supplemented with 15.96% inoculum size in 250 mL flasks at 26.9 °C for 48 h. Under optimal conditions, a surfactin yield of 15.03 mg/gds was attained in 1000-fold scale-up fermentation in a 50 L fermenter, thereby validating the accuracy of this approach. This study proposed an eco-friendly and economical way to convert agro-industrial byproducts into biosurfactant. PMID:23685270

  9. Plant genotype-specific archaeal and bacterial endophytes but similar Bacillus antagonists colonize Mediterranean olive trees

    Directory of Open Access Journals (Sweden)

    Henry eMueller

    2015-03-01

    Full Text Available Endophytes have an intimate and often symbiotic interaction with their hosts. Less is known about the composition and function of endophytes in trees. In order to evaluate our hypothesis that plant genotype and origin have a strong impact on both, endophytes of leaves from 10 Olea europaea L. cultivars from the Mediterranean basin growing at a single agricultural site in Spain and from nine wild olive trees located in natural habitats in Greece, Cyprus and on Madeira Island were studied. The composition of the bacterial endophytic communities as revealed by 16S rRNA gene amplicon sequencing and the subsequent PCoA analysis showed a strong correlation to the plant genotypes. The bacterial distribution patterns were congruent with the plant origins in Eastern and Western areas of the Mediterranean basin. Subsequently, the endophytic microbiome of wild olives was shown to be closely related to those of cultivated olives of the corresponding geographic origins. The olive leaf endosphere harbored mostly Proteobacteria, followed by Firmicutes, Actinobacteria and Bacteroidetes. The detection of a high portion of archaeal taxa belonging to the phyla Thaumarchaeota, Crenarchaeota and Euryarchaeota in the amplicon libraries was an unexpected discovery, which was confirmed by quantitative real-time PCR revealing an archaeal portion of up to 35.8%. Although the function of these Archaea for their host plant remains speculative, this finding suggests a significant relevance of archaeal endophytes for plant-microbe interactions. In addition, the antagonistic potential of culturable endophytes was determined; all isolates with antagonistic activity against the olive-pathogenic fungus Verticillium dahliae Kleb. belong to Bacillus amyloliquefaciens. In contrast to the specific global structural diversity, BOX-fingerprints of the antagonistic Bacillus isolates were highly similar and independent of the olive genotype from which they were isolated.

  10. Effect of temperature on In_x Ga_(1-x) As/GaAs quantum dot lasing

    CERN Document Server

    Borji, Mahdi Ahmadi

    2015-01-01

    In this paper, the strain, band-edge, and energy levels of pyramidal In_x Ga_(1-x) As/GaAs quantum dot lasers (QDLs) are investigated by 1-band effective mass approach. It is shown that while temperature has no remarkable effect on the strain tensor, the band gap lowers and the radiation wavelength elongates by rising temperature. Also, band-gap and laser energy do not linearly decrease by temperature rise. Our results appear to coincide with former researches. Keywords: quantum dot laser, strain tensor, band edge, nano-electronics, temperature effect

  11. Optical gain spectra of unstrained graded GaAs/AlxGa1−xAs quantum well laser

    International Nuclear Information System (INIS)

    We have calculated the optical gain spectra in unstrained graded GaAs/AlxGa1−xAs single quantum well lasers as a function of the energy of the radiation, the quantum well width and the interface thickness. The optical gain spectra were calculated using the density matrix approach (Luttinger–Kohn method), considering the parabolic band model (conduction band), all subband mixing between the heavy and light holes (valence band), and the transversal electrical light polarization. Our results show that the optical peak gain is sensitive to the width and the graded profile of the interfaces, and is blue-shifted as a function of the interface width.

  12. Plasmid pGA1 from Corynebacterium glutamicum codes for a gene product that positively influences plasmid copy number.

    OpenAIRE

    Nesvera, J; Pátek, M; Hochmannová, J; Abrhámová, Z; Becvárová, V; Jelínkova, M; Vohradský, J

    1997-01-01

    The complete nucleotide sequence (4,826 bp) of the cryptic plasmid pGA1 from Corynebacterium glutamicum was determined. DNA sequence analysis revealed four putative coding regions (open reading frame A [ORFA], ORFA2, ORFB, and ORFC). ORFC was identified as a rep gene coding for an initiator of plasmid replication (Rep) according to the high level of homology of its deduced amino acid sequence with the Rep proteins of plasmids pSR1 (from C. glutamicum) and pNG2 (from Corynebacterium diphtheria...

  13. Design, Fabrication and Characterization of a GaAs/InxGa1-xAs/GaAs Heterojunction Bipolar Transistor

    OpenAIRE

    Lidsky, David

    2014-01-01

    Designs for PnP GaAs/InxGa1-xAs/GaAs heterojunction bipolar transistors (HBTs) are proposed and simulated with the aid of commercial software. Band diagrams, Gummel plots and common emitter characteristics are shown for the specific case of x=1, x=0.7, and x linearly graded from 0.75 to 0.7. Of the three designs, it is found that the linearly graded case has the lowest leakage current and the highest current gain. IV curves for all four possible classes of InAs/GaAs heterojunction (nN, nP...

  14. Thermal expansion and thermal conductivity of CuGa1-xInxTe2 solid solutions

    International Nuclear Information System (INIS)

    The thermal expansion and thermal conductivity of the CuGa1-xInxTe2 solid solutions are studied on the crystals of the solid, obtained through the Bridgman method. It is established that the thermal expansion coefficient with the x-composition changes linearly and the thermal conductivity - with the minimum for the equimolar composition. The Debye temperatures and the root-mean-square dynamic shifts are calculated by the coefficient experimental data. It is shown that with increase of the indium atoms content in the solid solutions the Debye temperature decreases and the atoms root-mean-square dynamic shifts in the crystalline lattice increase

  15. Red to green photoluminescence of InP-quantum dots in AlxGa1-xInP

    Science.gov (United States)

    Roßbach, R.; Schulz, W. M.; Reischle, M.; Beirne, G. J.; Jetter, M.; Michler, P.

    2007-01-01

    InP-quantum dots were grown in between different Al-containing AlxGa1-xInP barriers in order to increase their emission energy and localization energy. We observed emission energies from 1.85 eV (670 nm) to 2.24 eV (554 nm). From time-resolved photoluminescence measurements performed at different temperatures we found a strong dependence of the excitonic decay times both on the Al-content of the barrier and the growth temperature of the quantum dots due to diffusion of Al and Ga from the barrier into the dots.

  16. Bacillus thuringiensis (Bt)

    Science.gov (United States)

    2004-01-01

    Bacillus thuringiensis (Bt), a natural bacteria found all over the Earth, has a fairly novel way of getting rid of unwanted insects. Bt forms a protein substance (shown on the right) that is not harmful to humans, birds, fish or other vertebrates. When eaten by insect larvae the protein causes a fatal loss of appetite. For over 25 years agricultural chemical companies have relied heavily upon safe Bt pesticides. New space based research promises to give the insecticide a new dimension in effectiveness and applicability. Researchers from the Consortium for Materials Development in Space along with industrial affiliates such as Abott Labs and Pern State University flew Bt on a Space Shuttle mission in the fall of 1996. Researchers expect that the Shuttle's microgravity environment will reveal new information about the protein that will make it more effective against a wider variety of pests.

  17. Role of electronic excitations and nuclear collisions for color center creation in AlxGa1-xN semiconductors

    Science.gov (United States)

    Moisy, F.; Grygiel, C.; Ribet, A.; Sall, M.; Balanzat, E.; Monnet, I.

    2016-07-01

    In this work, AlxGa1-xN (x = 0; 0.1; 0.3; 0.5; 0.65; 0.7; 0.8; 1) wurtzite epilayers, grown on c-plane sapphire substrates, have been irradiated with Swift Heavy Ions at GANIL facility. Modifications induced by irradiation are characterized with in-situ optical absorption spectroscopy at 15 K. Spectra of these irradiated alloys exhibit optical absorption band formation, related to new energy levels in their bandgaps, whose positions only depend on the composition of the layer. However, these absorption bands are not observed in the AlxGa1-xN with Al molar fraction less than 0.3, likely because the energy level of the corresponding defect is located above the conduction band. Moreover, using different irradiation conditions, a coupled effect between nuclear collisions and electronic excitations for these color center creation have been investigated. A synergy between these two phenomena has been shown and appears to be independent of the composition of the alloy.

  18. Transmission-mode GaN photocathode based on graded AlxGa1-xN buffer layer

    Institute of Scientific and Technical Information of China (English)

    Xiaoqing Du; Benkang Chang; Yunsheng Qian; Pin Gao

    2011-01-01

    @@ We create a GaN photocathode based on graded AlxGa1-xN buffer layers to overcome the influence of buffer-emission layer interface on the photoemission of transmission-mode GaN photocathodes. A gateshaped spectral response with a 260-nm starting wavelength and a 375-nm cut-off wavelength is obtained.Average quantum efficiency is 15% and short wavelength responses are almost equivalent to long wavelength ones. The fitted interface recombination velocity is 5×104 cm/s, with negligible magnitude, proving that the design of the graded buffer layers is efficient in obtaining good interface quality between the buffer and the emission layer.%We create a GaN photocathode based on graded AlxGa1-xN buffer layers to overcome the influence of buffer-emission layer interface on the photoemission of transmission-mode GaN photocathodes. A gateshaped spectral response with a 260-nm starting wavelength and a 375-nm cut-off wavelength is obtained. Average quantum efficiency is 15% and short wavelength responses are almost equivalent to long wavelength ones. The fitted interface recombination velocity is 5× 104 cm/s, with negligible magnitude, proving that the design of the graded buffer layers is efficient in obtaining good interface quality between the buffer and the emission layer.

  19. Al(x)Ga(1-x)N-based deep-ultraviolet 320×256 focal plane array.

    Science.gov (United States)

    Cicek, Erdem; Vashaei, Zahra; Huang, Edward Kwei-wei; McClintock, Ryan; Razeghi, Manijeh

    2012-03-01

    We report the synthesis, fabrication, and testing of a 320×256 focal plane array (FPA) of back-illuminated, solar-blind, p-i-n, Al(x)Ga(1-x)N-based detectors, fully realized within our research laboratory. We implemented a pulse atomic layer deposition technique for the metalorganic chemical vapor deposition growth of thick, high-quality, crack-free, high Al composition Al(x)Ga(1-x)N layers. The FPA is hybridized to a matching ISC 9809 readout integrated circuit and operated in a SE-IR camera system. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower, and falling off three orders of magnitude by ~285 nm. By developing an opaque masking technology, the visible response of the ROIC is significantly reduced; thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allows the FPA to achieve high external quantum efficiency (EQE); at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated. PMID:22378430

  20. Built-in-polarization field effect on lattice thermal conductivity of AlxGa1-xN/GaN heterostructure

    Science.gov (United States)

    Pansari, Anju; Gedam, Vikas; Kumar Sahoo, Bijaya

    2015-12-01

    The built-in-polarization field at the interface of AlxGa1-xN/GaN heterostructure enhances elastic constant, phonon velocity, Debye temperature and their bowing constants of barrier material AlxGa1-xN. The combined phonon relaxation time of acoustics phonons has been computed for with and without built-in-polarization field at room temperature for different aluminum (Al) content (x). Our result shows that the built-in-polarization field suppresses the scattering mechanisms and enhances the combined relaxation time. The thermal conductivity of AlxGa1-xN has been estimated as a function of temperature for x=0, 0.1, 0.5 and 1 for with and without polarization field. Minimum thermal conductivity has been observed for x=0.1 and 0.5. Analysis shows that up to a certain temperature (different for different x) the polarization field acts as negative effect and reduces the thermal conductivity and after this temperature thermal conductivity is significantly contributed by polarization field. This signifies pyroelectric character of AlxGa1-xN. The pyroelectric transition temperature of AlxGa1-xN alloy has been predicted for different x. Our study reports that room temperature thermal conductivity of AlxGa1-xN/GaN heterostructure is enhanced by built-in-polarization field. The temperature dependence of thermal conductivity for x=0.1 and 0.5 are in line with prior experimental studies. The method we have developed can be used for the simulation of heat transport in nitride devices to minimize the self heating processes and in polarization engineering strategies to optimize the thermoelectric performance of AlxGa1-xN/GaN heterostructures.

  1. Genome Differences That Distinguish Bacillus anthracis from Bacillus cereus and Bacillus thuringiensis

    OpenAIRE

    Radnedge, Lyndsay; Agron, Peter G.; Hill, Karen K.; Jackson, Paul J.; Ticknor, Lawrence O; Keim, Paul; Andersen, Gary L.

    2003-01-01

    The three species of the group 1 bacilli, Bacillus anthracis, B. cereus, and B. thuringiensis, are genetically very closely related. All inhabit soil habitats but exhibit different phenotypes. B. anthracis is the causative agent of anthrax and is phylogenetically monomorphic, while B. cereus and B. thuringiensis are genetically more diverse. An amplified fragment length polymorphism analysis described here demonstrates genetic diversity among a collection of non-anthrax-causing Bacillus speci...

  2. Growth and composition-dependent optoelectronic properties of Al x Ga1‑x N alloy nanowires arrays across the entire composition range on carbon cloth

    Science.gov (United States)

    Chen, Fei; Ji, Xiaohong; Zhang, Qinyuan

    2016-07-01

    Composition-tunable ternary Al x Ga1‑x N (0 ≤ x ≤ 1) alloy nanowires have been grown on flexible carbon cloth in large scale through a one-step and catalyst-free chemical vapor deposition method. Field emission scanning electron microscopy, x-ray diffraction analysis, transmission electron microscopy and x-ray energy-dispersive spectroscopy were employed to characterize the morphology, crystal structure, composition properties. All Al x Ga1‑x N samples exhibit hexagonal wurtzite single-phase structure and a preferred orientation along [0001] direction. The progressively evolutions in structural, Raman and field emission properties of Al x Ga1‑x N nanowires demonstrate the continuous composition tunability across the entire composition range. The enhancement in the field emission characteristic of Al x Ga1‑x N nanowires on carbon cloth is ascribed to the combined effect of the nanostructures and the excellent electron transport path of the conductive carbon cloth. The successful synthesis of Al x Ga1‑x N nanowires on carbon cloth provides the new possibility for the further development of flexible nano- and opto-electronic devices.

  3. Regions of Different Confinement in Low-Dimensional AlyInxGa1−x−yN Quantum Structures

    Directory of Open Access Journals (Sweden)

    A. Gröning

    2007-01-01

    Full Text Available The optical properties of metal-organic vapor phase epitaxy grown AlyInxGa1−x−yN quantum dot structures have been studied by time-resolved photoluminescence experiments. We investigated the recombination dynamics of the photo-exited carriers in dependence of the growth parameters such as aluminium flow and the duration of the growth interruption after the dot deposition. Our results confirm the presence of localized states, where the degree of localization is strongly dependent on the growth conditions. To describe this behavior, we propose a band structure with coupled potentials for these nanostructures. Finally, we demonstrate state filling to prove the zero-dimensional character of the strongly localized states in our quaternary quantum dots.

  4. Influence of Mn-Doped Content on Ferromagnetism of Ga1-xMnxN Film Grown by LPMOVPE

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; ZHANG Ya-Wei; YAO Shu-De; WANG Kun; DING Zhi-Bo; CHEN Zhi-Tao; SU Yue-Yong; ZHANG Guo-Yi; MA Hong-ji; NIE Rui

    2006-01-01

    The diluted magnetic semiconductor Ga1-xMnxN was achieved by low-pressure metal organic vapour-phase epitaxy (LP-MOVPE). Proton-induced x-ray emission was employed non-destructively, quickly and accurately to determine the Mn-doped content. The magnetic property was measured by a superconducting-quantum-interference-device (SQID) magnetometer. Apparent ferromagnetic hysteresis loops measured at or above room temperature are presented. No ferromagnetic secondary phases were detected by high-resolution x-ray diffraction. The experimental results show that the ferromagnetic signal firstly decreases and then increases with the increasing Mn-doped content from 0.23% to 4.69% and it is the weakest when Mn content is 0.51%. The annealing treatment could make the ferromagnetic property stronger.

  5. Bond-length variation in InxGa1-xAs/InP strained epitaxial layers

    Science.gov (United States)

    Romanato, F.; de Salvador, D.; Berti, M.; Drigo, A.; Natali, M.; Tormen, M.; Rossetto, G.; Pascarelli, S.; Boscherini, F.; Lamberti, C.; Mobilio, S.

    1998-06-01

    Tensile and compressive InxGa1-xAs epilayers grown on [001] InP substrates have been analyzed by fluorescence-detected x-ray-absorption fine structure in order to investigate the length variation suffered by Ga-As and In-As atomic bonds under epitaxial strain. A morphological and structural analysis had previously been performed in order to select only pseudomorphic samples with high lattice quality. A clear variation of the nearest-neighbor distances proportional to the tetragonal distortion of the film has been detected. We discuss the relationship between the long- and short-range descriptions of strain accommodation in the framework of an analytical model.

  6. Room-Temperature Ferromagnetism of Ga1-xMnxN Grown by Low-Pressure Metalorganic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhi-Tao; ZHANG Guo-Yi; SU Yue-Yong; YANG Zhi-Jian; ZHANG Yan; ZHANG Bin; GUO Li-Ping; XU Ke; PAN Yao-Bao; ZHANG Han

    2006-01-01

    @@ Epitaxial films of Ga1-xMnxN have been grown on c-sapphire substrates by low-pressure metal-organic vapour phase epitaxy. The samples show ferromagnetic behaviour up to a temperature of T = 380 K with hysteresis curves showing a coercivity of 50-100Oe. No ferromagnetic second phases and no significant deterioration in crystal quality with the incorporation of Mn can be detected by high-resolution x-ray diffraction. The result of x-ray absorption near-edge structures indicates that Mn atoms substitute for Ga atoms. The Mn concentrations of the layers are determined to reach x = 0.038 by proton-induced x-ray emission.

  7. Formation of misfit dislocations during growth of InxGa1-xAs/GaAs strained-layer heterostructures

    Science.gov (United States)

    Liu, X. W.; Hopgood, A. A.; Usher, B. F.; Wang, H.; Braithwaite, N. St. J.

    1999-12-01

    Transmission electron microscopy of GaAs/InxGa1-xAs/GaAs double heterostructures has enabled the onset and subsequent development of misfit dislocations to be followed for increasing strained-layer thicknesses, from sub- to supercritical. It has been observed that misfit segments are introduced into threading dislocations when the strained-layer thickness is close to, but below, the critical thickness predicted by the Matthews-Blakeslee (M-B) model. Analysis shows that threading dislocations may be able to glide to form interfacial misfit dislocation segments even though the critical thickness predicted by the M-B model has not been reached. It has also been observed that the total dislocation density rises slowly as the layer thickness increases above its critical value, until a sudden increase occurs. It is suggested that the sudden increase in dislocation density is associated with a different mechanism of misfit dislocation formation, which dominates the global relaxation of the structure.

  8. Arsenic Irradiation Induced Atomic Interdiffusion of InxGa1-xAs/InP Quantum Well Structures

    Directory of Open Access Journals (Sweden)

    P.L. Gareso,

    2012-12-01

    Full Text Available The atomic intermixing of InxGa1-xAs/InP quantum well structures induced by arsenic irradiation has been investigated using photoluminescence (PL measurement. The ion doses used were varried from 5x1011 As/cm2 to 1x1013 As/cm2. Also, the irradiation temperature were carried out from -200oC to 300oC. The samples were annealed under Argon flow in rapid thermal annealer (RTA at 750oC for 60 second. The photoluminescence result showed that there was increase in energy shift at lower doses. However, the energy shift was saturated at higher dose. At elevated temperature implantation showed that the energy shift did not change significantly for all the samples (LM, TS, CS. In additon to this, the higher energy shift was observed in the Compressive Strain (CS samples, but the lower of the energy shift was experienced in the Tensile Strain (TS samples

  9. Electrical Measurements of the Extrinsic Spin Hall Effect in Fe/ In x Ga 1-xAs Heterostructures

    Science.gov (United States)

    Geppert, Chad; Garlid, Eric; Chan, Mun; Crowell, Paul; Hu, Qi; Palmstrøm, Chris

    2011-03-01

    We report on all-electrical measurements of the extrinsic spin Hall effect in Fe/ In x Ga 1-x As heterostructures with n -type channel doping (Si) and highly doped Schottky tunnel barriers. The spin Hall effect refers to the transverse spin current generated by application of a longitudinal unpolarized charge current. Complementary spin accumulation at opposing edges of the channel is detected via a Hanle effect in the voltage measured by pairs of ferromagnetic Hall contacts. The spin Hall conductivity is extracted by fitting the data to a drift-diffusion model incorporating spin precession and relaxation. Tuning the channel conductivity with applied bias allows the skew and side-jump contributions to be determined independently. The resulting magnitude is in agreement with models based on ionized impurity scattering. Further quantitative comparison to theoretical models is achieved by increasing the In concentration beyond previously reported values. Supported by ONR and NSF.

  10. Growth and characterization of GaAs/InxGa1-xAs/GaAs axial nanowire heterostructures with symmetrical heterointerfaces

    Institute of Scientific and Technical Information of China (English)

    Lü Xiao-Long; Zhang Xia; Liu Xiao-Long; Yan Xin; Cui Jian-Gong; Li Jun-Shuai; Huang Yong-Qing

    2013-01-01

    We report on the Au-assisted vapour-liquid-solid (VLS) growth of GaAs/InxGa1-xAs/GaAs (0.2 ≤ x ≤ 1) axial double-heterostructure nanowires on GaAs (111) B substrates via the metal-organic chemical vapor deposition (MOCVD) technique.The influence of the indium (In) content in an Au particle on the morphology of nanowires is investigated systematically.A short period of pre-introduced In precursor before the growth of InxGa1-xAs segment,coupled with a group Ⅲ precursor interruption,is conducive to obtaining symmetrical heterointerfaces as well as the desired In/Ga ratio in the InxGa1 xAs section.The nanowire morphology,such as kinking and tapering,are thought to be related to the In composition in the catalyst alloy as well as the VLS growth mechanism.

  11. Self-consistent vertical transport calculations in AlxGa1-xN/GaN based resonant tunneling diode

    Science.gov (United States)

    Rached, A.; Bhouri, A.; Sakr, S.; Lazzari, J.-L.; Belmabrouk, H.

    2016-03-01

    The formation of two-dimensional electron gases (2DEGs) at AlxGa1-xN/GaN hexagonal double-barriers (DB) resonant tunneling diodes (RTD) is investigated by numerical self-consistent (SC) solutions of the coupled Schrödinger and Poisson equations. Spontaneous and piezoelectric effects across the material interfaces are rigorously taken into account. Conduction band profiles, band edges and corresponding envelope functions are calculated in the AlxGa1-xN/GaN structures and likened to those where no polarization effects are included. The combined effect of the polarization-induced bound charge and conduction band offsets between the hexagonal AlGaN and GaN results in the formation of 2DEGs on one side of the DB and a depletion region on the other side. Using the transfer matrix formalism, the vertical transport (J-V characteristics) in AlGaN/GaN RTDs is calculated with a fully SC calculation in the ballistic regime. Compared to standard calculations where the voltage drop along the structure is supposed to be linear, the SC method leads to strong quantitative changes in the J-V characteristics showing that the applied electric field varies significantly in the active region of the structure. The influences of the aluminum composition and the GaN(AlGaN) thickness layers on the evolution of the current characteristics are also self-consistently investigated and discussed. We show that the electrical characteristics are very sensitive to the potential barrier due to the interplay between the potential symmetry and the barrier height and width. More interestingly, we demonstrate that the figures of merit namely the peak-to-valley ratio (PVR) of GaN/AlGaN RTDs can be optimized by increasing the quantum well width.

  12. Lattice damage and compositional changes in Xe ion irradiated InxGa1-xN (x = 0.32-1.0) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Limin; Jiang, Weilin; Dissanayake, Amila C.; Peng, Jinxin; Ai, Wensi; Zhang, Jiandong; Zhu, Zihua; Wang, Tieshan; Shutthanandan, V.

    2016-06-27

    Lattice disorder and compositional changes in InxGa1-xN (x=0.32, 0.47, 0.7, 0.8 and 1.0) films on GaN/Al2O3 substrates, induced by room-temperature irradiation of 5 MeV Xe ions, have been investigated using both Rutherford backscattering spectrometry under ion-channeling conditions and time-of-flight secondary ion mass spectrometry. The results show that for a fluence of 3E13 cm-2, the relative level of lattice disorder in InxGa1-xN increases monotonically from 59% to 90% with increasing indium concentration x from 0.32 to 0.7; a further increase in x up to 1.0 leads to little increase in the disorder level. In contrast to Ga-rich InxGa1-xN (x=0.32 and 0.47), significant volume swelling of up to ~25% accompanied with oxidation in In-rich InxGa1-xN (x=0.7, 0.8 and 1.0) is observed. In addition, irradiation-induced atomic mixing occurs at the interface of In-rich InxGa1-xN and GaN. The results from this study indicate an extreme susceptibility of the high In-content InxGa1-xN to heavy-ion irradiation, and suggest that cautions must be exercised in applying ion-implantation techniques to these materials at room temperature. Further studies of the irradiation behavior at elevated temperatures are warranted.

  13. Low-temperature sequential pulsed chemical vapor deposition of ternary BxGa1-xN and BxIn1-xN thin film alloys

    International Nuclear Information System (INIS)

    In this work, the authors have performed sequential pulsed chemical vapor deposition of ternary BxGa1-xN and BxIn1-xN alloys at a growth temperature of 450 °C. Triethylboron, triethylgallium, trimethylindium, and N2 or N2/H2 plasma have been utilized as boron, gallium, indium, and nitrogen precursors, respectively. The authors have studied the compositional dependence of structural, optical, and morphological properties of BxGa1-xN and BxIn1-xN ternary thin film alloys. Grazing incidence X-ray diffraction measurements showed that boron incorporation in wurtzite lattice of GaN and InN diminishes the crystallinity of BxGa1-xN and BxIn1-xN sample. Refractive index decreased from 2.24 to 1.65 as the B concentration of BxGa1-xN increased from 35% to 88%. Similarly, refractive index of BxIn1-xN changed from 1.98 to 1.74 for increase in B concentration value from 32% to 87%, respectively. Optical transmission band edge values of the BxGa1-xN and BxIn1-xN films shifted to lower wavelengths with increasing boron content, indicating the tunability of energy band gap with alloy composition. Atomic force microscopy measurements revealed an increase in surface roughness with boron concentration of BxGa1-xN, while an opposite trend was observed for BxIn1-xN thin films

  14. Lattice damage and compositional changes in Xe ion irradiated InxGa1-xN (x = 0.32-1.0) single crystals

    Science.gov (United States)

    Zhang, Limin; Jiang, Weilin; Dissanayake, Amila; Peng, Jinxin; Ai, Wensi; Zhang, Jiandong; Zhu, Zihua; Wang, Tieshan; Shutthanandan, Vaithiyalingam

    2016-06-01

    Lattice disorder and compositional changes in InxGa1-xN (x = 0.32, 0.47, 0.7, 0.8, and 1.0) films on GaN/Al2O3 substrates, induced by room-temperature irradiation of 5 MeV Xe ions, have been investigated using both Rutherford backscattering spectrometry under ion-channeling conditions and time-of-flight secondary ion mass spectrometry. The results show that for a fluence of 3 × 1013 cm-2, the relative level of lattice disorder in InxGa1-xN increases monotonically from 59% to 90% with increasing indium concentration x from 0.32 to 0.7; a further increase in x up to 1.0 leads to little increase in the disorder level. In contrast to Ga-rich InxGa1-xN (x = 0.32 and 0.47), significant volume swelling of up to ˜25% accompanied with oxidation in In-rich InxGa1-xN (x = 0.7, 0.8, and 1.0) is observed. In addition, irradiation-induced atomic mixing occurs at the interface of In-rich InxGa1-xN and GaN. The results from this study indicate an extreme susceptibility of the high In-content InxGa1-xN to heavy-ion irradiation, and suggest that cautions must be exercised in applying ion-implantation techniques to these materials at room temperature. Further studies of the irradiation behavior at elevated temperatures are warranted.

  15. Composition Dependence of Surface Phonon Polariton Mode in Wurtzite InxGa1-xN (0 ≤ x ≤ 1) Ternary Alloy

    Institute of Scientific and Technical Information of China (English)

    S. S. Ng; Z. Hassan; H. Abu Hassan

    2008-01-01

    @@ We present a theoretical study on the composition dependence of the surface phonon polariton (SPP) mode in wurtzite structure α-Inx Ga1-xN ternary alloy over the whole composition range. The SPP modes are obtained by the theoretical simulations by means of an anisotropy model. The results reveal that the SPP mode of α-InxGa1-Xn semiconductors exhibits one-mode behaviour. From these data, composition dependence of the SPP mode with bowing parameter of -28.9 cm-1 is theoretically obtained.

  16. Effect of heterostructure design on current-voltage characteristics in AlxGa1-xN/GaN double-barriers resonant tunneling diode

    Science.gov (United States)

    Boucherit, M.; Soltani, A.; Rousseau, M.; Farvacque, J.-L.; DeJaeger, J.-C.

    2012-12-01

    Ballistic transport in double-barriers resonant tunneling diodes based on GaN is investigated in this work using the non-equilibrium Green's functions formalism. The electron density of states, the electrons concentration, and the current-voltage characteristics are calculated taking into account the internal electric field induced in the AlxGa1-xN/GaN heterostructures. The effect of the geometrical parameters on the evolution of the current resonances characteristics was analyzed qualitatively by varying GaN quantum well width, thicknesses and height of the AlxGa1-xN barriers.

  17. PROBLEM RELATED TO THE MBE GROWTH AT HIGH SUBSTRATE TEM0PERATURE FORGaAs-Ga1-xAlxAs DOUBLE HETEROSTRUCTURE LASERS

    OpenAIRE

    F Alexandre; Duhamel, N.; Ossart, P.; Masson, J.; Meillerat, C.

    1982-01-01

    The MBE growth at high substrate temperature (TS ≈ 600°C) is now often used to obtain GaAs and Ga1-xAlxAs layers with improved electrical and optical properties. In the case of GaAs-Ga1-xAlxAs DH lasers, the optimisation of the threshold current density is obtained for increasing TS ; the ultimate value we reached is l,5KA/cm2 for an active layer thickness of 0,16µm However above a critical value of TS ≈ 670°C, an increase of Jth is observed until a non laser emission. This behaviour is relat...

  18. Selection of Bacillus spp. for Cellulase and Xylanase Production as Direct-Fed Microbials to Reduce Digesta Viscosity and Clostridium perfringens Proliferation Using an in vitro Digestive Model in Different Poultry Diets

    Science.gov (United States)

    Latorre, Juan D.; Hernandez-Velasco, Xochitl; Kuttappan, Vivek A.; Wolfenden, Ross E.; Vicente, Jose L.; Wolfenden, Amanda D.; Bielke, Lisa R.; Prado-Rebolledo, Omar F.; Morales, Eduardo; Hargis, Billy M.; Tellez, Guillermo

    2015-01-01

    Previously, our laboratory has screened and identified Bacillus spp. isolates as direct-fed microbials (DFM). The purpose of the present study was to evaluate the cellulase and xylanase production of these isolates and select the most appropriate Bacillus spp. candidates for DFM. Furthermore, an in vitro digestive model, simulating different compartments of the gastrointestinal tract, was used to determine the effect of these selected candidates on digesta viscosity and Clostridium perfringens proliferation in different poultry diets. Production of cellulase and xylanase were based on their relative enzyme activity. Analysis of 16S rRNA sequence classified two strains as Bacillus amyloliquefaciens and one of the strains as Bacillus subtilis. The DFM was included at a concentration of 108 spores/g of feed in five different sterile soybean-based diets containing corn, wheat, rye, barley, or oat. After digestion time, supernatants from different diets were collected to measure viscosity, and C. perfringens proliferation. Additionally, from each in vitro simulated compartment, samples were taken to enumerate viable Bacillus spores using a plate count method after heat-treatment. Significant (P < 0.05) DFM-associated reductions in supernatant viscosity and C. perfringens proliferation were observed for all non-corn diets. These results suggest that antinutritional factors, such as non-starch polysaccharides from different cereals, can enhance viscosity and C. perfringens growth. Remarkably, dietary inclusion of the DFM that produce cellulase and xylanase reduced both viscosity and C. perfringens proliferation compared with control diets. Regardless of diet composition, 90% of the DFM spores germinated during the first 30 min in the crop compartment of the digestion model, followed by a noteworthy increased in the intestine compartment by ~2log10, suggesting a full-life cycle development. Further studies to evaluate in vivo necrotic enteritis effects are in

  19. Extracellular Ribonuclease from Bacillus licheniformis (Balifase), a New Member of the N1/T1 RNase Superfamily

    Science.gov (United States)

    Nadyrova, Alsu; Ulyanova, Vera; Ilinskaya, Olga

    2016-01-01

    The N1/T1 RNase superfamily comprises enzymes with well-established antitumor effects, such as ribotoxins secreted by fungi, primarily by Aspergillus and Penicillium species, and bacterial RNase secreted by B. pumilus (binase) and B. amyloliquefaciens (barnase). RNase is regarded as an alternative to classical chemotherapeutic agents due to its selective cytotoxicity towards tumor cells. New RNase with a high degree of structural similarity with binase (73%) and barnase (74%) was isolated and purified from Bacillus licheniformis (balifase, calculated molecular weight 12421.9 Da, pI 8.91). The protein sample with enzymatic activity of 1.5 × 106 units/A280 was obtained. The physicochemical properties of balifase are similar to those of barnase. However, in terms of its gene organization and promoter activity, balifase is closer to binase. The unique feature of balifase gene organization consists in the fact that genes of RNase and its inhibitor are located in one operon. Similarly to biosynthesis of binase, balifase synthesis is induced under phosphate starvation; however, in contrast to binase, balifase does not form dimers under natural conditions. We propose that the highest stability of balifase among analyzed RNase types allows the protein to retain its structure without oligomerization. PMID:27656652

  20. Extracellular Ribonuclease from Bacillus licheniformis (Balifase, a New Member of the N1/T1 RNase Superfamily

    Directory of Open Access Journals (Sweden)

    Yulia Sokurenko

    2016-01-01

    Full Text Available The N1/T1 RNase superfamily comprises enzymes with well-established antitumor effects, such as ribotoxins secreted by fungi, primarily by Aspergillus and Penicillium species, and bacterial RNase secreted by B. pumilus (binase and B. amyloliquefaciens (barnase. RNase is regarded as an alternative to classical chemotherapeutic agents due to its selective cytotoxicity towards tumor cells. New RNase with a high degree of structural similarity with binase (73% and barnase (74% was isolated and purified from Bacillus licheniformis (balifase, calculated molecular weight 12421.9 Da, pI 8.91. The protein sample with enzymatic activity of 1.5 × 106 units/A280 was obtained. The physicochemical properties of balifase are similar to those of barnase. However, in terms of its gene organization and promoter activity, balifase is closer to binase. The unique feature of balifase gene organization consists in the fact that genes of RNase and its inhibitor are located in one operon. Similarly to biosynthesis of binase, balifase synthesis is induced under phosphate starvation; however, in contrast to binase, balifase does not form dimers under natural conditions. We propose that the highest stability of balifase among analyzed RNase types allows the protein to retain its structure without oligomerization.

  1. Phages Preying on Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis: Past, Present and Future

    Directory of Open Access Journals (Sweden)

    Annika Gillis

    2014-07-01

    Full Text Available Many bacteriophages (phages have been widely studied due to their major role in virulence evolution of bacterial pathogens. However, less attention has been paid to phages preying on bacteria from the Bacillus cereus group and their contribution to the bacterial genetic pool has been disregarded. Therefore, this review brings together the main information for the B. cereus group phages, from their discovery to their modern biotechnological applications. A special focus is given to phages infecting Bacillus anthracis, B. cereus and Bacillus thuringiensis. These phages belong to the Myoviridae, Siphoviridae, Podoviridae and Tectiviridae families. For the sake of clarity, several phage categories have been made according to significant characteristics such as lifestyles and lysogenic states. The main categories comprise the transducing phages, phages with a chromosomal or plasmidial prophage state, γ-like phages and jumbo-phages. The current genomic characterization of some of these phages is also addressed throughout this work and some promising applications are discussed here.

  2. Phages preying on Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis: past, present and future.

    Science.gov (United States)

    Gillis, Annika; Mahillon, Jacques

    2014-07-01

    Many bacteriophages (phages) have been widely studied due to their major role in virulence evolution of bacterial pathogens. However, less attention has been paid to phages preying on bacteria from the Bacillus cereus group and their contribution to the bacterial genetic pool has been disregarded. Therefore, this review brings together the main information for the B. cereus group phages, from their discovery to their modern biotechnological applications. A special focus is given to phages infecting Bacillus anthracis, B. cereus and Bacillus thuringiensis. These phages belong to the Myoviridae, Siphoviridae, Podoviridae and Tectiviridae families. For the sake of clarity, several phage categories have been made according to significant characteristics such as lifestyles and lysogenic states. The main categories comprise the transducing phages, phages with a chromosomal or plasmidial prophage state, γ-like phages and jumbo-phages. The current genomic characterization of some of these phages is also addressed throughout this work and some promising applications are discussed here. PMID:25010767

  3. Microbial community profiling of the Chinoike Jigoku ("Blood Pond Hell") hot spring in Beppu, Japan: isolation and characterization of Fe(III)-reducing Sulfolobus sp. strain GA1.

    Science.gov (United States)

    Masaki, Yusei; Tsutsumi, Katsutoshi; Hirano, Shin-Ichi; Okibe, Naoko

    2016-09-01

    Chinoike Jigoku ("Blood Pond Hell") is located in the hot spring town of Beppu on the southern island of Kyushu in Japan, and is the site of a red-colored acidic geothermal pond. This study aimed to investigate the microbial population composition in this extremely acidic environment and to isolate/characterize acidophilic microorganism with metal-reducing ability. Initially, PCR (using bacteria- and archaea-specific primers) of environmental DNA samples detected the presence of bacteria, but not archaea. This was followed by random sequencing analysis, confirming the presence of wide bacterial diversity at the site (123 clones derived from 18 bacterial and 1 archaeal genera), including those closely related to known autotrophic and heterotrophic acidophiles (Acidithiobacillus sp., Sulfobacillus sp., Alicyclobacillus sp.). Nevertheless, successive culture enrichment with Fe(III) under micro-aerobic conditions led to isolation of an unknown archaeal organism, Sulfolobus sp. GA1 (with 99.7% 16S rRNA gene sequence identity with Sulfolobus shibatae). Unlike many other known Sulfolobus spp., strain GA1 was shown to lack sulfur oxidation ability. Strain GA1 possessed only minor Fe(II) oxidation ability, but readily reduced Fe(III) during heterotrophic growth under micro-aerobic conditions. Strain GA1 was capable of reducing highly toxic Cr(VI) to less toxic/soluble Cr(III), demonstrating its potential utility in bioremediation of toxic metal species. PMID:27208660

  4. Characteristics of cylindrical surrounding-gate GaAs x Sb1-x /In y Ga1-y As heterojunction tunneling field-effect transistors

    Science.gov (United States)

    Guan, Yun-He; Li, Zun-Chao; Luo, Dong-Xu; Meng, Qing-Zhi; Zhang, Ye-Fei

    2016-10-01

    A III-V heterojunction tunneling field-effect transistor (TFET) can enhance the on-state current effectively, and GaAs x Sb1-x /In y Ga1-y As heterojunction exhibits better performance with the adjustable band alignment by modulating the alloy composition. In this paper, the performance of the cylindrical surrounding-gate GaAs x Sb1-x /In y Ga1-y As heterojunction TFET with gate-drain underlap is investigated by numerical simulation. We validate that reducing drain doping concentration and increasing gate-drain underlap could be effective ways to reduce the off-state current and subthreshold swing (SS), while increasing source doping concentration and adjusting the composition of GaAs x Sb1-x /In y Ga1-y As can improve the on-state current. In addition, the resonant TFET based on GaAs x Sb1-x /In y Ga1-y As is also studied, and the result shows that the minimum and average of SS reach 11 mV/decade and 20 mV/decade for five decades of drain current, respectively, and is much superior to the conventional TFET. Project supported by the National Natural Science Foundation of China (Grant Nos. 61176038 and 61474093), the Science and Technology Planning Project of Guangdong Province, China (Grant No. 2015A010103002), and the Technology Development Program of Shaanxi Province, China (Grant No. 2016GY-075).

  5. Microbial community profiling of the Chinoike Jigoku ("Blood Pond Hell") hot spring in Beppu, Japan: isolation and characterization of Fe(III)-reducing Sulfolobus sp. strain GA1.

    Science.gov (United States)

    Masaki, Yusei; Tsutsumi, Katsutoshi; Hirano, Shin-Ichi; Okibe, Naoko

    2016-09-01

    Chinoike Jigoku ("Blood Pond Hell") is located in the hot spring town of Beppu on the southern island of Kyushu in Japan, and is the site of a red-colored acidic geothermal pond. This study aimed to investigate the microbial population composition in this extremely acidic environment and to isolate/characterize acidophilic microorganism with metal-reducing ability. Initially, PCR (using bacteria- and archaea-specific primers) of environmental DNA samples detected the presence of bacteria, but not archaea. This was followed by random sequencing analysis, confirming the presence of wide bacterial diversity at the site (123 clones derived from 18 bacterial and 1 archaeal genera), including those closely related to known autotrophic and heterotrophic acidophiles (Acidithiobacillus sp., Sulfobacillus sp., Alicyclobacillus sp.). Nevertheless, successive culture enrichment with Fe(III) under micro-aerobic conditions led to isolation of an unknown archaeal organism, Sulfolobus sp. GA1 (with 99.7% 16S rRNA gene sequence identity with Sulfolobus shibatae). Unlike many other known Sulfolobus spp., strain GA1 was shown to lack sulfur oxidation ability. Strain GA1 possessed only minor Fe(II) oxidation ability, but readily reduced Fe(III) during heterotrophic growth under micro-aerobic conditions. Strain GA1 was capable of reducing highly toxic Cr(VI) to less toxic/soluble Cr(III), demonstrating its potential utility in bioremediation of toxic metal species.

  6. Electron microscopic and optical investigations of the indium distribution GaAs capped InxGa1-xAs islands

    DEFF Research Database (Denmark)

    Woggon, U.; Langbein, Wolfgang Werner; Hvam, Jørn Märcher;

    1997-01-01

    Results from a structural and optical analysis of buried InxGa1-xAs islands carried out after the process of GaAs overgrowth are presented. It is found that during the growth process, the indium concentration profile changes and the thickness of the wetting layer emanating from a Stranski...

  7. Binding Energy of Ionized-Donor-Bound Excitons in the GaAs-AlxGa1-xAs Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Jun; ZHANG Shu-Fang; KONG Xiao-Jun; LI Shu-Shen

    2000-01-01

    The binding energy of an exciton bound to anionized donor impurity (D+, X) located at the center or the edgein GaAs-AlxGa1-xAs quantum wells is calculated variationally for the well width from 10 to 300 A by using atwo-parameter wave function, The theoretical results are discussed and compared with the previous experimentalresults.

  8. Phase diagram of a two-dimensional liquid in GaAs/AlxGa1-xAs biased double quantum wells

    DEFF Research Database (Denmark)

    Timofeev, V. B.; Larionov, A. V.; Alessi, M. G.;

    2000-01-01

    Photoluminescence (PL) and PL excitation (PLE) measurements have been performed in GaAs/AlxGa1-xAs biased double quantum well heterostructures. The recombination of electrons, e, with holes, h, located in the same or in two adjacent wells, has been investigated for different exciting power densit...

  9. Heterojunction DDR THz IMPATT diodes based on AlxGa1−xN/GaN material system

    International Nuclear Information System (INIS)

    Simulation studies are made on the large-signal RF performance and avalanche noise properties of heterojunction double-drift region (DDR) impact avalanche transit time (IMPATT) diodes based on AlxGa1−xN/GaN material system designed to operate at 1.0 THz frequency. Two different heterojunction DDR structures such as n-Al0.4Ga0.6N/p-GaN and n-GaN/p-Al0.4Ga0.6N are proposed in this study. The large-signal output power, conversion efficiency and noise properties of the heterojunction DDR IMPATTs are compared with homojunction DDR IMPATT devices based on GaN and Al0.4Ga0.6N. The results show that the n-Al0.4Ga0.6N/p-GaN heterojunction DDR device not only surpasses the n-GaN/p-Al0.4Ga0.6N DDR device but also homojunction DDR IMPATTs based on GaN and Al0.4Ga0.6N as regards large-signal conversion efficiency, power output and avalanche noise performance at 1.0 THz. (paper)

  10. Direct measurement of DX-centre related lattice relaxations in Al$_{x}$Ga$_{1-x}$As compounds

    CERN Multimedia

    2002-01-01

    Donor impurities from elements of group IV and VI form localized electronic states, so-called DX-centers, in AlGaAs and other semiconductors. One of the well known effects related to DX-centers is the persistent photoconductivity. In spite of extensive studies, the microscopic structure of the DX-center is still a matter of controversy. The direct determination of the donor lattice sites and their microscopical surrounding is a crucial point in understanding the relation of microscopic structure to the localized electronic state of the DX-center.\\\\ It is proposed to implant radioactive group VI elements $^{73}$Se (from $^{73}$Br) and $^{118}$Te (from $^{118}$Xe) into Al$_{x}$Ga$_{1-x}$As of different mole fractions ${x}$ and to determine (i) the lattice site of Te and Se impurities by emission channeling of decay positrons and electrons (ii) the local structure of Se impurities using the perturbed $\\gamma$-$\\gamma$-angular correlation technique (PAC). The appearance of the DX-center shall be check...

  11. 高抑制比背照式AlxGa1-xN pin日盲紫外探测器研究%Study on Back-illuminated AlxGa1-xN pin Solar-blind UV Photodetectors with High Rejection Ratio

    Institute of Scientific and Technical Information of China (English)

    赵文伯; 许华胜; 申志辉; 叶嗣荣; 周勋; 李艳炯; 黄烈云

    2014-01-01

    利用现有外延材料生长技术和器件工艺技术,生长了背照式AlxGa1-xN pin外延材料,并用生长的材料制作了日盲紫外探测器,测试结果表明器件在0V偏压下抑制比达到了6 400.在此基础上,较详细地分析了偏置电压、p-AlxGa1-xN载流子浓度和Al组分、极化效应对背照式AlxGa1-xN pin日盲紫外探测器抑制比的影响及非日盲先生载流子的限制机制.分析表明,提高p-AlxGa1-xN载流子浓度和GaN/AlxGa1-xN异质结极化强度是现有技术条件下提高器件抑制比的有效途径.

  12. Environmental Persistence of Bacillus anthracis and Bacillus subtilis Spores

    Science.gov (United States)

    Wood, Joseph P.; Meyer, Kathryn M.; Kelly, Thomas J.; Choi, Young W.; Rogers, James V.; Riggs, Karen B.; Willenberg, Zachary J.

    2015-01-01

    There is a lack of data for how the viability of biological agents may degrade over time in different environments. In this study, experiments were conducted to determine the persistence of Bacillus anthracis and Bacillus subtilis spores on outdoor materials with and without exposure to simulated sunlight, using ultraviolet (UV)-A/B radiation. Spores were inoculated onto glass, wood, concrete, and topsoil and recovered after periods of 2, 14, 28, and 56 days. Recovery and inactivation kinetics for the two species were assessed for each surface material and UV exposure condition. Results suggest that with exposure to UV, decay of spore viability for both Bacillus species occurs in two phases, with an initial rapid decay, followed by a slower inactivation period. The exception was with topsoil, in which there was minimal loss of spore viability in soil over 56 days, with or without UV exposure. The greatest loss in viable spore recovery occurred on glass with UV exposure, with nearly a four log10 reduction after just two days. In most cases, B. subtilis had a slower rate of decay than B. anthracis, although less B. subtilis was recovered initially. PMID:26372011

  13. FORMALDEHYDE GAS INACTIVATION OF BACILLUS ANTHRACIS, BACILLUS SUBTILIS AND GEOBACILLUS STEAROTHERMOPHILUS SPORES ON INDOOR SURFACE MATERIALS.

    Science.gov (United States)

    Research evaluated the decontamination of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface material using formaldehyde gas. Spores were dried on seven types of indoor surfaces and exposed to 1100 ppm formaldehyde gas for 10 hr. Fo...

  14. Screening of Bacillus Species with Potentials of Antibiotics Production

    Directory of Open Access Journals (Sweden)

    Faruk Adamu KUTA

    2009-07-01

    Full Text Available Sixteen soil samples were collected from different refuse dump sites in Minna, the capital Niger State, and analysed for the presence of Bacillus species. Physical-chemical analysis of the soil samples revealed the followings: PH value 6.89-8.47; moisture content 1.58 – 21.21% and temperature 27-28ºC. Using both pour plate and streak method of inoculation, total bacterial count in the soil samples ranged from 3.8×104 cfu/g 16.0×104 cfu/g. The identified Bacillus species included: Bacillus cereus (30.8%, Bacillus brevis (1.9% Bacillus polymyxa (3.8%, Bacillus lichenifomis (13.5%, Bacillus spherericus (7.7%, Bacillus mycoides (13.5%, Bacillus pumilus (7.7%, Bacillus subtilis (3.8%, Bacillus alvei (1.9%, Bacillus laterosporous (1.9%, Bacillus firmus (9.6% and Bacillus circulars (3.8%. Antibiotic production tests indicated that nine Bacillus species out of twelve isolated in this study could be used to produce antibiotics that had effect on the test organisms. However, Bacillus polymyxa, Bacillus sphaericus and Bacillus laterosporous had little or no effect on the tested organisms. This study suggests that some Bacillus species have potential to produce high quality antibiotics that can be use to control microbial growth in future.

  15. Identification of Bacillus strains isolated from Yacai by 16S rRNA gene sequencing%利用16S rRNA序列鉴定分离自芽菜中的芽孢杆菌

    Institute of Scientific and Technical Information of China (English)

    张良; 吴华昌; 邓静; 李萍萍; 肖辰; 沈芳

    2012-01-01

    从宜宾芽菜中分离优势菌群,选取4株芽孢杆菌,分别为B1、B2、B3、B4.对4株菌的16S rRNA基因经PCR扩增测序,将测序结果同该属内菌株的16S rRNA序列作多序列比较,并建立芽孢杆菌属的系统发育树.结合细菌形态学生理生化特性鉴定结果,结果表明菌株B1、B3为枯草芽孢杆菌,菌株B2为解淀粉芽孢杆菌,菌株B4为乙酰微小杆菌.%Four dominant Bacillus strains named Bl, B2, B3 and B4 were isolated from Yacai (a kind of Yibin pickles in China). The 16S rRNA genes of these strains were amplified in vitro and sequenced. Then a phylogenetic tree was constructed by multiple alignments of their sequences with other 16S rRNA gene sequences of Bacillus. According to 16S rRNA gene analysis combined with morphological, physiological and biochemical characteristics, B1 and B3 were identified as Bacillus subtilis, B2 was Bacillus amyloliquefaciens and B4 was Exiguobacterium acetylicum.

  16. Investigation on Photoluminescence of Ordered Structure in the (AlxGa1-x)0.51In0.49P(x= 0.29) Alloys

    Institute of Scientific and Technical Information of China (English)

    LU Yi-Jun; GAO Yu-Lin; ZHENG Jian-Sheng

    2000-01-01

    The temperature-dependent and excitation-intensity-dependent photoluminescence(PL) spectra are applied to investigate the quaternary (AlxGa1-x)0.51In0.49P(x = 0.29) alloys lattice-matched to GaAs. The PL peak is excitation intensity independent, but shows anomalous temperature behavior, where PL peak energy changes with temperature, exhibiting Z-shape dependence. The PL peak energy decreases with increasing temperaturefrom 19K, a blue-shift of PL peak energy occurs between 55K and 84K, afterwards, the PL peak energy de creases monotonously again. This confirms the existence of ordered structure caused by superlattice effect in the(Alx Ga1_x)0.51In0.49P(x = 0.29) alloys.

  17. Structural and Optical Investigations of Heterostructures Based on AlxGa1-xAsyP1-y:Si Solid Solutions Obtained by MOCVD

    Directory of Open Access Journals (Sweden)

    P. V. Seredin

    2014-01-01

    Full Text Available We investigated MOCVD epitaxial heterostructures based on AlxGa1−xAs ternary solid solutions, obtained in the range of compositions x~0.20–0.50 and doped with high concentrations of phosphorus and silicon atoms. Using the methods of high-resolution X-ray diffraction, scanning electron microscopy, X-ray microanalysis, Raman spectroscopy, and photoluminescence spectroscopy we have shown that grown epitaxial films represent five-component (AlxGa1−xAs1−yPy1−zSiz solid solutions. The implementation of silicon in solid solution with a concentration of ~ 0.01 at.% leads to the formation of the structure with deep levels, DX centers, the occurrence of which fundamentally affects the energy characteristics of received materials.

  18. Exchange Enhancement of Spin-Splitting in AlxGa1-xN/GaN Heterostructures in Tilted Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    TANG Ning; HAN Kui; LU Fang-Chao; DUAN Jun-Xi; XU Fu-Jun; SHEN Bo

    2011-01-01

    Alx Ga1-xN/GaN heterostructures are investigated by magnetotransport experiments in tilted magnetic fields at low temperatures.The spin-split peaks of the Shubnikov-de Haas(SdH)oscillations are observed at high magnetic fields, which are attributed to the Zeeman spin-splitting of the two-dimensional electron gas at the heterointerface. The exchange enhanced g* of the spin-splitting is investigated by measuring the positions of the pairs of spin-split SdH maxima. Moreover, it is found that g* becomes smaller with the increasing tilt angle,which suggests the anisotropy of g* is due to the strong polarization-induced electric field at the Alx Ga1-xN/GaN heterointerface.

  19. Dependence of third-order nonlinear susceptibility on strain induced piezoelectric field in InxGa1-xN/GaN quantum well

    Institute of Scientific and Technical Information of China (English)

    Yaochen Bai(白瑶晨); Jingliang Liu(刘景良); Duanzheng Yao(姚端正)

    2004-01-01

    The third-order susceptibility of InxGa1-xN/GaN quantum well (QW) has been investigated by taking into account the strain-induced piezoelectric (PZ) field, and the effective-mass SchrSdinger equation is solved numerically. It is shovn that the third-order susceptibility for third harmonic generation (THG)of InxGa1-x,N/GaN QW is related to indium content in QW and the intensity of the PZ field. The characteristics ofX(3)THG(-3ω,(3) ω, ω,ω) as the function of the wavelength of incident beam, well width and indium content, have been analyzed.

  20. Magneto-transport Study on the nanometer-scaled wires made of AlxGa1-xN/GaN heterostructures

    Science.gov (United States)

    Pang, Wen-Yuan; Lo, Ikai; Hsu, Yu-Chi; Chen, Yen-Liang; Gau, Ming-Hong; Lin, W. S.; Chen, C. H.; Chiang, J. C.; Tsai, Jen-Kai

    2008-03-01

    The electronic characteristics of nano-wires made of high-mobility AlxGa1-xN/GaN heterostructures have been studied. The AlxGa1-xN/GaN samples were grown on GaN-template buffer layer by plasma-assisted molecular beam epitaxy. We obtained the mobility and carrier density of two-dimensional electron gas to be 9328 cm^2/Vs and 7.917x10^12 cm-2 by conventional van der pauw Hall measurement at temperature of 77K, respectively. We prepared the samples of field-effect-transistors and reduced the width of the conducting channel from 1μm to 100 nm by Focus Ion Beam. The Shubnikov-de Haas oscillations were observed by magneto-resistance measurement at 0.3 K and the electronic properties for the samples of different channel widths were under investigation.

  1. Raman Scattering in GaxIn1-xP and (AlxGa1-x)0.51In0.49P Alloys

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Raman scattering spectroscopy is applied to investigate the phonon modes in GaxIn1-xP (x=0.52) and (AlxGa1-x)0.51In0.49P (x=0.29) alloys. Two-mode behavior in GaxIn1-xP and three-mode behavior in (AlxGa1-x)0.51In0.49P are observed. In ordered GaxIn1-xP, we clearly distinguish the TO1(GaP-like) mode and the splitting of LO1(GaP-like) and LO2 (InP-like) modes, which is believed to be the result of superlattice effect of ordering, and the LO1+LO2 mode, which is observed for the first time. In addition to the b/a ratio, it's found that the relative intensity of the FLA and the LO1+LO2 modes also corresponds to the degree of order. The TO1 and the splitting of LO1 and LO2 devote together to the reduction of the "valley depth". In (AlxGa1-x)0.51In0.49P, the doubling of FLA is observed. Due to the influence of Al composition, the GaP-like LO mode becomes a shoulder of the InP-like LO mode. The unresolved Raman spectra indicate the existence of ordered structure in (AlxGa1-x)0.51In0.49P alloys.

  2. Raman and photoluminescence mapping of InxGa1-xN (x ˜ 0.4) at high pressure: Optical determination of composition and stress

    Science.gov (United States)

    Gkrana, V.; Filintoglou, K.; Arvanitidis, J.; Christofilos, D.; Bazioti, C.; Dimitrakopulos, G. P.; Katsikini, M.; Ves, S.; Kourouklis, G. A.; Zoumakis, N.; Georgakilas, A.; Iliopoulos, E.

    2014-09-01

    The pressure response of a polar wurtzite InxGa1-xN (x = 0.37) film epitaxially grown on a GaN/sapphire template was studied by means of combined Raman and photoluminescence (PL) mappings. The pressure slopes of the Raman peaks (∂ω/∂P ˜ 4.7 cm-1.GPa-1) of the studied alloy are indicative of its intermediate stiffness between the end members of the InxGa1-xN system. The data analysis suggests that in our experiments the obtained slopes have marginal contribution, if any, from the substrate. Furthermore, the similarity of the ambient pressure value of the PL peak energy (˜1.97 eV) and its pressure slope (∂EPL/∂P ˜ 30 meV.GPa-1) with those obtained by absorption measurements implies that PL can be used to follow the pressure evolution of the energy bandgap. Finally, we demonstrate that all-optical characterization of the composition and residual stress of InxGa1-xN samples is feasible.

  3. The effect of δ-doping and modulation-doping on Si-doped high Al content n-AlxGa1-xN grown by MOCVD

    Institute of Scientific and Technical Information of China (English)

    Zhu Shaoxin; Yan Jianchang; Zeng Jianping; Zhang Ning; Si Zhao; Dong Peng; Li Jinmin

    2013-01-01

    The effect of periodic delta-doping and modulation-doping on high Al content n-AlxGa1-xN (x =0.55) epilayers grown by MOCVD has been investigated.Measured by XRD,AFM,contactless sheet resistance,and Hall-effect tests,δ-doped and modulation-doped n-AlxGa1-xN have better crystal quality,surface morphology and electrical properties as compared with uniformly-doped n-AlxGa1-xN.These improvements are attributed to the SiNx growth mask induced by δ-doping layers and the dislocation-blocking effect induced by both growth techniques.In addition,due to the broadened doping profile ascribed to enhanced dopant diffusion at high growth temperatures (1150 ℃) of n-Al0.55Ga0.45N,modulation-doped n-Al0.55Ga0.45N has similar properties as δ-doped n-Al0.55Ga0.45N.

  4. Antagonistic Activities of Bacillus spp. Strains Isolated from Tidal Flat Sediment Towards Anthracnose Pathogens Colletotrichum acutatum and C. gloeosporioides in South Korea

    Directory of Open Access Journals (Sweden)

    Joon-Hee Han

    2015-06-01

    Full Text Available Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous plant species. Anthracnose control with fungicides has both human health and environmental safety implications. Despite increasing public concerns, fungicide use will continue in the absence of viable alternatives. There have been relatively less efforts to search antagonistic bacteria from mudflats harboring microbial diversity. A total of 420 bacterial strains were isolated from mudflats near the western sea of South Korea. Five bacterial strains, LB01, LB14, HM03, HM17, and LB15, were characterized as having antifungal properties in the presence of C. acutatum and C. gloeosporioides. The three Bacillus atrophaeus strains, LB14, HM03, and HM17, produced large quantities of chitinase and protease enzymes, whereas the B. amyloliquefaciens strain LB01 produced protease and cellulase enzymes. Two important antagonistic traits, siderophore production and solubilization of insoluble phosphate, were observed in the three B. atrophaeus strains. Analyses of disease suppression revealed that LB14 was most effective for suppressing the incidence of anthracnose symptoms on pepper fruits. LB14 produced antagonistic compounds and suppressed conidial germination of C. acutatum and C. gloeosporioides. The results from the present study will provide a basis for developing a reliable alternative to fungicides for anthracnose control.

  5. GaN Epitaxial Layer Grown with Conductive Al(x)Ga(1-x)N Buffer Layer on SiC Substrate Using Metal Organic Chemical Vapor Deposition.

    Science.gov (United States)

    So, Byeongchan; Lee, Kyungbae; Lee, Kyungjae; Heo, Cheon; Pyeon, Jaedo; Ko, Kwangse; Jang, Jongjin; Nam, Okhyun

    2016-05-01

    This study investigated GaN epitaxial layer growth with a conductive Al(x)Ga(1-x)N buffer layer on n-type 4H-SiC by high-temperature metalorganic chemical vapor deposition (HT-MOCVD). The Al composition of the Al(x)Ga(1-x)N buffer was varied from 0% to 100%. In terms of the crystal quality of the GaN layer, 79% Al was the optimal composition of the Al(x)Ga(1-x)N buffer layer in our experiment. A vertical conductive structure was fabricated to measure the current voltage (I-V) characteristics as a function of Al composition, and the I-V curves showed that the resistance increased with increasing Al concentration of the Al(x)Ga(1-x)N buffer layer. PMID:27483845

  6. 鲟源病原性嗜水气单胞菌拮抗芽孢杆菌的鉴定及其生物学特性%Identification and biological characteristics of a Bacillus strain antagonistic against pathogenic Aeromonas hydrophila of sturgeons

    Institute of Scientific and Technical Information of China (English)

    曹海鹏; 何珊; 刘丽玲; 吕利群

    2011-01-01

    从养殖池污泥中分离筛选了1株优良的鲟源嗜水气单胞茵拮抗芽孢杆菌G1,其对鲟源嗜水气单胞茵S1产生的抑茵圈直径为18.50 mm.通过API50CH细菌鉴定系统以及16S rRNA序列分析法,菌株G1被鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens),GenBank登录号HM245965.1,其16S rRNA序列与基因库中芽孢杆菌属菌株的16S rRNA序列有99%- 100%的同源性,而且与解淀粉芽孢杆菌Ba-74501 (GenBank登录号:DQ422953.1)的亲缘关系最近.菌株G1的最适生长pH值为7,最适生长温度为30℃,其在30℃、200 r/min条件下的生长曲线为:0-6h为生长延迟期,6-54 h为对数生长期,54-90 h为稳定期,90 h以后为衰亡期.此外,菌株G1对其他实验选用的病原性嗜水气单胞菌也表现出良好的拮抗活性.本实验结果有利于填补嗜水气单胞茵拮抗菌在分类地位、生物学特性等方面的不足,为鲟鱼嗜水气单胞菌病的生物防控提供科学资料.%A good Bacillus strain Gl antagonistic against pathogenic Aeromonas hydrophila of sturgeons was isolated and screened from the sediment of aquaculture ponds, which produced the inhibitionzone of 18.50 ram in diameter against^, hydrophila strain SI. Strain Gl (GenBank accession number: HM245965.1) was identified as Bacillus amyloliquefaciens through APICH50 bacterial identification system and 16S rRNA sequence analysis. Its ]6S rRNA sequence had homology of 99%-100% with those of Bacillus sp. Strains submitted to GenBank, and showed the most close relative to Bacillus amyloliquefaciens strain Ba-74501 (GenBank accession number: DQ422953.1). The best growth pH and temperature of strain Gl were 7 and 30 DC, its growth curve in the condition of 30 °C and 200 r/min was as follows: the lag phase was 0-6 h, the log phase was 6-54 h, the stationary phase was 54-90 h, the decline phase was after 90 h. In addition, strain Gl also exhibited good antagonistic activity against other tested A. Hydrophila strains

  7. Theoretical investigations on the N-polar GaN/AlxGa1-xN/GaN heterostructures: Considering the existence of both two-dimensional hole and electron gases

    Science.gov (United States)

    Yan, Junda; Wang, Quan; Wang, Xiaoliang; Feng, Chun; Xiao, Hongling; Liu, Shiming; Gong, Jiamin; Liu, Fengqi; Li, Baiquan

    2016-09-01

    In this paper, a theoretical study of N-polar GaN/AlxGa1-xN/GaN heterostructures is conducted systematically. The dependence of two-dimensional hole gas (2DHG, at the bottom AlxGa1-xN/GaN interface) and electron gas (2DEG, at the upper GaN/AlxGa1-xN interface) sheet densities on variables, such as GaN top layer thickness, AlxGa1-xN back barrier thickness, and Al content, is investigated. The effect of n-type doping in AlxGa1-xN and δ-doping concentrations in the GaN buffer on 2DHG and 2DEG sheet densities is also presented. For the unintentionally doped structure, the 2DHG-induced electric field E2DHG provides the only driving force in the 2DEG formation. Thus, in order to get high dense of 2DEG in such heterostructure, 2DEG and 2DHG shall coexist through proper AlxGa1-xN back barrier design. While for intentionally doped structure (with the n-type doped AlxGa1-xN back barrier layer or δ-doped GaN buffer layer), ionized donor-induced electric field Edonor is another driving force for 2DEG. The obtained insight offers indications for the structure design of the N-polar GaN/AlxGa1-xN/GaN high electron mobility transistors.

  8. The sense and antisense expression of gibberellin 20-oxidase gene (rga5) in rice and its effects on GA1 level and agronomic traits

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A gibberellin 20-oxidase gene rga5 was isolated by PCR from genomic DNA of rice (Oryza sativa ssp indica) cultivars 'Aizizhan' and 'Nante'. Compared with the reported OsGA20ox, the rga5 was partial-frame-shifted with 11 different amino acids. Then the rga5 with CaMV 35S promotor and NOS terminator was inserted into the polylinker site of pCambia1301 to construct sense and antisense gene expressing vectors pSrga5 and pArga5. The transgenic plants were obtained by biolistic bombardment with pSrga5 or pArga5. The transgenic rice plants showed that the over- expression and antisense-expression of rga5 have remarkable effects on the biological characters of rice. The sense transgenic plants showed heightening with longer spike, more seed-bearing and unaffected flowering, whereas antisense transgenic plants showed dwarfing, early-flowering with slender stem, dark leaf color, shorter leaf and shorter spike. The PCR amplification and Southern blot hybridization showed that the rga5 has been integrated into the transgenic rice genome and the transcription of rga5 was identified by Northern blot hybridization. In the sense transgenic plants the GA1 content increased of about 50%, however, the antisense transgenic rice decreased of 90% approximately compared with control plant 'Zhonghua 8'. These results demonstrated that the rga5 is a functional gene encoding gibberellin 20-oxidase in rice. Over-expressing rga5 significantly increases the endogenous GA1 level and plant height of rice, whereas the expression of antisense rga5 decreases the GA1 level and plant height of rice dramatically.

  9. Kinetics versus thermodynamics of the metal incorporation in molecular beam epitaxy of (InxGa1−x2O3

    Directory of Open Access Journals (Sweden)

    Patrick Vogt

    2016-08-01

    Full Text Available We present a detailed study of the reaction kinetics and thermodynamics of the plasma-assisted oxide molecular beam epitaxy of the ternary compound (InxGa1−x2O3 for 0 ≤ x ≤ 1. We measured the growth rate of the alloy in situ by laser reflectrometry as a function of growth temperature TG for different metal-to-oxygen flux ratios rMe, and nominal In concentrations xnom in the metal flux. We determined ex situ the In and Ga concentrations in the grown film by energy dispersive X-ray spectroscopy. The measured In concentration x shows a strong dependence on the growth parameters TG, rMe, and xnom whereas growth on different co-loaded substrates shows that in the macroscopic regime of ∼μm3 x does neither depend on the detailed layer crystallinity nor on crystal orientation. The data unveil that, in presence of In, Ga incorporation is kinetically limited by Ga2O desorption the same way as during Ga2O 3 growth. In contrast, In incorporation during ternary growth is thermodynamically suppressed by the presence of Ga due to stronger Ga–O bonds. Our experiments revealed that Ga adatoms decompose/etch the In–O bonds whereas In adatoms do not decompose/etch the Ga–O bonds. This result is supported by our thermochemical calculations. In addition we found that a low TG and/or excessively low rMe kinetically enables In incorporation into (InxGa1−x2O3. This study may help growing high-quality ternary compounds (InxGa1−x2O3 allowing band gap engineering over the range of 2.7–4.7 eV.

  10. Time-resolved Photoluminescence Characterisation of GaAs/AlxGa1–xAs Structures Designed for Microwave and Terahertz Detectors

    Directory of Open Access Journals (Sweden)

    Aurimas ČERŠKUS

    2014-06-01

    Full Text Available The time-resolved photoluminescence of donor Si-doped GaAs/AlxGa1-xAs (x = 0.3 0.25, 0.2, 0.1 structures designed for microwave and terahertz detectors have been investigated at T = 3.6 K temperature. The excitonic, impurity and defect related emission lifetimes are revealed for these structures. Possible mechanisms of carrier recombination are discussed. Concentration of acceptor, carbon and silicon, are evaluated from measured lifetimes in the structures. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6317

  11. Quantum effects in linear and nonlinear transport of T -shaped ballistic junction patterned from GaAs/AlxGa1-xAs heterostructures

    Science.gov (United States)

    Wróbel, J.; Zagrajek, P.; Czapkiewicz, M.; Bek, M.; Sztenkiel, D.; Fronc, K.; Hey, R.; Ploog, K. H.; Bułka, B. R.

    2010-06-01

    We report low-temperature transport measurements of three-terminal T -shaped device patterned from GaAs/AlxGa1-xAs heterostructure. We demonstrate the mode branching and bend resistance effects predicted by numerical modeling for linear conductance data. We show also that the backscattering at the junction area depends on the wave function parity. We find evidence that in a nonlinear transport regime the voltage of floating electrode always increases as a function of push-pull polarization. Such anomalous effect occurs for the symmetric device, provided the applied voltage is less than the Fermi energy in equilibrium.

  12. Controllable GMR device in a δ-doped, magnetically and electrically modulated, GaAs /Alx Ga1-x As heterostructure

    Science.gov (United States)

    Shen, Li-Hua; Zhang, Gui-Lian; Yang, Duan-Chui

    2016-09-01

    We report on a theoretical study of giant magnetoresistance (GMR) effect in a δ-doped GaAs /Alx Ga1-x As heterostructure modulated by two stripes of ferromagnetic metal and a stripe of Schottky metal in parallel configuration. The δ-doping dependent transmission and conductance of the device are calculated. It is shown that a considerable giant magnetoresistance (GMR) effect exists in this structure. It is also shown that the magnetoresistance ratio (MR) can be switched by the δ-doping. The underlying physical mechanism of the results is analysed in light of δ-doping-dependent tunneling process in the device.

  13. Estudos de transições electrónicas e vibracionais em filmes finos de InxGa1-xN

    OpenAIRE

    Correia, Maria do Rosário Pimenta

    2005-01-01

    Os semicondutores baseados no InxGa1-xN são amplamente utilizados em dispositivos emissores de luz num conjunto diverso de novas aplicações tecnológicas. O conhecimento das propriedades físicas deste material tem progredido a um ritmo mais lento do que a tecnologia. No entanto, para que se concebam dispositivos no domínio da optoelectrónica adequados a necessidades específicas, é essencial adquirir um conhecimento profundo sobre a física fundamental deste sistema. O prese...

  14. Spectroscopic ellipsometry of interfacial phase transitions in fluid metallic systems: KxKCl1-x and Ga1-xBix [online

    OpenAIRE

    Dogel, Stanislav

    2004-01-01

    The investigation of the interfacial phase transitions in fluid systems with short-range intermetallic interactions are of great interest. The phenomena were studied in two systems exhibiting a liquid-liquid miscibility gap: at the fluid/wall interface in fluid KxKCl1-x and at the fluid/vacuum interface of the Ga1 xBix alloys. To characterize the interfacial changes of the ultra thin films (composition, thickness and their evolution with time) the spectroscopic ellipsometry was performed ove...

  15. 一株产脂肽类抗生素bacillopeptin A深海芽孢杆菌的筛选与鉴定%Screening and identification of a deep-sea derived Bacillus sp.producing lipopeptide bacillopeptin A

    Institute of Scientific and Technical Information of China (English)

    牛力轩; 王楠; 王雪梅; 胡江春; 王书锦

    2011-01-01

    Objective An anti-phytopathogenic bacterium was isolated from a deep sea-derived sediment collected from the South China Sea. The present study described the identification of the strain and active Hpopeptide metabolites it produced. Methods Acid precipitation, flash chromatography, SPE and semi-preparative HPLC were applied to isolate the pure lipopeptide from fermentation broth. Identification of the strain was based on combined using of the morphological, physiological, biochemical and 16S rDNA gene sequence analysis. Results A pure lipopeptide was isolated and identified as bacillopeptin A with a molecular weight of 1020.6Da. The strain was identified as Bacillus amyloliquefaciens SH-B74. Conclusion This strain has a wide antimicrobial spectrum to the phytopathogenic fungi, such as Rhizoctonia solani. The lipopeptide metabolite bacillopeptin A showed a good antagonistic effect against Botryosphaeria ribis. The results suggested that this strain and its metabolites may have the potential for further research and development values in biological control of plant fungal pathogens and soil bioremediation.%目的 筛选从中国南海深海3601m的海泥样品中分离得到的细菌,获得一株芽孢杆菌SH-B74,分离其产生抗植物病原真菌脂肽类化合物,并进行菌种鉴定.方法 使用酸沉淀、快速柱色谱、SPE和半制备反高效液相色谱技术分离发酵液中的脂肽类纯化合物,采用形态、生理生化特性和16S rDNA基因序列分析相结合方法鉴定菌株.结果 分离纯化得到一种拮抗植物病原真菌的脂肽类纯化合物bacillopeptin A,分子量为1020.6Da;菌株经鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens).结论 该菌株对玉米纹枯病等多种植物病原真菌具有拮抗作用,代谢产物bacillopeptin A对苹果干腐病菌具有良好的拮抗效果.显示了该菌及其代谢产物在植物病原真菌的生物防治和土壤生物修复方面具有潜在研发价值.

  16. 芽孢杆菌动态发酵产细菌纤维素工艺的优化%Optimization of Agitation Fermentation Process of Bacterial Cellulose Pro-duced by Bacillus

    Institute of Scientific and Technical Information of China (English)

    朱宏阳; 冯珊; 杨宏芳; 李泳宁; 林伟铃

    2015-01-01

    The agitation fermentation process of bacterial cellulose (BC) produced by Bacillus amyloliquefaciens ZF-7 was optimized in this study.The effect of agitation conditions such as rotation speed,medium volume,tempera-ture,inoculum volume and culture time on the production of BC pellets and the yield of 0.5cm~0.8cm BC pellets was investigated.The result showed that the optimal fermentation conditions were as followed:medium volume 70 mL per 250mL flask, inoculum 5%, rotation speed 150r · min-1 , temperature 32℃ and fermentation time 5d.Under these conditions,the yield of 0.5cm~0.8cm BC pellets reached 89.5%,and dry weight was 6.56g· L-1.%以解淀粉芽孢杆菌ZF-7(Bacillus amyloliquefaciens ZF-7)为菌源,对其动态发酵生产细菌纤维素(Bacterial cellulose,BC)的发酵工艺条件进行优化. 利用单因素试验,以粒径为0.5cm~0.8cm的BC颗粒产量及其占总纤维素比率为考察指标,考察摇床转速、装液量、温度、接种量及培养时间对其BC颗粒形成的影响,探索最佳动态发酵工艺. 结果表明:最优培养条件为装液量70mL/250mL三角瓶,接种量5%,150r· min -1 , 32℃振荡培养5d,在此条件下,可获得89.5%的φ0.5cm~0.8cm颗粒状BC,干重为6.56g· L -1.

  17. Effects of Cry8Ga1 toxin on the activities of main enzymes in Holotrichia oblita larvae%Cry8Ga1蛋白对华北大黑鳃金龟幼虫主要酶活性的影响

    Institute of Scientific and Technical Information of China (English)

    谭树乾; 尹姣; 李克斌; 束长龙; 刘春琴; 曹雅忠; 仵均祥

    2013-01-01

    华北大黑鳃金龟[Holotrichia oblita (Faldermann)]是一种危害严重的地下害虫,Cry8Ga1蛋白对其幼虫具有明显杀虫活性.本文比较了华北大黑鳃金龟幼虫取食Cry8Ga1蛋白后6种酶活性的变化,发现取食高浓度(5×LC50,50.767 μg/g土)Cry8Ga1蛋白幼虫的总蛋白酶、类胰凝乳蛋白酶、乙酰胆碱酯酶(AChE)、谷胱甘肽-S-转移酶(GST)以及氨肽酶(APN)的活性较对照均有不同程度的升高,在大多数处理时段差异显著(P<0.05),其中高浓度处理组的GST酶活性在12 h后升高倍数最大,是同时段对照的23.37倍;而取食低浓度(0.5×LC50,5.076 7μg/g土)Cry8Ga1蛋白时,乙酰胆碱酯酶和氨肽酶活性无明显差异(P≥0.05).类胰蛋白酶在整个试验中活性变化与对照相比仅有个别处理时段存在差异,由此推断,类胰蛋白酶不是华北大黑鳃金龟幼虫对Cry8Ga1蛋白的主要活化酶.%Holotrichia oblita,an underground insect pest,causes serious damages on crops in China.It is well known that Cry8Ga1 has a larvicidal activity against H.oblita.In this study,the larvae of H.oblita was fed with two concentrations of Cry8Ga1.Subsequently,the activities of 6 enzymes were assayed.It was found that when only applied with higher concentration of Cry8Ga1 (5 × LC50,50.767 μg/g soil),the activities of total protease,chymotrypsin-like enzyme,acetylcholinesterase (AChE),glutathione-S-transferase (GST) and aminopeptidase (APN) in larvae would significantly rise in most time of the experiment (P<0.05).And the GST activity after 12 h in higher-concentration group was 23.37 times as much as the control,which was the largest multiple of the elevatory enzymes activities.However,the differences of the activities of ACHE and APN in larvae were insignificant between the lower concentration (0.5 × LC50,5.076 7 μg/g soil) group and control (P≥0.05).The activities of the trypsin-like enzyme showed difference occasionally.It is therefore deduced that the

  18. Temperature Dependences of the Electron Energy in AlxGa1 – xAs / GaAs / AlxGa1 – xAs Nanofilms of Different Thickness and Composition of the Barrier Material

    Directory of Open Access Journals (Sweden)

    D.V. Kondryuk

    2014-11-01

    Full Text Available Temperature dependences of the energy of electron ground state in AlxGa1 – xAs / GaAs / AlxGa1 – xAs nanofilms of different thickness and concentrations (x of the barrier material were calculated. Calculations were performed by using the Green functions method, approximation of the effective masses for the electronic system and model of the dielectric continuum – for phonons. The interaction of all branches of the optical phonons: confined in the well material, semi-spaced – in barrier medium and interface has been taken into account. It is shown that the increase in the temperature from 0 to 300 K can cause the increase in the magnitude of long-wave shift of the electron energy about 25-30 % depending on the nanofilm thickness and concentration x.

  19. Triple fixation of Bacillus subtilis dormant spores.

    OpenAIRE

    Kozuka, S; Tochikubo, K

    1983-01-01

    A triple-fixation method with a sequential application of 5% glutaraldehyde, 1% osmium tetroxide, and 2% potassium permanganate gave superior preservation of the ultrastructure of Bacillus subtilis dormant spores with a thick spore coat.

  20. Narrow terahertz attenuation signatures in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Weidong; Brown, Elliott R; Viveros, Leamon; Burris, Kellie P; Stewart, C Neal

    2014-10-01

    Terahertz absorption signatures from culture-cultivated Bacillus thuringiensis were measured with a THz photomixing spectrometer operating from 400 to 1200 GHz. We observe two distinct signatures centered at ∼955 and 1015 GHz, and attribute them to the optically coupled particle vibrational resonance (surface phonon-polariton) of Bacillus spores. This demonstrates the potential of the THz attenuation signatures as "fingerprints" for label-free biomolecular detection. PMID:23821459

  1. Narrow terahertz attenuation signatures in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Weidong; Brown, Elliott R; Viveros, Leamon; Burris, Kellie P; Stewart, C Neal

    2014-10-01

    Terahertz absorption signatures from culture-cultivated Bacillus thuringiensis were measured with a THz photomixing spectrometer operating from 400 to 1200 GHz. We observe two distinct signatures centered at ∼955 and 1015 GHz, and attribute them to the optically coupled particle vibrational resonance (surface phonon-polariton) of Bacillus spores. This demonstrates the potential of the THz attenuation signatures as "fingerprints" for label-free biomolecular detection.

  2. Probing semiconductor band structures and heterojunction interface properties with ballistic carrier emission: GaAs/AlxGa1-xAs as a model system

    Science.gov (United States)

    Yi, Wei; Narayanamurti, Venkatesh; Lu, Hong; Scarpulla, Michael A.; Gossard, Arthur C.

    2010-06-01

    Utilizing three-terminal tunnel emission of ballistic electrons and holes in a planar tunnel transistor with a Mott-barrier collector, we have developed a method to self-consistently determine the energy gap of a semiconductor and band discontinuities at a semiconductor heterojunction without using a priori material parameters. Measurements are performed on lattice-matched GaAs/AlxGa1-xAs (100) single-barrier double heterostructures with AlxGa1-xAs as the model ternary III-V compounds. Electronic band gaps of the AlGaAs alloys and band offsets at the GaAs/AlGaAs (100) interfaces are measured with a resolution of several meV at 4.2 K. The direct-gap Γ band offset ratio for the GaAs/AlGaAs (100) interface is found to be 59:41 (±3%) . Reexamination of our previous experiment [W. Yi , Appl. Phys. Lett. 95, 112102 (2009)10.1063/1.3224914] revealed that, in the indirect-gap regime, ballistic electrons from direct tunnel emissions probe the X valley in the conduction band, while those from Auger-like scattering processes in the metal base film probe the higher-lying L valley. Such selective electron collection may be explained by their different momentum distributions and parallel momentum conservation at the quasiepitaxial Al/GaAs (100) interface. We argue that the present method is in principle applicable to arbitrary type-I semiconductor heterostructures.

  3. Epitaxial growth and magnetic properties of ultraviolet transparent Ga2O3/(Ga1-xFex)2O3 multilayer thin films

    Science.gov (United States)

    Guo, Daoyou; An, Yuehua; Cui, Wei; Zhi, Yusong; Zhao, Xiaolong; Lei, Ming; Li, Linghong; Li, Peigang; Wu, Zhenping; Tang, Weihua

    2016-04-01

    Multilayer thin films based on the ferromagnetic and ultraviolet transparent semiconductors may be interesting because their magnetic/electronic/photonic properties can be manipulated by the high energy photons. Herein, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films were obtained by alternating depositing of wide band gap Ga2O3 layer and Fe ultrathin layer due to inter diffusion between two layers at high temperature using the laser molecular beam epitaxy technique. The multilayer films exhibits a preferred growth orientation of crystal plane, and the crystal lattice expands as Fe replaces Ga site. Fe ions with a mixed valence of Fe2+ and Fe3+ are stratified distributed in the film and exhibit obvious agglomerated areas. The multilayer films only show a sharp absorption edge at about 250 nm, indicating a high transparency for ultraviolet light. What’s more, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films also exhibits room temperature ferromagnetism deriving from the Fe doping Ga2O3.

  4. Efficient rainbow color luminescence from InxGa1-xN single quantum wells fabricated on {112¯2} microfacets

    Science.gov (United States)

    Nishizuka, K.; Funato, M.; Kawakami, Y.; Narukawa, Y.; Mukai, T.

    2005-12-01

    Rainbow color luminescence from InxGa1-xN single quantum wells (SQWs) is achieved and almost covers the entire visible range when the layers are fabricated on {112¯2} facets with a few micron-width using a regrowth technique on striped GaN templates. These facets are tilted 56° with respect to the (0001) facets and border the (0001) and {112¯0} facets. The emission wavelength on the {112¯2} facets is redshifted from the {112¯0} side to (0001) side due to the variations of the In composition, which leads to the color contrast with the rainbow geometry. The temperature dependence of the photoluminescence intensity shows that the internal quantum efficiency at room temperature is 33% due to the very small internal electric fields and a small threading dislocation density compared to that in conventional (0001) InxGa1-xN SQWs. Since the emission efficiency does not show a noticeable emission wavelength dependence, this type of structure has potential as light-emitting devices with multiwavelengths that perform numerous color controllability such as pastel and white colors.

  5. Determination of the surface band bending in InxGa1−xN films by hard x-ray photoemission spectroscopy

    Directory of Open Access Journals (Sweden)

    Mickael Lozac'h, Shigenori Ueda, Shitao Liu, Hideki Yoshikawa, Sang Liwen, Xinqiang Wang, Bo Shen, Kazuaki Sakoda, Keisuke Kobayashi and Masatomo Sumiya

    2013-01-01

    Full Text Available Core-level and valence band spectra of InxGa1−xN films were measured using hard x-ray photoemission spectroscopy (HX-PES. Fine structure, caused by the coupling of the localized Ga 3d and In 4d with N 2s states, was experimentally observed in the films. Because of the large detection depth of HX-PES (~20 nm, the spectra contain both surface and bulk information due to the surface band bending. The InxGa1−xN films (x = 0–0.21 exhibited upward surface band bending, and the valence band maximum was shifted to lower binding energy when the mole fraction of InN was increased. On the other hand, downward surface band bending was confirmed for an InN film with low carrier density despite its n-type conduction. Although the Fermi level (EF near the surface of the InN film was detected inside the conduction band as reported previously, it can be concluded that EF in the bulk of the film must be located in the band gap below the conduction band minimum.

  6. Identification of the pathogen isolated from root rot of Taxus chinensis var.mairer and screening of its antagonistic Bacillus%南方红豆杉根腐病病原及其拮抗芽胞杆菌的鉴定

    Institute of Scientific and Technical Information of China (English)

    谯天敏; 罗蓉; 朱天辉

    2015-01-01

    In this study,the pathogen isolated from root rot of Taxus chinensis var.mairer was first indentified. Based on morphological characteristics,pathogenicity and rDNA ITS sequence analysis,the results showed that the pathogen of root-rot disease of T .chinensis var.mairer was Fusarium oxysporum .The tablet confrontation training method was adopted to screen the antagonistic Bacillus species from the healthy plant rhizosphere,and three strains with obvious antagonistic effect were obtained,namely YB6,YB1 5 and YB37.Through morphologi-cal,physiological,biochemical and 1 6S rDNA homology analysis as well as the construction of 1 6S rDNA phy-logenetic tree,we found that YB6,YB15 and YB37 were Bacillus cereus ,B .amyloliquefaciens and Paenibacillus poly-myxa ,respectively.The antagonistic effect of P .polymyxa was the best with further research and development potential. This study provides some valuable information for effective prevention and treatment of this disease.%经形态学特征观察、致病性测定及 rDNA-ITS 序列分析,首次确定红豆杉根腐病病原为尖孢镰刀菌(Fusari-um oxysporum )。采用平板对峙培养法从健康植株根际土壤中筛选得到3株对尖孢镰刀菌具有明显拮抗作用的芽胞杆菌 YB6、YB15、YB37。经形态学、生理生化及16S rDNA 同源性分析,并通过构建16S rDNA 系统发育树,将YB6、YB15和 YB37分别鉴定为蜡样芽胞杆菌(Bacillus cereus )、解淀粉芽胞杆菌(B .amyloliquefaciens )和多黏类芽胞杆菌(Paenibacillu polymyxa ),其中多黏类芽胞杆菌拮抗效果最好,具有进一步研究开发的潜力。本研究通过对南方红豆杉根腐病病原鉴定及其拮抗芽胞杆菌的筛选,对该病的防治提供了理论依据。

  7. Impact of interfacial misfit dislocation growth mode on highly lattice-mismatched InxGa1-xSb epilayer grown on GaAs substrate by metalorganic chemical vapor deposition

    Science.gov (United States)

    Huynh, Sa Hoang; Ha, Minh Thien Huu; Do, Huy Binh; Luc, Quang Ho; Yu, Hung Wei; Chang, Edward Yi

    2016-09-01

    Highly lattice-mismatch (over 8%) ternary InxGa1-xSb alloy directly grown on GaAs substrates was demonstrated by metalorganic chemical vapor deposition (MOCVD). The influence of growth parameters, such as growth temperature, indium vapor composition, and V/III ratio, on the film properties was investigated, and it was found that the growth temperature has the strongest effect on the surface morphology and the crystal quality of the InxGa1-xSb epilayer. An optimized growth temperature of ˜590 °C and a V/III ratio of 2.5 were used for the growth of the InxGa1-xSb epilayer on GaAs that displays a lower surface roughness. High-resolution transmission electron microscopy micrographs exhibit that InxGa1-xSb epilayer growth on GaAs was governed by the interfacial misfit dislocation growth mode. Furthermore, the variation of the intermixing layer thickness at the InxGa1-xSb/GaAs heterointerface was observed. These results provide an information of growing highly lattice-mismatched epitaxial material systems by MOCVD growth process.

  8. Hydrazine vapor inactivates Bacillus spores

    Science.gov (United States)

    Schubert, Wayne W.; Engler, Diane L.; Beaudet, Robert A.

    2016-05-01

    NASA policy restricts the total number of bacterial spores that can remain on a spacecraft traveling to any planetary body which might harbor life or have evidence of past life. Hydrazine, N2H4, is commonly used as a propellant on spacecraft. Hydrazine as a liquid is known to inactivate bacterial spores. We have now verified that hydrazine vapor also inactivates bacterial spores. After Bacillus atrophaeus ATCC 9372 spores deposited on stainless steel coupons were exposed to saturated hydrazine vapor in closed containers, the spores were recovered from the coupons, serially diluted, pour plated and the surviving bacterial colonies were counted. The exposure times required to reduce the spore population by a factor of ten, known as the D-value, were 4.70 ± 0.50 h at 25 °C and 2.85 ± 0.13 h at 35 °C. These inactivation rates are short enough to ensure that the bioburden of the surfaces and volumes would be negligible after prolonged exposure to hydrazine vapor. Thus, all the propellant tubing and internal tank surfaces exposed to hydrazine vapor do not contribute to the total spore count.

  9. Production of amylolytic enzymes by bacillus spp

    International Nuclear Information System (INIS)

    Sixty six bacteria and twenty fungi were isolated from various sources. These varied from rotten fruites to local drinks and soil samples from different parts of Sudan. On the basis of index of amylolytic activity, forty one bacteria and twelve fungi were found to hydrolyse strach. The best ten strach hydrolysing isolates were identified all as bacilli (Bacillus licheniformis SUD-K1, SUD-K2, SUD-K4, SUD-O, SUD-SRW, SUD-BRW, SUD-By, Bacillus subtilis SUD-K3, and Bacillus circulans SUD-D and SUD-K7). Their amylase productivity was studied with respect to temperature and time. Amylolytic activity was measured by spectrophotometer, the highest activity was produced in around 24 hours of growth in all; six of which gave the highest amylase activity at 50 deg C and the rest at 45C. Based on the thermal production six isolates were chosen for further investigation. These were Bacillus licheniformis SUD-K1, SUD-K2, SUD-K4, SUD-O, Bacillus subtilis SUD-K3 and Bacillus circulans SUD-K7. The inclusion of strach and Mg++ ions in the culture medium gave the highest enzyme yield. The Ph 9.0 was found to be the optimum for amylase production for all isolates except Bacillus subtilis SUD-K3 which had an optimum at pH 7.0. Three isolates (Bacillus licheniformis SUD-K1, SUD-K4 and SUD-O recorded highestamylase production in a medium supplemented with peptone while the rest (Bacillus licheniformis SUD-K2, Bacillus subtilis SUD-K3 and Bacillus circulans SUD-K7) gave highest amylase productivity in a medium supplemented with malt extract. Four isolates (Bacillus licheniformis SUD-K1 and Bacillus subtilis SUD-K3 gave maximum amylase production in a medium containing 0.5% soluble strach while the rest (gave maximum amylase production at 2%. Soluble strach was found to be best substrate among the different carbon sources tested. The maximum temperature for amylase activity ranged from 60-70 deg C and 1% strach concentration was optimum for all isolates. Addition of different metal ions

  10. Energy Level Engineering in In_x Ga_(1-x) As/GaAs Quantum Dots Applicable to QD-Lasers by Changing the Stoichiometric Percentage

    CERN Document Server

    Borji, Mahdi Ahmadi

    2015-01-01

    Band edge and energy levels of truncated pyramidal In_x Ga_(1-x) As/GaAs (001) quantum dots are studied by single-band effective mass approach, and the dependence to stoichiometric percentages is investigated. It is shown that enhancement of indium percentage decreases the band gap and the recombination energy of electrons and holes. Our principal result is that decrease of recombination energy and band gap is nonlinear and the slopes are different band gap and e-h recombination energy. In addition, it is proved that strain tensor is diagonal along z-axis and the absolute value of the components gets larger by more indium inclusion. Our results appear to be in very good consonance with similar studies. Keywords: quantum dot, band structure, strain tensor, indium percentage.

  11. Correlation of electronic structure and magnetic moment in Ga1-xMnxN : First-principles, mean field and high temperature series expansions calculations

    Science.gov (United States)

    Masrour, R.; Hlil, E. K.

    2016-08-01

    Self-consistent ab initio calculations based on density-functional theory and using both full potential linearized augmented plane wave and Korring-Kohn-Rostoker-coherent potential approximation methods, are performed to investigate both electronic and magnetic properties of the Ga1-xMnxN system. Magnetic moments considered to lie along (001) axes are computed. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters such as the magnetic phase diagram and the critical exponent. The increasing of the dilution x in this system has allowed to verify a series of HTSEs predictions on the possibility of ferromagnetism in dilute magnetic insulators and to demonstrate that the interaction changes from antiferromagnetic to ferromagnetic passing through the spins glace phase.

  12. Photoluminescence energy transitions in GaAs-Ga1-xAlxAs double quantum wells: Electric and magnetic fields and hydrostatic pressure effects

    International Nuclear Information System (INIS)

    The photoluminescence energy transitions in GaAs-Ga1-xAlxAs coupled double quantum wells are presented by considering the simultaneous effects of applied electric and magnetic fields and hydrostatic pressure. Calculations have been made in the framework of the effective mass and parabolic band approximations and using a variational procedure. The electric field is taken to be oriented along the growth direction of the heterostructure whereas for the magnetic field both in-plane and in-growth directions have been considered. The results show that the hydrostatic pressure and the applied electric field are two useful tools to tune the direct and indirect exciton transitions in such heterostructures. Our results are in good agreement with previous experimental findings in double quantum wells under applied electric field and hydrostatic pressure.

  13. Room Temperature Ferromagnetism in Ga1-xHoxN (x=0.0 and 0.05)Diluted Magnetic Semiconductor Thin Films

    Institute of Scientific and Technical Information of China (English)

    Ghulam Murtaza Rai; Muhammad Azhar Iqbal; Yong-bing Xu; lain Gordon Will; Qasim Mahmood

    2012-01-01

    Holmium doped GaN diluted magnetic semiconductor thin films have been prepared by thermal evaporation technique and subsequent ammonia annealing.X-ray diffraction measurements reveal all peaks belong to the purely hexagonal wurtzite structure.Surface morphology and composition analysis were carried out by scanning electron microscopy and energy dispersive spectroscopy respectively.The room temperature ferromagnetic properties of Ga1-xHoxN (x=0.0,0.05) films were analyzed using vibrating sample magnetometer at room temperature.Magnetic measurements showed that the undoped films (i.e.GaN)exhibited diamagnetic behavior,while the Ho-doped (Ga0.95Ho0.05N) film exhibited a ferromagnetic behavior.

  14. Hydrogenic-Donor Impurity States in GaAs/A1sGa1-xAs Quantum Dots in the Presence of an Electric Field

    Institute of Scientific and Technical Information of China (English)

    PAN Jiang-Hong; LIU Li-Zhe; LIU Min

    2011-01-01

    @@ We report a calculation of binding energy of the ground state of a hydrogenic donor in a quantum cylindrical GaAs dot surrounded by Ga1-xA1-xAs with finite confinement potentials, in the presence of a uniform electric field applied parallel to the dot axis.The binding energy increases inchmeal as the radius of the dot decreases until a maximum value for a certain value of the quantum dot radii, then begins to drop quickly.Results for the binding energies and electronic wave function density of the hydrogenic-donor as functions of the impurity position, dot thickness and applied electric field are also presented.

  15. X-ray reflectivity and atomic force microscopy studies of MOCVD grown AlxGa1-xN/GaN superlattice structures*

    Institute of Scientific and Technical Information of China (English)

    Wang Yuanzhang; Li Jinchai; Li Shuping; Chen Hangyang; Liu Dayi; Kang Junyong

    2011-01-01

    The grazing incidence X-ray reflectivity (GIXR) technique and atomic force microscopy (AFM) were exploited to obtain an accurate evaluation of the surfaces and interfaces for metalorganic chemical vapor deposition grown AlxGa1-xN/GaN superlattice structures. The X-ray diffraction results have been combined with reflectivity data to evaluate the layer thickness and Al mole fraction in the AlGaN layer. The presence ora smooth interface is responsible for the observation of intensity oscillation in GIXR, which is well correlated to step flow observation in AFM images of the surface. The structure with a low Al mole fraction (x = 0.25) and thin well width has a rather smooth surface for the Rrms of AFM data value is 0.45 nm.

  16. Photoluminescence Investigation of Two-Dimensional Electron Gas in an Undoped AlxGa1-xN/GaN Heterostructure

    Institute of Scientific and Technical Information of China (English)

    HAN Xiu-Xun; WU Jie-Jun; LI Jie-Min; CONG Guang-Wei; LIU Xiang-Lin; ZHU Qin-Sheng; WANG Zhan-Guo

    2005-01-01

    @@ Low-temperature photoluminescence measurement is performed on an undoped Alx Ga1-xN/GaN heterostructure. Temperature-dependent Hall mobility confirms the formation of two-dimensional electron gas (2DEG) near the heterointerface. A weak photoluminescence (PL) peak with the energy of ~79meV lower than the free exciton (FE) emission of bulk GaN is related to the radiative recombination between electrons confined in the triangular well and the holes near the flat-band region of GaN. Its identification is supported by the solution of coupled one-dimensional Poisson and Schrodinger equations. When the temperature increases, the red shift of the 2DEG related emission peak is slower than that of the FE peak. The enhanced screening effect coming from the increasing 2DEG concentration and the varying electron distribution at two lowest subbands as a function of temperature account for such behaviour.

  17. The Structural Quality of AlxGa1-xN Epitaxial Layers Grown by Digitally-AlloyedModulated Precursor Epitaxy Determined by Transmission Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hawkridge, Michael E; Liliental-Weber, Zuzanna; Kim, Hee Jin; Choi, Suk; Yoo, Dongwon; Ryou, Jae-Hyun; Dupuis, Russell

    2008-10-13

    Al(x)Ga(1-x)N layers of varying composition (0.5

  18. Crystal Growth of Ca3Nb(Ga1−xAlx3Si2O14 Piezoelectric Single Crystals with Various Al Concentrations

    Directory of Open Access Journals (Sweden)

    Yuui Yokota

    2015-08-01

    Full Text Available Ca3Nb(Ga1−xAlx3Si2O14 (CNGAS single crystals with various Al concentrations were grown by a micro-pulling-down (µ-PD method and their crystal structures, chemical compositions, crystallinities were investigated. CNGAS crystals with x = 0.2, 0.4 and 0.6 indicated a single phase of langasite-type structure without any secondary phases. In contrast, the crystals with x = 0.8 and 1 included some secondary phases in addition to the langasite-type phase. Lattice parameters, a- and c-axes lengths, of the langasite-type phase systematically decreased with an increase of Al concentration. The results of chemical composition analysis revealed that the actual Al concentrations in as-grown crystals were almost consistent with the nominal compositions. In addition, there was no large segregation of each cation along the growth direction.

  19. Crystal structure and magnetism of the MnxGa (1.15 ≤x ≤ 2.0 rare-earth-free permanent magnet system

    Directory of Open Access Journals (Sweden)

    Rasa Rejali

    2016-05-01

    Full Text Available Room temperature neutron powder diffraction has been used to investigate the chemical structure and magnetic ordering of a series of tetragonal (I4/mmm #139 MnxGa (1.15 ≤ x ≤ 2.0 alloys. Initially (x 1.5 Mn also appears on the 2a site. The manganese atoms on the 4d site carry an almost constant moment of 2.16(6 μB/Mn. The loss of magnetisation seen with increasing Mn content is shown to be the result of large (∼3 μB/Mn, antiparallel Mn moments on the 2b, and later 2a sites, and not to a reduction of the Mn moment on the 4d sites.

  20. Competitive In and Ga incorporations for InxGa1-xN (0.29

    Directory of Open Access Journals (Sweden)

    S. M. Hamad

    2013-07-01

    Full Text Available The kinetics of In and Ga incorporation into wurtzite InxGa1−xN nanorods, grown by plasma-assisted MBE under N-rich conditions at a moderate temperature, has been systematically investigated with Ga-flux set as a growth parameter at three distinct values while varying In-flux. The interplay of Ga and In fluxes in their contributions to the incorporation was found to disagree with the empirical Böttcher's formula, of which the reliability is based on the assumption of preeminent Ga incorporation. The competition between Ga and In for incorporations involves, we believe, the displacement of In from the weaker In-N bonds by Ga to form the Ga-N bonds at high In and Ga fluxes.

  1. DECONTAMINATION ASSESSMENT OF BACILLUS ANTHRACIS, BACILLUS SUBTILIS, AND GEOBACILLUS STEAROTHERMOPHILUS SPORES ON INDOOR SURFACTS USING A HYDROGEN PERIOXIDE GAS GENERATOR

    Science.gov (United States)

    Aims: To evaluate the decontamination of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface materials using hydrogen peroxide gas. Methods and Results: B. anthracis, B. subtilis, and G. Stearothermophilus spores were dried on seven...

  2. Bacillus cereus as a nongastrointestinal pathogen

    Directory of Open Access Journals (Sweden)

    Pavani G.

    2014-02-01

    Full Text Available The potential of Bacillus cereus to cause systemic infections is of serious concern. Apart from Gastrointestinal infections, it causes respiratory tract infections, nosocomial infections, eye infections, CNS infections, cutaneous infections, endocarditis, osteomyelitis and urinary tract infections. The potential of this bacterium to cause life threatening infections has increased. Trauma is an important predisposing factor for Bacillus cereus infections. The maintenance of skin and mucous membrane integrity limits infection by this micro-organism. [Int J Res Med Sci 2014; 2(1.000: 28-30

  3. First-Principles Study of Electronic and Optical Properties of BxGa1 - xAs Alloy%BxGa1-xAs合金电子结构与光学性质的第一性原理计算

    Institute of Scientific and Technical Information of China (English)

    闫映策; 王彦龙; 马会芳

    2016-01-01

    First⁃principles calculations based on density functional theory are performed for zinc⁃blende BxGa1 - xAs alloy with a special quasirandom structure (SQS) approach in a 64⁃atom supercell. Structural, electronic and optical properties of BxGa1 - xAs alloy are comprehensively investigated under optimized geometry structures. It was found that calculated lattice constant slightly deviated from Vegards law and significant bond length relaxation is shown. Calculated bowing parameters of energy gap are small (2 57 eV - 5 01 eV) and are weakly composition⁃dependent. Finally, effects of boron composition on optical parameters including dielectric function, reflectivity, refractive index, absorption coefficient and energy loss function are analyzed in detail.%基于密度泛函理论的第一性原理和特殊准随机近似方法,建立64原子的超胞并且对结构进行几何优化.计算和讨论具有闪锌矿结构的三元合金 BxGa1- xAs 的结构参数、电子结构和光学性质.结果表明:BxGa1- xAs 的晶格常数与使用 Vegard 定理计算得到的值有微弱的偏离,键长存在明显的弛豫;计算得到的合金带隙弯曲参数变化较小(2.57 eV -5.01 eV)而且对组分变化的依赖很弱;最后分析硼的并入对 GaAs 光学参数包括介电函数、反射率、折射率、吸收系数和能量耗散函数的影响.

  4. Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

    NARCIS (Netherlands)

    Been, M.W.H.J. de; Francke, C.; Moezelaar, R.; Abee, T.; Siezen, R.J.

    2006-01-01

    Members of the Bacillus cereus group are ubiquitously present in the environment and can adapt to a wide range of environmental fluctuations. In bacteria, these adaptive responses are generally mediated by two-component signal transduction systems (TCSs), which consist of a histidine kinase (HK) and

  5. BOOK REVIEW – BACILLUS THURINGIENSIS: A CORNERSTONE OF MODERN AGRICULTURE BACILLUS THURINGIENSIS

    Science.gov (United States)

    Are you interested in the technical issues surrounding the use of Bacillus thuringiensis pesticidal traits as sprays and as plant incorporated protectants (transgenic crops)? Should the dimensions of human health, ecology, entomology, risk assessment, resistance management, and d...

  6. INHIBITION OF SCLEROTIA FORMATION OF SCLEROTINIA SCLEROTIORUM BY BACILLUS AMYLOLIQUEFACIENS%一株抑制油菜核盘菌菌核形成的解淀粉芽孢杆菌

    Institute of Scientific and Technical Information of China (English)

    陈士云; 杨宝玉; 高梅影; 戴顺英

    2005-01-01

    检测了从不同土壤中分离的17株芽孢杆菌对油菜核盘菌的抑制效果,发现4株菌株具有不同程度的抑制菌丝生长的能力,其中地衣芽孢杆菌菌株AJH-1和解淀粉芽孢杆菌菌株CH-2的抑菌效果最好.CH-2菌株不仅能抑制菌丝的生长,而且能抑制菌核的形成.CH-2菌株培养液经硫酸铵沉淀后具有抑制核盘菌生长的效果,且稀释10倍后仍具有抗菌活性.初步认为CH-2菌株的抑菌活性可能是抗菌蛋白或多肽的作用.图1表5参12

  7. Differentiation of Bacillus anthracis from Bacillus cereus by gas chromatographic whole-cell fatty acid analysis.

    OpenAIRE

    Lawrence, D; Heitefuss, S; Seifert, H S

    1991-01-01

    Three strains of Bacillus anthracis and seven strains of Bacillus cereus were grown on complex medium and on synthetic medium. Gas chromatographic analysis of whole-cell fatty acids of strains grown on complex medium gave nearly identical fatty acid patterns. Fatty acid patterns of strains grown on synthetic medium showed a high content of branched-chain fatty acids. Significant differences between the fatty acid patterns of the two species were found. Odd iso/anteiso fatty acid ratios were a...

  8. Comparative genome analysis of Bacillus cereus group genomes withBacillus subtilis

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iain; Sorokin, Alexei; Kapatral, Vinayak; Reznik, Gary; Bhattacharya, Anamitra; Mikhailova, Natalia; Burd, Henry; Joukov, Victor; Kaznadzey, Denis; Walunas, Theresa; D' Souza, Mark; Larsen, Niels; Pusch,Gordon; Liolios, Konstantinos; Grechkin, Yuri; Lapidus, Alla; Goltsman,Eugene; Chu, Lien; Fonstein, Michael; Ehrlich, S. Dusko; Overbeek, Ross; Kyrpides, Nikos; Ivanova, Natalia

    2005-09-14

    Genome features of the Bacillus cereus group genomes (representative strains of Bacillus cereus, Bacillus anthracis and Bacillus thuringiensis sub spp israelensis) were analyzed and compared with the Bacillus subtilis genome. A core set of 1,381 protein families among the four Bacillus genomes, with an additional set of 933 families common to the B. cereus group, was identified. Differences in signal transduction pathways, membrane transporters, cell surface structures, cell wall, and S-layer proteins suggesting differences in their phenotype were identified. The B. cereus group has signal transduction systems including a tyrosine kinase related to two-component system histidine kinases from B. subtilis. A model for regulation of the stress responsive sigma factor sigmaB in the B. cereus group different from the well studied regulation in B. subtilis has been proposed. Despite a high degree of chromosomal synteny among these genomes, significant differences in cell wall and spore coat proteins that contribute to the survival and adaptation in specific hosts has been identified.

  9. Draft genome sequence of Bacillus endophyticus 2102.

    Science.gov (United States)

    Lee, Yong-Jik; Lee, Sang-Jae; Kim, Sun Hong; Lee, Sang Jun; Kim, Byoung-Chan; Lee, Han-Seung; Jeong, Haeyoung; Lee, Dong-Woo

    2012-10-01

    Bacillus endophyticus 2102 is an endospore-forming, plant growth-promoting rhizobacterium isolated from a hypersaline pond in South Korea. Here we present the draft sequence of B. endophyticus 2102, which is of interest because of its potential use in the industrial production of algaecides and bioplastics and for the treatment of industrial textile effluents. PMID:23012284

  10. Diagnostic Oligonucleotide Microarray Fingerprinting of Bacillus Isolates

    OpenAIRE

    Chandler, Darrell P.; Alferov, Oleg; Chernov, Boris; Daly, Don S; Golova, Julia; Perov, Alexander; Protic, Miroslava; Robison, Richard; Schipma, Matthew; White, Amanda; Willse, Alan

    2006-01-01

    A genome-independent microarray and new statistical techniques were used to genotype Bacillus strains and quantitatively compare DNA fingerprints with the known taxonomy of the genus. A synthetic DNA standard was used to understand process level variability and lead to recommended standard operating procedures for microbial forensics and clinical diagnostics.

  11. Complete Genome of Bacillus thuringiensis Myophage Spock

    OpenAIRE

    Maroun, Justin W.; Whitcher, Kelvin J.; Chamakura, Karthik R.; Kuty Everett, Gabriel F.

    2013-01-01

    Bacillus thuringiensis is a Gram-positive, sporulating soil microbe with valuable pesticide-producing properties. The study of bacteriophages of B. thuringiensis could provide new biotechnological tools for the use of this bacterium. Here, we present the complete annotated genome of Spock, a myophage of B. thuringiensis, and describe its features.

  12. Surfactin production by strains of Bacillus mojavensis

    Science.gov (United States)

    Bacillus mojavensis, RRC101 is an endophytic bacterium patented for control of fungal diseases in maize and other plants. DNA fingerprint analysis of the rep-PCR fragments of 35 B. mojavensis and 4 B. subtilis strains using the Diversilab genotyping system revealed genotypic distinctive strains alon...

  13. Protein-Tyrosine Phosphorylation in Bacillus subtilis

    DEFF Research Database (Denmark)

    Mijakovic, Ivan; Petranovic, Dina; Bottini, N.;

    2005-01-01

    phosphorylation, indicating that this post-translational modifi cation could regulate physiological processes ranging from stress response and exopolysaccharide synthesis to DNA metabolism. Some interesting work in this fi eld was done in Bacillus subtilis , and we here present the current state of knowledge...

  14. The Preparation and Characteristics of InxGa1-xN (0.06 ≤ x ≤ 0.58) Films Deposited by ECR-PEMOCVD

    Institute of Scientific and Technical Information of China (English)

    LIU Xing-Long; JIANG Xin; QIN Fu-Wen; BIAN Ji-Ming; ZHANG Dong; CHEN Wei-Ji; ZHOU Zhi-Feng; ZHI An-Bo; YU Bo; WU Ai-Min

    2011-01-01

    We investigate the structural property and surface morphology of Inx Ga1-xN films for In compositions ranging from 0.06 to 0.58,which are deposited by electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD).The results of x-ray diffraction (XRD) in InGaN filns confirm that they have excellent c-axis orientation.The In content in the InGaN epilayers is checked by electron probe microanalysis (EPMA),which reveals that In fractions determined by XRD are in good agreement with the EPMA results.Atomic force microscopy measurements reveal that the grown films have a surface roughness that varies between 4.16 and 8.14nm.The results suggest that it is possible to deposit high-c-axis-orientation InGaN films with different In contents.The InGaN ternary alloy is intensively studied and of great interest because its bandgap energy can be continuously varied from the near-infrared region of ~0.7eV (InN) to the near-UV region of ~3.4eV (GaN),[1-4] and it is corrosion resistant.[6] Therefore,InGaN ternary alloys,particularly high-quality In-rich InGaN alloys,give potential applications in many crucial fields such as the whole solar spectrum,high efficiency and radiation hard multijunction solar cells,[5] high-brightness nitride green light emitting diodes and laser diodes,[1] and high-quality photoelectrodes for hydrogen production.[6]%We investigate the structural property and surface morphology of InxGa1-xN Rims for In compositions ranging from 0.06 to 0.58, which are deposited by electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD). The results of x-ray diffraction (XRD) in InGaN 61ms confirm that they have excellent c-axis orientation. The In content in the InGaN epilayers is checked by electron probe microanalysis (EPMA), which reveals that In fractions determined by XRD are in good agreement with the EPMA results. Atomic force microscopy measurements reveal that the grown films have

  15. Phylogenomic analysis shows that ‘Bacillus vanillea’ is a later heterotypic synonym of Bacillus siamensis.

    Science.gov (United States)

    Dunlap, Christopher A

    2015-10-01

    Bacillus vanillea’ XY18 ( = CGMCC 8629 = NCCB 100507) was isolated from cured vanilla beans and involved in the formation of vanilla aroma compounds. A draft genome of this strain was assembled and yielded a length of 3.71 Mbp with a DNA G+C content of 46.3 mol%. Comparative genomic analysis with its nearest relatives showed only minor differences between this strain and the genome of the Bacillus siamensis KCTC 13613T ( = BCC 22614T = KACC 16244T), with a calculated DNA–DNA hybridization (DDH) value of 91.2 % and an average nucleotide identity (ANI) of 98.9 %. This DDH value is well above the recommended 70 % threshold for species delineation, as well as the ANI threshold of 95 %. In addition, the results of morphological, physiological, chemotaxonomic and phylogenetic analyses indicate that the type strains of these two taxa are highly similar with phenotype coherence. A core genome multi-locus sequencing analysis was conducted for the strains and the results show that ‘Bacillus vanillea’ XY18 clusters closely to the type strain of Bacillus siamensis. Therefore, it is proposed that the species ‘Bacillus vanillea’ XY18 ( = CGMCC 8629 = NCCB 100507) should be reclassified as a later heterotypic synonym of Bacillus siamensis KCTC 13613T ( = BCC 22614T = KACC 16244T). An emended description of Bacillus siamensis is provided. PMID:26296875

  16. Investigation of biosurfactant production by Bacillus pumilus 1529 and Bacillus subtilis WPI

    Directory of Open Access Journals (Sweden)

    shila khajavi shojaei

    2016-06-01

    Full Text Available Introduction: Biosurfactants are unique amphipathic molecules with extensive application in removing organic and metal contaminants. The purpose of this study was to investigate production of biosurfactant and determine optimal conditions to produce biosurfactant by Bacillus pumilus 1529 and Bacillus subtilis WPI. Materials and methods: In this study, effect of carbon source, temperature and incubation time on biosurfactant production was evaluated. Hemolytic activity, emulsification activity, oil spreading, drop collapse, cell hydrophobicity and measurement of surface tension were used to detect biosurfactant production. Then, according to the results, the optimal conditions for biosurfactant production by and Bacillus subtilis WPI was determined. Results: In this study, both bacteria were able to produce biosurfactant at an acceptable level. Glucose, kerosene, sugarcane molasses and phenanthrene used as a sole carbon source and energy for the mentioned bacteria. Bacillus subtilis WPI produced maximum biosurfactant in the medium containing kerosene and reduced surface tension of the medium to 33.1 mN/m after 156 hours of the cultivation at 37°C. Also, the highest surface tension reduction by Bacillus pumilus 1529 occurred in the medium containing sugarcane molasses and reduce the surface tension of culture medium after 156 hours at 37°C from 50.4 to 28.83 mN/m. Discussion and conclusion: Bacillus pumilus 1529 and Bacillus subtilis WPI had high potential in production of biosurfactant and degradation of petroleum hydrocarbons and Phenanthrene. Therefore, it could be said that these bacteria had a great potential for applications in bioremediation and other environmental process.

  17. Anisotropic optical polarization dependence on internal strain in AlGaN epilayer grown on Al x Ga1-x N templates

    Science.gov (United States)

    Long, Hanling; Wu, Feng; Zhang, Jun; Wang, Shuai; Chen, Jingwen; Zhao, Chong; Feng, Zhe Chuan; Xu, Jintong; Li, Xiangyang; Dai, Jiangnan; Chen, Changqing

    2016-10-01

    Anisotropic optical polarization of AlGaN has been one of the major challenges responsible for the poor efficiency of AlGaN-based ultraviolet light emitting diodes (UV LEDs). In this work, we experimentally investigated the effect of internal strain on the optical polarization of AlGaN epilayers which were pseudomorphically grown on Al x Ga1-x N templates with Al composition changing from 0.1 to 0.42. High-resolution x-ray diffraction and reciprocal space mapping were conducted to determine the crystal quality and strain status. Polarization-dependent photoluminescence (PL) measurement was performed to study the degree of polarization (DOP) of light emission from lateral facet of the AlGaN epilayer. The result showed that the DOP increased from  -0.69 to  -0.24 with the in-plane strain changing from tensile status (1.19%) to compressive status (-0.70%) and it exhibited a strong dependence of the DOP on the strain. These results demonstrated that the compressive in-plane strain could facilitate TE mode emission from AlGaN, which providing a potential way to enhance the surface light emission of AlGaN-based UV LEDs via strain management of the active region.

  18. An analysis of the growth of silver catalyzed InxGa1-xAs nanowires on Si (100) by metal organic chemical vapor deposition

    Science.gov (United States)

    Sarkar, K.; Palit, M.; Chattopadhyay, S.; Banerji, P.

    2016-08-01

    A model is proposed here to understand the nucleation of III-V semiconductor nanowires (NW). Whereas the classical nucleation theory is not adequately sufficient in explaining the evolution of the shape of the NWs under different chemical environment such as flow rate or partial pressure of the precursors, the effect of adsorption and desorption mediated growth, and diffusion limited growth are taken into account to explain the morphology and the crystal structure of InxGa1-xAs nanowires (NW) on Silicon (100) substrates grown by a metalorganic chemical vapor deposition technique. It is found that the monolayer nucleus that originates at the triple phase line covers the entire nucleus-substrate (NS) region at a specific level of supersaturation and there are cases when the monolayer covers a certain fraction of the NS interface. When the monolayer covers the total NS interface, NWs grow with perfect cylindrical morphology and whenever a fraction of the interface is covered by the nucleus, the NWs become curved as observed from high resolution transmission electron microscopy images. The supersaturation, i.e., the chemical potential is found to be governed by the concentration of precursors into the molten silver which in the present case is taken as a catalyst. Our study provides new insights into the growth of ternary NWs which will be helpful in understanding the behavior of growth of different semiconducting NWs.

  19. The Increase of Radiative Lifetime of Free Excitons in Selectively Si-doped GaAs/AlxGa1-xAs Heterostructures

    Directory of Open Access Journals (Sweden)

    Jurgis KUNDROTAS

    2014-06-01

    Full Text Available The time resolved photoluminescence spectra of selectively Si-doped GaAs/AlxGa1-xAs heterostructures have been investigated over a wide temperature range from 3.6 K to 300 K in order to identify possible mechanisms behind the observed increase in radiative lifetime of free excitons. Possible mechanisms of carrier recombination are discussed with emphasis on the unique traits of excitonic photoluminescence. The intensive lines found in the spectra of the heterostructures are associated with the formation and enhancement of free exciton emission in the flat band region of an active i-GaAs layer. We have established that the free exciton radiative lifetime in the heterostructures increases about two times, up to 1.44 ns in comparison with lifetime 0.6 ns of i-GaAs layer without a heterostructure for first sample and up to 0.92 ns from 0.4 ns for second sample at 3.6 K temperature. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6329

  20. Influence of Indium-Percentage Variation on Dynamical Characteristics of InxGa1-xAs/GaAs(001) Quantum Dot Lasers

    CERN Document Server

    Borji, Mahdi Ahmadi

    2015-01-01

    The influence of indium percentage on dynamical characteristics of InxGa1-xAs/GaAs(001) quantum dot lasers (QDLs) is investigated. Energy levels of self-organized truncated-cone-shape QDs are calculated by means of the eight-band k.p model, and their dependence to indium percentage is surveyed. Then, by presenting a three-level model and numerical solution of the resulting rate equations, laser properties are determined. Our results show that inclusion of more indium gives rise in the reduced energy gap and electron-hole recombination energy. Moreover, lasing process for both Ground State (GS) and Excited States (ES) sound to be sensitive to indium percentage. It is shown that rise of indium percentage at fixed injected current results in the increased ES turn-on delay and GS photon number and 3dB modulation bandwidth, and decreased ES photon number, GS turn on delay, amplitude of relaxation oscillations, output power, and ES 3dB modulation bandwidth; but has no effect on threshold current and laser gain. At ...

  1. Impact of photoluminescence temperature and growth parameter on the exciton localized in BxGa1-xAs/GaAs epilayers grown by MOCVD

    Science.gov (United States)

    Hidouri, Tarek; Saidi, Faouzi; Maaref, Hassen; Rodriguez, Philippe; Auvray, Laurent

    2016-10-01

    In this work, BxGa1-xAs/GaAs epilayers with three different boron compositions were elaborated by metal organic chemical vapor deposition (MOCVD) on GaAs (001) substrate. Structural study using High resolution X-ray diffraction (HRXRD) spectroscopy and Atomic Force Microscopy (AFM) have been used to estimate the boron fraction. The luminescence keys were carried out as functions of temperature in the range 10-300 K, by the techniques of photoluminescence (PL). The low PL temperature has shown an abnormal emission appeared at low energy side witch attributed to the recombination through the deep levels. In all samples, the PL peak energy and the full width at half maximum (FWHM), present an anomalous behavior as a result of the competition process between localized and delocalized carriers. We propose the Localized-state Ensemble model to explain the unusual photoluminescence behaviors. Electrical carriers generation, thermal escape, recapture, radiative and non-radiative lifetime are taken into account. The temperature-dependent photoluminescence measurements were found to be in reasonable agreement with the model of localized states. We controlled the evolution of such parameters versus composition by varying the V/III ratio to have a quantitative and qualitative understanding of the recombination mechanisms. At high temperature, the model can be approximated to the band-tail-state emission.

  2. Strain relaxation in GaN/AlxGa1-xN superlattices grown by plasma-assisted molecular-beam epitaxy

    International Nuclear Information System (INIS)

    We have investigated the misfit relaxation process in GaN/AlxGa1-xN (x = 0.1, 0.3, 0.44) superlattices (SL) deposited by plasma-assisted molecular beam epitaxy. The SLs under consideration were designed to achieve intersubband absorption in the mid-infrared spectral range. We have considered the case of growth on GaN (tensile stress) and on AlGaN (compressive stress) buffer layers, both deposited on GaN-on-sapphire templates. Using GaN buffer layers, the SL remains almost pseudomorphic for x = 0.1, 0.3, with edge-type threading dislocation densities below 9 x 108 cm-2 to 2 x 109 cm-2. Increasing the Al mole fraction to 0.44, we observe an enhancement of misfit relaxation resulting in dislocation densities above 1010 cm-2. In the case of growth on AlGaN, strain relaxation is systematically stronger, with the corresponding increase in the dislocation density. In addition to the average relaxation trend of the SL, in situ measurements indicate a periodic fluctuation of the in-plane lattice parameter, which is explained by the different elastic response of the GaN and AlGaN surfaces to the Ga excess at the growth front. The results are compared with GaN/AlN SLs designed for near-infrared intersubband absorption.

  3. Density Profiles in Sputtered Molybdenum Thin Films and Their Effects on Sodium Diffusion in Cu(InxGa1-x)Se2 Photovoltaics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Li, J.; Glynn, S.; Mansfield, L.; Young, M.; Yan, Y.; Contreras, M.; Noufi, R.; Levi, D.; Terry Jr., F. L.

    2011-07-01

    Molybdenum (Mo) thin films were sputtered onto soda lime glass (SLG) substrates. The main variable in the deposition parameters, the argon (Ar) pressure pAr, was varied in the range of 6 - 20 mTorr. Ex situ spectroscopic ellipsometry (SE) was performed to find out that the dielectric functions of the Mo films were strongly dependent on pAr, indicating a consistent and significant decrease in the Mo film density pMo with increasing pAr. This trend was confirmed by high-angle-annular-dark-field scanning transmission electron microscopy. Dielectric functions of Mo were then found to be correlated with secondary ion mass spectroscopy profiles of Sodium (Na) in the Cu(InxGa1-x)Se2 (CIGS) layer grown on top of Mo/SLG. Therefore, in situ optical diagnostics can be applied for process monitoring and optimization in the deposition of Mo for CIGS solar cells. Such capability is demonstrated with simulated optical transmission and reflectance of variously polarized incident light, using dielectric functions deduced from SE.

  4. Influence of In-N Clusters on Band Gap Energy of Dilute Nitride In x Ga1‑x N y As1‑y

    Science.gov (United States)

    Zhao, Chuan-Zhen; Guo, Heng-Fei; Chen, Li-Ying; Tang, Chun-Xiao; Lu, Ke-Qing

    2016-05-01

    The In-N clusters form in the dilute nitride InxGa1‑xNyAs1‑y alloys after annealing. It is found that the formation of the In-N clusters not only raises the N levels lying above the conduction band minimum (CBM) of InGaAs, but also raises the N levels below the CBM of InGaAs, leading to the variation of the impurity-host interaction. The blueshift of the band gap energy is relative to the variation of the impurity-host interaction. In order to describe the blueshift of the band gap energy due to the formation of the In-N clusters, a model is developed. It is found that the model can describe the blueshift of the band gap energy well. In addition, it is found the blueshift of the band gap energy due to the atom interdiffusion at the interface can be larger than that due to the formation of the In-N clusters. Supported by the National Natural Science Foundation of China under Grant No. 61504094, Tinjin Research Program of Application Foundation and Advanced Technology under No. 15JCYBJC16300, and Tianjin City High School Science and Technology Fund Planning Project No. 20120609

  5. Silicon doping of semipolar (11 2 bar 2)Alx Ga1-x N (0.50 ≤ x ≤ 0.55)

    Science.gov (United States)

    Dinh, Duc V.; Pampili, Pietro; Parbrook, Peter J.

    2016-10-01

    The effect of silicon doping on the growth and properties of ∼ 1.0 μm-thick Alx Ga1-x N(0.50 ≤ x ≤ 0.55) layers grown on semipolar (11 2 bar 2) AlN templates by metalorganic vapour phase epitaxy was studied. The layers were grown with different disilane/group-III precursors ratios that varied from 2.8×10-5 to 3.4×10-4. The surface morphology of the Si-doped (11 2 bar 2) AlGaN layers showed undulations along [ 1 1 bar 00 ] AlGaN , AlN with a root-mean square roughness of about 4.0 nm within a scan range of 20 × 20 μm2 . Different photoluminescence peaks have been linked to negatively charged cation vacancies (VIII3-) and their complexes with impurities such as VIII3- - 3 ON1+, (VIII complex)1-, and (VIII complex)2-. The optimised AlGaN:Si layer exhibited a carrier concentration of ∼1.2×1019 cm-3, a carrier mobility of 30.7 cm2/V s, and a resistivity of 0.018 Ω cm , as determined by Hall-effect measurements at room temperature. A correlation between the resistivity and luminescence emission intensities of AlGaN near-band-edge and impurity-related complexes was found.

  6. Synthesis of (Ga1-xZnx)(N1-xOx) with Enhanced Visible-Light Absorption and Reduced Defects by Suppressing Zn Volatilization.

    Science.gov (United States)

    Chen, Dennis P; Skrabalak, Sara E

    2016-04-18

    (Ga1-xZnx)(N1-xOx) (GZNO) particles with enhanced optical absorption were synthesized by topotactic transformation of Zn(2+)/Ga(3+) layered double hydroxides. This outcome was achieved by suppressing Zn volatilization during nitridation by maintaining a low partial pressure of O2 (pO2). Zn-rich (x > (1)/3) variants of GZNO were achieved and compared to those prepared by conventional ammonoylsis conditions. The optical absorption and structural properties of these samples were compared to those prepared in the absence of O2 by diffuse-reflectance spectroscopy and powder X-ray diffraction methods. Notably, suppression of Zn volatilization leads to smaller-band-gap materials (2.30 eV for x = 0.42 versus 2.71 eV for x = 0.21) and reduced structural defects. This synthetic route and set of characterizations provide useful structure-property studies of GZNO and potentially other oxynitrides of interest as photocatalysts. PMID:26840948

  7. X-ray luminescence spectra of graded-gap Al xGa 1- xAs structures irradiated by alpha particle

    Science.gov (United States)

    Šilėnas, A.; Požela, J.; Požela, K.; Jucienė, V.; Dapkus, L.

    2011-12-01

    The influence of 241Am alpha particle irradiation on X-ray luminescence spectra of the graded-gap AlxGa1-xAs structures of different thicknesses is investigated. It is observed that the integral X-ray luminescence intensity of nonirradiated thin (15 μm) structure is 1.4 times less than that in the thick (32 μm) structure, and this difference increases to 3 times after 3×1010 cm-2 dose of irradiation by alpha particle. The X-ray luminescence intensity of the energy hνFgg is responsible of that large difference, because it shifts the X-ray generated carriers to the narrow-gap surface with great nonradiative surface recombination rate. The alpha particle irradiation increases nonradiative recombination rate and causes a decrease of the X-ray luminescence intensity of all spectra lines in the thin (15 μm) detector. The most significant drop in X-ray luminescence efficiency is observed from the region at narrow-gap surface after the initial stage (109 cm-2 dose) of alpha particle irradiation. In the 32 μm thick detector, the luminescence intensity of the energy hν=1.8 eV does not change up to 2×1010 cm-2 of alpha particle irradiation dose. That means the high irradiation hardness of the thick graded-gap X-ray detector with optical response.

  8. Solar-blind Al x Ga1- x N ( x > 0.45) p- i- n photodiodes with a polarization- p-doped emitter

    Science.gov (United States)

    Kuznetsova, N. V.; Nechaev, D. V.; Shmidt, N. M.; Karpov, S. Yu.; Rzheutskii, N. V.; Zemlyakov, V. E.; Kaibyshev, V. Kh.; Kazantsev, D. Yu.; Troshkov, S. I.; Egorkin, V. I.; Ber, B. Ya.; Lutsenko, E. V.; Ivanov, S. V.; Jmerik, V. N.

    2016-06-01

    Polarization-induced p-type doping of AlGaN layers with high aluminum content during plasmaassisted MBE growth has been studied. It is shown that a gradient of the AlN molar fraction in AlGaN (composition gradient) on a level of 0.005 nm-1 must be set in order to obtain a hole concentration of ~1018 cm-3 (measured by the C- V method) in Al x Ga1- x N:Mg ( x = 0.52-0.32) layers with dopant concentration [Mg] = 1.3 × 1018 cm-3. p- i- n photodiodes based on AlGaN heterostructures with such layers as p-emitters showed maximum photoresponsitivity in the solar-blind wavelength range (λ = 281 nm) about 35 and 48 mA/W at reverse bias voltage U = 0 and-5 V, respectively, and exhibited a dark current density of 3.9 × 10-8 A/cm2 at U =-5 V.

  9. Effect of Misfit Dislocation Originated from Strained Layer on Photoluminescence Properties of InxGa1-xN/GaN Multiple Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    L(U) Wei; LI Da-Bing; LI Chao-Rong; CHEN Gang; ZHANG Ze

    2005-01-01

    @@ Inx Ga1-xN/GaN multiple quantum well (MQW) samples with strain-layer thickness larger/less than the critical one are investigated by temperature-dependent photoluminescence and transmission electron microscopy, and double crystal x-ray diffraction.For the sample with the strained-layer thickness greater than the critical thickness, we observe a high density of threading dislocations generated at the MQW layers and extended to the cap layer.These dislocations result from relaxation of the strain layer when its thickness is beyond the critical thickness.For the sample with the strained-layer thickness greater than the critical thickness, temperature-dependent photoluminescence measurements give evidence that dislocations generated from the MQW layers due to strain relaxation are main reason of the poor photoluminescence property, and the dominating status change of the main peak with increasing temperature is attributed to the change of the radiative recombination from the areas including dislocations to the ones excluding dislocations.

  10. Lattice vibrations study of Ga1-xInxAsySb1-y quaternary alloys with low (In, As) content grown by liquid phase epitaxy

    International Nuclear Information System (INIS)

    Raman scattering spectroscopy was used to measure and analyze the lattice vibrations in some quaternary Ga1-xInxAsySb1-y alloys with low (In, As) contents (0.03 0C. High Resolution X-Ray Diffraction results showed profiles associated with a quaternary layer lattice matched to the GaSb substrate as obtained from the (004) reflection. The experimental diffractograms were simulated to estimate alloy composition, thickness and lattice mismatch of the layer. Raman scattering results show phonon frequencies associated to the TO and LO GaAs-like modes as well as GaSb + InAs-like mode, which are characteristic of this quaternary alloy. The As content dependence of the phonon frequency measured in this alloy for low (In, As) contents agree well with the modified Random-Element Isodisplacement (REI) model and also with other available experimental reports. This method can also be used to estimate alloy compositions for this kind of quaternary alloys

  11. Magnetic breakdown and quantum magnetotransport with a constant pseudospin under tilted magnetic fields in an n-InxGa1-xAs/GaAs double quantum well

    International Nuclear Information System (INIS)

    A procedure is proposed for precise scanning of the (Bperpendicular , Bparallel) plane between the magnetic field projections that are perpendicular and parallel to (quasi-)two-dimensional layers when measuring their longitudinal and Hall magnetoresistances. Investigations of a n-InxGa1-xAs/GaAs double quantum well (x ∼ 0.2) performed using this procedure make it possible to reveal a number of the features of the magnetoresistance, which appear due to a complex energy spectrum of the double quantum well in a parallel field, and to separate them from the structures associated with the magnetic breakdown. The trajectories representing the features of the magnetoresistance in the (Bperpendicular , Bparallel) plane are described by the semiclassical calculations of the quantization of the energy spectrum of the double quantum well under the action of the perpendicular field component. The structures appearing due to the magnetic breakdown are amplified with increasing the total magnetic field magnitude and, in the samples with low mobility, completely suppress the features caused by the motion of an electron with a constant pseudospin component. The peaks corresponding to the magnetic breakdown are split in a strong parallel field due to the spin splitting of the Landau levels. These splittings correspond to the effective Lande factor vertical bar g* vertical bar ∼ 3

  12. Optical and structural properties of InP quantum dots embedded in (AlxGa1-x)0.51In0.49P

    Science.gov (United States)

    Schulz, W.-M.; Roßbach, R.; Reischle, M.; Beirne, G. J.; Bommer, M.; Jetter, M.; Michler, P.

    2009-01-01

    Within this work we present optical and structural properties of InP quantum dots embedded in (AlxGa1-x)0.51In0.49P barriers. Atomic force microscopy measurements show a mainly bimodal height distribution with aspect ratios (ratio of width to height) of about 10:1 and quantum dot heights of around 2 nm for the smaller quantum dot class (type A) and around 4 nm for the larger quantum dot class (type B). From ensemble-photoluminescence measurements we estimated thermal activation energies of up to 270 meV for the type-A quantum dots, resulting in a 300 times higher luminescence intensity at 200 K in comparison to our InP quantum dots in Ga0.51In0.49P at the same emission wavelength. Photon statistic measurements clearly display that InP quantum dots in (Al0.20Ga0.80)0.51In0.49P emit single photons up to 80 K, making them promising candidates for high-temperature single-photon emitters.

  13. Interplay of boron localized states and electron transport in B x Ga1-x As0.11 P0.89:Te

    Science.gov (United States)

    Ostheim, L.; Klar, P. J.; Liebich, S.; Ludewig, P.; Volz, K.; Stolz, W.

    2016-07-01

    We study the magnetotransport properties of n-type B x Ga1-x As0.11 P0.89:Te alloy samples with 0≤slant x≤slant 0.038 in magnetic fields up to 4 T between 10 and 280 K, some samples also under hydrostatic pressure up to 15 kbar. As a general trend the resistivity increases with increasing x, as both the carrier concentration and the mobility of electrons decrease. The free carrier concentration and mobility of the reference sample GaAs0.11 P0.89:Te is almost independent of the applied hydrostatic pressure, in particular, at higher temperatures whereas the B0.018Ga0.982As0.11P0.89:Te sample exhibits a different behavior. Its resistivity decreases due to a substantial increase of its free carrier concentration under pressure. This behavior is explained by the existence of a boron-related density of localized states in the vicinity of the conduction band edge of the alloy. The boron states act as electron traps as well as efficient scattering centers. Applying hydrostatic pressure shifts the energetic positions of conduction band edge at the X-point and of the boron states apart, reducing the impact of boron on the electronic transport properties of the alloy.

  14. Bacillus caldolyticus prs gene encoding phosphoribosyldiphosphate synthase

    DEFF Research Database (Denmark)

    Krath, Britta N.; Hove-Jensen, Bjarne

    1996-01-01

    The prs gene, encoding phosphoribosyl-diphosphate (PRPP) synthase, as well as the flanking DNA sequences were cloned and sequenced from the Gram-positive thermophile, Bacillus caldolyticus. Comparison with the homologous sequences from the mesophile, Bacillus subtilis, revealed a gene (gca......D) encoding N-acetylglucosamine-l-phosphate uridyltransferase upstream of prs, and a gene homologous to ctc downstream of prs. cDNA synthesis with a B. caldolyticus gcaD-prs-ctc-specified mRNA as template, followed by amplification utilising the polymerase chain reaction indicated that the three genes are co......-transcribed. Comparison of amino acid sequences revealed a high similarity among PRPP synthases across a wide phylogenetic range. An E. coli strain harbouring the B. caldolyticus prs gene in a multicopy plasmid produced PRPP synthase activity 33-fold over the activity of a haploid B. caldolyticus strain. B. caldolyticus...

  15. Bacillus cereus Biofilms—Same, Only Different

    Science.gov (United States)

    Majed, Racha; Faille, Christine; Kallassy, Mireille; Gohar, Michel

    2016-01-01

    Bacillus cereus displays a high diversity of lifestyles and ecological niches and include beneficial as well as pathogenic strains. These strains are widespread in the environment, are found on inert as well as on living surfaces and contaminate persistently the production lines of the food industry. Biofilms are suspected to play a key role in this ubiquitous distribution and in this persistency. Indeed, B. cereus produces a variety of biofilms which differ in their architecture and mechanism of formation, possibly reflecting an adaptation to various environments. Depending on the strain, B. cereus has the ability to grow as immersed or floating biofilms, and to secrete within the biofilm a vast array of metabolites, surfactants, bacteriocins, enzymes, and toxins, all compounds susceptible to act on the biofilm itself and/or on its environment. Within the biofilm, B. cereus exists in different physiological states and is able to generate highly resistant and adhesive spores, which themselves will increase the resistance of the bacterium to antimicrobials or to cleaning procedures. Current researches show that, despite similarities with the regulation processes and effector molecules involved in the initiation and maturation of the extensively studied Bacillus subtilis biofilm, important differences exists between the two species. The present review summarizes the up to date knowledge on biofilms produced by B. cereus and by two closely related pathogens, Bacillus thuringiensis and Bacillus anthracis. Economic issues caused by B. cereus biofilms and management strategies implemented to control these biofilms are included in this review, which also discuss the ecological and functional roles of biofilms in the lifecycle of these bacterial species and explore future developments in this important research area. PMID:27458448

  16. Anthrose Biosynthetic Operon of Bacillus anthracis▿

    OpenAIRE

    Dong, Shengli; McPherson, Sylvia A.; Tan, Li; Chesnokova, Olga N.; Turnbough, Charles L.; Pritchard, David G.

    2008-01-01

    The exosporium of Bacillus anthracis spores consists of a basal layer and an external hair-like nap. The nap is composed primarily of the glycoprotein BclA, which contains a collagen-like region with multiple copies of a pentasaccharide side chain. This oligosaccharide possesses an unusual terminal sugar called anthrose, followed by three rhamnose residues and a protein-bound N-acetylgalactosamine. Based on the structure of anthrose, we proposed an enzymatic pathway for its biosynthesis. Exam...

  17. Antimicrobial Effects of Honey on Bacillus Cereus

    OpenAIRE

    This paper should be cited as: Javadzadeh M, Najafi M, Rezaei M, Dastoor M, Behzadi AS, Amiri A . [ Antimicrobial Effects of Honey on Bacillus Cereus ]. MLJ. 201 4 ; 8 ( 2 ): 55 - 61 [Article in Persian] Javadzadeh, M. (MSc; M Najafi; Rezaei, M. (MSc; Dastoor, M. (BSc; Behzadi, AS. (MSc; Amiri, A. (MSc

    2014-01-01

    Background and Objective: Honey is a healthy and nutritious food that has been used for a long time as a treatment for different diseases. One of the applied properties of honey is its antimicrobial effect, which differs between different types of honey due to variation of phenolic and antioxidant compositions. This study aimed to assess antimicrobial effect of honey on Bacillus cereus, considering its chemical properties. Material and Methods: Three samples of honey (A1 and A2 of Khorasan Ra...

  18. Electronic band structure of GaAs/AlxGa1-xAs superlattice in a periodic magnetic field%GaAs/AlxGa1-xAs超晶格在周期性磁场中电子的能带结构

    Institute of Scientific and Technical Information of China (English)

    张彦敏; 成泽

    2006-01-01

    在有效质量理论近似下,采用磁Kronig-Penny势场,精确求解了GaAs/AlxGa1-xAs超晶格中的电子在周期性磁场中形成的能带结构.考虑不同方向上的周期性磁调制以及电调制的作用下三维电子的运动行为,发现电子不仅在z方向形成能带,而且在y方向也可以形成一些可允许的能带.同时详细讨论了电子能带结构的特点及其形成机制.

  19. Ga1-xInxNyAs1-y/GaAs量子阱中电子-LO声子的散射率%Electron-LO phonon scattering in Ga1-xInxNyAs1-y/GaAs quantum well

    Institute of Scientific and Technical Information of China (English)

    陈茜; 王海龙; 汪辉; 龚谦; 宋志棠

    2013-01-01

    Within the framework of effective mass approximation, the values of energy eigenvalue En in Ga1−xInxNyAs1−y/GaAs quantum well are theoretically calculated using shooting method. In addition, we calculate the electron-LO phonon scattering and mean scat-tering rate at different temperatures, well width, N concentrations and In concentrations for an electron initially in the second subband and finally in the ground state using Fermi’s golden rule. It is shown that the electron-LO phonon scattering and mean scattering rate increase with the increase of N concentration under the In concentration constant. The electron-LO phonon scattering and mean scattering rate decrease with the increase of In concentration under the In concentration constant. The electron-LO phonon scattering increases monotonically with the increase of temperature. When the temperature is relatively low, the variation of mean scattering rate is not obvious with the increase of temperature When the temperature is relatively high, mean scattering rate increases with the increase of temperature. The scattering and mean scattering rate increase up to their maxima and then begin to decrease as the well width increases. The maximum value is reached when the well width is about 200 ˚A. Our calculated results are meaningful and can be used for designing the optoelectronic devices based on Ga1−xInxNyAs1−y/GaAs quantum well.%在有效质量近似下利用打靶法求出Ga1−xInxNyAs1−y/GaAs量子阱中的本征能级En,并通过费米黄金规则计算电子-LO声子由第一激发态到基态的散射率和平均散射率随温度、阱宽以及氮(N)和铟(In)组分变化的规律。计算结果表明:在In组分恒定的情况下,随着N组分的增加,散射率和平均散射率增加;在N组分恒定的情况下,随着In组分的增加,散射率和平均散射率减小;随着温度的增加,在温度较低时散射率和平均散射率随温度的增加变化不大,在温度较高时

  20. Influence of the Active Layer on Exponential-Doping Ga1-xAlxAs/GaAs Photocathode Performances%发射层对指数掺杂Ga1-χAlχ As/GaAs光阴极性能的影响

    Institute of Scientific and Technical Information of China (English)

    赵静; 常本康; 熊雅娟; 张益军; 张俊举

    2011-01-01

    For research on the influence of the active layer on optical and photoelectric performances of exponentialdoping Ga1-x Alx As/GaAs photocathode, we prepared two samples with different thicknesses of 1.6 μm and 2.0 μm for the active layer. The reflectance, transmittance and spectral response curves were measured ranging from 400 nm to 1000 nm. The experimental result showed that the thicker sample possesed better performance than the other one. Theoretical reflectance,transmittance and absorptivity are derived as functions of the thickness from matrix theory in thin film optics. And the original quantum efficiency formula is modified by reflectance spectrum and shortwave limit. Based on the modification, absorptivity and spectral response are simulated with various thicknesses. It illuminates that the influence of the active layer is inconsistent on both the performances. Additionally, the scope of the optimal thickness is calculated as 1.8 μm ~2.4 μm in the case of exponential-doping Ga1-xAlxAs/GaAs photocathode.%为了探索发射层厚度对指数掺杂Ga1-χAlχAs/GaAs光电阴极光学性能与光电发射性能的影响,实验制备了两种发射层厚度不同的阴极样品,并测试得到400μm~1 000 nm内反射率、透射率与光谱响应曲线.实验结果说明发射层2.0 μm厚的样品比1.6μm厚的样品性能更好.利用薄膜光学矩阵理论公式计算阴极膜系反射率、透射率、吸收率与发射层厚度的关系公式,并对原有的量子效率公式进行光谱反射率和短波截止限的修正.用修正后的公式仿真不同发射层厚度下光阴极吸收率与光谱响应曲线,指出发射层厚度对阴极光学性能与光电发射性能的不同影响.进一步计算得到指数掺杂的Ga1-χAlχAs/GaAs光电阴极最佳发射层厚度范围是1.8μm~2.4μm.

  1. BACILLUS CEREUS: ISOLATION IN JENNET MILK

    Directory of Open Access Journals (Sweden)

    M.L. Scatassa

    2011-01-01

    Full Text Available Jennet milk as human food is hypoallergenic for patients affected by Cow Milk Protein Allergy and multiple food allergies. For these pathologies, jennet milk represents the best alternative to other types of milk. Therefore, jennet milk consumers are very sensible to the effects of pathogens' contaminations, and several hygienic practices during the milk production need to be adopted. During regular monitoring in one Sicilian jennet farm, Bacillus cereus in the milk was detected. In 3 bulk milk samples (maximum concentration: 1.2 x 103 ufc/ml, in 3 individual milk samples (10, 20 e 60 ufc/ml, in the milk filter (5 ufc/cm2, in the soil (maximum concentration: 1.5 x 103 ufc/g, on the hands and the gloves of two milkers, on the animal hide (from 1 to 3 ufc/cm2. No spores were detected. A total of 8 Bacillus cereus s.s. strains were analyzed for diarrhoic toxin, and 6 strains producing enterotoxins resulted. The improvement of environmental and milking hygienic conditions reduced Bacillus cereus concentration.

  2. Bioaccumulation of copper, zinc, cadmium and lead by Bacillus sp., Bacillus cereus, Bacillus sphaericus and Bacillus subtilis Bioacumulação de cobre, zinco, cádmio e chumbo por Bacillus sp., Bacillus cereus, Bacillus sphaericus e Bacillus subtilis

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Augusto da Costa

    2001-03-01

    Full Text Available This work presents some results on the use of microbes from the genus Bacillus for uptake of cadmium, zinc, copper and lead ions. Maximum copper bioaccumulations were 5.6 mol/g biomass for B. sphaericus, 5.9 mol/g biomass for B. cereus and B. subtilis, and 6.4 mol/g biomass for Bacillus sp. Maximum zinc bioaccumulations were 4.3 mol/g biomass for B. sphaericus, 4.6 mol/g biomass for B. cereus, 4.8 mol/g biomass for Bacillus sp. and 5.0 mol/g biomass for B. subtilis. Maximum cadmium bioaccumulations were 8.0 mol/g biomass for B. cereus, 9.5 mol/g biomass for B. subtilis, 10.8 mol/g biomass for Bacillus sp. and 11.8 mol/g biomass for B. sphaericus. Maximum lead biomaccumulations were 0.7 mol/g biomass for B. sphaericus, 1.1 mol/g biomass for B. cereus, 1.4 mol/g biomass for Bacillus sp. and 1.8 mol/g biomass for B. subtilis. The different Bacillus strains tested presented distinct uptake capacities, and the best results were obtained for B. subtilis and B. cereus.Este trabalho apresenta resultados de acumulação dos íons metálicos cádmio, zinco, cobre e chumbo por bactérias do gênero Bacillus. A bioacumulação máxima de cobre foi 5,6 mol/g biomassa para B. sphaericus, 5,9 mol/g biomassa para B. cereus e B. subtilis, e 6,4 mol/g biomassa para Bacillus sp.. A bioacumulação máxima de zinco foi 4,3 mol/g biomassa para B. sphaericus, 4,6 mol/g biomassa para B. cereus, 4,8 mol/g biomassa para Bacillus sp. e 5,0 mol/g biomassa para B. subtilis. A bioacumulação máxima de cádmio foi 8,0 mol/g biomassa para B. cereus, 9,5 mol/g biomassa para B. subtilis, 10,8 mol/g biomassa para Bacillus sp. e 11,8 mol/g biomassa para B. sphaericus. A bioacumulação máxima de chumbo foi 0,7 mol/g biomassa para B. sphaericus, 1,1 mol/g biomassa para B. cereus, 1,4 mol/g biomassa para Bacillus sp. e 1,8 mol/g biomassa para B. subtilis. As distintas linhagens de Bacillus testadas apresentaram variáveis capacidades de carregamento de íons metálicos, sendo os

  3. Isolation of bacillus thuringiensis from different samples from Mansehra District

    International Nuclear Information System (INIS)

    The insecticidal activity of Bacillus thuringiensis has made it very interesting for the control of a variety of agricultural pests and human disease vectors. The present study is an attempt to explore the potential and diversity. of Bacillus thuringiensis. from the local environment for the control of cotton spotted bollworm (Earias sp.), a major pest of cotton. Two hundred and ninety eight samples of soil, grain dust, wild animal dung, birds dropping, decaying leaves and dead insects were collected from different ecological environments of Mansehra District yielding 438 Bacillus thuringiensis isolates that produce parasporal crystalline inclusions. In this study the soil samples were found to be the richest source for Bacillus thuringiensis. (author)

  4. Admittance–voltage profiling of AlxGa1−xN/GaN heterostructures: Frequency dependence of capacitance and conductance

    International Nuclear Information System (INIS)

    Admittance–voltage profiling of AlxGa1−xN/GaN heterostructures was used to determine the frequency dependent capacitance and conductance of FET devices in the frequency range from 50 Hz to 1 MHz. The nominally undoped low pressure metal-organic vapor-phase epitaxy structures were grown with an Al-content of 30%. An additional 1 nm thick AlN interlayer was placed in one structure before the Al0.3Ga0.7N layer growth. For frequencies below 108 Hz it is convenient to use equivalent circuits to represent electric or dielectric properties of a material, a method widely used, for example, in impedance spectroscopy. We want to emphasize the relation between frequency dependent admittance–voltage profiling and the corresponding equivalent circuits to the complex dielectric function. Debye and Drude models are used for the description of the frequency dependent admittance profiles in a range of depletion onset of the two-dimensional electron gas. Capacitance- and conductance-frequency profiles are fitted in the entire measured range by combining both models. Based on our results, we see contributions to the two-dimensional electron gas for our samples from surface states (80%) as well as from background doping in the Al0.3Ga0.7N barriers (20%). The specific resistance of the layers below the gate is above 105 Ω cm for both samples and increases with increasing negative bias, i.e., the layers below the gate are essentially depleted. We propose that the resistance due to free charge carriers, determined by the Drude model, is located between gate and drain and, because of the AlN interlayer, the resistance is lowered by a factor of about 30 if compared to the sample without an AlN layer

  5. Properties of Schottky Barrier Diodes on (In(x)Ga(1-x))₂O₃ for 0.01 ≤ x ≤ 0.85 Determined by a Combinatorial Approach.

    Science.gov (United States)

    von Wenckstern, H; Splith, D; Werner, A; Müller, S; Lorenz, M; Grundmann, M

    2015-12-14

    We investigated properties of an (In(x)Ga(1-x))2O3 thin film with laterally varying cation composition that was realized by a large-area offset pulsed laser deposition approach. Within a two inch diameter thin film, the composition varies between 0.01 ≤ x ≤ 0.85, and three crystallographic phases (cubic, hexagonal, and monoclinic) were identified. We observed a correlation between characteristic parameters of Schottky barrier diodes fabricated on the thin film and its chemical and structural material properties. The highest Schottky barriers and rectification of the diodes were found for low indium contents. The thermal stability of the diodes is also best for Ga-rich parts of the sample. Conversely, the series resistance is lowest for large In content. Overall, the (In(x)Ga(1-x))2O3 alloy is well-suited for potential applications such as solar-blind photodetectors with a tunable absorption edge.

  6. Spectroscopic characterization of the plasma generated during the deposition of AlxGa1−xN films by pulsed laser co-ablation of Al and GaAs targets in electron cyclotron resonance nitrogen plasma

    International Nuclear Information System (INIS)

    A nitrogen–aluminum–gallium–arsenic plasma is formed by pulsed laser co-ablation of an Al target and a GaAs target in electron cyclotron resonance discharge-generated nitrogen plasma for AlxGa1−xN film deposition. The formed plasma was characterized by time-integrated and time-resolved optical emission spectroscopy measurements and the process of AlxGa1−xN deposition was discussed. The plasma contains excited species originally present in the working N2 gas and energetic species ablated from the targets, and its emission is abundant in the emission bands of diatomic nitrogen molecules and molecular ions and the emission lines of monoatomic aluminum, gallium, and arsenic atoms and atomic ions. The temporal and spatial features of the plasma emission reveal that the nitrogen species in the electron cyclotron resonance nitrogen plasma experience additional excitations due to the expanding ablation plumes, and the ablated species are excited frequently when traveling with the expanding plumes in the nitrogen plasma, making the formed plasma very reactive, which is very important in the process of AlxGa1−xN film deposition. The deposited film was evaluated for composition analysis by energy-dispersive x-ray spectroscopy and structure characterization by x-ray diffraction. The AlxGa1−xN film is slightly nitrogen rich with an aluminum content x of about 0.6 and featured with hexagonal wurtzite crystal structure with preferred c-axis orientation. (paper)

  7. Effect of oral administration of Bacillus coagulans B37 and Bacillus pumilus B9 strains on fecal coliforms, Lactobacillus and Bacillus spp. in rat animal model

    OpenAIRE

    Lopamudra Haldar; Gandhi, D.N.

    2016-01-01

    Aim: To investigate the effect of oral administration of two Bacillus strains on fecal coliforms, Lactobacillus and Bacillus spp. in rat animal model. Materials and Methods: An in vivo experiment was conducted for 49-day period on 36 adult male albino Wister rats divided equally into to four groups. After 7-day adaptation period, one group (T1) was fed on sterile skim milk along with basal diet for the next 28 days. Second (T2) and (T3) groups received spore biomass of Bacillus coagulans B...

  8. The AlxGa1-xAs window composition effect on the hardness improvement of a p+-n-n+GaAs solar cell exposed to the electron irradiation

    International Nuclear Information System (INIS)

    Numerical simulation was used to study the AlxGa1-xAs window composition effect on the current-voltage characteristics of a p+-n-n+GaAs solar cell under AM0 illumination and exposed to 1 MeV electron irradiation. Such solar cells are used in satellites and undergo severe degradation in their performance due to induced structural defects. The irradiation induced defects are modeled as energy levels in the energy gap of GaAs. To predict this effect, the current voltage characteristic and the spectral response are evaluated for different electron irradiation fluences for two types of cells. In the first we use a narrow Al0.31Ga0.69As window as a small part of the p+ layer while in the second type we use an AlxGa1-xAs window with a gradual Al mole fraction. The obtained results show that the AlxGa1-xAs window with a gradual Al mole fraction reduces the degradation of the output parameters of the solar cell and its spectral response by irradiation in particular for the short wavelengths.

  9. Emetic toxin-producing strains of Bacillus cereus show distinct characteristics within the Bacillus cereus group.

    NARCIS (Netherlands)

    Carlin, Frédéric; Fricker, Martina; Pielaat, Annemarie; Heisterkamp, Simon; Shaheen, Ranad; Salonen, Mirja Salkinoja; Svensson, Birgitta; Nguyen-the, Christophe; Ehling-Schulz, Monika

    2006-01-01

    One hundred representative strains of Bacillus cereus were selected from a total collection of 372 B. cereus strains using two typing methods (RAPD and FT-IR) to investigate if emetic toxin-producing hazardous B. cereus strains possess characteristic growth and heat resistance profiles. The strains

  10. Detection of Anthrax Simulants with Microcalorimetric Spectroscopy: Bacillus subtilis and Bacillus cereus Spores

    Science.gov (United States)

    Arakawa, Edward T.; Lavrik, Nickolay V.; Datskos, Panos G.

    2003-04-01

    Recent advances in the development of ultrasensitive micromechanical thermal detectors have led to the advent of novel subfemtojoule microcalorimetric spectroscopy (CalSpec). On the basis of principles of photothermal IR spectroscopy combined with efficient thermomechanical transduction, CalSpec provides acquisition of vibrational spectra of microscopic samples and absorbates. We use CalSpec as a method of identifying nanogram quantities of biological micro-organisms. Our studies focus on Bacillus subtilis and Bacillus cereus spores as simulants for Bacillus anthracis spores. Using CalSpec, we measured IR spectra of B. subtilis and B. cereus spores present on surfaces in nanogram quantities (approximately 100 -1000 spores). The spectra acquired in the wavelength range of 690 -4000 cm-1 (2.5 -14.5 μm) contain information-rich vibrational signatures that reflect the different ratios of biochemical makeup of the micro-organisms. The distinctive features in the spectra obtained for the two types of micro-organism can be used to distinguish between the spores of the Bacillus family. As compared with conventional IR and Fourier-transform IR microscopic spectroscopy techniques, the advantages of the present technique include significantly improved sensitivity (at least a full order of magnitude), absence of expensive IR detectors, and excellent potential for miniaturization.

  11. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage Smudge.

    Science.gov (United States)

    Cornell, Jessica L; Breslin, Eileen; Schuhmacher, Zachary; Himelright, Madison; Berluti, Cassandra; Boyd, Charles; Carson, Rachel; Del Gallo, Elle; Giessler, Caris; Gilliam, Benjamin; Heatherly, Catherine; Nevin, Julius; Nguyen, Bryan; Nguyen, Justin; Parada, Jocelyn; Sutterfield, Blake; Tukruni, Muruj; Temple, Louise

    2016-01-01

    Smudge, a bacteriophage enriched from soil using Bacillus thuringiensis DSM-350 as the host, had its complete genome sequenced. Smudge is a myovirus with a genome consisting of 292 genes and was identified as belonging to the C1 cluster of Bacillus phages. PMID:27540049

  12. Complete Genome of Bacillus thuringiensis Myophage BigBertha

    OpenAIRE

    Ting, Jose H.; Smyth, Trinity B.; Chamakura, Karthik R.; Kuty Everett, Gabriel F.

    2013-01-01

    BigBertha is a myophage of Bacillus thuringiensis, a widely used biocontrol agent that is active against many insect pests of plants. Here, we present the complete annotated genome of BigBertha. The genome shares 85.9% sequence identity with Bacillus cereus phage B4.

  13. Non-peptide metabolites from the genus Bacillus.

    Science.gov (United States)

    Hamdache, Ahlem; Lamarti, Ahmed; Aleu, Josefina; Collado, Isidro G

    2011-04-25

    Bacillus species produce a number of non-peptide metabolites that display a broad spectrum of activity and structurally diverse bioactive chemical structures. Biosynthetic, biological, and structural studies of these metabolites isolated from Bacillus species are reviewed. This contribution also includes a detailed study of the activity of the metabolites described, especially their role in biological control mechanisms.

  14. Quantitative immunofluorescence studies of the serology of Bacillus anthracis spores.

    OpenAIRE

    Phillips, A. P.; Martin, K L

    1983-01-01

    A fluorescein-conjugated antibody against formalin-inactivated spores of Bacillus anthracis Vollum reacted only weakly with a variety of Bacillus species in microfluorometric immunofluorescence assays. A conjugated antibody against spores of B. anthracis Sterne showed little affinity for spores of several B. anthracis isolates including B. anthracis Vollum, indicating that more than one anthrax spore serotype exists.

  15. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage Smudge

    Science.gov (United States)

    Cornell, Jessica L.; Breslin, Eileen; Schuhmacher, Zachary; Himelright, Madison; Berluti, Cassandra; Boyd, Charles; Carson, Rachel; Del Gallo, Elle; Giessler, Caris; Gilliam, Benjamin; Heatherly, Catherine; Nevin, Julius; Nguyen, Bryan; Nguyen, Justin; Parada, Jocelyn; Sutterfield, Blake; Tukruni, Muruj

    2016-01-01

    Smudge, a bacteriophage enriched from soil using Bacillus thuringiensis DSM-350 as the host, had its complete genome sequenced. Smudge is a myovirus with a genome consisting of 292 genes and was identified as belonging to the C1 cluster of Bacillus phages. PMID:27540049

  16. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage Smudge.

    Science.gov (United States)

    Cornell, Jessica L; Breslin, Eileen; Schuhmacher, Zachary; Himelright, Madison; Berluti, Cassandra; Boyd, Charles; Carson, Rachel; Del Gallo, Elle; Giessler, Caris; Gilliam, Benjamin; Heatherly, Catherine; Nevin, Julius; Nguyen, Bryan; Nguyen, Justin; Parada, Jocelyn; Sutterfield, Blake; Tukruni, Muruj; Temple, Louise

    2016-08-18

    Smudge, a bacteriophage enriched from soil using Bacillus thuringiensis DSM-350 as the host, had its complete genome sequenced. Smudge is a myovirus with a genome consisting of 292 genes and was identified as belonging to the C1 cluster of Bacillus phages.

  17. Genetic map of the Bacillus stearothermophilus NUB36 chromosome

    Energy Technology Data Exchange (ETDEWEB)

    Vallier, H.; Welker, N.E. (Northwestern Univ., Evanston, IL (USA))

    1990-02-01

    A circular genetic map of Bacillus stearothermophilus NUB36 was constructed by transduction with bacteriophage TP-42C and protoplast fusion. Sixty-four genes were tentatively assigned a cognate Bacillus subtilis gene based on growth response to intermediates or end products of metabolism, cross-feeding, accumulation of intermediates, or their relative order in a linkage group. Although the relative position of many genes on the Bacillus subtilis genetic map appears to be similar, some differences were detected. The tentative order of the genes in the Bacillus stearothermophilus aro region is aspB-aroBAFEC-tyra-hisH-(trp), whereas it is aspB-aroE-tyrA-hisH-(trp)-aroHBF in Bacillus subtilis. The aroA, aroC, and aroG genes in Bacillus subtilis are located in another region. The tentative order of genes in the trp operon of Bacillus stearothermophilus is trpFCDABE, whereas it is trpABFCDE in Bacillus subtilis.

  18. Bacillus subtilis regulatory protein GerE

    OpenAIRE

    Ducros, V M A; Brannigan, J.A.; Lewis, R J; Wilkinson, A.J.

    1998-01-01

    GerE is the latest-acting of a series of factors which regulate gene expression in the mother cell during sporulation in Bacillus. The gene encoding GerE has been cloned from B. subtilis and overexpressed in Escherichia coli. Purified GerE has been crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol as a precipitant. The small plate-like crystals belong to the monoclinic space group C2 and diffract beyond 2.2 Angstrom resolution with a synchrotron radiation X-ra...

  19. Structural, magnetic and Mossbauer studies of TI doped Gd2Fe17-xTix and Gd2Fe16Ga1-xTix (0≤x≤1)

    Science.gov (United States)

    Pokharel, G.; Syed Ali, K. S.; Mishra, S. R.

    2015-05-01

    Magnetic compounds of the type Gd2Fe17-xTix and Gd2Fe16Ga1-xTix (x=0.0-1.0) were prepared by arc melting and their structural and magnetic properties were studied by X-ray diffraction (XRD), magnetometery and Mossbauer spectroscopy. The Rietveld analysis of X-ray data shows that these α-Fe free solid-solutions crystallize with Th2Ni17-type structure as main phase along with GdFe2 and TiFe2 as additional phases at higher, x≥0.5 contents. The unit cell volume expands with Ga and Ti content. The Rietveld analysis indicate that both Ti and Ga atoms prefer 12j and 12k sites in both compounds. The effect of Ti and co-substituted Ga-Ti on the bond length are quite different. The saturation magnetization Ms, at 300 K for Gd2Fe17-xTix and Gd2Fe16Ga1-xTix was found to decrease linearly with increasing Ti content. The Ms in both compounds at x=1 reduced by 9% as compared to their parent compounds at x=0. The Curie temperature, Tc, for Gd2Fe17-xTix increased from 513 K (x=0) to 544 K (x=1) while Tc for Gd2Fe16Ga1-xTix reduced from 560 (x=0) to 544 K (x=1) with increase in Ti content. Thus the observed variation in Tc follows Gd2Fe17variation in the unit cell volume of compounds which has direct effect on the strength of Fe-Fe exchange-interaction. The Mossbauer results indicate decrease in hyperfine fields and increase in the isomer shifts with the increase in Ti content. Overall co-substituted Ga-Ti, Gd2Fe16Ga1-xTix show high Tc with marginal decline in saturation magnetization. Thus α-Fe free Gd2Fe16Ga1-xTix compounds can be potential candidate for high temperature permanent magnet industrial applications.

  20. Enhanced transformation efficiency of recalcitrant Bacillus cereus and Bacillus weihenstephanensis isolates upon in vitro methylation of plasmid DNA

    NARCIS (Netherlands)

    Nierop Groot, M.N.; Nieboer, F.; Abee, T.

    2008-01-01

    Digestion patterns of chromosomal DNAs of Bacillus cereus and Bacillus weihenstephanensis strains suggest that Sau3AI-type restriction modification systems are widely present among the isolates tested. In vitro methylation of plasmid DNA was used to enhance poor plasmid transfer upon electroporation

  1. ABILITY OF BACTERIAL CONSORTIUM: Bacillus coagulans, Bacilus licheniformis, Bacillus pumilus, Bacillus subtilis, Nitrosomonas sp. and Pseudomonas putida IN BIOREMEDIATION OF WASTE WATER IN CISIRUNG WASTE WATER TREATMENT PLANT

    Directory of Open Access Journals (Sweden)

    Ratu SAFITRI

    2015-10-01

    Full Text Available This study was conducted in order to determine the ability of bacterial consortium: Bacillus coagulans, Bacilus licheniformis, Bacillus pumilus, Bacillus subtilis, Nitrosomonas sp., and Pseudomonas putida in bioremediation of wastewater origin Cisirung WWTP. This study uses an experimental method completely randomized design (CRD, which consists of two treatment factors (8x8 factorial design. The first factor is a consortium of bacteria (K, consisting of 8 level factors (k1, k2, k3, k4, k5, k6, k7, and k8. The second factor is the time (T, consisting of a 7 level factors (t0, t1, t2, t3, t4, t5, t6, and t7. Test parameters consist of BOD (Biochemical Oxygen Demand, COD (Chemical Oxygen Demand, TSS (Total Suspended Solid, Ammonia and Population of Microbes during bioremediation. Data were analyzed by ANOVA, followed by Duncan test. The results of this study showed that the consortium of Bacillus pumilus, Bacillus subtilis, Bacillus coagulans, Nitrosomonas sp., and Pseudomonas putida with inoculum concentration of 5% (k6 is a consortium of the most effective in reducing BOD 71.93%, 64.30% COD, TSS 94.85%, and 88.58% of ammonia.

  2. The Phylogeny of Bacillus cereus sensu lato.

    Science.gov (United States)

    Okinaka, Richard T; Keim, Paul

    2016-02-01

    The three main species of the Bacillus cereus sensu lato, B. cereus, B. thuringiensis, and B. anthracis, were recognized and established by the early 1900s because they each exhibited distinct phenotypic traits. B. thuringiensis isolates and their parasporal crystal proteins have long been established as a natural pesticide and insect pathogen. B. anthracis, the etiological agent for anthrax, was used by Robert Koch in the 19th century as a model to develop the germ theory of disease, and B. cereus, a common soil organism, is also an occasional opportunistic pathogen of humans. In addition to these three historical species designations, are three less-recognized and -understood species: B. mycoides, B. weihenstephanensis, and B. pseudomycoides. All of these "species" combined comprise the Bacillus cereus sensu lato group. Despite these apparently clear phenotypic definitions, early molecular approaches to separate the first three by various DNA hybridization and 16S/23S ribosomal sequence analyses led to some "confusion" because there were limited differences to differentiate between these species. These and other results have led to frequent suggestions that a taxonomic change was warranted to reclassify this group to a single species. But the pathogenic properties of B. anthracis and the biopesticide applications of B. thuringiensis appear to "have outweighed pure taxonomic considerations" and the separate species categories are still being maintained. B. cereus sensu lato represents a classic example of a now common bacterial species taxonomic quandary. PMID:26999390

  3. Fast Neutron Radiation Effects on Bacillus Subtili

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiaoming; REN Zhenglong; ZHANG Jianguo; ZHENG Chun; TAN Bisheng; YANG Chengde; CHU Shijin

    2009-01-01

    To examine the sterilizing effect and mechanism of neutron radiation, Bacillus sub-tilis vat. niger, strain (ATCC 9372) spores were irradiated with the fast neutron from the Chinese fast burst reactor Ⅱ(CFBR-Ⅱ). The plate-count results indicated that the D10 value was 384.6 Gy with a neutron radiation dose rate of 7.4 Gy/min. The rudimental catalase activity of the spores declined obviously with the increase in the radiation dose. Meanwhile, under the scanning electron microscope, no visible influence of the neutron radiation on the spore configuration was detected even if the dose was increased to 4 kGy. The content and distribution of DNA double-strand breaks induced by neutron radiation at different doses were measured and quantified by pulsed-field gel electrophoresis (PFGE). Further analysis of the DNA release percentage (PR), the DNA breakage level (L), and the average molecular weight, indicated that DNA fragments were obvi-ously distributed around the 5 kb regions at different radiation doses, which suggests that some points in the DNA molecule were sensitive to neutron radiation. Both PR and L varied regularly to some extent with the increase in radiation dose. Thus neutron radiation has a high sterilization power, and can induce falling enzyme activity and DNA breakage in Bacillus subtilis spores

  4. Biodiversity of aerobic endospore-forming bacterial species occurring in Yanyanku and Ikpiru, fermented seeds of Hibiscus sabdariffa used to produce food condiments in Benin

    DEFF Research Database (Denmark)

    Agbobatinkpo, Pélagie B.; Thorsen, Line; Nielsen, Dennis Sandris;

    2013-01-01

    were identified using phenotypic and genotypic methods, including GTG5-PCR, M13-PCR, 16S rRNA, gyrA and gyrB gene sequencing. Generally, the same 5-6 species of the genus Bacillus predominated: Bacillus subtilis (17-41% of isolates), Bacillus cereus (8-39%), Bacillus amyloliquefaciens (9-22%), Bacillus...

  5. GaAs/AlxGa1-xAs超晶格束缚态电子能级结构的理论研究%Theoretical Study of Bound State Electronic Energy Level Structure in GaAs/AlxGa1-x As Superlattice

    Institute of Scientific and Technical Information of China (English)

    李文兵

    2006-01-01

    我们运用Kronig-Penney模型,研究了GaAs/AlxGa1-xAs超晶格的束缚态电子能级结构、带宽,跃迁矩随超晶格的结构参量(阱宽、垒宽和Al组分)变化关系,以及子带能量色散关系.计算结果表明:影响光跃迁频率的最大因素是阱宽,随着阱宽的增加,光跃迁频率逐渐减小;影响带宽的较大因素是垒宽,随垒宽的增大,带宽逐渐减小;超晶格结构参量对跃迁矩的影响很小;随着Al组分的增加,光跃迁频率逐渐增大;第一子能带随波矢的变化不是很明显,第二子能带随波矢变化比较明显.这些将对实验测量和器件应用有一定的参考价值和指导意义.

  6. ISOLATION AND CHARACTERIZATION OF CRUDE OIL DEGRADING BACILLUS SPP.

    Directory of Open Access Journals (Sweden)

    A. Akhavan Sepahi, I. Dejban Golpasha, M. Emami, A. M. Nakhoda

    2008-07-01

    Full Text Available Today, application of microorganisms for removing crude oil pollution from contaminated sites as bioremediation studies, was considered by scientists because other methods such as surfactant washing and incineration lead to production of more toxic compounds and they are non-economic. Fifteen crude oil degrading bacillus spp. were isolated from contaminated sites. Two isolated showed best growth in liquid media with 1-3% (v/v crude oil and mineral salt medium, then studied for enzymatic activities on tested media. The results showed maximal increase in optical densities and total viable count concomitant with decrease in pH on fifth day of experimental period for bacillus S6. Typical generation time on mineral salt with 1% crude oil is varying between 18-20h, 25-26h respectively for bacillus S6 and S35. Total protein was monitored at determined time intervals as biodegradation indices. Increasing of protein concentration during the incubation period reveals that isolated bacillus can degrade crude oil and increase microbial biomass. These bacillus spp. reduced surface tension from 60 (mN/m to 31 and 38 (mN/m, It means that these bacillus spp. can produce sufficient surfactant and have good potential of emulsification capacity. The results demonstrated that these bacillus spp. can utilize crude oil as a carbon and energy source.

  7. Occurrence and significance of Bacillus cereus and Bacillus thuringiensis in ready-to-eat food

    DEFF Research Database (Denmark)

    Rosenquist, Hanne; Ørum-Smidt, Lasse; Andersen, Sigrid R;

    2005-01-01

    had at least one gene or component involved in human diarrhoeal disease, while emetic toxin was related to only one B. cereus strain. A new observation was that 31 out of the 40 randomly selected B. cereus-like strains could be classified as Bacillus thuringiensis due to crystal production and......Among 48,901 samples of ready-to-eat food products at the Danish retail market, 0.5% had counts of Bacillus cereus-like bacteria above 10(4) cfu g(-1). The high counts were most frequently found in starchy, cooked products, but also in fresh cucumbers and tomatoes. Forty randomly selected strains....../or content of cry genes. Thus, a large proportion of the B. cereus-like organisms present in food may belong to B. thuringiensis....

  8. Expression, purification, and characterization of a thermophilic neutral protease from Bacillus stearothermophilus in Bacillus subtilis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The gene coding for a thermophilic neutral protease from Bacillus stearothermophilus was expressed in Bacillus subtilis DB104, under the control of the sacB gene promoter. This was followed by either the native signal peptide sequence of this protease or the signal peptide sequence of the sacB gene. The protease was purified 3.8-fold, with a specific activity of 16530 U mg-1. As analyzed by SDS-PAGE, the molecular mass of the expressed protease was about 35 kDa, and the optimal temperature and pH of the protease were 65℃ and 7.5, respectively. Moreover, it still had about 80% activity after 1 h reaction at 65℃.

  9. Expression, purification, and characterization of a thermophilic neutral protease from Bacillus stearothermophilus in Bacillus subtilis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The gene coding for a thermophilic neutral protease from Bacillus stearothermophilus was expressed in Bacillus subtilis DB104, under the control of the sacB gene promoter. This was followed by either the native signal peptide sequence of this protease or the signal peptide sequence of the sacB gene. The protease was purified 3.8-fold, with a specific activity of 16530 U mg-1. As analyzed by SDS-PAGE, the molecular mass of the expressed protease was about 35 kDa, and the optimal temperature and pH of the protease were 65℃ and 7.5, respectively. Moreover, it still had about 80% activity after 1 h reaction at 65 ℃ .

  10. An Optical Biosensor for Bacillus Cereus Spore Detection

    Science.gov (United States)

    Li, Chengquan; Tom, Harry W. K.

    2005-03-01

    We demonstrate a new transduction scheme for optical biosensing. Bacillus cereus is a pathogen that may be found in food and dairy products and is able to produce toxins and cause food poisoning. It is related to Bacillus anthracis (anthrax). A CCD array covered with micro-structured glass coverslip is used to detect the optical resonant shift due to the binding of the antigen (bacillus cereus spore) to the antibody (polyclonal antibody). This novel optical biosensor scheme has the potential for detecting 10˜100 bioagents in a single device as well as the potential to test for antigens with multiple antibody tests to avoid ``false positives.''

  11. Flow-cytometric Analysis of Bacillus anthracis Spores

    Directory of Open Access Journals (Sweden)

    D. V. Kamboj

    2006-11-01

    Full Text Available Flow-cytometric technique has been established as a powerful tool for detection andidentification of microbiological agents. Unambiguous and rapid detection of Bacillus anthracisspores has been reported using immunoglobulin G-fluorescein isothiocyanate conjugate againstlive spores. In addition to the high sensitivity, the present technique could differentiate betweenspores of closely related species, eg, Bacillus cereus and Bacillus subtilis using fluorescenceintensity. The technique can be used for detection of live as well as inactivated spores makingit more congenial for screening of suspected samples of bioterrorism.

  12. Genetic Differentiation between Sympatric Populations of Bacillus cereus and Bacillus thuringiensis

    Science.gov (United States)

    Vilas-Boas, Gislayne; Sanchis, Vincent; Lereclus, Didier; Lemos, Manoel Victor F.; Bourguet, Denis

    2002-01-01

    Little is known about genetic exchanges in natural populations of bacteria of the spore-forming Bacillus cereus group, because no population genetics studies have been performed with local sympatric populations. We isolated strains of Bacillus thuringiensis and B. cereus from small samples of soil collected at the same time from two separate geographical sites, one within the forest and the other at the edge of the forest. A total of 100 B. cereus and 98 B. thuringiensis strains were isolated and characterized by electrophoresis to determine allelic composition at nine enzymatic loci. We observed genetic differentiation between populations of B. cereus and B. thuringiensis. Populations of a given Bacillus species—B. thuringiensis or B. cereus—were genetically more similar to each other than to populations of the other Bacillus species. Hemolytic activity provided further evidence of this genetic divergence, which remained evident even if putative clones were removed from the data set. Our results suggest that the rate of gene flow was higher between strains of the same species, but that exchanges between B. cereus and B. thuringiensis were nonetheless possible. Linkage disequilibrium analysis revealed sufficient recombination for B. cereus populations to be considered panmictic units. In B. thuringiensis, the balance between clonal proliferation and recombination seemed to depend on location. Overall, our data indicate that it is not important for risk assessment purposes to determine whether B. cereus and B. thuringiensis belong to a single or two species. Assessment of the biosafety of pest control based on B. thuringiensis requires evaluation of the extent of genetic exchange between strains in realistic natural conditions. PMID:11872495

  13. Transmission electron microscopy of InxGa1-xNyAs1-y nanostructures using ab-initio structure factors for strain-relaxed supercells

    International Nuclear Information System (INIS)

    This thesis reports on theoretical, methodical and experimental studies concerning scattering and structural properties of InxGa1-xNyAs1-y using transmission electron microscopy (TEM). First, theoretical concepts to describe electron scattering at real crystals including the effects of bonding and static atomic displacements (SAD) are considered. The approach of modified atomic scattering amplitudes (MASA), which uses density functional theory (DFT) to model bonding in an atomistic manner, is exploited to calculate compositiondependent MASA for InGaNAs. Valence force field (VFF) calculations are applied to determine SAD caused by atom size effects. Huang scattering caused by SAD is shown to pile up in the vicinity of Bragg peaks, contrary to the smooth background caused by thermal diffuse scattering (TDS). Furthermore, results for composition-dependent structure factors calculated by full DFT and atomistic models are compared. Second, structure factors for GaAs and InAs are measured by parallel and convergent beam electron diffraction (PBED and CBED) to verify the MASA approach. The PBED method was implemented in Bloch wave routines embedded in a least-squares refinement that allows for a refinement of structure factors, Debye-Waller factors, specimen thickness and -orientation. Errors in PBED are estimated from the application to simulated diffraction patterns with TDS background, and rules for the recognition of reasonable initial refinement conditions are derived. Then, PBED is applied to the measurement of the 200 structure factors of GaAs and InAs. Conversion to X-ray structure factors yields XGaAs200=-6.366±0.015 and XInAs200=53.687±0.110, respectively. By CBED, XGaAs200=-6.350±0.015 is measured. Additionally, Debye-Waller factors for GaAs have been refined to BGa=0.275±0.003 Aa2 and BAs=0.242±0.003 Aa2 at 99 K using PBED. Third, above theoretical scattering data is used in composition measurements in InGaNAs solar cell and laser structures via TEM

  14. Bacillus subtilis as potential producer for polyhydroxyalkanoates

    Directory of Open Access Journals (Sweden)

    Patel Sanjay KS

    2009-07-01

    Full Text Available Abstract Polyhydroxyalkanoates (PHAs are biodegradable polymers produced by microbes to overcome environmental stress. Commercial production of PHAs is limited by the high cost of production compared to conventional plastics. Another hindrance is the brittle nature and low strength of polyhydroxybutyrate (PHB, the most widely studied PHA. The needs are to produce PHAs, which have better elastomeric properties suitable for biomedical applications, preferably from inexpensive renewable sources to reduce cost. Certain unique properties of Bacillus subtilis such as lack of the toxic lipo-polysaccharides, expression of self-lysing genes on completion of PHA biosynthetic process – for easy and timely recovery, usage of biowastes as feed enable it to compete as potential candidate for commercial production of PHA.

  15. Bacillus circulans exopolysaccharide: Production, characterization and bioactivities.

    Science.gov (United States)

    Vidhyalakshmi, R; Valli, Nachiyar C; Narendra Kumar, G; Sunkar, Swetha

    2016-06-01

    A bacterium with the ability to produce appreciable amount of exopolysaccharide was isolated from slimy layer of coconut. 16S rDNA analysis identified the organism as Bacillus circulans. EPS production was observed at all stages of culture growth and reached maximum of 0.065mg/ml by 96h, which on further incubation started to decrease. Response Surface Methodology using Box Behnken design has shown the influence of sucrose which was found to be directly proportional to exopolysaccharide production with production reaching 1.09mg/ml. HPLC analysis identified the presence of glucose, mannose, fructose and verbascose and NMR analysis confirmed the presence of glucose, mannose and galactose. Even though the extracted B. circulans EPS did not show appreciable anti-bacterial or anti-fungal activity, it exhibited appreciable antioxidant, anti-inflammatory and anti-tumor activity. PMID:26902891

  16. Characterization of Bacillus anthracis persistence in vivo.

    Directory of Open Access Journals (Sweden)

    Sarah A Jenkins

    Full Text Available Pulmonary exposure to Bacillus anthracis spores initiates inhalational anthrax, a life-threatening infection. It is known that dormant spores can be recovered from the lungs of infected animals months after the initial spore exposure. Consequently, a 60-day course antibiotic treatment is recommended for exposed individuals. However, there has been little information regarding details or mechanisms of spore persistence in vivo. In this study, we investigated spore persistence in a mouse model. The results indicated that weeks after intranasal inoculation with B. anthracis spores, substantial amounts of spores could be recovered from the mouse lung. Moreover, spores of B. anthracis were significantly better at persisting in the lung than spores of a non-pathogenic Bacillus subtilis strain. The majority of B. anthracis spores in the lung were tightly associated with the lung tissue, as they could not be readily removed by lavage. Immunofluorescence staining of lung sections showed that spores associated with the alveolar and airway epithelium. Confocal analysis indicated that some of the spores were inside epithelial cells. This was further confirmed by differential immunofluorescence staining of lung cells harvested from the infected lungs, suggesting that association with lung epithelial cells may provide an advantage to spore persistence in the lung. There was no or very mild inflammation in the infected lungs. Furthermore, spores were present in the lung tissue as single spores rather than in clusters. We also showed that the anthrax toxins did not play a role in persistence. Together, the results suggest that B. anthracis spores have special properties that promote their persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence.

  17. Effects of an intense, high-frequency laser field on bound states in Ga1 − x In x N y As1 − y /GaAs double quantum well

    OpenAIRE

    Ungan, Fatih; Yesilgul, Unal; Şakiroğlu, Serpil; Kasapoglu, Esin; Erol, Ayse; Arikan, Mehmet Cetin; Sarı, Huseyin; Sökmen, Ismail

    2012-01-01

    Within the envelope function approach and the effective-mass approximation, we have investigated theoretically the effect of an intense, high-frequency laser field on the bound states in a Ga x In1 − x N y As1 − y /GaAs double quantum well for different nitrogen and indium mole concentrations. The laser-dressed potential, bound states, and squared wave functions related to these bound states in Ga1 − x In x N y As1 − y /GaAs double quantum well are investigated as a function of the position a...

  18. Genome Sequence of Bacillus thuringiensis subsp. kurstaki Strain HD-1

    OpenAIRE

    Day, Michael; Ibrahim, Mohamed; Dyer, David; Bulla, Lee

    2014-01-01

    We report here the complete genome sequence of Bacillus thuringiensis subsp. kurstaki strain HD-1, which serves as the primary U.S. reference standard for all commercial insecticidal formulations of B. thuringiensis manufactured around the world.

  19. Effects of probiotic Bacillus species in aquaculture – An overview

    Directory of Open Access Journals (Sweden)

    Cristian-Teodor BURUIANĂ

    2014-12-01

    Full Text Available The ingestion of a large amount of certain types of beneficial bacteria can reduce the multiplication and development of pathogenic bacteria in the gut. A “probiotic” is a product that contains live microorganisms which positively influence the host intestinal microbiota by preventing the proliferation of pathogenic bacteria and promoting the growth and development of beneficial bacteria. Bacillus spp. are Gram-positive endospore-forming bacteria with beneficial effects in aquaculture industry. The dietary supplementation of Bacillus spp. in fish culture improved especially growth performance, immune response and the disease resistance of fish against pathogenic bacterial infections. The objective of the current paper is to review the recent published investigations reported in the scientific literature on the use of probiotic Bacillus spp. in aquaculture, focusing on their beneficial effects on the host. This review includes the main effects of Bacillus spp. administration in shrimp culture, carp culture, tilapia culture, and other fish culture.

  20. Two Genes Encoding Uracil Phosphoribosyltransferase Are Present in Bacillus subtilis

    DEFF Research Database (Denmark)

    Martinussen, Jan; Glaser, Philippe; Andersen, Paal S.;

    1995-01-01

    Uracil phosphoribosyltransferase (UPRTase) catalyzes the key reaction in the salvage of uracil in many microorganisms. Surprisingly, two genes encoding UPRTase activity were cloned from Bacillus subtilis by complementation of an Escherichia coli mutant. The genes were sequenced, and the putative...

  1. The Complete Genome Sequence of Bacillus thuringiensis AlHakam

    Energy Technology Data Exchange (ETDEWEB)

    Challacombe, Jean F.; Altherr, Michael R.; Xie, Gary; Bhotika,Smriti S.; Brown, Nancy; Bruce, David; Campbell, Connie S.; Campbell,Mary L.; Chen, Jin; Chertkov, Olga; Cleland, Cathy; Dimitrijevic, Mira; Doggett, Norman A.; Fawcett, John J.; Glavina, Tijana; Goodwin, Lynne A.; Green, Lance D.; Han, Cliff S.; Hill, Karen K.; Hitchcock, Penny; Jackson, Paul J.; Keim, Paul; Kewalramani, Avinash Ramesh; Longmire, Jon; Lucas, Susan; Malfatti, Stephanie; Martinez, Diego; McMurry, Kim; Meincke, Linda J.; Misra, Monica; Moseman, Bernice L.; Mundt, Mark; Munk,A. Christine; Okinaka, Richard T.; Parson-Quintana, B.; Reilly, LeePhilip; Richardson, Paul; Robinson, Donna L.; Rubin, Eddy; Saunders,Elizabeth; Tapia, Roxanne; Tesmer, Judith G.; Thayer, Nina; Thompson,Linda S.; Tice, Hope; Ticknor, Lawrence O.; Wills, Patti L.; Gilna, Paul; Brettin, Thomas S.

    2007-04-01

    Bacillus thuringiensis is an insect pathogen that is widelyused as a biopesticide (3). Here we report the finished, annotated genomesequence of B. thuringiensis Al Hakam, which was collected in Iraq by theUnited Nations Special Commission (2).

  2. BOOK REVIEW: BACILLUS THURINGIENSIS: A CORNERSTONE OF MODERN AGRICULTURE

    Science.gov (United States)

    Are you interested in the technical issues surrounding the use of Bacillus thuringiensis pesticidal traits as sprays and as plant incorporated protectants (transgenic crops)? Should the dimensions of human health, ecology, entomology, risk assessment, resistance management, and d...

  3. Antifungal activity of Bacillus sp. isolated from compost.

    Science.gov (United States)

    Czaczyk, K; Stachowiak, B; Trojanowska, K; Gulewicz, K

    2000-01-01

    Four strains of Bacillus isolated from lupine compost exhibited an antifungal activity against six plant fungal pathogens (Rhizoctonia solani, Bipolaris sorokiniana, Sclerotinia sclerotiorum, Trichothecium roseum, Fusarium solani, Fusarium oxysporum). It was significantly influenced by the composition of the cultivation media.

  4. Selection of Bacillus subtilis mutants impaired in ammonia assimilation.

    OpenAIRE

    Dean, D R; Aronson, A I

    1980-01-01

    The selection of Bacillus subtilis mutants capable of using D-histidine to fulfill a requirement for L-histidine resulted in mutants with either no glutamate synthase activity or increased amounts of an altered glutamine synthetase.

  5. Protein engineering of cyclodextrin glycosyltransferase from Bacillus circulans strain 251

    NARCIS (Netherlands)

    Penninga, Dirk

    1996-01-01

    An enormous diversity of molecular functions in living organisms is carried out by proteins. Our studies have focussed on the functional analysis of a starch-converting enzyme, cyclodextrin glycosyltransferase (CGTase) from Bacillus circulans strain 251. Zie: Summary

  6. Efficient transformation of Bacillus thuringiensis requires nonmethylated plasmid DNA.

    OpenAIRE

    Macaluso, A; Mettus, A M

    1991-01-01

    The transformation efficiency of Bacillus thuringiensis depends upon the source of plasmid DNA. DNA isolated from B. thuringiensis, Bacillus megaterium, or a Dam- Dcm- Escherichia coli strain efficiently transformed several B. thuringiensis strains, B. thuringiensis strains were grouped according to which B. thuringiensis backgrounds were suitable sources of DNA for transformation of other B. thuringiensis strains, suggesting that B. thuringiensis strains differ in DNA modification and restri...

  7. Regulation of cry Gene Expression in Bacillus thuringiensis

    OpenAIRE

    Chao Deng; Qi Peng; Fuping Song; Didier Lereclus

    2014-01-01

    Bacillus thuringiensis differs from the closely related Bacillus cereus group species by its ability to produce crystalline inclusions. The production of these crystals mainly results from the expression of the cry genes, from the stability of their transcripts and from the synthesis, accumulation and crystallization of large amounts of insecticidal Cry proteins. This process normally coincides with sporulation and is regulated by various factors operating at the transcriptional, post-transcr...

  8. Natural Dissemination of Bacillus anthracis Spores in Northern Canada

    OpenAIRE

    Dragon, D C; Bader, D. E.; Mitchell, J.; Woollen, N.

    2005-01-01

    Soil samples were collected from around fresh and year-old bison carcasses and areas not associated with known carcasses in Wood Buffalo National Park during an active anthrax outbreak in the summer of 2001. Sample selection with a grid provided the most complete coverage of a site. Soil samples were screened for viable Bacillus anthracis spores via selective culture, phenotypic analysis, and PCR. Bacillus anthracis spores were isolated from 28.4% of the samples. The highest concentrations of...

  9. Genetic analysis of petrobactin transport in Bacillus anthracis

    OpenAIRE

    Carlson, Paul E.; Dixon, Shandee D.; Janes, Brian K.; Carr, Katherine A.; Nusca, Tyler D.; Anderson, Erica C.; Keene, Sarra E.; Sherman, David H.; Hanna, Philip C.

    2010-01-01

    Iron acquisition mechanisms play an important role in the pathogenesis of many infectious microbes. In Bacillus anthracis, the siderophore petrobactin is required for both growth in iron depleted conditions and for full virulence of the bacterium. Here we demonstrate the roles of two putative petrobactin binding proteins FatB and FpuA (encoded by GBAA5330 and GBAA4766, respectively) in Bacillus anthracis iron acquisition and pathogenesis. Markerless deletion mutants were created using allelic...

  10. Expression of UGA-Containing Mycoplasma Genes in Bacillus subtilis

    OpenAIRE

    Kannan, T. R.; Baseman, Joel B.

    2000-01-01

    We used Bacillus subtilis to express UGA-containing Mycoplasma genes encoding the P30 adhesin (one UGA) of Mycoplasma pneumoniae and methionine sulfoxide reductase (two UGAs) of Mycoplasma genitalium. Due to natural UGA suppression, these Mycoplasma genes were expressed as full-length protein products, but at relatively low efficiency, in recombinant wild-type Bacillus. The B. subtilis-expressed Mycoplasma proteins appeared as single bands and not as multiple bands compared to expression in r...

  11. Laser-induced speckle scatter patterns in Bacillus colonies

    Directory of Open Access Journals (Sweden)

    Huisung eKim

    2014-10-01

    Full Text Available Label-free bacterial colony phenotyping technology called BARDOT (BActerial Rapid Detection using Optical scattering Technology provided successful classification of several different bacteria at the genus, species, and serovar level. Recent experiments with colonies of Bacillus species provided strikingly different characteristics of elastic light scatter (ELS patterns, which were comprised of random speckles compared to other bacteria, which are dominated by concentric rings and spokes. Since this laser-based optical sensor interrogates the whole volume of the colony, 3-D information of micro- and macro-structures are all encoded in the far-field scatter patterns. Here, we present a theoretical model explaining the underlying mechanism of the speckle formation by the colonies from Bacillus species. Except for Bacillus polymyxa, all Bacillus spp. produced random bright spots on the imaging plane, which presumably dependent on the cellular and molecular organization and content within the colony. Our scatter model-based analysis revealed that colony spread resulting in variable surface roughness can modify the wavefront of the scatter field. As the center diameter of the Bacillus spp. colony grew from 500 μm to 900 μm, average speckles area decreased 2-fold and the number of small speckles increased 7-fold. In conclusion, as Bacillus colony grows, the average speckle size in the scatter pattern decreases and the number of smaller speckle increases due to the swarming growth characteristics of bacteria within the colony.

  12. Transfer of the toxin protein genes of Bacillus sphaericus into Bacillus thuringiensis subsp. israelensis and their expression.

    OpenAIRE

    Bourgouin, C.; Delécluse, A; La Torre, F.; Szulmajster, J

    1990-01-01

    The genes encoding the toxic determinants of Bacillus sphaericus have been expressed in a nontoxic and a toxic strain of Bacillus thuringiensis subsp. israelensis. In both cases, the B. sphaericus toxin proteins were produced at a high level during sporulation of B. thuringiensis and accumulated as crystalline structures. B. thuringiensis transformants expressing B. sphaericus and B. thuringiensis subsp. israelensis toxins did not show a significant enhancement of toxicity against Aedes aegyp...

  13. Ground Anthrax Bacillus Refined Isolation (GABRI) method for analyzing environmental samples with low levels of Bacillus anthracis contamination

    OpenAIRE

    Fasanella, Antonio; Di Taranto, Pietro; Garofolo, Giuliano; Colao, Valeriana; Marino, Leonardo; Buonavoglia, Domenico; Pedarra, Carmine; Adone, Rosanna; Hugh-Jones, Martin

    2013-01-01

    Background In this work are reported the results of a qualitative analytical method capable of detecting Bacillus anthracis spores when they are present in very low concentration in the soil. The Ground Anthrax Bacillus Refined Isolation (GABRI) method, assessed in our laboratory, was compared with the classic method. The comparison involved artificially anthrax-contaminated soil samples (500 spores/7.5 grams soil) and naturally contaminated soil samples collected in Bangladesh during a field...

  14. Formation of Ni Diffusion-Induced Surface Traps in GaN/Al x Ga1- x N/GaN Heterostructures on Silicon Substrate During Gate Metal Deposition

    Science.gov (United States)

    Kajen, R. S.; Bera, L. K.; Tan, H. R.; Dolmanan, S. B.; Cheong, Z. W.; Tripathy, S.

    2016-01-01

    The diffusion of the Schottky metal (Ni) in GaN is known to occur at elevated temperatures and as a result of prolonged electric field-driven stress. This leads to device degradation and reliability issues in Al x Ga1- x N/GaN-on-silicon high electron mobility transistors (HEMTs). In this study, we have investigated the formation of Ni-induced deep level traps across the Ni-GaN interface in Al x Ga1- x N/GaN HEMT-based Schottky diodes on Si substrates during the Schottky metal deposition process prior to any gate/Schottky metal annealing step. Two deep level traps were detected at 0.14 eV and 0.54 eV using Fourier deep level transient spectroscopy, which correlated well with nitrogen vacancies and nitrogen antisite defects, respectively. Our results are further supported by transmission electron microscopy-based energy dispersive x-ray analysis and electron energy loss spectroscopy measurements which confirm the interdiffusion of Ga and Ni across the Ni/GaN interface on the HEMT structure. Understanding the nature of such defects may help to employ suitable growth or passivation schemes for development of improved GaN-based electronic devices.

  15. Magnetic and chemical order-disorder transformations in Co2Fe(Ga1-xSix) and Co2Fe(Al1-ySiy) Heusler alloys

    Science.gov (United States)

    Umetsu, Rie Y.; Okubo, Akinari; Kainuma, Ryosuke

    2012-04-01

    The concentration dependence of the order-disorder phase transformation temperature from the L21 to the B2 phase (TtL21/B2) and magnetic properties of Co2Fe(Ga1-xSix) and Co2Fe(Al1-ySiy) Heusler alloys were investigated. In the phase diagrams, a crossover of the Curie temperature (TC) and TtL21/B2 was confirmed at around y = 0.45 in Co2Fe(Al1-ySiy), whereas the TC and TtL21/B2 monotonically changed with x in Co2Fe (Ga1-xSix). The slopes of the linear concentration dependence of TtL21/B2 for Co2Fe(Al1-ySiy) drastically changed at about y = 0.45, suggesting that the chemical interchange energy between Fe and Al in Co2FeAl alloy is affected by the magnetic ordering.

  16. Role of InxGa1-xAs Layer Composition in Modifying Strain Fields and Carrier Confinement Potentials in a Close-stacked InAs/GaAs Quantum Dot System

    Science.gov (United States)

    Lee, Woong; Yoo, Yo-Han; Shin, Hyunho; Myoung, Jae-Min

    2005-05-01

    Role of the composition of InxGa1-xAs strain-relief layer (SRL) in controlling the strain fields and consequent modification of band structures in a close-stacked multi-layer InAs/GaAs quantum dot (QD) system was investigated within the framework of continuum elasticity and model solid theory. It was predicted that strains in the QDs are significantly relieved in proportion to the In concentration in the InxGa1-xAs SRLs between InAs QD and GaAs cap layer. The relaxation of strains caused substantial shift of the conduction band edge in the QDs mainly by the relief of hydrostatic strain component resulting in narrower bandgap within the QDs with increasing In concentration. It is interpreted that such strain relaxation and subsequent band structure modifications are responsible for the experimentally observed redshift of photo-luminescence (PL) spectra elsewhere. Therefore, together with existing experimental work, it is confirmed that conduction band edges of QD systems can be tailored by the control of the SRL composition allowing more flexibility in bandgap engineering.

  17. Comparative sequence analyses on the 16S rRNA (rDNA) of Bacillus acidocaldarius, Bacillus acidoterrestris, and Bacillus cycloheptanicus and proposal for creation of a new genus, Alicyclobacillus gen. nov

    Science.gov (United States)

    Wisotzkey, J. D.; Jurtshuk, P. Jr; Fox, G. E.; Deinhard, G.; Poralla, K.

    1992-01-01

    Comparative 16S rRNA (rDNA) sequence analyses performed on the thermophilic Bacillus species Bacillus acidocaldarius, Bacillus acidoterrestris, and Bacillus cycloheptanicus revealed that these organisms are sufficiently different from the traditional Bacillus species to warrant reclassification in a new genus, Alicyclobacillus gen. nov. An analysis of 16S rRNA sequences established that these three thermoacidophiles cluster in a group that differs markedly from both the obligately thermophilic organisms Bacillus stearothermophilus and the facultatively thermophilic organism Bacillus coagulans, as well as many other common mesophilic and thermophilic Bacillus species. The thermoacidophilic Bacillus species B. acidocaldarius, B. acidoterrestris, and B. cycloheptanicus also are unique in that they possess omega-alicylic fatty acid as the major natural membranous lipid component, which is a rare phenotype that has not been found in any other Bacillus species characterized to date. This phenotype, along with the 16S rRNA sequence data, suggests that these thermoacidophiles are biochemically and genetically unique and supports the proposal that they should be reclassified in the new genus Alicyclobacillus.

  18. Inactivation of Bacillus atrophaeus by OH radicals

    Science.gov (United States)

    Ono, Ryo; Yonetamari, Kenta; Tokumitsu, Yusuke; Yonemori, Seiya; Yasuda, Hachiro; Mizuno, Akira

    2016-08-01

    The inactivation of Bacillus atrophaeus by OH radicals is measured. This study aims to evaluate the bactericidal effects of OH radicals produced by atmospheric-pressure nonthermal plasma widely used for plasma medicine; however, in this study, OH radicals are produced by vacuum ultraviolet (VUV) photolysis of water vapor instead of plasma to allow the production of OH radicals with almost no other reactive species. A 172 nm VUV light from a Xe2 excimer lamp irradiates a He–H2O mixture flowing in a quartz tube to photodissociate H2O to produce OH, H, O, HO2, H2O2, and O3. The produced reactive oxygen species (ROS) flow out of the quartz tube nozzle to the bacteria on an agar plate and cause inactivation. The inactivation by OH radicals among the six ROS is observed by properly setting the experimental conditions with the help of simulations calculating the ROS densities. A 30 s treatment with approximately 0.1 ppm OH radicals causes visible inactivation.

  19. Bacillus anthracis diversity in Kruger National Park.

    Science.gov (United States)

    Smith, K L; DeVos, V; Bryden, H; Price, L B; Hugh-Jones, M E; Keim, P

    2000-10-01

    The Kruger National Park (KNP), South Africa, has a recorded history of periodic anthrax epidemics causing widespread disease among wild animals. Bacillus anthracis is the causative agent of anthrax, a disease primarily affecting ungulate herbivores. Worldwide there is little diversity among B. anthracis isolates, but examination of variable-number tandem repeat (VNTR) loci has identified six major clones, with the most dissimilar types split into the A and B branches. Both the A and B types are found in southern Africa, giving this region the greatest genetic diversity of B. anthracis worldwide. Consequently, southern Africa has been hypothesized to be the geographic origin of B. anthracis. In this study, we identify the genotypic types of 98 KNP B. anthracis isolates using multiple-locus VNTR analysis. Two major types are evident, the A branch and the B branch. The spatial and temporal distribution of the different genotypes indicates that anthrax epidemic foci are independent, though correlated through environmental cues. Kruger B isolates were found on significantly higher-calcium and higher-pH soils than were Kruger type A. This relationship between genotype and soil chemistry may be due to adaptive differences among divergent anthrax strains. While this association may be simply fortuitous, adaptation of A types to diverse environmental conditions is consistent with their greater geographic dispersal and genetic dissimilarity.

  20. Cannibalism stress response in Bacillus subtilis.

    Science.gov (United States)

    Höfler, Carolin; Heckmann, Judith; Fritsch, Anne; Popp, Philipp; Gebhard, Susanne; Fritz, Georg; Mascher, Thorsten

    2016-01-01

    When faced with carbon source limitation, the Gram-positive soil organism Bacillus subtilis initiates a survival strategy called sporulation, which leads to the formation of highly resistant endospores that allow B. subtilis to survive even long periods of starvation. In order to avoid commitment to this energy-demanding and irreversible process, B. subtilis employs another strategy called 'cannibalism' to delay sporulation as long as possible. Cannibalism involves the production and secretion of two cannibalism toxins, sporulation delaying protein (SDP) and sporulation killing factor (SKF), which are able to lyse sensitive siblings. The lysed cells are thought to then provide nutrients for the cannibals to slow down or even prevent them from entering sporulation. In this study, we uncovered the role of the cell envelope stress response (CESR), especially the Bce-like antimicrobial peptide detoxification modules, in the cannibalism stress response during the stationary phase. SDP and SKF specifically induce Bce-like systems and some extracytoplasmic function σ factors in stationary-phase cultures, but only the latter provide some degree of protection. A full Bce response is only triggered by mature toxins, and not by toxin precursors. Our study provides insights into the close relationship between stationary-phase survival and the CESR of B. subtilis. PMID:26364265

  1. Comparison of different Bacillus subtilis expression systems.

    Science.gov (United States)

    Vavrová, Ludmila; Muchová, Katarína; Barák, Imrich

    2010-11-01

    Bacillus subtilis is considered to have great potential as a host for the production and secretion of recombinant proteins. Many different expression systems have been developed for B. subtilis. Here we compare two widely used expression systems, the IPTG-inducible derivative of spac system (hyper-spank) and the xylose-inducible (xyl) to the SURE (subtilin-regulated gene expression) system. Western blot analysis of the membrane protein SpoIISA together with its protein partner SpoIISB showed that the highest expression level of this complex is obtained using the SURE system. Measurement of β-galactosidase activities of the promoter-lacZ fusions in individual expression systems confirmed that the P(spaS) promoter of the SURE system is the strongest of those compared, although the induction/repression ratio reached only 1.84. Based on these results, we conclude that the SURE system is the most efficient of these three B. subtilis expression systems in terms of the amount of expressed product. Remarkably, the yield of the SpoIISA-SpoIISB complex obtained from B. subtilis was comparable to that normally obtained from the Escherichia coli arabinose-inducible expression system. PMID:20863884

  2. Bacillus thuringiensis Conjugation in Simulated Microgravity

    Science.gov (United States)

    Beuls, Elise; van Houdt, Rob; Leys, Natalie; Dijkstra, Camelia; Larkin, Oliver; Mahillon, Jacques

    2009-10-01

    Spaceflight experiments have suggested a possible effect of microgravity on the plasmid transfer among strains of the Gram-positive Bacillus thuringiensis, as opposed to no effect recorded for Gram-negative conjugation. To investigate these potential effects in a more affordable experimental setup, three ground-based microgravity simulators were tested: the Rotating Wall Vessel (RWV), the Random Positioning Machine (RPM), and a superconducting magnet. The bacterial conjugative system consisted in biparental matings between two B. thuringiensis strains, where the transfer frequencies of the conjugative plasmid pAW63 and its ability to mobilize the nonconjugative plasmid pUB110 were assessed. Specifically, potential plasmid transfers in a 0-g position (simulated microgravity) were compared to those obtained under 1-g (normal gravity) condition in each device. Statistical analyses revealed no significant difference in the conjugative and mobilizable transfer frequencies between the three different simulated microgravitational conditions and our standard laboratory condition. These important ground-based observations emphasize the fact that, though no stimulation of plasmid transfer was observed, no inhibition was observed either. In the case of Gram-positive bacteria, this ability to exchange plasmids in weightlessness, as occurs under Earth's conditions, should be seen as particularly relevant in the scope of spread of antibiotic resistances and bacterial virulence.

  3. A pangenomic study of Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    Yongjun Fang; Songnian Hu; Jie Zhang; Ibrahim A1-Mssallem; Jun Yu; Zhaolong Li; Jiucheng Liu; Changlong Shu; Xumin Wang; Xiaowei Zhang; Xiaoguang Yu; Duojun Zhao; Guiming Liu

    2011-01-01

    Bacillus thuringiensis (B.thuringiensis) is a soil-dwelling Gram-positive bacterium and its plasmid-encoded toxins (Cry) are commonly used as biological alternatives to pesticides.In a pangenomic study,we sequenced seven B.thuringiensis isolates in both high coverage and base quality using the next-generation sequencing platform.The B.thuringiensis pangenome was extrapolated to have 4196 core genes and an asymptotic value of 558 unique genes when a new genome is added.Compared to the pangenomes of its closely related species of the same genus,B.thuringiensis pangenome shows an open characteristic,similar to B.cereus but not to B.anthracis; the latter has a closed pangenome.We also found extensive divergence among the seven B.thuringiensis genome assemblies,which harbor ample repeats and single nucleotide polymorphisms (SNPs).The identities among orthologous genes are greater than 84.5% and the hotspots for the genome variations were discovered in genomic regions of 2.3-2.8 Mb and 5.0-5.6 Mb.We concluded that high-coverage sequence assemblies from multiple strains,before all the gaps are closed,are very useful for pangenomic studies.

  4. Surface topography of the Bacillus stearothermophilus ribosome

    International Nuclear Information System (INIS)

    The surface topography of the intact 70S ribosome and free 30S and 50S subunits from Bacillus stearothermophilus strain 2,184 was investigated by lactoperoxidase-catalyzed iodination. Two-dimensional polyacrylamide gel electrophoresis was employed to separate ribosomal proteins for analysis of their reactivity. Free 50S subunits incorporated about 18% more 125I than did 50S subunits derived from 70S ribosomes, whereas free 30S subunits and 30S subunits derived from 70S ribosomes incorporated similar amounts of 125I. Iodinated 70S ribosomes and subunits retained 62-78% of the protein synthesis activity of untreated particles and sedimentation profiles showed no gross conformational changes due to iodination. The proteins most reactive to enzymatic iodination were S4, S7, S10 and Sa of the small subunit and L2, L4, L5/9, L6 and L36 of the large subunit. Proteins S2, S3, S7, S13, Sa, L5/9, L10, L11 and L24/25 were labeled substantially more in the free subunits than in the 70S ribosome. Other proteins, including S5, S9, S12, S15/16, S18 and L36 were more extensively iodinated in the 70S ribosome than in the free subunits. The locations of tyrosine residues in some homologus ribosomal proteins from B. stearothermophilus and E. coli are compared. (orig.)

  5. Extended genetic analysis of Brazilian isolates of Bacillus cereus and Bacillus thuringiensis

    Science.gov (United States)

    Zahner, Viviane; Silva, Ana Carolina Telles de Carvalho e; de Moraes, Gabriela Pinhel; McIntosh, Douglas; de Filippis, Ivano

    2013-01-01

    Multiple locus sequence typing (MLST) was undertaken to extend the genetic characterization of 29 isolates of Bacillus cereus and Bacillus thuringiensis previously characterized in terms of presence/absence of sequences encoding virulence factors and via variable number tandem repeat (VNTR). Additional analysis involved polymerase chain reaction for the presence of sequences (be, cytK, inA, pag, lef, cya and cap), encoding putative virulence factors, not investigated in the earlier study. MLST analysis ascribed novel and unique sequence types to each of the isolates. A phylogenetic tree was constructed from a single sequence of 2,838 bp of concatenated loci sequences. The strains were not monophyletic by analysis of any specific housekeeping gene or virulence characteristic. No clear association in relation to source of isolation or to genotypic profile based on the presence or absence of putative virulence genes could be identified. Comparison of VNTR profiling with MLST data suggested a correlation between these two methods of genetic analysis. In common with the majority of previous studies, MLST was unable to provide clarification of the basis for pathogenicity among members of the B. cereus complex. Nevertheless, our application of MLST served to reinforce the notion that B. cereus and B. thuringiensis should be considered as the same species. PMID:23440117

  6. Architecture and High-Resolution Structure of Bacillus thuringiensis and Bacillus cereus Spore Coat Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Plomp, M; Leighton, T; Wheeler, K; Malkin, A

    2005-02-18

    We have utilized atomic force microscopy (AFM) to visualize the native surface topology and ultrastructure of Bacillus thuringiensis and Bacillus cereus spores in water and in air. AFM was able to resolve the nanostructure of the exosporium and three distinctive classes of appendages. Removal of the exosporium exposed either a hexagonal honeycomb layer (B. thuringiensis) or a rodlet outer spore coat layer (B. cereus). Removal of the rodlet structure from B. cereus spores revealed an underlying honeycomb layer similar to that observed with B. thuringiensis spores. The periodicity of the rodlet structure on the outer spore coat of B. cereus was {approx}8 nm, and the length of the rodlets was limited to the cross-patched domain structure of this layer to {approx}200 nm. The lattice constant of the honeycomb structures was {approx}9 nm for both B. cereus and B. thuringiensis spores. Both honeycomb structures were composed of multiple, disoriented domains with distinct boundaries. Our results demonstrate that variations in storage and preparation procedures result in architectural changes in individual spore surfaces, which establish AFM as a useful tool for evaluation of preparation and processing ''fingerprints'' of bacterial spores. These results establish that high-resolution AFM has the capacity to reveal species-specific assembly and nanometer scale structure of spore surfaces. These species-specific spore surface structural variations are correlated with sequence divergences in a spore core structural protein SspE.

  7. Occurrence of Toxigenic Bacillus cereus and Bacillus thuringiensis in Doenjang, a Korean Fermented Soybean Paste.

    Science.gov (United States)

    Park, Kyung Min; Kim, Hyun Jung; Jeong, Moon Cheol; Koo, Minseon

    2016-04-01

    This study determined the prevalence and toxin profile of Bacillus cereus and Bacillus thuringiensis in doenjang, a fermented soybean food, made using both traditional and commercial methods. The 51 doenjang samples tested were broadly contaminated with B. cereus; in contrast, only one sample was positive for B. thuringiensis. All B. cereus isolates from doenjang were positive for diarrheal toxin genes. The frequencies of nheABC and hblACD in traditional samples were 22.7 and 0%, respectively, whereas 5.1 and 5.1% of B. cereus isolates from commercial samples possessed nheABC and hblACD, respectively. The detection rate of ces gene was 10.8%. The predominant toxin profile among isolates from enterotoxigenic B. cereus in doenjang was profile 4 (entFM-bceT-cytK). The major enterotoxin genes in emetic B. cereus were cytK, entFM, and nheA genes. The B. thuringiensis isolate was of the diarrheagenic type. These results provide a better understanding of the epidemiology of the enterotoxigenic and emetic B. cereus groups in Korean fermented soybean products.

  8. Extended genetic analysis of Brazilian isolates of Bacillus cereus and Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Viviane Zahner

    2013-02-01

    Full Text Available Multiple locus sequence typing (MLST was undertaken to extend the genetic characterization of 29 isolates of Bacillus cereus and Bacillus thuringiensis previously characterized in terms of presence/absence of sequences encoding virulence factors and via variable number tandem repeat (VNTR. Additional analysis involved polymerase chain reaction for the presence of sequences (be, cytK, inA, pag, lef, cya and cap, encoding putative virulence factors, not investigated in the earlier study. MLST analysis ascribed novel and unique sequence types to each of the isolates. A phylogenetic tree was constructed from a single sequence of 2,838 bp of concatenated loci sequences. The strains were not monophyletic by analysis of any specific housekeeping gene or virulence characteristic. No clear association in relation to source of isolation or to genotypic profile based on the presence or absence of putative virulence genes could be identified. Comparison of VNTR profiling with MLST data suggested a correlation between these two methods of genetic analysis. In common with the majority of previous studies, MLST was unable to provide clarification of the basis for pathogenicity among members of the B. cereus complex. Nevertheless, our application of MLST served to reinforce the notion that B. cereus and B. thuringiensis should be considered as the same species.

  9. Genome Sequence of Bacillus endophyticus and Analysis of Its Companion Mechanism in the Ketogulonigenium vulgare-Bacillus Strain Consortium.

    Directory of Open Access Journals (Sweden)

    Nan Jia

    Full Text Available Bacillus strains have been widely used as the companion strain of Ketogulonigenium vulgare in the process of vitamin C fermentation. Different Bacillus strains generate different effects on the growth of K. vulgare and ultimately influence the productivity. First, we identified that Bacillus endophyticus Hbe603 was an appropriate strain to cooperate with K. vulgare and the product conversion rate exceeded 90% in industrial vitamin C fermentation. Here, we report the genome sequencing of the B. endophyticus Hbe603 industrial companion strain and speculate its possible advantage in the consortium. The circular chromosome of B. endophyticus Hbe603 has a size of 4.87 Mb with GC content of 36.64% and has the highest similarity with that of Bacillus megaterium among all the bacteria with complete genomes. By comparing the distribution of COGs with that of Bacillus thuringiensis, Bacillus cereus and B. megaterium, B. endophyticus has less genes related to cell envelope biogenesis and signal transduction mechanisms, and more genes related to carbohydrate transport and metabolism, energy production and conversion, as well as lipid transport and metabolism. Genome-based functional studies revealed the specific capability of B. endophyticus in sporulation, transcription regulation, environmental resistance, membrane transportation, extracellular proteins and nutrients synthesis, which would be beneficial for K. vulgare. In particular, B. endophyticus lacks the Rap-Phr signal cascade system and, in part, spore coat related proteins. In addition, it has specific pathways for vitamin B12 synthesis and sorbitol metabolism. The genome analysis of the industrial B. endophyticus will help us understand its cooperative mechanism in the K. vulgare-Bacillus strain consortium to improve the fermentation of vitamin C.

  10. Genome Sequence of Bacillus endophyticus and Analysis of Its Companion Mechanism in the Ketogulonigenium vulgare-Bacillus Strain Consortium.

    Science.gov (United States)

    Jia, Nan; Du, Jin; Ding, Ming-Zhu; Gao, Feng; Yuan, Ying-Jin

    2015-01-01

    Bacillus strains have been widely used as the companion strain of Ketogulonigenium vulgare in the process of vitamin C fermentation. Different Bacillus strains generate different effects on the growth of K. vulgare and ultimately influence the productivity. First, we identified that Bacillus endophyticus Hbe603 was an appropriate strain to cooperate with K. vulgare and the product conversion rate exceeded 90% in industrial vitamin C fermentation. Here, we report the genome sequencing of the B. endophyticus Hbe603 industrial companion strain and speculate its possible advantage in the consortium. The circular chromosome of B. endophyticus Hbe603 has a size of 4.87 Mb with GC content of 36.64% and has the highest similarity with that of Bacillus megaterium among all the bacteria with complete genomes. By comparing the distribution of COGs with that of Bacillus thuringiensis, Bacillus cereus and B. megaterium, B. endophyticus has less genes related to cell envelope biogenesis and signal transduction mechanisms, and more genes related to carbohydrate transport and metabolism, energy production and conversion, as well as lipid transport and metabolism. Genome-based functional studies revealed the specific capability of B. endophyticus in sporulation, transcription regulation, environmental resistance, membrane transportation, extracellular proteins and nutrients synthesis, which would be beneficial for K. vulgare. In particular, B. endophyticus lacks the Rap-Phr signal cascade system and, in part, spore coat related proteins. In addition, it has specific pathways for vitamin B12 synthesis and sorbitol metabolism. The genome analysis of the industrial B. endophyticus will help us understand its cooperative mechanism in the K. vulgare-Bacillus strain consortium to improve the fermentation of vitamin C.

  11. The Bacillus anthracis Exosporium: What's the Big "Hairy" Deal?

    Science.gov (United States)

    Bozue, Joel A; Welkos, Susan; Cote, Christopher K

    2015-10-01

    In some Bacillus species, including Bacillus subtilis, the coat is the outermost layer of the spore. In others, such as the Bacillus cereus family, there is an additional layer that envelops the coat, called the exosporium. In the case of Bacillus anthracis, a series of fine hair-like projections, also referred to as a "hairy" nap, extends from the exosporium basal layer. The exact role of the exosporium in B. anthracis, or for any of the Bacillus species possessing this structure, remains unclear. However, it has been assumed that the exosporium would play some role in infection for B. anthracis, because it is the outermost structure of the spore and would make initial contact with host and immune cells during infection. Therefore, the exosporium has been a topic of great interest, and over the past decade much progress has been made to understand its composition, biosynthesis, and potential roles. Several key aspects of this spore structure, however, are still debated and remain undetermined. Although insights have been gained on the interaction of exosporium with the host during infection, the exact role and significance of this complex structure remain to be determined. Furthermore, because the exosporium is a highly antigenic structure, future strategies for the next-generation anthrax vaccine should pursue its inclusion as a component to provide protection against the spore itself during the initial stages of anthrax. PMID:26542035

  12. Bacillus as a potential diagnostic marker for yellow tongue coating.

    Science.gov (United States)

    Ye, Juan; Cai, Xueting; Yang, Jie; Sun, Xiaoyan; Hu, Chunping; Xia, Junquan; Shen, Jianping; Su, Kelei; Yan, Huaijiang; Xu, Yuehua; Zhang, Yiyan; Zhang, Sujie; Yang, Lijun; Zhi, Hao; Gao, Sizhi Paul; Yu, Qiang; Hu, Jingqing; Cao, Peng

    2016-01-01

    Observation of tongue coating, a foundation for clinical diagnosis and treatment in traditional Chinese medicine (TCM), is a major indicator of the occurrence, development, and prognosis of disease. The biological basis of tongue diagnosis and relationship between the types and microorganisms of tongue coating remain elusive. Thirteen chronic erosive gastritis (CEG) patients with typical yellow tongue coating (YTC) and ten healthy volunteers with thin white tongue coating (WTC) were included in this study. Patients were provided a 2-course targeted treatment of a herbal medicine Ban Xia Xie Xin decoction, traditionally prescribed for CEG patients with YTC, to evaluate the relationship between tongue coating microbiota and diagnosis of CEG with typical YTC. The tongue coating segregation structure was determined using Illumina Miseq sequencing of the V4-V5 region of the 16S ribosomal RNA gene. Bacillus was significantly observed only in CEG patients with YTC, but not in patients who received the decoction. YTC (n = 22) and WTC (n = 29) samples were collected for bacterial culturing to illustrate the relationship between Bacillus and YTC. The Bacillus positivity rate of YTC samples was 72.7%; Bacillus was not observed in WTC samples. In conclusion, Bacillus was strongly associated with YTC. PMID:27578261

  13. Production of Alpha Amylase by Bacillus cereus in Submerged Fermentation

    Directory of Open Access Journals (Sweden)

    Helen H. Raplong

    2014-09-01

    Full Text Available Microorganisms have the ability to secrete enzymes when they are grown in the presence of certain substrates. Amylases are among the most important industrial enzymes and are of great significance in biotechnological studies. Bacteria belonging to the genus Bacillus were isolated using mannitol egg yolk polymyxin B (MYP agar a highly selective media for Bacillus cereus isolation. The isolates were tested for α-amylase production on nutrient agar supplemented with starch and in submerged fermentation. The bacteria isolated and identified (using the Microgen Bacillus identification kit were all Bacillus cereus and SB2 had the largest zone of hydrolysis of 12mm on nutrient agar supplemented with starch as well as the highest enzyme activity of 1.62U/ml. Amylase activity of 2.56U/ml was obtained after 24 hours incubation in submerged fermentation. When amylase enzyme production parameters where optimized, maximum amylase activity was obtained at a pH of 6.5, temperature of 350C, incubation time of 24 hours and 4% inoculums concentration. Bacillus cereus SB2 is a potential isolate for alpha-amylase production with soluble starch as the sole carbon source in submerged fermentation.

  14. UJI TOKSISITAS ISOLAT Bacillus thuringiensis dari Kabupaten Lahat, Palembang, Sumatera Selatan TERHADAP LARVA NYAMUK Culex sp.

    OpenAIRE

    Chandra, Welianto

    2016-01-01

    This study aims to determine the optimal concentration of isolates of Bacillus thuringiensis to control larvae of the mosquito Culex sp. The method used is the isolation of the bacterium Bacillus thuringiensis, then the inoculation of bacteria. Bacillus thuringiensis mud samples, as much as 25 grams, obtained in the area of Lahat, South Sumatra containing Bacillus thuringiensis which includes five districts, namely Sub Gumay Talang, Jaray, Kikim West, South Kikim, and Central Kikim. Gumay ...

  15. 40 CFR 180.1128 - Bacillus subtilis MBI 600; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus subtilis MBI 600; exemption... FOOD Exemptions From Tolerances § 180.1128 Bacillus subtilis MBI 600; exemption from the requirement of... biofungicide Bacillus subtilis MBI 600 in or on all food commodities, including residues resulting from...

  16. Evaluation of in situ valine production by Bacillus subtilis in young pigs

    DEFF Research Database (Denmark)

    Nørgaard, Jan Værum; Canibe, Nuria; Assadi Soumeh, Elham;

    2016-01-01

    Mutants of Bacillus subtilis can be developed to overproduce Val in vitro. It was hypothesized that addition of Bacillus subtilis mutants to pig diets can be a strategy to supply the animal with Val. The objective was to investigate the effect of Bacillus subtilis mutants on growth performance an...

  17. 芽胞杆菌CQBS03抑菌蛋白TasA基因的克隆及原核表达%Cloning antagonistic protein TasA gene in Bacillus CQBS03 and its prokaryotic expression

    Institute of Scientific and Technical Information of China (English)

    龙贤梨; 王中康; 陈玉龙; 殷幼平

    2012-01-01

    In order to study the function of TasA gene of biocontrol bacteria Bacillus CQBS03 which was isolated from citrus leaf and had bactcriostasis activity to Xanthomonas citri cirri, the full-length DNA se- quence encoding TasA gene was amplified from Bacillus CQBS03 genomic DNA by PCR. After that, we constructed the prokaryotic expression vector pEASY-E1/TasA and expressed in Escherichia coli BL21. The antagonism of the expression fused protein to X. cirri citri was tested with filter paper-petri dish meth- od. The sequencing result showed that full-length DNA sequence of TasA gene included a complete ORF of 786 base pairs, ( GenBank accession number JQ309841 ) , which encoded 261 amino acid residues The TasA gene of CQBS03 had a high sequence similarity with TasA gene of Bacillus amyloliquefaciens (as high as 99.75% ). A 31 kD fused protein was obtained from mutant E. coli BI21-pEASY-E1/TasA cells. Fused protein of TasA gene purified by Ni-NTA chromatography revealed obvious antibacterial ac- tivities to X. citri citri, and the diameter of antagonism zone reached 11.5 mm after 72 hours. The resultsproved that the TasA gene was one of the most efficient antagonism function genes of bacteria CQBS03, and it can be used in citrus canker biocontrol.%为了探讨柑桔溃疡病生防菌芽胞杆菌Bacillus CQBS03菌株TasA基因的功能,采用PCR方法从CQBS03基因组DNA中扩增出编码TasA基因的全长DNA序列,并构建pEASY-E1/TasA原核表达载体,经大肠杆菌Escherichia coli表达获得TasA基因的融合表达蛋白,纸碟法检验融合蛋白对柑桔溃疡病菌Xanthomonas citri citri的抑制作用。结果显示,CQBS03菌株的TasA基因包含1个786 bp的完整开放阅读框(GenBank登录号为JQ309841),编码261个氨基酸残基;该序列与来源于解淀粉芽胞杆菌B.amyloliquefaciens的1个已知同源TasA基因序列FJ713580的相似性达99.75%。原核表达产物经SDS-PAGE分析,检测到约31 kD的融合蛋白;纯化后的融合蛋

  18. Genetic Characterization of Bacillus anthracis 17 JB strain

    Directory of Open Access Journals (Sweden)

    Sakineh Seyed-Mohamadi

    2015-11-01

    Full Text Available Background and Objectives: Bacillus anthracis is one of the most homogenous bacteria ever described. Bacillus anthracis 17JB is a laboratory strain. It is broadly used as a challenge strain in guinea pigs for potency test of anthrax vaccine.Material and Methods: This work describes genetic characterization of B. anthracis 17 JB strain using the SNPs and MLVA genotyping.Results and Conclusion: In SNPs typing, the originally French 17JB strain represented the A. Br. 008/009 subgroup. In Levy's genotyping method, 843, 451 and 864 bp long fragments were identified at AA03, AJ03 and AA07 loci, respectively. In the vaccine manufacturer perspective these findings are much valuable on their own account, but similar research is required to extend molecular knowledge of B. anthracis epidemiology in Persia.Keywords: Bacillus anthracis 17JB, Genetic characterization, SNPs typing

  19. Bacillus cereus food poisoning: international and Indian perspective.

    Science.gov (United States)

    Tewari, Anita; Abdullah, Swaid

    2015-05-01

    Food borne illnesses result from eating food or drinking beverages that are contaminated with chemical matter, heavy metals, parasites, fungi, viruses and Bacteria. Bacillus cereus is one of the food-borne disease causing Bacteria. Species of Bacillus and related genera have long been troublesome to food producers on account of their resistant endospores. Their spores may be present on various types of raw and cooked foods, and their ability to survive high cooking temperatures requires that cooked foods be served hot or cooled rapidly to prevent the growth of this bacteria. Bacillus cereus is well known as a cause of food poisoning, and much more is now known about the toxins produced by various strains of this species, so that its significance in such episodes are clearer. However, it is still unclear why such cases are so rarely reported worldwide.

  20. Genotyping of Bacillus cereus strains by microarray-based resequencing.

    Directory of Open Access Journals (Sweden)

    Michael E Zwick

    Full Text Available The ability to distinguish microbial pathogens from closely related but nonpathogenic strains is key to understanding the population biology of these organisms. In this regard, Bacillus anthracis, the bacterium that causes inhalational anthrax, is of interest because it is closely related and often difficult to distinguish from other members of the B. cereus group that can cause diverse diseases. We employed custom-designed resequencing arrays (RAs based on the genome sequence of Bacillus anthracis to generate 422 kb of genomic sequence from a panel of 41 Bacillus cereus sensu lato strains. Here we show that RAs represent a "one reaction" genotyping technology with the ability to discriminate between highly similar B. anthracis isolates and more divergent strains of the B. cereus s.l. Clade 1. Our data show that RAs can be an efficient genotyping technology for pre-screening the genetic diversity of large strain collections to selected the best candidates for whole genome sequencing.

  1. BACILLUS THURINGIENSIS ELASTASES WITH INSECTICIDE ACTIVITY

    Directory of Open Access Journals (Sweden)

    E. V. Matseliukh

    2015-10-01

    Full Text Available The purpose of the research was a screening of proteases with elastase activity among Bacillus thuringiensis strains, their isolation, partially purification, study of physicochemical properties and insecticide activity in relation to the larvae of the Colorado beetle. The objects of the investigation were 18 strains of B. thuringiensis, isolated from different sources: sea water, dry biological product "Bitoksibatsillin" and also from natural populations of Colorado beetles of the Crimea, Kherson, Odesa, Mykolaiv and Zaporizhiia regions of Ukraine. Purification of enzymes with elastase activity isolated from above mentioned strains was performed by gel-chromatography and insecticide activity was studied on the 3–4 larvae instar of Colorado beetle. The ability of a number of B. thuringiensis strains to synthesize the proteases with elastase activity has been established. The most active were enzymes obtained from strains IMV B-7465, IMV B-7324 isolated from sea water, and strains 9, 902, Bt-H and 0-239 isolated from Colorado beetles. The study of the physicochemical properties of the partially purified proteases of these strains showed that they belonged to enzymes of the serine type. Peptidases of a number of B. thuringiensis strains (IMV B-7324, IMV B-7465, 902, 0-239, 9 are metal-dependent enzymes. Optimal conditions of action of all tested enzymes are the neutral and alkaline рН values and the temperatures of 30–40 °С. The studies of influence of the complex enzyme preparations and partially purified ones of B. thuringiensis strains on the larvae instar of Colorado beetles indicated that enzymes with elastase activity could be responsible for insecticide action of the tested strains.

  2. Production and Characterization of Bacillus firmus pectinase

    Directory of Open Access Journals (Sweden)

    Anna Roosdiana

    2013-03-01

    Full Text Available Pectinase is enzyme which functions to hydrolyze pectin become D-galacturonic acid unit. This enzyme is potential in various industries, especially in fruit juice industry.  Pectinase can be derived from various microorganisms resulting in different pectinase character. The aims of this research were to determine the optimum condition of pectinase production and to characterize the resulted pectinase including optimum condition of pectinase activity and the influence of metal ion.  The optimum condition of pectinase production was carried out by growing Bacillus firmus on basal media containing pectin as inducer at various  pH (5, 6, 7, 8, 9, 10, temperature (30, 35, 40, 45, 50 oC and fermentation time (6, 12, 18, 24, 30, 36 hours. while the optimum pectinase activity was done at various pH ( 4, 6, 7, 8, 10 , temperature (30, 35, 40, 45, 50 oC and reaction time (10, 20, 30, 40, 50 minutes. The influence of Zn2+, Mg2+, K+ at 2-10 mM to pectinase activity were also investigated. The result showed that optimum condition of pectinase production occurred at pH7-8, temperature 40-50 oC and fermentation time 18hours, while the optimum condition of pectinase activity was pH 7, temperature 50 oC and reaction time 30 minutes. The existence of Zn2+, Mg2+, K+ ions  affected significantly to pectinase activity.  Mg2+ acted as non competitive inhibitor; however K+ and Zn2+ acted as un competitive inhibitor.

  3. Identification and Pathogenic Potential of Clinical Bacillus and Paenibacillus Isolates.

    Science.gov (United States)

    Celandroni, Francesco; Salvetti, Sara; Gueye, Sokhna Aissatou; Mazzantini, Diletta; Lupetti, Antonella; Senesi, Sonia; Ghelardi, Emilia

    2016-01-01

    The soil-related Bacillus and Paenibacillus species have increasingly been implicated in various human diseases. Nevertheless, their identification still poses problems in the clinical microbiology laboratory and, with the exception of Bacillus anthracis and Bacillus cereus, little is known on their pathogenicity for humans. In this study, we evaluated the use of matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) in the identification of clinical isolates of these genera and conducted genotypic and phenotypic analyses to highlight specific virulence properties. Seventy-five clinical isolates were subjected to biochemical and MALDI-TOF MS identification. 16S rDNA sequencing and supplemental tests were used to solve any discrepancies or failures in the identification results. MALDI-TOF MS significantly outperformed classical biochemical testing for correct species identification and no misidentification was obtained. One third of the collected strains belonged to the B. cereus species, but also Bacillus pumilus and Bacillus subtilis were isolated at high rate. Antimicrobial susceptibility testing showed that all the B. cereus, B. licheniformis, B. simplex, B. mycoides, Paenibacillus glucanolyticus and Paenibacillus lautus isolates are resistant to penicillin. The evaluation of toxin/enzyme secretion, toxin-encoding genes, motility, and biofilm formation revealed that B. cereus displays the highest virulence potential. However, although generally considered nonpathogenic, most of the other species were shown to swim, swarm, produce biofilms, and secrete proteases that can have a role in bacterial virulence. In conclusion, MALDI-TOF MS appears useful for fast and accurate identification of Bacillus and Paenibacillus strains whose virulence properties make them of increasing clinical relevance.

  4. Identification and Pathogenic Potential of Clinical Bacillus and Paenibacillus Isolates.

    Directory of Open Access Journals (Sweden)

    Francesco Celandroni

    Full Text Available The soil-related Bacillus and Paenibacillus species have increasingly been implicated in various human diseases. Nevertheless, their identification still poses problems in the clinical microbiology laboratory and, with the exception of Bacillus anthracis and Bacillus cereus, little is known on their pathogenicity for humans. In this study, we evaluated the use of matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS in the identification of clinical isolates of these genera and conducted genotypic and phenotypic analyses to highlight specific virulence properties. Seventy-five clinical isolates were subjected to biochemical and MALDI-TOF MS identification. 16S rDNA sequencing and supplemental tests were used to solve any discrepancies or failures in the identification results. MALDI-TOF MS significantly outperformed classical biochemical testing for correct species identification and no misidentification was obtained. One third of the collected strains belonged to the B. cereus species, but also Bacillus pumilus and Bacillus subtilis were isolated at high rate. Antimicrobial susceptibility testing showed that all the B. cereus, B. licheniformis, B. simplex, B. mycoides, Paenibacillus glucanolyticus and Paenibacillus lautus isolates are resistant to penicillin. The evaluation of toxin/enzyme secretion, toxin-encoding genes, motility, and biofilm formation revealed that B. cereus displays the highest virulence potential. However, although generally considered nonpathogenic, most of the other species were shown to swim, swarm, produce biofilms, and secrete proteases that can have a role in bacterial virulence. In conclusion, MALDI-TOF MS appears useful for fast and accurate identification of Bacillus and Paenibacillus strains whose virulence properties make them of increasing clinical relevance.

  5. Low-temperature microwave characteristics of 0.1 micron gate-length pseudomorphic In(0.52)Al(0.48)As/In(x)Ga(1-x)As (x = 0.85 and 0.95) MODFET's

    Science.gov (United States)

    Yang, D.; Bhattacharya, P. K.; Brock, T.; Alterovitz, S. A.; Taub, S. R.; Young, P. G.

    1994-06-01

    We have studied the microwave characteristics of 0.1 micron gate-length pseudomorphic In(0.52)Al(0.48)As/In(x)Ga(1-x)As (x = 0.85 and 0.95) modulation-doped field-effect transistors (MODFET's) at 300 K and lower temperatures down to 77 K. A maximum f(sub T) of 151 GHz has been measured for a 0.1 x 55 micron(exp 2) gate In(0.52)Al(0.48)As/In(0.85)Ga(0.15)As MODFET at 77 K and this represents an improvement of 33% over the room temperature value. This behavior has been analyzed.

  6. Atmospheric pressure organometallic vapor-phase epitaxial growth of (Al/x/Ga/1-x/)0.51In0.49P (x from 0 to 1) using trimethylalkyls

    Science.gov (United States)

    Cao, D. S.; Kimball, A. W.; Stringfellow, G. B.

    1990-01-01

    This paper describes growth of (Al/x/Ga/1-x)0.51In0.49P layers (with x from 0 to 1) lattice-matched to (001)-oriented GaAs substrates by atmospheric-pressure OMVPE, using trimethylindium, trimethylaluminum, and trimethylgallium and PH3 as source materials in a horizontal reactor. Excellent surface morphologies were obtained over the entire range of Al compositions at a growth temperature of 680 C. Photoluminescence (PL) was observed for all samples with x values not below 0.52, with PL peak energies as high as 2.212 eV. The PL FWHM for Ga(0.51)In(0.49)P was 7.2 meV at 10 K and 35 meV at 300 K. At 10 K, the PL intensity was nearly a constant over the composition range from x = 0 to 0.52.

  7. Effect of ‘Al’ concentration on spin-dependent resonant tunnelling in InAs/Ga$_{1−y}$Al$_y$As symmetrical double-barrier heterostructures

    Indian Academy of Sciences (India)

    L BRUNO CHANDRASEKAR; K GNANASEKAR; M KARUNAKARAN; R CHANDRAMOHAN

    2016-10-01

    The effect of ‘Al’ concentration on spin-dependent tunnelling in strained non-magnetic symmetric double-barrier semiconductor has been theoretically investigated. The separation between spin-up and spin-down components, barrier transparency, polarization efficiency and tunnelling lifetime were calculated using the transfer matrix approach. The separation between spin-up and spin-down resonances and tunnelling lifetime were reportedfor the first time in the case of InAs/Ga$_{1−y}$Al$_y$As heterostructures for various ‘Al’ concentrations and for various barrier widths. Cent percentage polarization can be obtained in this strained non-magnetic double-barriersemiconductor even without any external field.

  8. High-quality uniaxial In(x)Ga(1-x)N/GaN multiple quantum well (MQW) nanowires (NWs) on Si(111) grown by metal-organic chemical vapor deposition (MOCVD) and light-emitting diode (LED) fabrication.

    Science.gov (United States)

    Ra, Yong-Ho; Navamathavan, R; Park, Ji-Hyeon; Lee, Cheul-Ro

    2013-03-01

    This article describes the growth and device characteristics of vertically aligned high-quality uniaxial p-GaN/InxGa1-xN/GaN multiple quantum wells (MQW)/n-GaN nanowires (NWs) on Si(111) substrates grown by metal-organic chemical vapor deposition (MOCVD) technique. The resultant nanowires (NWs), with a diameter of 200-250 nm, have an average length of 2 μm. The feasibility of growing high-quality NWs with well-controlled indium composition MQW structure is demonstrated. These resultant NWs grown on Si(111) substrates were utilized for fabricating vertical-type light-emitting diodes (LEDs). The steep and intense photoluminescence (PL) and cathodoluminescence (CL) spectra are observed, based on the strain-free NWs on Si(111) substrates. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that the MQW NWs are grown along the c-plane with uniform thickness. The current-voltage (I-V) characteristics of these NWs exhibited typical p-n junction LEDs and showed a sharp onset voltage at 2.75 V in the forward bias. The output power is linearly increased with increasing current. The result indicates that the pulsed MOCVD technique is an effective method to grow uniaxial p-GaN/InxGa1-xN/GaN MQW/n-GaN NWs on Si(111), which is more advantageous than other growth techniques, such as molecular beam epitaxy. These results suggest the uniaxial NWs are promising to allow flat-band quantum structures, which can enhance the efficiency of LEDs. PMID:23432423

  9. High-quality uniaxial In(x)Ga(1-x)N/GaN multiple quantum well (MQW) nanowires (NWs) on Si(111) grown by metal-organic chemical vapor deposition (MOCVD) and light-emitting diode (LED) fabrication.

    Science.gov (United States)

    Ra, Yong-Ho; Navamathavan, R; Park, Ji-Hyeon; Lee, Cheul-Ro

    2013-03-01

    This article describes the growth and device characteristics of vertically aligned high-quality uniaxial p-GaN/InxGa1-xN/GaN multiple quantum wells (MQW)/n-GaN nanowires (NWs) on Si(111) substrates grown by metal-organic chemical vapor deposition (MOCVD) technique. The resultant nanowires (NWs), with a diameter of 200-250 nm, have an average length of 2 μm. The feasibility of growing high-quality NWs with well-controlled indium composition MQW structure is demonstrated. These resultant NWs grown on Si(111) substrates were utilized for fabricating vertical-type light-emitting diodes (LEDs). The steep and intense photoluminescence (PL) and cathodoluminescence (CL) spectra are observed, based on the strain-free NWs on Si(111) substrates. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that the MQW NWs are grown along the c-plane with uniform thickness. The current-voltage (I-V) characteristics of these NWs exhibited typical p-n junction LEDs and showed a sharp onset voltage at 2.75 V in the forward bias. The output power is linearly increased with increasing current. The result indicates that the pulsed MOCVD technique is an effective method to grow uniaxial p-GaN/InxGa1-xN/GaN MQW/n-GaN NWs on Si(111), which is more advantageous than other growth techniques, such as molecular beam epitaxy. These results suggest the uniaxial NWs are promising to allow flat-band quantum structures, which can enhance the efficiency of LEDs.

  10. Developments in the use of Bacillus species for industrial production.

    Science.gov (United States)

    Schallmey, Marcus; Singh, Ajay; Ward, Owen P

    2004-01-01

    Bacillus species continue to be dominant bacterial workhorses in microbial fermentations. Bacillus subtilis (natto) is the key microbial participant in the ongoing production of the soya-based traditional natto fermentation, and some Bacillus species are on the Food and Drug Administration's GRAS (generally regarded as safe) list. The capacity of selected Bacillus strains to produce and secrete large quantities (20-25 g/L) of extracellular enzymes has placed them among the most important industrial enzyme producers. The ability of different species to ferment in the acid, neutral, and alkaline pH ranges, combined with the presence of thermophiles in the genus, has lead to the development of a variety of new commercial enzyme products with the desired temperature, pH activity, and stability properties to address a variety of specific applications. Classical mutation and (or) selection techniques, together with advanced cloning and protein engineering strategies, have been exploited to develop these products. Efforts to produce and secrete high yields of foreign recombinant proteins in Bacillus hosts initially appeared to be hampered by the degradation of the products by the host proteases. Recent studies have revealed that the slow folding of heterologous proteins at the membrane-cell wall interface of Gram-positive bacteria renders them vulnerable to attack by wall-associated proteases. In addition, the presence of thiol-disulphide oxidoreductases in B. subtilis may be beneficial in the secretion of disulphide-bond-containing proteins. Such developments from our understanding of the complex protein translocation machinery of Gram-positive bacteria should allow the resolution of current secretion challenges and make Bacillus species preeminent hosts for heterologous protein production. Bacillus strains have also been developed and engineered as industrial producers of nucleotides, the vitamin riboflavin, the flavor agent ribose, and the supplement poly

  11. Sigma A recognition sites in the Bacillus subtilis genome

    DEFF Research Database (Denmark)

    Jarmer, Hanne Østergaard; Larsen, Thomas Schou; Krogh, Anders Stærmose;

    2001-01-01

    A hidden Markov model of sigma (A) RNA polymerase cofactor recognition sites in Bacillus subtilis, containing either the common or the extended -10 motifs, has been constructed based on experimentally verified sigma (A) recognition sites. This work suggests that more information exists at the ini......A hidden Markov model of sigma (A) RNA polymerase cofactor recognition sites in Bacillus subtilis, containing either the common or the extended -10 motifs, has been constructed based on experimentally verified sigma (A) recognition sites. This work suggests that more information exists...

  12. Characterization of an L-arabinose isomerase from Bacillus subtilis

    DEFF Research Database (Denmark)

    Kim, Jin-Ha; Prabhu, Ponnandy; Jeya, Marimuthu;

    2010-01-01

    An isolated gene from Bacillus subtilis str. 168 encoding a putative isomerase was proposed as an L-arabinose isomerase (L-AI), cloned into Escherichia coli, and its nucleotide sequence was determined. DNA sequence analysis revealed an open reading frame of 1,491 bp, capable of encoding a polypep......An isolated gene from Bacillus subtilis str. 168 encoding a putative isomerase was proposed as an L-arabinose isomerase (L-AI), cloned into Escherichia coli, and its nucleotide sequence was determined. DNA sequence analysis revealed an open reading frame of 1,491 bp, capable of encoding...

  13. Aerobic granulation of pure bacterial strain Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    Sunil S ADAV; Duu-Jong LEE

    2008-01-01

    The objective of this study is to cultivate aer-obic granules by pure bacterial strain, Bacillus thuringien-sis, in a sequencing batch reactor. Stable granules sized 2.0-2.2 mm were formed in the reactor after a five-week cultivation. These granules exhibited excellent settling attributes, and degraded phenol at rates of 1.49 and concentration, respectively. Confocal laser scanning microscopic test results show that Bacillus thuringiensis was distributed over the initial small aggregates, and the outer edge of the granule was away from the core regime in the following stage.

  14. Effect of oral administration of Bacillus coagulans B37 and Bacillus pumilus B9 strains on fecal coliforms, Lactobacillus and Bacillus spp. in rat animal model

    Directory of Open Access Journals (Sweden)

    Lopamudra Haldar

    2016-07-01

    Full Text Available Aim: To investigate the effect of oral administration of two Bacillus strains on fecal coliforms, Lactobacillus and Bacillus spp. in rat animal model. Materials and Methods: An in vivo experiment was conducted for 49-day period on 36 adult male albino Wister rats divided equally into to four groups. After 7-day adaptation period, one group (T1 was fed on sterile skim milk along with basal diet for the next 28 days. Second (T2 and (T3 groups received spore biomass of Bacillus coagulans B37 and Bacillus pumilus B9, respectively, suspended in sterilized skim milk at 8-9 log colony-forming units/ml plus basal diet for 28 days, while control group (T4 was supplied with clean water along with basal diet. There was a 14-day post-treatment period. A total of 288 fecal samples (8 fecal collections per rat were collected at every 7-day interval starting from 0 to 49 days and subjected to the enumeration of the counts of coliforms and lactobacilli and Bacillus spores using respective agar media. In vitro acid and bile tolerance tests on both the strains were performed. Results: The rats those (T2 and T3 received either B. coagulans B37 or B. pumilus B9 spore along with non-fermented skim milk showed decrease (p<0.01 in fecal coliform counts and increase (p<0.05 in both fecal lactobacilli and Bacillus spore counts as compared to the control group (T4 and the group fed only skim milk (T1. In vitro study indicated that both the strains were found to survive at pH 2.0 and 3.0 even up to 3 h and tolerate bile up to 2.0% concentration even after 12 h of exposure. Conclusions: This study revealed that oral administration of either B. coagulans B37 or B. pumilus B9 strains might be useful in reducing coliform counts accompanied by concurrent increase in lactobacilli counts in the intestinal flora in rats.

  15. Ecological aspects of Bacillus thuringiensis in an Oxisol Ecologia do Bacillus thuringiensis num Latossolo

    Directory of Open Access Journals (Sweden)

    Lessandra Heck Paes Leme Ferreira

    2003-02-01

    Full Text Available Bacillus thuringiensis is a Gram positive, sporangial bacterium, known for its insecticidal habilities. Survival and conjugation ability of B. thuringiensis strains were investigated; vegetative cells were evaluated in non-sterile soil. Vegetative cells decreased rapidly in number, and after 48 hours the population was predominantly spores. No plasmid transfer was observed in non-sterile soil, probably because the cells died and the remaining cells sporulated quickly. Soil is not a favorable environment for B. thuringiensis multiplication and conjugation. The fate of purified B. thuringiensis toxin was analyzed by extractable toxin quantification using ELISA. The extractable toxin probably declined due to binding on surface-active particles in the soil.O comportamento de células vegetativas do Bacillus thuringiensis foi estudado em solo não esterilizado. Após o inóculo grande parte das células morrem e o restante esporula em 24 horas. Não foi observada conjugação provavelmente porque poucas células sobrevivem no solo e rapidamente esporulam, mostrando que este não é o ambiente propício para a multiplicação e conjugação desta bactéria. A toxina purificada, portanto livre de células, diminui rapidamente sua quantidade em solo não esterilizado. Provavelmente a ligação da toxina na fração argilosa do solo é a principal responsável por este fenômeno.

  16. Novel giant siphovirus from Bacillus anthracis features unusual genome characteristics.

    Directory of Open Access Journals (Sweden)

    Holly H Ganz

    Full Text Available Here we present vB_BanS-Tsamsa, a novel temperate phage isolated from Bacillus anthracis, the agent responsible for anthrax infections in wildlife, livestock and humans. Tsamsa phage is a giant siphovirus (order Caudovirales, featuring a long, flexible and non-contractile tail of 440 nm (not including baseplate structure and an isometric head of 82 nm in diameter. We induced Tsamsa phage in samples from two different carcass sites in Etosha National Park, Namibia. The Tsamsa phage genome is the largest sequenced Bacillus siphovirus, containing 168,876 bp and 272 ORFs. The genome features an integrase/recombinase enzyme, indicative of a temperate lifestyle. Among bacterial strains tested, the phage infected only certain members of the Bacillus cereus sensu lato group (B. anthracis, B. cereus and B. thuringiensis and exhibited moderate specificity for B. anthracis. Tsamsa lysed seven out of 25 B. cereus strains, two out of five B. thuringiensis strains and six out of seven B. anthracis strains tested. It did not lyse B. anthracis PAK-1, an atypical strain that is also resistant to both gamma phage and cherry phage. The Tsamsa endolysin features a broader lytic spectrum than the phage host range, indicating possible use of the enzyme in Bacillus biocontrol.

  17. Live-imaging of Bacillus subtilis spore germination and outgrowth

    NARCIS (Netherlands)

    R. Pandey

    2014-01-01

    Spores of Gram-positive bacteria such as Bacillus and Clostridium cause huge economic losses to the food industry. In food products, spores survive under food preservation conditions and subsequent germination and outgrowth eventually causes food spoilage. Therefore efforts are being made to elimina

  18. Global network reorganization during dynamic adaptations of Bacillus subtilis metabolism

    DEFF Research Database (Denmark)

    Buescher, Joerg Martin; Liebermeister, Wolfram; Jules, Matthieu;

    2012-01-01

    Adaptation of cells to environmental changes requires dynamic interactions between metabolic and regulatory networks, but studies typically address only one or a few layers of regulation. For nutritional shifts between two preferred carbon sources of Bacillus subtilis, we combined statistical and...

  19. The fate of Bacillus cereus in the gastrointestinal tract

    NARCIS (Netherlands)

    Pielaat A; Wijnands LM; Takumi K; Nauta MJ; Leusden FM van; MGB

    2006-01-01

    This report presents a mathematical dynamical model for the behaviour of Bacillus cereus in the gastro-intestinal tract. Biological processes and system dynamics are simultaneously incorporated in this mechanistic model. Variability in growth characteristics and physical traits of different B. cereu

  20. Transformation of undomesticated strains of Bacillus subtilis by protoplast electroporation

    NARCIS (Netherlands)

    Romero, Diego; Perez-Garcia, Alejandro; Veening, Jan-Willem; de Vicente, Antonio; Kuipers, Oscar P.; de, Vicente A.

    2006-01-01

    A rapid method combining the use of protoplasts and electroporation was developed to transform recalcitrant wild strains of Bacillus subtilis. The method described here allows transformation with both replicative and integrative plasmids, as well as with chromosomal DNA, and provides a valuable tool

  1. Antimicrobial activity of carvacrol toward Bacillus cereus on rice

    NARCIS (Netherlands)

    Ultee, A.; Slump, R.A.; Steging, G.; Smid, E.J.

    2000-01-01

    The antimicrobial activity of carvacrol, a compound present in the essential oil fraction of oreganum and thyme, toward the foodborne pathogen Bacillus cereus on rice was studied. Carvacrol showed a dose-related inhibition of growth of the pathogen. Concentrations of 0.15 mg/g and higher inhibited t

  2. Bacillus cereus: emetic toxin production and gamma hypothesis for growth

    NARCIS (Netherlands)

    Biesta-Peters, E.G.

    2011-01-01

    Bacillus cereus is a food spoilage microorganism and a pathogen. Growth of B. cereus can be prevented or delayed by adding growth limiting compounds to the food product or by altered storage conditions. Combinations of growth limiting factors

  3. Binding Affinity of Glycoconjugates to BACILLUS Spores and Toxins

    Science.gov (United States)

    Rasol, Aveen; Eassa, Souzan; Tarasenko, Olga

    2010-04-01

    Early recognition of Bacillus cereus group species is important since they can cause food-borne illnesses and deadly diseases in humans. Glycoconjugates (GCs) are carbohydrates covalently linked to non-sugar moieties including lipids, proteins or other entities. GCs are involved in recognition and signaling processes intrinsic to biochemical functions in cells. They also stimulate cell-cell adhesion and subsequent recognition and activation of receptors. We have demonstrated that GCs are involved in Bacillus cereus spore recognition. In the present study, we have investigated whether GCs possess the ability to bind and recognize B. cereus spores and Bacillus anthracis recombinant single toxins (sTX) and complex toxins (cTX). The affinity of GCs to spores + sTX and spores + cTX toxins was studied in the binding essay. Our results demonstrated that GC9 and GC10 were able to selectively bind to B. cereus spores and B. anthracis toxins. Different binding affinities for GCs were found toward Bacillus cereus spores + sTX and spores + cTX. Dilution of GCs does not impede the recognition and binding. Developed method provides a tool for simultaneous recognition and targeting of spores, bacteria toxins, and/or other entities.

  4. Molecular physiology of weak organic acid stress in Bacillus subtilis

    OpenAIRE

    Brul, S.; Beilen, van, J.W.A.

    2013-01-01

    The mechanism by which weak organic acid (WOA) preservatives inhibit growth of microorganisms may differ between different WOAs and these differences are not well understood. The aim of this thesis has been to obtain a better understanding of the mode of action of these preservatives by which they inhibit the growth of spore-forming bacteria (more specifically Bacillus subtilis).

  5. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage BMBtp2

    OpenAIRE

    Dong, Zhaoxia; Peng, Donghai; Wang, Yueying; Zhu, Lei; Ruan, Lifang; Sun, Ming

    2013-01-01

    Bacillus thuringiensis is an insect pathogen which has been widely used for biocontrol. During B. thuringiensis fermentation, lysogenic bacteriophages cause severe losses of yield. Here, we announce the complete genome sequence of a bacteriophage, BMBtp2, which is induced from B. thuringiensis strain YBT-1765, which may be helpful to clarify the mechanism involved in bacteriophage contamination.

  6. Characterization of the parasporal inclusion of Bacillus thuringiensis subsp. kyushuensis.

    OpenAIRE

    Held, G. A.; Kawanishi, C. Y.; Huang, Y. S.

    1990-01-01

    Electron microscopy of Bacillus thuringiensis subsp. kyushuensis revealed that the parasporal inclusions are composed of a homogeneous center surrounded by a thick, electron-dense coating. Antibodies directed against the 135- and 65-kilodalton B. thuringiensis subsp. israelensis peptides cross-reacted with the 70- and 26-kilodalton peptides, respectively, of B. thuringiensis subsp. kyushuensis.

  7. Structural relatedness between mosquitocidal endotoxins of Bacillus thuringiensis subsp. israelensis.

    OpenAIRE

    Garduno, F; Thorne, L.; Walfield, A M; Pollock, T J

    1988-01-01

    A mosquitocidal toxin gene, cloned from Bacillus thuringiensis subsp. israelensis, was introduced into mutant crystal-negative B. thuringiensis subsp. israelensis cells. Partial toxicity to mosquitos was restored. The 58-kilodalton cloned gene product is a minor protein component of B. thuringiensis subsp. israelensis crystals and is structurally related to a major, 135-kilodalton crystal toxin.

  8. Bacillus subtilis Vegetative Catalase Is an Extracellular Enzyme

    OpenAIRE

    Naclerio, G; Baccigalupi, L; Caruso, C; De Felice, M; Ricca, E

    1995-01-01

    Strong catalase activity was secreted by Bacillus subtilis cells during stationary growth phase in rich medium but not in sporulation-inducing medium. N-terminal sequencing indicated that the secreted activity was due to the vegetative catalase KatA, previously considered an endocellular enzyme. Extracellular catalase protected B. subtilis cells from oxidative assault.

  9. Manipulating the autolytic pathway of a Bacillus protease

    NARCIS (Netherlands)

    VandenBurg, B; Eijsink, VGH; Vriend, G; Veltman, OR; Venema, G; HopsuHavu, VK; Jarvinen, M; Kirschke, H

    1997-01-01

    Autolytic degradation of Bacillus subtilis thermolysin-like proteinase (TLP-sub) is responsible for the irreversible inactivation of the enzyme at elevated temperatures. Previously, we reported five autolysis sites in B. subtilis neutral protease (Van den Burg et al., 1990, Biochem. J. 272:93-97). I

  10. Draft Genome Sequence of Biocontrol Agent Bacillus cereus UW85.

    Science.gov (United States)

    Lozano, Gabriel L; Holt, Jonathan; Ravel, Jacques; Rasko, David A; Thomas, Michael G; Handelsman, Jo

    2016-01-01

    Bacillus cereus UW85 was isolated from a root of a field-grown alfalfa plant from Arlington, WI, and identified for its ability to suppress damping off, a disease caused by Phytophthora megasperma f. sp. medicaginis on alfalfa. Here, we report the draft genome sequence of B. cereus UW85, obtained by a combination of Sanger and Illumina sequencing. PMID:27587823

  11. The transcriptionally active regions in the genome of Bacillus subtilis

    DEFF Research Database (Denmark)

    Rasmussen, Simon; Nielsen, Henrik Bjørn; Jarmer, Hanne Østergaard

    2009-01-01

    The majority of all genes have so far been identified and annotated systematically through in silico gene finding. Here we report the finding of 3662 strand-specific transcriptionally active regions (TARs) in the genome of Bacillus subtilis by the use of tiling arrays. We have measured the genome...

  12. A New Saponin Transformed from Ginsenoside Rhl by Bacillus subtilis

    Institute of Scientific and Technical Information of China (English)

    Guo Hong LI; Yue Mao SHEN; Ke Qin ZHANG

    2005-01-01

    A novel saponin was isolated from the transformed products of ginsenoside Rh1 by Bacillus subtilis. It's structure was determined to be 3-O-β-D-glucopyranosyl-6-O-β-D-glucopyranosyl-20 (S)-protopanaxatriol on the basis of the spectral data.

  13. Draft Genome Sequence of Bacillus subtilis strain KATMIRA1933

    OpenAIRE

    Karlyshev, Andrey V.; Melnikov, Vyacheslav G.; Chikindas, Michael L.

    2014-01-01

    In this report, we present a draft sequence of Bacillus subtilis KATMIRA1933. Previous studies demonstrated probiotic properties of this strain partially attributed to production of an antibacterial compound, subtilosin. Comparative analysis of this strain’s genome with that of a commercial probiotic strain, B. subtilis Natto, is presented.

  14. Genome Sequence of Bacillus cereus Group Phage SalinJah.

    Science.gov (United States)

    Erill, Ivan; Caruso, Steven M

    2016-01-01

    The double-stranded DNA (dsDNA) Myoviridae Bacillus cereus group bacteriophage SalinJah was isolated from soil collected in Gyeonggi-do, South Korea. SalinJah, a cluster C phage with a broad host range, suggests the need to create a new subcluster with SalinJah and Helga as founding members. PMID:27688335

  15. The impact of manganese on biofilm development of Bacillus subtilis

    NARCIS (Netherlands)

    Mhatre, Eisha; Troszok, Agnieszka; Gallegos-Monterrosa, Ramses; Lindstädt, Stefanie; Hölscher, Theresa; Kuipers, Oscar P.; Kovács, Ákos T.

    2016-01-01

    Bacterial biofilms are dynamic and structurally complex communities, involving cell-to-cell interactions. In recent years, various environmental signals were identified that induce the complex biofilm development of the Gram-positive bacterium Bacillus subtilis. These signaling molecules are often m

  16. Thermostable, Raw-Starch-Digesting Amylase from Bacillus stearothermophilus

    OpenAIRE

    Kim, Jaeyoung; Nanmori, Takashi; Shinke, Ryu

    1989-01-01

    An endospore-forming thermophilic bacterium, which produced amylase and was identified as Bacillus stearothermophilus, was isolated from soil. The amylase had an optimum temperature of 70°C and strongly degraded wheat starch granules (93%) and potato starch granules (80%) at 60°C.

  17. Fungicidal effect of bacteriocins harvested from Bacillus spp.

    Directory of Open Access Journals (Sweden)

    Adetunji, V. O.

    2013-01-01

    Full Text Available Aims: This study investigated the ability of bacteriocins isolated from Bacillus spp. (Bacillus species to inhibit fourdifferent yeast isolates obtained from common food products (nono, yoghurt, ogi and cheese commonly consumed byNigerians with minimal heat treatment.Methodology and results: Forty-five Bacillus spp. was isolated and identified from common food products usingcultural, morphological, physiological and biochemical characteristics. These isolates were tested for antimicrobialactivity against Salmonella enteritidis (3, Micrococcus luteus (1 and Staphylococcus aureus (2. Eight bacteriocinproducing strains were identified from an over- night broth culture centrifugated at 3500 revolutions for five minutes.Fungicidal effects of these bacteriocins were tested against four yeast strains using the Agar Well Diffusion method. Thebacteriocins produced wide zones of inhibition ranging from 5.9±0.000 to 24.00±0.000 mm against the 4 yeast strainstested. There was a significant difference (at p<0.05 between the yeast organisms and the bacteriocins from theBacillus spp.Conclusion, significance and impact of study: The study reveals the antifungal property of bacteriocins from Bacillusspp. and serves therefore as a base for further studies in its use in the control of diseases and extension of shelf-life ofproducts prone to fungi contamination.

  18. Complete Genome Sequences of Nine Bacillus cereus Group Phages

    Science.gov (United States)

    Foltz, Samantha

    2016-01-01

    We report the sequences of nine novel Bacillus cereus group bacteriophages: DIGNKC, Juglone, Nemo, Nigalana, NotTheCreek, Phrodo, SageFayge, Vinny, and Zuko. These bacteriophages are double-stranded DNA-containing Myoviridae isolated from soil samples using B. thuringiensis subsp. kurstaki as the host bacterium. PMID:27417827

  19. Fatal Sepsis by Bacillus Circulans in an Immunocompromised Patient

    Directory of Open Access Journals (Sweden)

    S Jahani Sherafat

    2011-12-01

    Full Text Available An immunosuppressed man was admitted to hospital with diarrhea and a history of urinary tract infection. He was subjected to treatment with antibiotics. The patient died of putative severe sepsis. The etiological agent was a carbapenemase producing isolate of Bacillus circulans with resistance to all prescribed antimicrobial agents.

  20. Linking Bacillus cereus genotypes and carbohydrate utilization capacity

    NARCIS (Netherlands)

    Warda, Alicja K.; Siezen, Roland J.; Boekhorst, Jos; Wells-Bennik, Marjon H.J.; Jong, de Anne; Kuipers, Oscar P.; Nierop Groot, Masja N.; Abee, Tjakko

    2016-01-01

    We characterised carbohydrate utilisation of 20 newly sequenced Bacillus cereus strains isolated from food products and food processing environments and two laboratory strains, B. cereus ATCC 10987 and B. cereus ATCC 14579. Subsequently, genome sequences of these strains were analysed together wi

  1. Linking Bacillus cereus Genotypes and Carbohydrate Utilization Capacity

    NARCIS (Netherlands)

    Warda, Alicja K.; Siezen, Roland J.; Boekhorst, Jos; Wells-Bennik, Marjon H.J.; Jong, de Anne; Kuipers, Oscar P.; Nierop Groot, Masja N.; Abee, Tjakko

    2016-01-01

    We characterised carbohydrate utilisation of 20 newly sequenced Bacillus cereus strains isolated from food products and food processing environments and two laboratory strains, B. cereus ATCC 10987 and B. cereus ATCC 14579. Subsequently, genome sequences of these strains were analysed together with

  2. Induction of natural competence in Bacillus cereus ATCC14579

    NARCIS (Netherlands)

    Mironczuk, Aleksandra M.; Kovács, Ákos T.; Kuipers, O.P.

    2008-01-01

    Natural competence is the ability of certain microbes to take up exogenous DNA from the environment and integrate it in their genome. Competence development has been described for a variety of bacteria, but has so far not been shown to occur in Bacillus cereus. However, orthologues of most proteins

  3. Factors affecting the solubility of Bacillus halmapalus alpha-amylase

    DEFF Research Database (Denmark)

    Faber, Cornelius; Hobley, Timothy John; Mollerup, Jørgen;

    2008-01-01

    A detailed study of the solubility of recombinant Bacillus halmapalus alpha-amylase has been conducted. A semi-purified preparation from a bulk crystallisation was chos en that contained six isoforms with pI-values of between 5.5 and 6.1. The solubility was strongly affected by pH and could...

  4. Progress in food-related research focussing on Bacillus cereus

    NARCIS (Netherlands)

    Vries, de Y.P.; Voort, van der M.; Schaik, van W.; Hornstra, L.M.; Vos, de W.M.; Abee, T.

    2004-01-01

    Bacillus cereus is a gram-positive, rod-shaped, endospore-forming bacterium that occurs ubiquitously and is frequently isolated from soil and food products. When B. cereus is present in foods, it can cause spoilage and poisoning. The work of our group is focussed on several properties of B. cereus t

  5. Isolation and identification of local Bacillus isolates for xylanase biosynthesis.

    Directory of Open Access Journals (Sweden)

    Hassan Ammoneh

    2014-04-01

    Full Text Available Bacillus species are attractive industrial organisms due to their rapid growth rates leading to a short fermentation cycle and for their capacity to secrete important enzymes and proteins such as xylanase into the extracellular medium. Considering the industrial importance of xylanase, in this current study, Bacillus spp. were isolated from different soils and were screened for their xylanase production.Bacillus isolates used in this study were obtained from a national screening program carried out during 2006-2007 in which soil samples that covered areas throughout the interior of Syria were collected. The prepared inoculum from each of Bacillus isolates was aliquoted onto xylan agar plates, incubated at 30°C for 72 h and screened for xylanase synthesis.Xylanolytic isolates were selected depending on the clear zones of xylan hydrolysis. Fifteen isolates having the highest clearing zone were determined and grown in a solid state fermentation. Of the 15 isolates, three bacilli namely SY30A, SY185C and SY190E that showed maximum xylanase production, were identified using the 16S rDNA sequencing method. According to 16S rDNA gene sequence data, the closest phylogenetic neighbor for SY30A was Bacillus pumilus and for SY185C and SY190E isolates was Bacillus subtilis. Optimal pH and temperature for xylanase activity was 7.0 and 55ºC for SY30A and 6.0 and 60ºC for SY185C and SY190E, respectively. Under these conditions, the following activities were found to be around 1157 ± 58, 916 ± 46 and 794 ± 39 (U/g for SY30A, SY185C and SY190E, respectivly.Selected local Bacillus isolates were found to be a potential source of xylanase which was proven to be quite suitable for multiple biotechnological applications. These isolates might after extensive optimization steps be an alternative to commercially available strains.

  6. Glycosylation of BclA Glycoprotein from Bacillus cereus and Bacillus anthracis Exosporium Is Domain-specific.

    Science.gov (United States)

    Maes, Emmanuel; Krzewinski, Frederic; Garenaux, Estelle; Lequette, Yannick; Coddeville, Bernadette; Trivelli, Xavier; Ronse, Annette; Faille, Christine; Guerardel, Yann

    2016-04-29

    The spores of the Bacillus cereus group (B. cereus, Bacillus anthracis, and Bacillus thuringiensis) are surrounded by a paracrystalline flexible yet resistant layer called exosporium that plays a major role in spore adhesion and virulence. The major constituent of its hairlike surface, the trimerized glycoprotein BclA, is attached to the basal layer through an N-terminal domain. It is then followed by a repetitive collagen-like neck bearing a globular head (C-terminal domain) that promotes glycoprotein trimerization. The collagen-like region of B. anthracis is known to be densely substituted by unusual O-glycans that may be used for developing species-specific diagnostics of B. anthracis spores and thus targeted therapeutic interventions. In the present study, we have explored the species and domain specificity of BclA glycosylation within the B. cereus group. First, we have established that the collagen-like regions of both B. anthracis and B. cereus are similarly substituted by short O-glycans that bear the species-specific deoxyhexose residues anthrose and the newly observed cereose, respectively. Second we have discovered that the C-terminal globular domains of BclA from both species are substituted by polysaccharide-like O-linked glycans whose structures are also species-specific. The presence of large carbohydrate polymers covering the surface of Bacillus spores may have a profound impact on the way that spores regulate their interactions with biotic and abiotic surfaces and represents potential new diagnostic targets. PMID:26921321

  7. Phylogeny and Molecular Taxonomy of the Bacillus subtilis species Complex and the Description of Bacillus subtilis subsp. inaquosorum subsp. nov

    Science.gov (United States)

    The Bacillus subtilis species complex is a tight assemblage of closely related species. For many years, it has been recognized that these species cannot be differentiated on the basis of phenotypic characteristics. Recently, it has been shown that phylogenetic analysis of the 16S ribosomal RNA gen...

  8. Comparative genomics analysis of the companion mechanisms of Bacillus thuringiensis Bc601 and Bacillus endophyticus Hbe603 in bacterial consortium.

    Science.gov (United States)

    Jia, Nan; Ding, Ming-Zhu; Gao, Feng; Yuan, Ying-Jin

    2016-01-01

    Bacillus thuringiensis and Bacillus endophyticus both act as the companion bacteria, which cooperate with Ketogulonigenium vulgare in vitamin C two-step fermentation. Two Bacillus species have different morphologies, swarming motility and 2-keto-L-gulonic acid productivities when they co-culture with K. vulgare. Here, we report the complete genome sequencing of B. thuringiensis Bc601 and eight plasmids of B. endophyticus Hbe603, and carry out the comparative genomics analysis. Consequently, B. thuringiensis Bc601, with greater ability of response to the external environment, has been found more two-component system, sporulation coat and peptidoglycan biosynthesis related proteins than B. endophyticus Hbe603, and B. endophyticus Hbe603, with greater ability of nutrients biosynthesis, has been found more alpha-galactosidase, propanoate, glutathione and inositol phosphate metabolism, and amino acid degradation related proteins than B. thuringiensis Bc601. Different ability of swarming motility, response to the external environment and nutrients biosynthesis may reflect different companion mechanisms of two Bacillus species. Comparative genomic analysis of B. endophyticus and B. thuringiensis enables us to further understand the cooperative mechanism with K. vulgare, and facilitate the optimization of bacterial consortium. PMID:27353048

  9. Comparative genomics analysis of the companion mechanisms of Bacillus thuringiensis Bc601 and Bacillus endophyticus Hbe603 in bacterial consortium.

    Science.gov (United States)

    Jia, Nan; Ding, Ming-Zhu; Gao, Feng; Yuan, Ying-Jin

    2016-06-29

    Bacillus thuringiensis and Bacillus endophyticus both act as the companion bacteria, which cooperate with Ketogulonigenium vulgare in vitamin C two-step fermentation. Two Bacillus species have different morphologies, swarming motility and 2-keto-L-gulonic acid productivities when they co-culture with K. vulgare. Here, we report the complete genome sequencing of B. thuringiensis Bc601 and eight plasmids of B. endophyticus Hbe603, and carry out the comparative genomics analysis. Consequently, B. thuringiensis Bc601, with greater ability of response to the external environment, has been found more two-component system, sporulation coat and peptidoglycan biosynthesis related proteins than B. endophyticus Hbe603, and B. endophyticus Hbe603, with greater ability of nutrients biosynthesis, has been found more alpha-galactosidase, propanoate, glutathione and inositol phosphate metabolism, and amino acid degradation related proteins than B. thuringiensis Bc601. Different ability of swarming motility, response to the external environment and nutrients biosynthesis may reflect different companion mechanisms of two Bacillus species. Comparative genomic analysis of B. endophyticus and B. thuringiensis enables us to further understand the cooperative mechanism with K. vulgare, and facilitate the optimization of bacterial consortium.

  10. Bacillus thuringiensis: legado para el siglo XXI Bacillus thuringiensis: the legacy to the XXI century

    Directory of Open Access Journals (Sweden)

    Orduz S.

    1998-06-01

    Full Text Available

    Los insecticidas basados en la bacteria Bacillus thuringiensis son el principal renglón productivo del mercado mundial de biopesticidas. La investigación dedicada a esta área, promovida por la urgente necesidad de resolver problemas agrícolas y de salud pública, ha dado lugar a un conocimiento exhaustivo de su biología. La diversidad de cepas diferentes de B. thuringiensis ha permitido desarrollar productos principalmente, pero no exclusivamente, para el control de insectos. Con los nuevos desarrollos de la biología molecular, se ha logrado comprender su mecanismo de acción a nivel molecular y también se ha logrado extender sus capacidades entomopatógenas. Como producto de su amplio uso en muchos países, se han presentado casos de resistencia en poblaciones de insectos susceptibles. Con esta revisión se pretende elaborar un contexto teórico del estado actual de la investigación sobre B. thuringiensis, describiendo brevemente el conocimiento sobre esta bacteria, haciendo hincapié en los fenómenos biológicos que subyacen su actividad tóxica y la problemática que se avecina en el próximo siglo con los fenómenos de resistencia cada vez más comunes, todo esto analizado desde una perspectiva biotecnológica.

    Bacillus thuringiensis-based insecticides are the main production line of the biopesticides world market. The research devoted to this area, promoted by the necessity to solve problems in agriculture and public health has resulted in an exhaustive knowledge of its biology. The diversity of the B. thuringiensis strains has permitted to develop several products mainly, but not exclusively, for insect control. With the new developments in the field of molecular biology, it has been possible to understand the molecular basis of the mode of action and to increase the range of activity as well. As a result

  11. Isolation and characterization of protease from Bacillus subtilis 1012M15

    Directory of Open Access Journals (Sweden)

    ELFI SUSANTI

    2003-01-01

    Full Text Available A local strain of Bacillus sp. BAC4, is known to produce penicillin G acylase (PGA enzyme with relatively high activity. This strain secretes the PGA into the culture medium. However, it has been reported that PGA activity fall and rise during culture, and the activity plummets during storege at –200C, which probably due to usage protease activity of Bacillus sp. BAC4. To study the possible use of Bacillus subtilis 1012M15 as a host cell for cloning the pga gene from Bacillus sp. BAC4, the protease activity of Bacillus subtilis 1012M15 were studied. Protease activity was determined by Horikoshi method. In this experiment, maximum protease activity in Bacillus subtilis 1012M15 culture was obsereved after 8 hours. At this optimum condition, protease activity of Bacillus sp. BAC4 is five time higher than that of Bacillus subtilis 1012M15. This situation promised the possible usage of Bacillus subtilis 1012M15 as a host cell for pga expression. For protease characterization, the bacterial culture had been separated from the cell debris by centrifugation. The filtrate was concentrated by freeze drying, fractionated by ammonium sulphate, dialyzed in selovan tube, and then fractionated by ion exchance chromatography employing DEAE-cellulose. The five peaks resulted indicated the presence of five protease. Based on inhibitor and activator influence analysis, it could be concluded that proteases from Bacillus subtilis 1012M15 contained of serin protease as well as metalloprotease and serin protease mixture.

  12. Characterization and functional expression in Escherichia coli of the sodium/proton/glutamate symport proteins of Bacillus stearothermophilus and Bacillus caldotenax

    NARCIS (Netherlands)

    TOLNER, B; POOLMAN, B; KONINGS, WN

    1992-01-01

    The genes encoding the Na+/H+/L-glutamate symport proteins of the thermophilic organisms Bacillus stearothermophilus (gltT(Bs)) and Bacillus caldotenax (gltT(Bc)) were cloned by complementation of Escherichia coli JC5412 for growth on glutamate as sole source of carbon, energy and nitrogen. The nucl

  13. Effect of antimicrobial peptide APNT-6 produced by Bacillus natto on fresh-keeping of Litopenaeus vannamei at low temperature%纳豆菌抗菌肽APNT-6对凡纳滨对虾的低温保鲜效果

    Institute of Scientific and Technical Information of China (English)

    王东; 孙力军; 王雅玲; 刘唤明; 徐德峰; 邓楚津; 杜焕妍; 励建荣

    2012-01-01

    A new biological preservative—antimicrobial peptide APNT-6 produced by Bacillus natto NT-6 and purified by column chromatography will be applied in the fresh-keeping of Litopenaeus vannamei. Bacillus antimicrobial peptides are a series of lipopeptides substances produced by represented Bacillus strains of B. subtilis, B. amyloliquefaciens and B. natto, which include surfactin, iturin, fengycin, subtilin and so on. Numerous studies show that Bacillus antimicrobial peptides have a startling range of antimicrobial activities that can include action against most Gram-negative and Gram-positive bacteria, fungi, enveloped viruses, and eukaryotic parasites. Recently, our research group isolated a highly antibiotic activity and largely antimicrobial spectrum strain—B. natto NT-6 from the Chinese traditional food—lobster sauce. According to the mass spectrometry (ESI /MS /CID) analysis,we know the mainly antimicrobial substances produced by this strain is Bacillus antimicrobial peptides, mainly including surfactin, fengycin, and iturin(called after APNT-6). Through oral acute toxicity in mice we found that its LDso greater than 5000 mg/kg body weight, indicating that antimicrobial peptide APNT-6 has high food safety. In this paper, the antibacterial activities of antimicrobial peptide on spoilage organisms were determined by Oxford cup assay. Then the quality changes of L vannamei during storage at (4±1) ℃ were investigated, including the pH, total volatile basic nitrogen (TVB-N), aerobic plate count (APC) and sensory assessment. The results showed that antimicrobial peptide APNT-6 can effectively inhibit 8 strains of spoilage organisms isolated from L. vannamei. During storage at (4±1) ℃, with the extension of storage time, the gradually increasing values of pH, TVB-N and APC of L.vannamei were observed during the 7 days storage. However, incubated 0.5 mg/mL antimicrobial peptide can effectively slow down the value increasing, which extends the shelf-life of L

  14. Equilibrium Lattice Relaxation and Misfit Dislocations in Step-Graded In x Ga1- x As/GaAs (001) and In x Al1- x As/GaAs (001) Metamorphic Buffer Layers

    Science.gov (United States)

    Kujofsa, Tedi; Ayers, John E.

    2016-06-01

    The inclusion of metamorphic buffer layers (MBLs) in the design of lattice-mismatched semiconductor heterostructures is important in enhancing reliability and performance of optoelectronic and electronic devices through proper control of threading dislocations; threading dislocation can be reduced by allowing the distribution of the misfit dislocations throughout the MBL, rather than concentrating them at the interface where substrate defects and tangling can pin dislocations or otherwise reduce their mobility. Compositionally graded layers have been particularly used for this purpose and in this work we considered heterostructures involving a step-graded In x Ga1- x As or In x Al1- x As epitaxial layer on a GaAs (001) substrate. For each structure type, we present minimum energy calculations including (i) the surface and (ii) average in-plane strain and (iii) the misfit dislocation density profile with various grading coefficients (thickness and indium composition variation). In both types of structures, the average in-plane strain and misfit dislocation density profile scale with the average grading coefficient, but In x Al1- x As structures with a greater average elastic stiffness constants exhibit slightly higher average compressive in-plane strain (absolute valued) which is associated with higher misfit dislocation densities. However, the rate of change in the normalized relaxation percentage per unit thickness of each step with respect to the lattice mismatch of the step is lower in the In x Al1- x As material system. The difference of the in-plane strain is small (elastic constants).

  15. Hydrostatic Pressure and Built-In Electric Field Effects on the Donor Impurity States in Cylindrical Wurtzite GaN/AlxGa1−xN Quantum Rings

    Directory of Open Access Journals (Sweden)

    Guangxin Wang

    2015-01-01

    Full Text Available Within the framework of the effective mass approximation, the ground-state binding energy of a hydrogenic impurity is investigated in cylindrical wurtzite GaN/AlxGa1-xN strained quantum ring (QR by means of a variational approach, considering the influence of the applied hydrostatic pressure along the QR growth direction and the strong built-in electric field (BEF due to the piezoelectricity and spontaneous polarization. Numerical results show that the donor binding energy for a central impurity increases inchmeal firstly as the QR radial thickness (ΔR decreases gradually and then begins to drop quickly. In addition, the donor binding energy is an increasing (a decreasing function of the inner radius (height. It is also found that the donor binding energy increases almost linearly with the increment of the applied hydrostatic pressure. Moreover, we also found that impurity positions have an important influence on the donor binding energy. The physical reasons have been analyzed in detail.

  16. Nonlinear optical rectification and optical absorption in GaAs-Ga1-xAlxAs asymmetric double quantum wells: Combined effects of applied electric and magnetic fields and hydrostatic pressure

    International Nuclear Information System (INIS)

    The intersubband electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga1-xAlxAs asymmetric double quantum wells are studied, under the influence of combined or independent applied electric and magnetic fields as well as hydrostatic pressure. The outcome of the density matrix formalism and the effective mass, and parabolic-band approximations have been considered as main theoretical tools for the description. It is obtained that under particular geometrical conditions, with or without electric and/or magnetic field strength, the optical rectification is null and, simultaneously, in such circumstances the optical absorption has a relative maximum. It is also detected that the influence of the hydrostatic pressure leads to increasing or decreasing behaviors of the nonlinear optical absorption in dependence of the particular regime of pressure values considered, with significant distinction of the cases of opposite electric field orientations. - Highlights: → Maxima of the NOA correspond to zero in the NOR. → Electric fields can couple the double quantum wells. → Hydrostatic pressure can couple the double quantum wells. → NOA can increase/decrease with hydrostatic pressure. → Overlap between wave functions depends on the magnetic field.

  17. Absence of lactobacilli containing glycolipids with the α-galactose epitope and the enhanced fucosylation of a receptor glycolipid GA1 in the digestive tracts of immune-deficient scid mice.

    Science.gov (United States)

    Iwamori, Masao; Tanaka, Kyoko; Adachi, Shigeki; Aoki, Daisuke; Nomura, Taisei

    2015-07-01

    The Lactobacillus species in the digestive tracts of immune-deficient scid mice was distinct from that in control mice, i.e. Lactobacillus murinus in scid and L. johnsonii in control mice, according to their 16S-rRNA, indicating that a symbiotic relationship between lactobacilli and a host is established under pressure from the immune system. The caecal and colonal contents rich in L. murinus of scid mice were loose with a strong sour smell, resulting in diarrhoea, and those with L. johnsonii in control mice included abundant solid materials. Lactobacillus glycolipids were revealed to be recognized by the immune system, and by TLC-immunostaining, LacTetH-DG (Galα1-6Galα1-6Galα1-2Glcα1-3'DG) of L. johnsonii was detected in the stomach, caecum and colon of control mice, but not in those of scid ones, in which fucosylation of a receptor GA1 for L. johnsonii was enhanced more than 4-fold compared with in the control mice. Thus, structural modification of receptor glycolipids was revealed to occur in the process of establishment of a symbiotic relationship between lactobacilli and a host. LacTetH-DG was also immunogenic to human, because of the presence of natural antibodies against it, and the antibody binding to it was comparable to that of blood group- and species-related glycosphingolipids.

  18. Young’s modulus and creep compliance of GaAs and Ga1-xMnxAs ferromagnetic thin films under thermal stress at varied manganese doping levels

    Directory of Open Access Journals (Sweden)

    Kemei S.K.

    2015-06-01

    Full Text Available Dynamical mechanical analysis yields information about the mechanical properties of a material as a function of deforming factors, such as temperature, oscillating stress and strain amplitudes. GaAs and Mn-doped GaAs at varied levels, used in making electronic devices, suffer from damage due to changes in environmental temperatures. This is a defective factor experienced during winter and summer seasons. Hence, there was a need to establish the best amount of manganese to be doped in GaAs so as to obtain a mechanically stable spin injector material to make electronic devices. Mechanical properties of Ga1-xMnxAs spin injector were studied in relation to temperatures above room temperature (25 °C. Here, creep compliance, Young’s moduli and creep recovery for all studied samples with different manganese doping levels (MDLs were determined using DMA 2980 Instrument from TA instruments Inc. The study was conducted using displace-recover programme on DMA creep mode with a single cantilever clamp. The samples were prepared using RF sputtering techniques. From the creep compliance study it was found that MDL of 10 % was appropriate at 30 °C and 40 °C. The data obtained can be useful to the spintronic and electronic device engineers in designing the appropriate devices to use at 30 °C and above or equal to 40 °C.

  19. Structural study of ZnSe films grown on substrate with InxGa1-xAs and Al1-xGaxAs buffer layers: strain, relaxation and lattice parameter

    International Nuclear Information System (INIS)

    ZnSe layers of various thickness were grown on (001) GaAs substrates, using InxGa1-xAs or Al1-xGaxAs as buffer layers by molecular beam epitaxy and were studied by high-resolution x-ray diffraction. The principal structural characteristics of ZnSe layer and buffer layer were determined using several reflections, such as (004) and two pairs of coupled asymmetric reflections, namely (224), (-2-24) and (115) (-1-15). In order to evaluate their validity, the experimental data obtained from these reflections were handled by means of two known expressions found in the literature. We have found the relaxation process of ZnSe layers is well described by a geometrical model including the thermal strain and small strain due to work hardening. The relaxation process is faster for ZnSe grown on ternary buffer layers despite the fact that, some buffer layers are pseudomorphically grown to the substrate; therefore we conclude that not only the lattice mismatches have effect on the relaxation process but also the surface state of the buffer layer has an influence in this process. (author)

  20. Genetic analysis of Bacillus stearothermophilus by protoplast fusion

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.; Wojcik, S.F.; Welker, N.E.

    1986-03-01

    Efficient and reliable protoplasting, regeneration, and fusion techniques were established for the prototrophic strain Bacillus stearothermophilus NUB36. Auxotrophic mutants were isolated, and protoplast fusion was used to construct isogenic mutant strains and for chromosomal mapping. Markers were mapped using two-, three-, and four-factor crosses. The order of the markers was hom-1-thr-1-his-1-(gly-1 or gly-2)-pur-1-pur-2. These markers may be analogous to hom, thrA, hisA, glyC, and purA markers on the Bacillus subtilis chromosome. No analogous pur-1 marker has been reported in B. subtilis. The relative order of three of the markers (hom-1-thr-1-gly-1) was independently confirmed by transduction.