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Sample records for bacillus amyloliquefaciens ga1

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

    Directory of Open Access Journals (Sweden)

    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

  2. Bacillus velezensis is not a later heterotypic synonym of Bacillus amyloliquefaciens; Bacillus methylotrophicus, Bacillus amyloliquefaciens subsp plantarum and ‘Bacillus oryzicola’ are later heterotypic synonyms of Bacillus

    Science.gov (United States)

    The rhizosphere isolated bacteria belonging to the Bacillus amyloliquefaciens subsp. plantarum and Bacillus methylotrophicus clades are an important group of strains that are used as plant growth promoters and antagonists of plant pathogens. These properties have made these strains the focus of comm...

  3. 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.

  4. Degradation of ochratoxin A by Bacillus amyloliquefaciens ASAG1.

    Science.gov (United States)

    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

  5. 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.

  6. High-Quality Draft Genome Sequence of Bacillus amyloliquefaciens Strain 629, an Endophyte from Theobroma cacao.

    Science.gov (United States)

    SantAnna, Brena M M; Marbach, Phellippe P A; Rojas-Herrera, Marcelo; De Souza, Jorge T; Roque, Milton R A; Queiroz, Artur T L

    2015-01-01

    Bacillus amyloliquefaciens strain 629 is an endophyte isolated from Theobroma cacao L. Here, we report the draft genome sequence (3.9 Mb) of B. amyloliquefaciens strain 629 containing 16 contigs (3,903,367 bp), 3,912 coding sequences, and an average 46.5% G+C content. PMID:26586881

  7. 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.

  8. 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.

  9. GENOTOXICIDADE DO EXTRATO BRUTO ANTIBACTERIANO DE BACILLUS AMYLOLIQUEFACIENS R 10 FRENTE A CÉLULAS VERO

    OpenAIRE

    Schulz, D; T. CAON; C. S. MUSSI; C. R. V. BATISTA

    2008-01-01

    O presente estudo teve como objetivo obter um extrato bruto antibacteriano de Bacillus amyloliquefaciens R 10, e investigar sua genotoxicidade frente a células VERO. O extrato bruto antibacteriano de Bacillus amyloliquefaciens R 10 foi obtido por técnicas de precipitação de proteínas, centrifugação, diálise e esterilização por filtração. A padronização do teste de ge...

  10. Draft Genome Sequence of the Ionic Liquid-Tolerant Bacterium Bacillus amyloliquefaciens CMW1

    OpenAIRE

    Kurata, Atsushi; Hirose, Yuu; Misawa, Naomi; Hurunaka, Kohei; Kishimoto, Noriaki

    2014-01-01

    Here, we report the draft genome sequence of an ionic liquid-tolerant bacterium, Bacillus amyloliquefaciens CMW1, which is newly isolated from a Japanese fermented soybean paste. The genome sequence will allow for a characterization of the molecular mechanism of its ionic liquid tolerance.

  11. 77 FR 745 - Bacillus Amyloliquefaciens Strain D747; Exemption From the Requirement of a Tolerance

    Science.gov (United States)

    2012-01-06

    ... lethal dose, (LD 50 ) > 5,050 mg/kg. EPA Toxicity Category IV.] 6. Acute dermal irritation (OCSPP...-5805. II. Background and Statutory Findings In the Federal Register of February 4, 2011 (76 FR 6465.../pathogenicity studies show that Bacillus amyloliquefaciens strain D747 is not toxic, infective, or pathogenic...

  12. GENOTOXICIDADE DO EXTRATO BRUTO ANTIBACTERIANO DE BACILLUS AMYLOLIQUEFACIENS R 10 FRENTE A CÉLULAS VERO

    Directory of Open Access Journals (Sweden)

    D. SCHULZ

    2008-12-01

    Full Text Available

    O presente estudo teve como objetivo obter um extrato bruto antibacteriano de Bacillus amyloliquefaciens R 10, e investigar sua genotoxicidade frente a células VERO. O extrato bruto antibacteriano de Bacillus amyloliquefaciens R 10 foi obtido por técnicas de precipitação de proteínas, centrifugação, diálise e esterilização por filtração. A padronização do teste de genotoxicidade foi realizada pela determinação da concentração de proteínas do extrato bruto antibacteriano de Bacillus amyloliquefaciens R 10. A investigação da genotoxicidade com células VERO ATCCCCL 81 foi realizada pelo Ensaio do Cometa, utilizando-se 60, 80 e 100µg de proteína do extrato bruto. Como controle positivo utilizou-se lâminas preparadas com células VERO tratadas com uma solução de peróxido de hidrogênio (H2O2. O extrato bruto antibacteriano de Bacillus amyloliquefaciens R 10 não foi genotóxico para células VERO na concentração de 60µg/mL, porém apresentou genotoxicidade nas concentrações de 80 e 100 µg/mL. O indicativo de genotoxicidade do extrato bruto antibacteriano de Bacillus amyloliquefaciens R 10 apresentado no Ensaio do Cometa, indica a necessidade da realização de análises toxicológicas in vivo

  13. Biocontrol Activity of Bacillus amyloliquefaciens CNU114001 against Fungal Plant Diseases

    OpenAIRE

    Ji, Seung Hyun; Paul, Narayan Chandra; Deng, Jian Xin; Kim, Young Sook; Yun, Bong-Sik; Yu, Seung Hun

    2013-01-01

    A total of 62 bacterial isolates were obtained from Gomsohang mud flat, Mohang mud flat, and Jeju Island, Republic of Korea. Among them, the isolate CNU114001 showed significant antagonistic activity against pathogenic fungi by dual culture method. The isolate CNU114001 was identified as Bacillus amyloliquefaciens by morphological observation and molecular data analysis, including 16SrDNA and gyraseA (gyrA) gene sequences. Antifungal substances of the isolate were extracted and purified by si...

  14. 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...

  15. In-vitro antibacterial, antifungal, antioxidant and functional properties of Bacillus amyloliquefaciens

    OpenAIRE

    Kadaikunnan, Shine; Rejiniemon, Thankappan Sarasam; Khaled, Jamal M.; Alharbi, Naiyf S; Mothana, Ramzi

    2015-01-01

    Background Food born pathogenic bacteria and filamentous fungi are able to grow on most foods, including natural foods, processed foods, and fermented foods and create considerable economic loss. The aim of this study was to determine the antibacterial, antifungal, antioxidant and functional properties of Bacillus amyloliquefaciens recovered from silage. Methods Minimum Inhibitory Concentration (MIC) of the compounds was assessed by using broth micro dilution method. The 1,1-diphenyl–2-picryl...

  16. Improving The Quality of Tofu Waste as A Source of Feed Through Fermentation Using the Bacillus amyloliquefaciens Culture

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    Anggraeni Anggraeni

    2013-01-01

    Full Text Available High levels of crude fiber contained in tofu waste become a limiting factor for its use as a source of feed. The purpose of this research is to improve the quality of tofu waste as a source of feed through the ensilage  process using the Bacillus amyloliquefaciens bacteria. The design used was the Factorial Complete Random Design with two treatments, i.e. the Bacillus amyloliquefaciens concentration and fermentation time. This research used three Bacillus amyloliquefaciens concentrations, i.e. 5 %, 10 %, and 15 %, and six fermentation times, i.e. 2 days, 3 days, 4 days, 5 days, 6 days, and 7 days. Based on the analysis of variance, the treatment of Bacillus amyloliquefaciens concentration and fermentation time and their interaction had an effect on the level of crude fiber and the total silage acid of tofu waste (P<0.01, but did not have an effect on its water level (P>0.05. The greater the dose of Bacillus amyloliquefaciens inoculated on the tofu waste, the smaller the average value of its crude fiber; contrary to the total lactic acid produced. The best treatment was obtained at doses of Bacillus amyloliquefaciens of 15 % fermented for 5 days with an average of crude fiber level of 17.3 % and total acid average of 0.87 %, which means they meet the requirements of SNI (Indonesian National Standard for the ideal total acid criteria, i.e. 0.5-2.0 %. A decline in the level of silage crude fiber of tofu waste reached 44 % compared to tofu waste raw material. Based on the organoleptic test, the silage resulting from the fermentation of Bacillus amyloliquefaciens with a 15 % dose had the best aroma, color and texture compared to doses of 5 % and 10 %.

  17. Purification and Identification of Two Antifungal Cyclic Peptides Produced by Bacillus amyloliquefaciens L-H15.

    Science.gov (United States)

    Han, Yuzhu; Zhang, Bao; Shen, Qian; You, Chengzhen; Yu, Yaqiong; Li, Pinglan; Shang, Qingmao

    2015-08-01

    Bacillus amyloliquefaciens L-H15 with broad spectrum antifungal activity was used as a biocontrol agent to suppress Fusarium oxysporum and other soil-borne fungal plant pathogens. Two antifungal fractions were isolated by bioactivity-guided reversed-phase high-performance liquid chromatography. The two compounds were identified by tandem Q-TOF mass spectroscopy as C15 Iturin A (1) and a novel cyclic peptide with a molecular weight of 852.4 Da (2). Both compounds showed good inhibitory activities against three plant fungal pathogens in cylinder-plate diffusion assay. To our best knowledge, this is the first report on a cyclic antifungal peptide with a molecular weight of 852.4 Da. The strong antifungal activity suggests that the B. amyloliquefaciens L-H15 and its bioactive components might provide an alternative resource for the biocontrol of plant diseases and sustainable agriculture. PMID:26123083

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

    OpenAIRE

    Schulz, D; M.R.F. Marques; I. C. MÜLLER; C. R. V. BATISTA

    2008-01-01

    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 d...

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

    Science.gov (United States)

    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

  20. 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), ...

  1. Probiotic Bacillus amyloliquefaciens SC06 Prevents Bacterial Translocation in Weaned Mice

    OpenAIRE

    Ji, Jian; Hu, Shenglan; Li, Weifen

    2013-01-01

    Probiotic is a preparation containing microorganisms that confers beneficial effect to the host. This work assessed whether oral administration of Bacillus amyloliquefaciens SC06 (Ba) could decrease bacterial translocation in weaned mice. Weaned C57BL/6 were randomly allocated into three groups: group I as the control group, group II were treated with 0.85 % NaCl. Group III was administered with probiotic Ba 1 × 109 CFU/day dissolved in 100 μl of 0.85 % NaCl for 30 days. Mice were then sacrif...

  2. 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...

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  9. 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.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  12. 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.

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

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    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.

  14. [Degradation of lignocellulose in the corn straw by Bacillus amyloliquefaciens MN-8].

    Science.gov (United States)

    Li, Hong-ya; Li, Shu-na; Wang, Shu-xiang; Wang, Quan; Xue, Yin-yin; Zhu, Bao-cheng

    2015-05-01

    Microbial degradation of lignocellulose is one of the key problems that need to be solved urgently in the process of utilizing biomass resource. Bacillus amyloliquefaciens MN-8 is our previously isolated bacterium capable of degrading lignin. To determine the capability of strain MN-8 to degrade lignocellulose of corn straw, B. amyloliquefaciens MN-8 was inoculated and fermented with solid-state corn straw powder-MSM culture medium. The changes in the enzyme activity and degradation products of lignocellulose were monitored in the process of fermentation using the FTIR and GC/MS. The results showed that B. amyloliquefaciens MN-8 could produce lignin peroxidase, manganese peroxidase, cellulase and hemicellulase enzymes. The activities of all these enzymes reached the peak after being incubated for 10-16 days, and the highest enzyme activities were 55.0, 16.7, 45.4 and 60.5 U · g(-1), respectively. After 24 d of incubation, the degradation percentages of lignin, cellulose and hemicellulose were up to 42.9%, 40.6% and 27.1%, respectively. The spectroscopic data by FTIR indicated that the intensities of characteristic absorption peaks of lignin, cellulose and hemicellulose of the corn straw were decreased, indicating that the lignocellulose was degraded partly after being fermented by B. amyloliquefaciens MN-8. GC/MS analysis also demonstrated that strain MN-8 could degrade lignocellulose efficiently. It could depolymerize lignin into some monomeric compounds with retention of phenylpropane structure unit, such as amphetamine, benzene acetone and benzene propanoic acids, by the rupture of β-O-4 bond connected between lignin monomer, and it further oxidized some monomer compounds into Cα carbonyl compounds, such as 2-amino-1-benzeneacetone and 4-hydroxy-3,5-dimethoxy-acetophenone. The GC/MS analysis of the degradation products of cellulose and hemicellulose showed that there were not only monosaccharide compounds, such as glucose, mannose and galactose, but also some

  15. Compounds produced by two robust Bacillus amyloliquefaciens biocontrol strains involved in antimicrobial activity and plant-growth promotion

    OpenAIRE

    Magno-Pérez, Maria Concepción; Hierrezuelo, Jesús; de Vicente, Antonio; Pérez-García, Alejandro; Romero, Diego

    2015-01-01

    Several members of the Bacillus genus are potential candidates to be used as biological control agents to combat pests or plant diseases. The bacterial attributes associated to Bacillus behaviour are mainly: the production of antimicrobial compounds, the plant-growth promotion capability and the induction of systemic resistance in plant host. In previous works, we have demonstrated this multifaceted biocontrol activity of B. amyloliquefaciens CECT8237 (UMAF6639) and CECT8238 (UMAF6614) strain...

  16. 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%...

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

    OpenAIRE

    Dong, Peng; Georget, Erika S.; Aganovic, Kemal; Heinz, Volker; Mathys, Alexander

    2015-01-01

    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 subjecte...

  18. Iturin levels on wheat spikes linked to biological control of Fusarium head blight by Bacillus amyloliquefaciens.

    Science.gov (United States)

    Crane, J M; Gibson, D M; Vaughan, R H; Bergstrom, G C

    2013-02-01

    The TrigoCor strain of Bacillus amyloliquefaciens provides consistent control against Fusarium head blight of wheat in controlled settings but there is a lack of disease and deoxynivalenol suppression in field settings. Since production of antifungal compounds is thought to be the main mode of action of TrigoCor control, we quantified levels of a key family of antifungal metabolites, iturins, as well as monitored Bacillus populations on wheat spikes over 14 days post-application in both the greenhouse and the field. We found that initial iturin levels on spikes in the greenhouse were three times greater than on spikes in the field, but that by 3 days post-application, iturin levels were equivalent and very low in both settings. We also determined that iturins declined rapidly over a 3-day post-application period on wheat spikes in both environments, despite the presence of significant Bacillus populations. Greenhouse trials and antibiosis tests indicated that the lower iturin levels on wheat spikes in the field could be a major factor limiting disease control in field settings. Future efforts to improve Bacillus disease control on wheat spikes and in the phyllosphere of various plants should focus on maintaining higher levels of iturins over critical infection periods. PMID:23075168

  19. 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

  20. 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

  1. Lipopeptides as main ingredients for inhibition of fungal phytopathogens by Bacillus subtilis/amyloliquefaciens

    Science.gov (United States)

    Cawoy, Hélène; Debois, Delphine; Franzil, Laurent; De Pauw, Edwin; Thonart, Philippe; Ongena, Marc

    2015-01-01

    Some isolates of the Bacillus subtilis/amyloliquefaciens species are known for their plant protective activity against fungal phytopathogens. It is notably due to their genetic potential to form an impressive array of antibiotics including non-ribosomal lipopeptides (LPs). In the work presented here, we wanted to gain further insights into the relative role of these LPs in the global antifungal activity of B. subtilis/amyloliquefaciens. To that end, a comparative study was conducted involving multiple strains that were tested against four different phytopathogens. We combined various approaches to further exemplify that secretion of those LPs is a crucial trait in direct pathogen ward off and this can actually be generalized to all members of these species. Our data illustrate that for each LP family, the fungitoxic activity varies in function of the target species and that the production of iturins and fengycins is modulated by the presence of pathogens. Our data on the relative involvement of these LPs in the biocontrol activity and modulation of their production are discussed in the context of natural conditions in the rhizosphere. PMID:25529983

  2. Antimicrobial factor from Bacillus amyloliquefaciens inhibits Paenibacillus larvae, the causative agent of American foulbrood.

    Science.gov (United States)

    Benitez, Lisianne Brittes; Velho, Renata Voltolini; de Souza da Motta, Amanda; Segalin, Jéferson; Brandelli, Adriano

    2012-03-01

    Bacillus amyloliquefaciens LBM 5006 produces an antimicrobial factor active against Paenibacillus larvae, a major honeybee pathogen. The antagonistic effect and the mode of action of the antimicrobial factor were investigated. The antibacterial activity was produced starting at mid-logarithmic growth phase, reaching its maximum during the stationary phase. Exposure of cell suspensions of P. larvae to this antimicrobial resulted in loss of cell viability and reduction in optical density associated with cell lysis. Scanning electron microscopy showed damaged cell envelope and loss of protoplasmic material. The antimicrobial factor was stable for up to 80°C, but it was sensitive to proteinase K and trypsin. Mass spectrometry analysis indicates that the antimicrobial activity is associated with iturin-like peptides. The antimicrobial factor from B. amyloliquefaciens LBM 5006 showed a bactericidal effect against P. larvae cells and spores. This is the first report on iturin activity against P. larvae. This antimicrobial presents potential for use in the control of American foulbrood disease. PMID:21858429

  3. 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.

  4. A new strategy to express the extracellular α-amylase from Pyrococcus furiosus in Bacillus amyloliquefaciens

    Science.gov (United States)

    Wang, Ping; Wang, Peili; Tian, Jian; Yu, Xiaoxia; Chang, Meihui; Chu, Xiaoyu; Wu, Ningfeng

    2016-01-01

    Extracellular α-amylase from Pyrococcus furiosus (PFA) shows great starch-processing potential for industrial application due to its thermostability, long half-life and optimal activity at low pH; however, it is difficult to produce in large quantities. In contrast, α-amylase from Bacillus amyloliquefaciens (BAA) can be produced in larger quantities, but shows lower stability at high temperatures and low pH. Here, we describe a BAA protein expression pattern-mimicking strategy to express PFA in B. amyloliquefaciens using the expression and secretion elements of BAA, including the codon usage bias and mRNA structure of gene, promoter, signal peptide, host and cultivation conditions. This design was assessed to be successful by comparing the various genes (mpfa and opfa), promoters (PamyA and P43), and strains (F30, F31, F32 and F30-∆amyA). The final production of PFA yielded 2714 U/mL, about 3000- and 14-fold that reportedly produced in B. subtilis or E. coli, respectively. The recombinant PFA was optimally active at ~100 °C and pH 5 and did not require Ca2+ for activity or thermostability, and >80% of the enzyme activity was retained after treatment at 100 °C for 4 h. PMID:26916714

  5. Biological Control Potential of Bacillus amyloliquefaciens KB3 Isolated from the Feces of Allomyrina dichotoma Larvae.

    Science.gov (United States)

    Nam, Hyo-Song; Yang, Hyun-Ju; Oh, Byung Jun; Anderson, Anne J; Kim, Young Cheol

    2016-06-01

    Most biocontrol agents for plant diseases have been isolated from sources such as soils and plants. As an alternative source, we examined the feces of tertiary larvae of the herbivorous rhino beetle, Allomyrina dichotoma for presence of biocontrol-active microbes. The initial screen was performed to detect antifungal activity against two common fungal plant pathogens. The strain with strongest antifungal activity was identified as Bacillus amyloliquefaciens KB3. The inhibitory activity of this strain correlated with lipopeptide productions, including iturin A and surfactin. Production of these surfactants in the KB3 isolate varied with the culture phase and growth medium used. In planta biocontrol activities of cell-free culture filtrates of KB3 were similar to those of the commercial biocontrol agent, B. subtilis QST-713. These results support the presence of microbes with the potential to inhibit fungal growth, such as plant pathogens, in diverse ecological niches. PMID:27298603

  6. Bacillus amyloliquefaciens AG1 biosurfactant: Putative receptor diversity and histopathological effects on Tuta absoluta midgut.

    Science.gov (United States)

    Ben Khedher, Saoussen; Boukedi, Hanen; Kilani-Feki, Olfa; Chaib, Ikbel; Laarif, Asma; Abdelkefi-Mesrati, Lobna; Tounsi, Slim

    2015-11-01

    The use of biosurfactant in pest management has received much attention for the control of plant pathogens, but few studies reported their insecticidal activity. The present study describes the insecticidal activity of biosurfactant extracted from Bacillus amyloliquefaciens strain AG1. This strain produces a lipopeptide biosurfactant exhibiting an LC50 of about 180ng/cm(2) against Tuta absoluta larvae. Accordingly, the histopathologic effect of this biosurfactant on T. absoluta larvae showed serious damages of the midgut tissues including rupture and disintegration of epithelial layer and cellular vacuolization. By PCR, we showed that this biosurfactant could be formed by several lipopeptides and polyketides including iturin, fengycin, surfactin, bacyllomicin, bacillaene, macrolactin and difficidin. Binding experiment revealed that it recognized five putative receptors located in the BBMV of T. absoluta with sizes of 68, 63, 44, 30 and 19kDa. Therefore, biosurfactant AG1 hold potential for use as an environmentally friendly agent to control the tomato leaf miner. PMID:26299754

  7. 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

  8. 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.

  9. Production of 2,3-butanediol from glucose by GRAS microorganism Bacillus amyloliquefaciens.

    Science.gov (United States)

    Yang, Taowei; Rao, Zhiming; Zhang, Xian; Lin, Qing; Xia, Haifeng; Xu, Zhenghong; Yang, Shangtian

    2011-12-01

    In the current study, a GRAS (Generally Recognized As Safe) strain of Bacillus amyloliquefaciens producing 2,3-butanediol (2,3-BD) designated as B10-127 was isolated in our lab. The strain B10-127 produced 2,3-BD effectively under the condition of 20% glucose (quality concentration), showed a high-glucose tolerance. The effects of initial glucose concentration, temperature, pH and agitation on 2,3-BD production were investigated in this work and the proper parameters were identified. Accordingly, the fed-batch culture of B10-127 in larger scales (5 l) showed a remarkable 2,3-BD producing potency. The maximum 2,3-BD concentration reached 92.3 g/l at 96 h with a 2,3-BD productivity of 0.96 g/l h. To our knowledge, the results were new records on 2,3-BD fermentation by Bacillus, which shown an excellent candidate for the microbial fermentation of 2,3-BD on an industrial scale. PMID:21780143

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. Studies of plant colonisation by closely related Bacillus amyloliquefaciens biocontrol agents using strain specific quantitative PCR assays.

    Science.gov (United States)

    Johansson, Anna H; Bejai, Sarosh; Niazi, Adnan; Manzoor, Shahid; Bongcam-Rudloff, Erik; Meijer, Johan

    2014-12-01

    Certain strains of Bacillus amyloliquefaciens can colonize plants and improve growth and stress management. In order to study these effects, bacterial growth dynamics on plants and in the rhizosphere are of interest calling for specific analytical tools. For that purpose, quantitative real-time PCR (qPCR) assays were developed in order to differentiate among three closely related B. amyloliquefaciens subsp. plantarum strains (UCMB5033, UCMB5036, UCMB5113) and to determine their levels with high accuracy. Oligonucleotide primers were designed for strain unique gene sequences and used for SYBR green based qPCR analysis. Standard curves covered a wide linear range (10(6)) of DNA amounts with the lowest detection level at 50 fg. Post-reaction melting curve analysis showed only a single product. Accurate threshold cycles were obtained, even in the presence of high excess of related Bacillus strains and total bacterial DNA from soil. Analysis of Bacillus colonisation after seed treatment of two oilseed rape cultivars (Oase and Ritz) grown on agar support showed a time dependent effect but that the bacteria mostly were found on root tissues and little on green tissues. The colonisation on plants grown in soil varied among the Bacillus strains where Oase seemed to house more bacteria than Ritz. Applied as a mixture, all three Bacillus strains co-existed on the roots of plants grown in soil. The qPCR assay in combination with other techniques will be a powerful tool to study plant interactions of these B. amyloliquefaciens biocontrol agents to further understand the requirements for successful interactions and improvement of plant properties. PMID:25294724

  15. 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

  16. 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

  17. [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

  18. 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

  19. 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

  20. Biocontrol Activity of Bacillus amyloliquefaciens CNU114001 against Fungal Plant Diseases.

    Science.gov (United States)

    Ji, Seung Hyun; Paul, Narayan Chandra; Deng, Jian Xin; Kim, Young Sook; Yun, Bong-Sik; Yu, Seung Hun

    2013-12-01

    A total of 62 bacterial isolates were obtained from Gomsohang mud flat, Mohang mud flat, and Jeju Island, Republic of Korea. Among them, the isolate CNU114001 showed significant antagonistic activity against pathogenic fungi by dual culture method. The isolate CNU114001 was identified as Bacillus amyloliquefaciens by morphological observation and molecular data analysis, including 16SrDNA and gyraseA (gyrA) gene sequences. Antifungal substances of the isolate were extracted and purified by silica gel column chromatography, thin layer chromatography, and high performance liquid chromatography. The heat and UV ray stable compound was identified as iturin, a lipopeptide (LP). The isolate CNU114001 showed broad spectrum activity against 12 phytopathogenic fungi by dual culture method. The semi purified compound significantly inhibits the mycelial growth of pathogenic fungi (Alternaria panax, Botrytis cinera, Colletotrichum orbiculare, Penicillium digitatum, Pyricularia grisea and Sclerotinia sclerotiorum) at 200 ppm concentration. Spore germ tube elongation of Botrytis cinerea was inhibited by culture filtrate of the isolate. Crude antifungal substance showed antagonistic activity against cucumber scleotiorum rot in laboratory, and showed antagonistic activity against tomato gray mold, cucumber, and pumpkin powdery mildew in greenhouse condition. PMID:24493945

  1. Protective effect of Bacillus amyloliquefaciens against infections of Citrus aurantium seedlings by Phoma tracheiphila.

    Science.gov (United States)

    Kalai-Grami, L; Ben Slimane, I; Mnari-Hattab, M; Rezgui, S; Aouani, M A; Hajlaoui, M R; Limam, F

    2014-02-01

    Isolate TEB1 an antagonistic endophytic bacterium, obtained from citrus leaves and identified as Bacillus amyloliquefaciens by 16S rDNA sequencing, was used for the biological control of mal secco disease of Citrus aurantium seedlings caused by the mitosporic fungus Phoma tracheiphila. The isolate TEB1 exhibited a good in vitro activity against P. tracheiphila in dual cultures as well as with the well diffusion method. C. aurantium seedlings watered with a suspension of TEB1 cells showed a reduction of 53.61 and 48.63% in disease severity and incidence, respectively. A PCR test with specific primers was performed 365 days after inoculation and P. tracheiphila was detected along the whole stem in inoculated control plant while no amplification product was obtained in TEB1 treated seedlings. Molecular analysis of TEB1 revealed a positive amplification of fenD and ituC genes responsible of the biosynthesis of fengycin and iturin lipopeptides, respectively. Moreover, observations by optical microscope showed that TEB1 reduced by 55% the germination of P. tracheiphila conidia and exhibited a marked effect on mycelia structure. Data suggest that lipopeptides produced by the bacterium interact with the cytoplasmic membrane of the fungus causing pore formation. TEB1 appears a potential candidate for the biological control of citrus mal secco disease. PMID:23990072

  2. 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

  3. Synergistic effect of Pseudomonas putida and Bacillus amyloliquefaciens ameliorates drought stress in chickpea (Cicer arietinum L.).

    Science.gov (United States)

    Kumar, Manoj; Mishra, Sankalp; Dixit, Vijaykant; Kumar, Manoj; Agarwal, Lalit; Chauhan, Puneet Singh; Nautiyal, Chandra Shekhar

    2016-01-01

    Two plant growth promoting rhizobacteria (PGPR) Pseudomonas putida NBRIRA and Bacillus amyloliquefaciens NBRISN13 with ability to tolerate abiotic stress along with multiple PGP traits like ACC deaminase activity, minerals solubilisation, hormones production, biofilm formation, siderophore activity were evaluated for their synergistic effect to ameliorate drought stress in chickpea. Earlier we have reported both the strains individually for their PGP attributes and stress amelioration in host plants. The present study explains in detail the possibilities and benefits of utilizing these 2 PGPR in consortium for improving the chickpea growth under control and drought stressed condition. In vitro results clearly demonstrate that both the PGPR strains are compatible to each other and their synergistic growth enhances the PGP attributes. Greenhouse experiments were conducted to evaluate the effect of inoculation of both strains individually and consortia in drought tolerant and sensitive cultivars (BG362 and P1003). The growth parameters were observed significantly higher in consortium as compared to individual PGPR. Colonization of both PGPR in chickpea rhizosphere has been visualized by using gfp labeling. Apart from growth parameters, defense enzymes, soil enzymes and microbial diversity were significantly modulated in individually PGPR and in consortia inoculated plants. Negative effects of drought stress has been ameliorated and apparently seen by higher biomass and reversal of stress indicators in chickpea cultivars treated with PGPR individually or in consortia. Findings from the present study demonstrate that synergistic application has better potential to improve plant growth promotion under drought stress conditions. PMID:26362119

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. Stimulation by Hyphopichia burtonii and Bacillus amyloliquefaciens of aflatoxin production by Aspergillus flavus in irradiated maize and rice grains

    Energy Technology Data Exchange (ETDEWEB)

    Cuero, R.G.; Smith, J.E.; Lacey, J.

    1987-05-01

    Aspergillus flavus was grown on maize and rice extract agars and on irradiated viable cracked maize and rice grains, either in pure culture or in dual culture with wild strains of either Hyphopichia burtonii or Bacillus amyloliquefaciens. Aflatoxin production by A. flavus and its growth and interactions with the other microorganisms were studied at three water activities (a/sub w/) (0.98, 0.95, and 0.90) and two temperatures (25 and 16/sup 0/C). Both H. burtonii and B. amyloliquefaciens markedly stimulated growth and aflotoxin production by A. flavus on cracked maize, especially at 25/sup 0/C and 0.95 and 0.98 a/sub w/. No aflatoxin was detected in pure cultures of A. flavus on cracked rice after 12 days of incubation at 25/sup 0/C, but some was produced by mixed cultures at 16/sup 0/C and 0.98 a/sub w/. The morphological interactions among A. flavus, H. burtonii, and B. amyloliquefaciens were also examined on maize and rice extract agars under similar controlled conditions.

  9. Stimulation by Hyphopichia burtonii and Bacillus amyloliquefaciens of aflatoxin production by Aspergillus flavus in irradiated maize and rice grains

    International Nuclear Information System (INIS)

    Aspergillus flavus was grown on maize and rice extract agars and on irradiated viable cracked maize and rice grains, either in pure culture or in dual culture with wild strains of either Hyphopichia burtonii or Bacillus amyloliquefaciens. Aflatoxin production by A. flavus and its growth and interactions with the other microorganisms were studied at three water activities (a/sub w/) (0.98, 0.95, and 0.90) and two temperatures (25 and 160C). Both H. burtonii and B. amyloliquefaciens markedly stimulated growth and aflotoxin production by A. flavus on cracked maize, especially at 250C and 0.95 and 0.98 a/sub w/. No aflatoxin was detected in pure cultures of A. flavus on cracked rice after 12 days of incubation at 250C, but some was produced by mixed cultures at 160C and 0.98 a/sub w/. The morphological interactions among A. flavus, H. burtonii, and B. amyloliquefaciens were also examined on maize and rice extract agars under similar controlled conditions

  10. 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

    Aims: To identify and screen dominant Bacillus spp. strains isolated from Bikalga, fermented seeds of Hibiscus sabdariffa for their antimicrobial activities in brain heart infusion (BHI) medium and in a H. sabdariffa seed-based medium. Further, to characterize the antimicrobial substances produced...... 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 as...

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

    Science.gov (United States)

    Dong, Peng; Georget, Erika S; Aganovic, Kemal; Heinz, Volker; Mathys, Alexander

    2015-01-01

    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 ~10(6) 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 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 log10CFU/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. PMID:26236296

  12. Isolation of Bacillus amyloliquefaciens S20 and its application in control of eggplant bacterial wilt.

    Science.gov (United States)

    Chen, Da; Liu, Xin; Li, Chunyu; Tian, Wei; Shen, Qirong; Shen, Biao

    2014-05-01

    Bacterial strain S20 was isolated and identified as Bacillus amyloliquefaciens based on physiological and biochemical characteristics and a 16S rRNA gene sequence analysis. Strain S20 inhibits the growth of Fusarium oxysporum and Ralstonia solanacearum. Some genes associated with the synthesis of some lipopeptides were detected in strain S20 by PCR. Iturins A were identified as the main antagonistic substrates by analysis with electrospray ionization mass spectrometry/collision-induced dissociation (ESI-MS/CID). Four homologues of iturin A (C13-C16) were identified. Pot experiments showed that the application of strain S20 alone could control eggplant wilt with an efficacy of 25.3% during a 40 day experiment. If strain S20 was used with organic fertilizer, the control efficacy against eggplant wilt reached as high as 70.7%. The application of organic fertilizer alone promotes the growth of R. solanacearum, resulting in a higher wilt incidence than that observed in control plants. The application of strain S20 effectively inhibits R. solanacearum in the rhizosphere soil of eggplant. The combined use of strain S20 and organic fertilizer more effectively controlled R. solanacearum in soil than the use of strain S20 alone. The soil count of strain S20 decreased gradually during the course of the experiment after inoculation. Organic fertilizer was beneficial for the survival of the antagonistic bacterial strain S20; a higher level of these bacteria could be maintained. The application of organic fertilizer with strain S20 increased bacterial diversity in rhizosphere soil. PMID:24632400

  13. Obtaining a mutant of Bacillus amyloliquefaciens xylanase A with improved catalytic activity by directed evolution.

    Science.gov (United States)

    Xu, Xin; Liu, Ming-Qi; Huo, Wen-Kang; Dai, Xian-Jun

    2016-05-01

    This study aimed to obtain xylanase exhibiting improved enzyme properties to satisfy the requirements for industrial applications. The baxA gene encoding Bacillus amyloliquefaciens xylanase A was mutated by error-prone touchdown PCR. The mutant, pCbaxA50, was screened from the mutant library by using the 96-well plate high-throughput screening method. Sequence alignment revealed the identical mutation point S138T in xylanase (reBaxA50) produced by the pCbaxA50. The specific activity of the purified reBaxA50 was 9.38U/mg, which was 3.5 times higher than that of its parent expressed in Escherichia coli BL21 (DE3), named reBaxA. The optimum temperature of reBaxA and reBaxA50 were 55°C and 50°C, respectively. The optimum pH of reBaxA and reBaxA50 were pH 6 and pH 5, respectively. Moreover, reBaxA50 was more stable than reBaxA under thermal and extreme pH treatment. The half-life at 60°C and apparent melting temperature of reBaxA50 were 9.74min and 89.15°C, respectively. High-performance liquid chromatography showed that reBaxA50 released xylooligosaccharides from oat spelt, birchwood, and beechwood xylans, with xylotriose as the major product; beechwood xylan was also the most thoroughly hydrolyzed. This study demonstrated that the S138T mutation possibly improved the catalytic activity and thermostability of reBaxA50. PMID:26992794

  14. 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.

  15. Optimization of α-amylase production by Bacillus amyloliquefaciens using response surfaces methodology

    Directory of Open Access Journals (Sweden)

    Hami Kaboosi

    2014-11-01

    α-amylase. The results showed that the RSM applied for optimizing parameters of submerged fermentation condition aimed at producing maximum quantities of α-amylase by B. amyloliquefaciens acts with high efficiency.

  16. 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.

  17. The Complete Genome of Bacillus amyloliquefaciens subsp. plantarum CAU B946 Contains a Gene Cluster for Nonribosomal Synthesis of Iturin A

    OpenAIRE

    Blom, Jochen; Rueckert, Christian; Niu, Ben; Wang, Qi; Borriss, Rainer

    2012-01-01

    The genome of the rhizobacterium Bacillus amyloliquefaciens subsp. plantarum CAU B946 was 4.02 Mb in size and harbored 3,823 genes (coding sequences [CDS]). Nine giant gene clusters were dedicated to nonribosomal synthesis of antimicrobial compounds. Remarkably, strain CAU B946 possessed a gene cluster involved in synthesis of iturin A.

  18. The complete genome of Bacillus amyloliquefaciens subsp. plantarum CAU B946 contains a gene cluster for nonribosomal synthesis of iturin A.

    Science.gov (United States)

    Blom, Jochen; Rueckert, Christian; Niu, Ben; Wang, Qi; Borriss, Rainer

    2012-04-01

    The genome of the rhizobacterium Bacillus amyloliquefaciens subsp. plantarum CAU B946 was 4.02 Mb in size and harbored 3,823 genes (coding sequences [CDS]). Nine giant gene clusters were dedicated to nonribosomal synthesis of antimicrobial compounds. Remarkably, strain CAU B946 possessed a gene cluster involved in synthesis of iturin A. PMID:22408246

  19. 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

  20. 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.

  1. 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...

  2. 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

  3. 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. PMID:26808445

  4. Effects of critical medium components on the production of antifungal lipopeptides from Bacillus amyloliquefaciens Q-426 exhibiting excellent biosurfactant properties.

    Science.gov (United States)

    Zhao, Pengchao; Quan, Chunshan; Jin, Liming; Wang, Lina; Wang, Jianhua; Fan, Shengdi

    2013-03-01

    In this study, influence of three critical parameters nitrogen sources, initial pH and metal ions was discussed in the production of antifungal lipopeptides from Bacillus amyloliquefaciens Q-426. The results revealed that lipopeptide biosynthesis might have relations with the population density of strain Q-426 and some special amino acids. Also, the alkali-resistant strain Q-426 could grow well in the presence of Fe(2+) ions below 0.8 M l(-1) and still maintain the competitive advantage below 0.2 M l(-1). Moreover, lipopeptides exhibited significant inhibitory activities against Curvularia lunata (Walk) Boed even at the extreme conditions of temperature, pH and salinity. Finally, biosurfactant properties of lipopeptides mixture were evaluated by use with totally six different methods including bacterial adhesion to hydrocarbons assay, lipase activity, hemolytic activity, emulsification activity, oil displacement test and surface tension measurement. The research suggested that B. amyloliquefaciens Q-426 may have great potential in agricultural and environmental fields. PMID:23329061

  5. 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.

  6. Scientific Opinion on the safety and efficacy of Bacillus amyloliquefaciens (NCIMB 30229) as a silage feed additive for all species

    OpenAIRE

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP)

    2013-01-01

    A strain of Bacillus amyloliquefaciens is intended to be added to forages to promote the ensiling process (technological additive, functional group: silage additive). The identity of the strain and its susceptibility to relevant antibiotics has been established. However, the strain produces cyclic lipopeptides which possess potent surfactant activity, known to be involved in food intoxication. Although the strain is intended for use only in the production of silage, as a spore former it will ...

  7. 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.

  8. Antagonistic Mechanism of Iturin A and Plipastatin A from Bacillus amyloliquefaciens S76-3 from Wheat Spikes against Fusarium graminearum

    OpenAIRE

    Gong, An-Dong; Li, He-Ping; Yuan, Qing-Song; Song, Xiu-Shi; YAO, Wei; He, Wei-Jie; Zhang, Jing-Bo; Liao, Yu-Cai

    2015-01-01

    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 differ...

  9. 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 ...

  10. Effects of Bacillus amyloliquefaciens FZB42 on Lettuce Growth and Health under Pathogen Pressure and Its Impact on the Rhizosphere Bacterial Community

    OpenAIRE

    Chowdhury, Soumitra Paul; Dietel, Kristin; Rändler, Manuela; Schmid, Michael; Junge, Helmut; Borriss, Rainer; Hartmann, Anton; Grosch, Rita

    2013-01-01

    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 bacteri...

  11. 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

  12. Impact of rhizosphere factors on cyclic lipopeptide signature from the plant beneficial strain Bacillus amyloliquefaciens S499.

    Science.gov (United States)

    Nihorimbere, Venant; Cawoy, Hélène; Seyer, Alexandre; Brunelle, Alain; Thonart, Philippe; Ongena, Marc

    2012-01-01

    Cyclic lipopeptides (cLPs) of the surfactin, iturin and fengycin families synthesized by plant-associated Bacilli represent an important class of antibiotics as they may be tightly involved in the protective effect of selected strains against phytopathogens. However, their production by Bacillus cells developing on roots under rhizosphere conditions is still poorly understood. In this work, we combined electrospray and imaging mass spectrometry-based approaches to determine the detailed pattern of surfactins, iturins and fengycins produced in planta by Bacillus amyloliquefaciens S499. Very different production rates were observed for the three cLPs families. Whereas surfactin accumulated in significant amounts, much lower quantities of iturins and fengycins were detected in the environment of colonized roots in comparison with laboratory medium. In addition, the surfactin pattern produced by strain S499 evolving on roots is enriched in homologues with long fatty acid chains (C15) compared with the chains typically secreted under in vitro conditions. Additional experiments revealed that lipopeptide production by root-associated S499 cells is qualitatively and quantitatively dictated by the specific nutritional context of the rhizosphere (exudates enriched in organic acids, oxygen limitation) but also by the formation of biofilm-related structures around root hairs. As surfactins, iturins and fengycins retain specific functions and bioactivities, the biological relevance of their differential production observed in planta is discussed in the context of biocontrol of plant diseases. PMID:22029651

  13. Bacillus amyloliquefaciens subsp. plantarum GR53, a potent biocontrol agent resists Rhizoctonia disease on Chinese cabbage through hormonal and antioxidants regulation.

    Science.gov (United States)

    Kang, Sang-Mo; Radhakrishnan, Ramalingam; Lee, In-Jung

    2015-10-01

    The fungus Rhizoctonia solani is one of the causal agents of numerous diseases that affect crop growth and yield. The aim of this present investigation was to identify a biocontrol agent that acts against R. solani and to determine the agent's protective effect through phytohormones and antioxidant regulation in experimentally infected Chinese cabbage plants. Four rhizospheric soil bacterial isolates GR53, GR169, GR786, and GR320 were tested for their antagonistic activity against R. solani. Among these isolates, GR53 significantly suppressed fungal growth. GR53 was identified as Bacillus amyloliquefaciens subsp. plantarum by phylogenetic analysis of the 16S rDNA sequence. The biocontrol activity of B. amyloliquefaciens subsp. plantarum GR53 was tested in Chinese cabbage plants under controlled conditions. Results showed that R. solani inhibited plant growth (length, width, fresh and dry weight of leaves) by reducing chlorophyll and total phenolic content, as well as by increasing the levels of salicylic acid, jasmonic acid, abscisic acid, and DPPH scavenging activity. By regulating the levels of these compounds, the co-inoculation of B. amyloliquefaciens subsp. plantarum GR53 heightened induced systemic resistance in infected Chinese cabbage, effectively mitigating R. solani-induced damaging effects and improving plant growth. The results obtained from this study suggest that B. amyloliquefaciens subsp. plantarum GR53 is an effective biocontrol agent to prevent the damage caused by R. solani in Chinese cabbage plants. PMID:26160009

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

    OpenAIRE

    Brans Alain; Lara Yannick; Halimi Badre; Ongena Marc; Arguelles-Arias Anthony; Joris Bernard; Fickers Patrick

    2009-01-01

    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 deman...

  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. Scientific Opinion on the safety and efficacy of Bacillus amyloliquefaciens (NCIMB 30229 as a silage feed additive for all species

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2013-01-01

    Full Text Available A strain of Bacillus amyloliquefaciens is intended to be added to forages to promote the ensiling process (technological additive, functional group: silage additive. The identity of the strain and its susceptibility to relevant antibiotics has been established. However, the strain produces cyclic lipopeptides which possess potent surfactant activity, known to be involved in food intoxication. Although the strain is intended for use only in the production of silage, as a spore former it will survive the ensiling process and be ingested by target animals. The spores will also survive passage through the gastrointestinal tract of animals and be a potential source of contamination of food of animal origin and of the environment. The greatest risk would be to those handling the product on farm following oral, dermal and respiratory exposure. Consequently, the FEEDAP Panel concludes that use of the strain in the production of silage presents a hazard to consumers, users and the environment, and potentially also to the target animals. A total of three laboratory experiments with laboratory-scale silos, each lasting at least 90 days, were carried out using samples of forage of differing dry matter and water-soluble carbohydrate content. In each case, replicate silos containing treated forage were compared with identical silos containing the same but untreated forage. The potential of the additive to improve aerobic stability of silages at the proposed dose of 5.0 x 107 CFU/kg fresh materials was not convincingly demonstrated.

  17. Organic acids from root exudates of banana help root colonization of PGPR strain Bacillus amyloliquefaciens NJN-6.

    Science.gov (United States)

    Yuan, Jun; Zhang, Nan; Huang, Qiwei; Raza, Waseem; Li, Rong; Vivanco, Jorge M; Shen, Qirong

    2015-01-01

    The successful colonization of plant growth promoting rhizobacteria (PGPR) in the rhizosphere is an initial and compulsory step in the protection of plants from soil-borne pathogens. Therefore, it is necessary to evaluate the role of root exudates in the colonization of PGPR. Banana root exudates were analyzed by high pressure liquid chromatography (HPLC) which revealed exudates contained several organic acids (OAs) including oxalic, malic and fumaric acid. The chemotactic response and biofilm formation of Bacillus amyloliquefaciens NJN-6 were investigated in response to OA's found in banana root exudates. Furthermore, the transcriptional levels of genes involved in biofilm formation, yqxM and epsD, were evaluated in response to OAs via quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Results suggested that root exudates containing the OAs both induced the chemotaxis and biofilm formation in NJN-6. In fact, the strongest chemotactic and biofilm response was found when 50 μM of OAs were applied. More specifically, malic acid showed the greatest chemotactic response whereas fumaric acid significantly induced biofilm formation by a 20.7-27.3% increase and therefore biofilm formation genes expression. The results showed banana root exudates, in particular the OAs released, play a crucial role in attracting and initiating PGPR colonization on the host roots. PMID:26299781

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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

  3. Multiple effects of Bacillus amyloliquefaciens volatile compounds: plant growth promotion and growth inhibition of phytopathogens.

    Science.gov (United States)

    Asari, Shashidar; Matzén, Staffan; Petersen, Mikael Agerlin; Bejai, Sarosh; Meijer, Johan

    2016-06-01

    Biotic interactions through volatile organic compounds (VOC) are frequent in nature. This investigation aimed to study the role of ITALIC! BacillusVOC for the beneficial effects on plants observed as improved growth and pathogen control. Four ITALIC! Bacillus amyloliquefacienssubsp. ITALIC! plantarumstrains were screened for VOC effects on ITALIC! Arabidopsis thalianaCol-0 seedlings and ITALIC! Brassicafungal phytopathogens. VOC from all four ITALIC! Bacillusstrains could promote growth of ITALIC! Arabidopsisplants resulting in increased shoot biomass but the effects were dependent on the growth medium. Dose response studies with UCMB5113 on MS agar with or without root exudates showed significant plant growth promotion even at low levels of bacteria. ITALIC! BacillusVOC antagonized growth of several fungal pathogens ITALIC! in vitro However, the plant growth promotion efficacy and fungal inhibition potency varied among the ITALIC! Bacillusstrains. VOC inhibition of several phytopathogens indicated efficient microbial antagonism supporting high rhizosphere competence of the ITALIC! Bacillusstrains. GC-MS analysis identified several VOC structures where the profiles differed depending on the growth medium. The ability of ITALIC! Bacillusstrains to produce both volatile and soluble compounds for plant growth promotion and disease biocontrol provides examples of rhizosphere microbes as an important ecosystem service with high potential to support sustainable crop production. PMID:27053756

  4. 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

  5. Sequence characterization and computational analysis of the non-ribosomal peptide synthetases controlling biosynthesis of lipopeptides, fengycins and bacillomycin D, from Bacillus amyloliquefaciens Q-426.

    Science.gov (United States)

    Zhao, Pengchao; Quan, Chunshan; Jin, Liming; Wang, Lina; Guo, Xinjuan; Fan, Shengdi

    2013-12-01

    Lipopeptides secreted by bacteria attract interest because of their uses in biomedicine, biotechnology and food technology; however, harnessing their megasynthases (non-ribosomal peptide synthetases, NRPSs) has met with some difficulties in heterologous expression and crystallization. Here, we used similarity and phylogenetic analysis of NRPS sequences, including the fengycin and iturin family synthetases from Bacillus spp., and have developed a novel approach for delineating the length and boundaries of NRPS domains from Bacillus amyloliquefaciens strain Q-426. The sequences were further characterized (including specific residues and conserved motifs) that gave insight into the basis of the substrate specificity. Data from the prediction of the NRPS domains, obtained by the self-optimized prediction method with Alignment program, showed they are all structurally unstable, making it difficult to determine their crystal structures. PMID:24068498

  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. 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 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 content had been degraded by B. amyloliquefaciens WB1 could improve the growth performance of A. japonicus as well its resistance to bacterial infection. It could therefore act as an alternative to S. thunbergii and is economical at the same time. PMID:25895094

  8. 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)

  9. 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.

  10. Improved production of 2,3-butanediol in Bacillus amyloliquefaciens by over-expression of glyceraldehyde-3-phosphate dehydrogenase and 2,3-butanediol dehydrogenase.

    Directory of Open Access Journals (Sweden)

    Taowei Yang

    Full Text Available BACKGROUND: Previously, a safe strain, Bacillus amyloliquefaciens B10-127 was identified as an excellent candidate for industrial-scale microbial fermentation of 2,3-butanediol (2,3-BD. However, B. amyloliquefaciens fermentation yields large quantities of acetoin, lactate and succinate as by-products, and the 2,3-BD yield remains prohibitively low for commercial production. METHODOLOGY/PRINCIPAL FINDINGS: In the 2,3-butanediol metabolic pathway, glyceraldehyde-3-phosphate dehydrogenase (GAPDH catalyzes the conversion of 3-phosphate glyceraldehyde to 1,3-bisphosphoglycerate, with concomitant reduction of NAD(+ to NADH. In the same pathway, 2,3-BD dehydrogenase (BDH catalyzes the conversion of acetoin to 2,3-BD with concomitant oxidation of NADH to NAD(+. In this study, to improve 2,3-BD production, we first over-produced NAD(+-dependent GAPDH and NADH-dependent BDH in B. amyloliquefaciens. Excess GAPDH reduced the fermentation time, increased the 2,3-BD yield by 12.7%, and decreased the acetoin titer by 44.3%. However, the process also enhanced lactate and succinate production. Excess BDH increased the 2,3-BD yield by 16.6% while decreasing acetoin, lactate and succinate production, but prolonged the fermentation time. When BDH and GAPDH were co-overproduced in B. amyloliquefaciens, the fermentation time was reduced. Furthermore, in the NADH-dependent pathways, the molar yield of 2,3-BD was increased by 22.7%, while those of acetoin, lactate and succinate were reduced by 80.8%, 33.3% and 39.5%, relative to the parent strain. In fed-batch fermentations, the 2,3-BD concentration was maximized at 132.9 g/l after 45 h, with a productivity of 2.95 g/l·h. CONCLUSIONS/SIGNIFICANCE: Co-overexpression of bdh and gapA genes proved an effective method for enhancing 2,3-BD production and inhibiting the accumulation of unwanted by-products (acetoin, lactate and succinate. To our knowledge, we have attained the highest 2,3-BD fermentation yield thus far

  11. Isolation and structural analysis of bamylocin A, novel lipopeptide from Bacillus amyloliquefaciens LP03 having antagonistic and crude oil-emulsifying activity.

    Science.gov (United States)

    Lee, Sang-Cheol; Kim, Sun-Hee; Park, In-Hye; Chung, Soo-Yeol; Choi, Yong-Lark

    2007-10-01

    Bacillus amyloliquefaciens strain LP03 isolated from soil, produced an antagonistic compound that strongly inhibited the growth of plant-pathogenic fungi and a lipopeptide biosurfactant. Also, isolated strain LP03 had a marked crude oil-emulsifying activity as it developed a clear zone around the colony after incubation for 24 h at 37 degrees C. LP03 was identified as Bacillus amyloliquefaciens by analysis of partial 16 S rRNA gene and partial gyrA gene sequence. The lipopeptide was purified by acid precipitation of cell-free culture broth, extraction of the precipitates with methanol, silica gel column chromatography, and reverse-phase, high-pressure liquid chromatography. The purified biosurfactant was analyzed biochemical structure by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) and electrospray ionization mass spectrometry/mass spectrometry (ESI-MS/MS). The masses of the two peaks were observed by HPLC chromatography. Their masses were determined to be 1,044 and 1,058 m/z with MALDI-TOF mass spectrometry. As constituents of the peptide and lipophilic part of the m/z 1,022.6, seven amino acids (Glu-Leu-Met-Leu-Pro-Leu-Leu) and beta-hydroxy-C13 fatty acid were determined by ESI-MS/MS. The lipopeptide of 1,022.6 Da differed from surfactins in the substitution of leucine, valine and aspartic acid in positions 3, 4, and 5 by methionine, leucine, and proline, respectively. Novel lipopeptide was designated as bamylocin A. PMID:17530228

  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. [Effects of pH and oxygen supply on production of 2,3-butanediol from biodiesel-derived glycerol by Bacillus amyloliquefaciens].

    Science.gov (United States)

    Yang, Taowei; Rao, Zhiming; Zhang, Xian; Xu, Meijuan; Xu, Zhenghong

    2013-12-01

    Bacillus amyloliquefaciens B10-127 was used to produce 2,3-butanediol (2,3-BD) from residual glycerol obtained from biodiesel synthesis. Important variables for 2,3-BD fermentation, pH and dissolved oxygen, were studied. When pH was maintained constant, the yield of 2,3-BD was inhibited. The highest 2,3-BD yields were achieved by fermentation without any pH control with an optimized initial pH 6.5. Batch fermentative production of 2,3-BD by B. amyloliquefaciens was investigated using various oxygen supply methods by changing agitation speed. Based on the analysis of three kinetic parameters including specific cell growth rate (micro), specific glucose consumption rate (q(s)) and specific 2,3-BD formation rate (q(p)), a three-stage agitation speed control strategy was proposed, aimed at achieving high concentration, high yield and high productivity of 2,3-BD. Maximum concentration of 2,3-BD reached 38.1 g/L, with the productivity of 1.06 g/(L x h), which were 14.8% and 63.1% over the best results from constant agitation speeds. In a pulse fed-batch fermentation, 2,3-BD concentration and productivity were significantly improved to 71.2 g/L and 0.99 g/(L x h), respectively. To our knowledge, these results were the highest for 2,3-BD production from biodiesel-derived glycerol. PMID:24660634

  14. 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。

  15. Cloning of the Endoglucanase Gene from a Bacillus amyloliquefaciens PSM 3.1 in Escherichia coli Revealed Catalytic Triad Residues Thr-His-Glu

    Directory of Open Access Journals (Sweden)

    Zeily Nurachman

    2010-01-01

    Full Text Available Problem statement:  An Indonesian marine bacterial isolate, Bacillus amyloliquefaciens PSM 3.1 was isolated for hydrolyzing cellulose. A 1500-bp nucleotide fragment was amplified from the chromosomal DNA by the use of primers directed against the conserved sequence of Bacilli endoglucanase genes obtained from GenBank. Approach: The fragment was cloned and expressed in Escherichia coli. Results: The endoglucanase gene (eglII gene had an open reading frame of 1500 nucleotides encoding a protein of 499 amino acids. The EglII protein belonged to Glycosyl Hydrolase family 5 (GH5 with a Cellulose Binding Module 3 (CBM 3. The structure model of the EglII protein revealed that the catalytic residues seemed to be Glu169 (as proton donor and Glu257 (as nucleophile and the catalytic triad residues were Thr256, His229 and Glu169. The EglII endoglucanase exhibited an optimum pH of 6.0 and temperature of 50°C and the enzyme tolerated to high salt concentration. Conclusion/Recommendations: This EglII endoglucanase is a promising candidate for many applications in biomass degradation.

  16. Response of tomato wilt pathogen Ralstonia solanacearum to the volatile organic compounds produced by a biocontrol strain Bacillus amyloliquefaciens SQR-9

    Science.gov (United States)

    Raza, Waseem; Ling, Ning; Yang, Liudong; Huang, Qiwei; Shen, Qirong

    2016-01-01

    It is important to study the response of plant pathogens to the antibiosis traits of biocontrol microbes to design the efficient biocontrol strategies. In this study, we evaluated the role of volatile organic compounds (VOCs) produced by a biocontrol strain Bacillus amyloliquefaciens SQR-9 on the growth and virulence traits of tomato wilt pathogen Ralstonia solanacearum (RS). The VOCs of SQR-9 significantly inhibited the growth of RS on agar medium and in soil. In addition, the VOCs significantly inhibited the motility traits, production of antioxidant enzymes and exopolysaccharides, biofilm formation and tomato root colonization by RS. The strain SQR-9 produced 22 VOCs, but only nine VOCs showed 1–11% antibacterial activity against RS in their corresponding amounts; however, the consortium of all VOCs showed 70% growth inhibition of RS. The proteomics analysis showed that the VOCs of SQR-9 downregulated RS proteins related to the antioxidant activity, virulence, carbohydrate and amino acid metabolism, protein folding and translation, while the proteins involved in the ABC transporter system, amino acid synthesis, detoxification of aldehydes and ketones, methylation, protein translation and folding, and energy transfer were upregulated. This study describes the significance and effectiveness of VOCs produced by a biocontrol strain against tomato wilt pathogen. PMID:27103342

  17. Biocontrol traits and antagonistic potential of Bacillus amyloliquefaciens strain NJZJSB3 against Sclerotinia sclerotiorum, a causal agent of canola stem rot.

    Science.gov (United States)

    Wu, Yuncheng; Yuan, Jun; Raza, Waseem; Shen, Qirong; Huang, Qiwei

    2014-10-01

    Bacillus amyloliquefaciens strain NJZJSB3 has shown antagonism of several phytopathogens in vitro, especially Sclerotinia sclerotiorum. Both the broth culture and cell suspension of strain NJZJSB3 could completely protect the detached leaves of canola (Brassica napus) from S. sclerotiorum infection. In pot experiments, the application of strain NJZJSB3 cell suspension (10(8) CFU/ml) decreased the disease incidence by 83.3%, a result similar to commercially available fungicide (Dimetachlone). In order to investigate the potential biocontrol mechanisms of strain NJZJSB3, the nonvolatile antifungal compounds it produces were identified as iturin homologs using HPLC-ESI-MS. Antifungal volatile organic compounds were identified by gas chromatography-mass spectrometry. The detected volatiles toluene, phenol, and benzothiazole showed antifungal effects against S. sclerotiorum in chemical control experiments. Strain NJZJSB3 also produced biofilm, siderophores and cell-wall-degrading enzymes (protease and β-1,3-glucanase). These results suggest that strain NJZJSB3 can be a tremendous potential agent for the biological control of sclerotinia stem rot. PMID:24861342

  18. Plant growth-promoting rhizobacteria strain Bacillus amyloliquefaciens NJN-6-enriched bio-organic fertilizer suppressed Fusarium wilt and promoted the growth of banana plants.

    Science.gov (United States)

    Yuan, Jun; Ruan, Yunze; Wang, Beibei; Zhang, Jian; Waseem, Raza; Huang, Qiwei; Shen, Qirong

    2013-04-24

    Bacillus amyloliquefaciens strain NJN-6 is an important plant growth-promoting rhizobacteria (PGPR) which can produce secondary metabolites antagonistic to several soil-borne pathogens. In this study, the ability of a bio-organic fertilizer (BIO) containing NJN-6 strain to promote the growth and suppress Fusarium wilt of banana plants was evaluated in a pot experiment. The results showed that the application of BIO significantly decreased the incidence of Fusarium wilt and promoted the growth of banana plants compared to that for the organic fertilizer (OF). To determine the beneficial mechanism of the strain, the colonization of NJN-6 strain on banana roots was evaluated using scanning electron microscopy (SEM). The plant growth-promoting hormones indole-3-acetic acid (IAA) and gibberellin A3 (GA3), along with antifungal lipopeptides iturin A, were detected when the NJN-6 strain was incubated in both Landy medium with additional l-tryptophan and in root exudates of banana plants. In addition, some antifungal volatile organic compounds and iturin A were also detected in BIO. In summary, strain NJN-6 could colonize the roots of banana plants after the application of BIO and produced active compounds which were beneficial for the growth of banana plants. PMID:23541032

  19. Response of tomato wilt pathogen Ralstonia solanacearum to the volatile organic compounds produced by a biocontrol strain Bacillus amyloliquefaciens SQR-9.

    Science.gov (United States)

    Raza, Waseem; Ling, Ning; Yang, Liudong; Huang, Qiwei; Shen, Qirong

    2016-01-01

    It is important to study the response of plant pathogens to the antibiosis traits of biocontrol microbes to design the efficient biocontrol strategies. In this study, we evaluated the role of volatile organic compounds (VOCs) produced by a biocontrol strain Bacillus amyloliquefaciens SQR-9 on the growth and virulence traits of tomato wilt pathogen Ralstonia solanacearum (RS). The VOCs of SQR-9 significantly inhibited the growth of RS on agar medium and in soil. In addition, the VOCs significantly inhibited the motility traits, production of antioxidant enzymes and exopolysaccharides, biofilm formation and tomato root colonization by RS. The strain SQR-9 produced 22 VOCs, but only nine VOCs showed 1-11% antibacterial activity against RS in their corresponding amounts; however, the consortium of all VOCs showed 70% growth inhibition of RS. The proteomics analysis showed that the VOCs of SQR-9 downregulated RS proteins related to the antioxidant activity, virulence, carbohydrate and amino acid metabolism, protein folding and translation, while the proteins involved in the ABC transporter system, amino acid synthesis, detoxification of aldehydes and ketones, methylation, protein translation and folding, and energy transfer were upregulated. This study describes the significance and effectiveness of VOCs produced by a biocontrol strain against tomato wilt pathogen. PMID:27103342

  20. 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

  1. 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.

  2. Effect of organic fertilizers prepared from organic waste materials on the production of antibacterial volatile organic compounds by two biocontrol Bacillus amyloliquefaciens strains.

    Science.gov (United States)

    Raza, Waseem; Wei, Zhong; Ling, Ning; Huang, Qiwei; Shen, Qirong

    2016-06-10

    Three organic fertilizers made of different animal and plant waste materials (BOFs) were evaluated for their effects on the production of antibacterial volatile organic compounds (VOCs) by two Bacillus amyloliquefaciens strains SQR-9 and T-5 against the tomato wilt pathogen Ralstonia solanacearum (RS). Both strains could produce VOCs that inhibited the growth and virulence traits of RS; however, in the presence of BOFs, the production of antibacterial VOCs was significantly increased. The maximum inhibition of growth and virulence traits of RS by VOCs of T-5 and SQR-9 was determined at 1.5% BOF2 and 2% BOF3, respectively. In case of strain T-5, 2-nonanone, nonanal, xylene, benzothiazole, and butylated hydroxy toluene and in case of strain SQR-9, 2-nonanone, nonanal, xylene and 2-undecanone were the main antibacterial VOCs whose production was increased in the presence of BOFs. The results of this study reveal another significance of using organic fertilizers to improve the antagonistic activity of biocontrol agents against phytopathogens. PMID:27067079

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

    Science.gov (United States)

    Chowdhury, Soumitra Paul; Dietel, Kristin; Rändler, Manuela; Schmid, Michael; Junge, Helmut; Borriss, Rainer; Hartmann, Anton; Grosch, Rita

    2013-01-01

    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. PMID:23935892

  4. 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

  5. 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.

  6. 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.

  7. 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

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

    Science.gov (United States)

    Gong, An-Dong; Li, He-Ping; Yuan, Qing-Song; Song, Xiu-Shi; Yao, Wei; He, Wei-Jie; Zhang, Jing-Bo; Liao, Yu-Cai

    2015-01-01

    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. PMID:25689464

  9. 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.

  10. 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

  11. Cyclic Lipopeptides of Bacillus amyloliquefaciens subsp. plantarum Colonizing the Lettuce Rhizosphere Enhance Plant Defense Responses Toward the Bottom Rot Pathogen Rhizoctonia solani.

    Science.gov (United States)

    Chowdhury, Soumitra Paul; Uhl, Jenny; Grosch, Rita; Alquéres, Sylvia; Pittroff, Sabrina; Dietel, Kristin; Schmitt-Kopplin, Philippe; Borriss, Rainer; Hartmann, Anton

    2015-09-01

    The commercially available inoculant Bacillus amyloliquefaciens FZB42 is able to considerably reduce lettuce bottom rot caused by Rhizoctonia solani. To understand the interaction between FZB42 and R. solani in the rhizosphere of lettuce, we used an axenic system with lettuce bacterized with FZB42 and inoculated with R. solani. Confocal laser scanning microscopy showed that FZB42 could delay the initial establishment of R. solani on the plants. To show which secondary metabolites of FZB42 are produced under these in-situ conditions, we developed an ultra-high performance liquid chromatography coupled to time of flight mass spectrometry-based method and identified surfactin, fengycin, and bacillomycin D in the lettuce rhizosphere. We hypothesized that lipopeptides and polyketides play a role in enhancing the plant defense responses in addition to the direct antagonistic effect toward R. solani and used a quantitative real-time polymerase chain reaction-based assay for marker genes involved in defense signaling pathways in lettuce. A significant higher expression of PDF 1.2 observed in the bacterized plants in response to subsequent pathogen challenge showed that FZB42 could enhance the lettuce defense response toward the fungal pathogen. To identify if surfactin or other nonribosomally synthesized secondary metabolites could elicit the observed enhanced defense gene expression, we examined two mutants of FZB42 deficient in production of surfactin and the lipopetides and polyketides, by expression analysis and pot experiments. In the absence of surfactin and other nonribosomally synthesized secondary metabolites, there was no enhanced PDF 1.2-mediated response to the pathogen challenge. Pot experiment results showed that the mutants failed to reduce disease incidence in lettuce as compared with the FZB42 wild type, indicating, that surfactin as well as other nonribosomally synthesized secondary metabolites play a role in the actual disease suppression and on lettuce

  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. 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

  15. 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...

  16. 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。

  17. 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.

  18. 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 ...

  19. Topraktan İzole Edilen Bacillus Türlerinin Tanımlanması ve Bakteriosin Üretimlerinin Belirlenmesi

    OpenAIRE

    Topçal, Fadime; Dığrak, Metin; Gündoğan, Recep

    2014-01-01

    In this study, Bacillus sp. was isolated from the soil seeded with Hordeum sp. and Vicia sp. and was identified. 121 Bacillus isolates were derived from soil samples. It was determined that 114 isolates gave 16SrRNA pcr products with primers specific for Bacillus genus. Classical methods were used to identify the species: Bacillus subtilis, B. mycoides, B. megaterium and B. amyloliquefaciens species. It was determined that metabolic products of four isolates inhibited Escherichia coli and Mic...

  20. Increase of the a-amylase yield by Some Bacillus Strains

    OpenAIRE

    SARIKAYA, Elif

    2000-01-01

    In order to obtain high amounts of a-amylase enzyme from Bacillus bacteria a new medium was developed. In this medium, three strains of Bacillus bacteria were grown in the presence of different carbon, nitrogen and metal ions. The highest a-amylase yield was obtained by addition of Na-citrate, strach and sucrose for the strains of B. subtilis, B. amyloliquefaciens I and B. amyloliquefaciens II, respectively. As a nitrogen source, yeast extract was found to be effective on enzyme yield for...

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

    OpenAIRE

    Supuk Mahadtanapuk; Mondhon Sanguansermsri; Robert W. Cutler; Vicha Sardsud; Somboon Anuntalabhochai

    2007-01-01

    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 ...

  2. The ultrasound-assisted extraction and identification of antifungal substances from B. amyloliquefaciens strain NJN-6 suppressing Fusarium oxysporum.

    Science.gov (United States)

    Yuan, Jun; Raza, Waseem; Huang, Qiwei; Shen, Qirong

    2012-12-01

    The primary mechanism underlying antagonism among microorganisms is the production of antagonistic substances called antibiotics that inhibit the growth of pathogens. In this study, the antagonistic substances produced by the Bacillus amyloliquefaciens strain NJN-6 that had antifungal activity against Fusarium oxysporum were extracted and identified. The active antifungal substance was extracted from dried leavening with ultrasound-assisted extraction (UAE), using n -butanol as the extractant. HPLC/ESI-MS was performed to investigate the components of the extracts. The results of the study showed that the antimicrobial substances consisted of three homologues of the iturin A family with molecular weights of 1043, 1057 and 1071 Da and of two homologues of the fengycin family with molecular weights of 1477 and 1491 Da. The effects of ultrasonic treatment time, extraction time and extractant volume, three major methodological parameters, were also studied to determine the optimal conditions for extraction. Compared with traditional extraction techniques, UAE is a simple, cheap and environmentally friendly method that represents a new option for the isolation and identification of lipopeptides and other active compounds. These antifungal substances extracted and identified from Bacillus amyloliquefaciens NJN-6 will help us to understand its biocontrol mechanism against Fusarium oxysporum. PMID:22581589

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. Isolation of enriched-yielders and fed-batch production of alkaline protease from the newly isolated Bacillus sp. BHA

    OpenAIRE

    Bhawana Agarwal; Brajesh S. Katiyar

    2013-01-01

    An alkalophilc and thermophilic Bacillus sp. BHA that produced a thermostable alkaline protease was isolated from decaying protein substrates. The isolate was found to grow in pH range 7 - 11 with an optimum pH 9.0 and temperature up to 55℃. The activity of alkaline protease of Bacillus sp. BHA (68.98 APU/ml) was found higher than the standard strains of Bacillus amyloliquefaciens MTCC 610 (8.98 APU/ml) and Bacillus subtilis MTCC 8349 (12.14 APU/ml, used in this study, and was comparable (68...

  8. Studies of plant interactions with other organisms to understand Bacillus mediated stress management

    OpenAIRE

    Johansson, Anna

    2013-01-01

    The naturally evolved plant defense system is not always effective, due to adaptations among the attackers. Crop protective chemicals have many negative effects on the environment. Ecosystem services, like beneficial microorganisms, are of great interest for plant stress management in sustainable crop production. In this study, the rhizobacterium Bacillus amyloliquefaciens, known to protect oilseed rape (Brassica napus) to fungal diseases, was investigated. The aims were to tes...

  9. 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

  10. 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.

  11. Bacillus coagulans

    Science.gov (United States)

    ... and, as a result, is often misclassified as lactic acid bacteria such as lactobacillus. In fact, some commercial products ... sporogenes or "spore-forming lactic acid bacterium." Unlike lactic acid bacteria such as lactobacillus or bifidobacteria, Bacillus coagulans forms ...

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

    OpenAIRE

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

    2013-01-01

    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...

  13. Expression of essential genes for biosynthesis of antimicrobial peptides of Bacillus is modulated by inactivated cells of target microorganisms.

    Science.gov (United States)

    Leães, Fernanda Leal; Velho, Renata Voltolini; Caldas, Danielle Gregório Gomes; Ritter, Ana Carolina; Tsai, Siu Mui; Brandelli, Adriano

    2016-01-01

    Certain Bacillus strains are important producers of antimicrobial peptides with great potential for biological control. Antimicrobial peptide production by Bacillus amyloliquefaciens P11 was investigated in the presence of heat-inactivated cells of bacteria and fungi. B. amyloliquefaciens P11 exhibited higher antimicrobial activity in the presence of inactivated cells of Staphylococcus aureus and Aspergillus parasiticus compared to other conditions tested. Expression of essential genes related to biosynthesis of the antimicrobial peptides surfactin (sfp), iturin A (lpa-14 and ituD), subtilosin A (sboA) and fengycin (fenA) was investigated by quantitative real-time PCR (qRT-PCR). The genes lpa-14 and ituD were highly expressed in the presence of S. aureus (inactivated cells), indicating induction of iturin A production by B. amyloliquefaciens P11. The other inducing condition (inactivated cells of A. parasiticus) suppressed expression of lpa-14, but increased expression of ituD. A twofold increase in fenA expression was observed for both conditions, while strong suppression of sboA expression was observed in the presence of inactivated cells of S. aureus. An increase in antimicrobial activity was observed, indicating that synthesis of antimicrobial peptides may be induced by target microorganisms. PMID:26577655

  14. 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.

  15. [Screening and identification of low temperature-adapted antagonistic Bacillus isolated from Kekexili region of West China and the analysis of the isolates lipopeptide compounds].

    Science.gov (United States)

    Xie, Yong-Li; Gao, Xue-Wen

    2013-01-01

    The research and exploitation of special microbial resources in extreme environment is of scientific significance and has broad applied prospect. In this paper, eight Bacillus strains isolated from the vegetation rhizospheres in Kekexili extreme region of Qinghai Province and presented good growth status at low temperature 4 and 10 degrees C were identified. Through physiological and biochemical analysis, rep-PCR fingerprinting, and 16S rDNA and gyrB partial sequence analyses, the eight strains were identified as Bacillus mojavensis (3 isolates), Bacillus amyloliquefaciens (1 isolate), and Bacillus simplex (4 isolates). The agar plate antagonistic test showed that four of the isolates presented distinct antagonistic activity to Sclerotinia sclerotiorum and Xanthomonas oryzae pv. oryzae. The MALDI-TOF-MS analysis showed that the strain KKD1 (B. mojavensis) produced fengycin and surfactin, whereas the strain KKD2 (B. amyloliquefaciens) produced iturin A, surfactin and fengycin, suggesting that the bio-control efficacy of the Bacillus strains could be related to the synthesis and excretion of the antifungal lipopeptide compounds. This study provided the bacterial resources for the research and exploitation of low temperature-adapted Bacillus bio-fertilizers and bio-pesticides. PMID:23718003

  16. 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)

  17. 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).

  18. 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...

  19. 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...

  20. Non-magnetic compensation in ferromagnetic Ga1-xMnxAs and Ga1-xMnxP synthesized by ion implantation and pulsed-laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Scarpulla, M.A.; Stone, P.R.; Sharp, I.D.; Haller, E.E.; Dubon, O.D.; Beeman, J.W.; Yu, K.M.

    2008-02-05

    The electronic and magnetic effects of intentional compensation with non-magnetic donors are investigated in the ferromagnetic semiconductors Ga1-xMnxAs and Ga1-xMnxP synthesized using ion implantation and pulsed-laser melting (II-PLM). It is demonstrated that compensation with non-magnetic donors and MnI have similarqualitative effects on materials properties. With compensation TC decreases, resistivity increases, and stronger magnetoresistance and anomalous Hall effect attributed to skew scattering are observed. Ga1-xMnxAs can be controllably compensated with Te through a metal-insulator transition through which the magnetic and electrical properties vary continuously. The resistivity of insulating Ga1-xMnxAs:Te can be described by thermal activation to the mobility edge and simply-activated hopping transport. Ga1-xMnxP doped with S is insulating at all compositions but shows decreasing TC with compensation. The existence of a ferromagnetic insulating state in Ga1-xMnxAs:Te and Ga1-xMnxP:S having TCs of the same order as the uncompensated materials demonstrates that localized holes are effective at mediating ferromagnetism in ferromagnetic semiconductors through the percolation of ferromagnetic 'puddles' which at low temperatures.

  1. 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

  2. Purification and crystallization of α-amylases from mucoid and non-mucoid B. amyloliquefaciens strains

    Science.gov (United States)

    Sarikaya, Elif; Mikami, Bunzo

    2001-11-01

    The purified α-amylases from mucoid and non-mucoid B. amyloliquefaciens strains were crystallized in forms suitable for X-ray diffraction analysis. Crystals were grown by the hanging-drop vapor diffusion method. Very thin crystals of α-amylase of non-mucoid strain were obtained in the presence 15% propanol, 12% PEG 6000 and 0.1 M PIPES (pH: 7.1) at the end of 3 months and these were not suitable for X-ray diffraction analysis. Crystals of the mucoid strain of B. amyloliquefaciens α-amylase were obtained with 30% PEG 6000, 0.2 M (NH 4) 2SO 4 and 0.1 M PIPES (pH: 6.5) at the end of 3 months and these were suitable for X-ray diffraction analysis.

  3. Genomics of Bacillus Species

    Science.gov (United States)

    Økstad, Ole Andreas; Kolstø, Anne-Brit

    Members of the genus Bacillus are rod-shaped spore-forming bacteria belonging to the Firmicutes, the low G+C gram-positive bacteria. The Bacillus genus was first described and classified by Ferdinand Cohn in Cohn (1872), and Bacillus subtilis was defined as the type species (Soule, 1932). Several Bacilli may be linked to opportunistic infections. However, pathogenicity among Bacillus spp. is mainly a feature of bacteria belonging to the Bacillus cereus group, including B. cereus, Bacillus anthracis, and Bacillus thuringiensis. Here we review the genomics of B. cereus group bacteria in relation to their roles as etiological agents of two food poisoning syndromes (emetic and diarrhoeal).

  4. 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...

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Taxonomy Icon Data: Bacillus subtilis [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available Bacillus subtilis Bacillus subtilis Bacillus_subtilis_L.png Bacillus_subtilis_NL.png 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.j...p/taxonomy_icon/icon.cgi?i=Bacillus+subtilis&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Bacillus

  14. Band gaps of wurtzite ScxGa1−xN alloys

    International Nuclear Information System (INIS)

    Optical transmittance measurements on epitaxial, phase-pure, wurtzite-structure ScxGa1−xN films with 0 ≤ x ≤ 0.26 showed that their direct optical band gaps increased from 3.33 eV to 3.89 eV with increasing x, in agreement with theory. These films contained I1- and I2-type stacking faults. However, the direct optical band gaps decreased from 3.37 eV to 3.26 eV for ScxGa1−xN films, which additionally contained nanoscale lamellar inclusions of the zinc-blende phase, as revealed by aberration-corrected scanning transmission electron microscopy. Therefore, we conclude that the apparent reduction in ScxGa1−xN band gaps with increasing x is an artefact resulting from the presence of nanoscale zinc-blende inclusions

  15. Properties of Ferromagnetic Ga1-xMnxN Films Grown by Ammonia-MBE

    OpenAIRE

    Sonoda, Saki; Hori, Hidenobu; Yamamoto, Yoshiyuki; Sasaki, Takahiko; Sato, Masugu; Shimizu, Saburo; Suga, Ken-ichi; Kindo, Koichi

    2002-01-01

    Using ammonia as nitrogen source for molecular beam epitaxy, the GaN-based diluted magnetic semiconductor Ga1-xMnxN is successfully grown with Mn concentration up to x~6.8% and with p-type conductivity. The films have wurtzite structure with substitutional Mn on Ga site in GaN. Magnetization measurements revealed that Ga1-xMnxN is ferromagnetic at temperatures higher than room temperature. The ferromagnetic-paramagnetic transition temperature, Tc, depends on the Mn concentration of the film. ...

  16. 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...

  17. 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...

  18. Characterization of Bacillus isolates of potato rhizosphere from andean soils of Peru and their potential PGPR characteristics

    Directory of Open Access Journals (Sweden)

    Pamela Calvo

    2010-12-01

    Full Text Available Bacillus spp. are well known rhizosphere residents of many crops and usually show plant growth promoting (PGP activities that include biocontrol capacity against some phytopatogenic fungi. Potato crops in the Andean Highlands of Peru face many nutritional and phytophatogenic problems that have a significant impact on production. In this context is important to investigate the natural presence of these microorganisms in the potato rhizosphere and propose a selective screening to find promising PGP strains. In this study, sixty three Bacillus strains isolated from the rhizosphere of native potato varieties growing in the Andean highlands of Peru were screened for in vitro antagonism against Rhizoctonia solani and Fusarium solani. A high prevalence (68% of antagonists against R. solani was found. Ninety one percent of those strains also inhibited the growth of F. solani. The antagonistic strains were also tested for other plant growth promotion activities. Eighty one percent produced some level of the auxin indole-3-acetic acid, and 58% solubilized tricalcium phosphate. Phylogenetic analysis revealed that the majority of the strains belonged to the B. amyloliquefaciens species, while strains Bac17M11, Bac20M1 and Bac20M2 may correspond to a putative new Bacillus species. The results suggested that the rhizosphere of native potatoes growing in their natural habitat in the Andes is a rich source of Bacillus fungal antagonists, which have a potential to be used in the future as PGP inoculants to improve potato crop.

  19. Effects of Si-doping on magnetic properties of Ga1−xCrxN

    International Nuclear Information System (INIS)

    Ga1−xCrxN thin films with and without the Si doping have been prepared by molecular beam epitaxy. The samples have been investigated by X-ray diffraction, X-ray photoemission spectroscopy, photoluminescence, optical absorption spectra and magnetic measurements. It has been confirmed that for the undoped samples Cr in GaN is predominantly trivalent when substituting for Ga and that the Cr 3d state appears within the band gap of GaN. In Si doped specimens the upward shifts of the chemical potential are observed, and the electrons supplied by the Si doping are trapped at Cr sites forming Cr2+. As a result, the Si doping effects show an increase of the Curie temperature, and a reduction of the saturation magnetization in the Ga1−xCrxN:Si samples. The significant effect on the ferromagnetism with Si doping in Ga1−xCrxN is explained by the percolation theory of bound magnetic polarons. - Highlights: • Clarify the mechanism of the room temperature ferromagnetism in Ga1−xCrxN. • The upward chemical-potential shift caused by the Si doping is confirmed

  20. Hydrogen patterning of Ga1-xMnxAs for planar spintronics

    International Nuclear Information System (INIS)

    We demonstrate two patterning techniques based on hydrogen passivation of Ga1-xMnxAs to produce isolated ferromagnetically active regions embedded uniformly in a paramagnetic, insulating host. The first method consists of selective hydrogenation of Ga1-xMnxAs by lithographic masking. Magnetotransport measurements of Hall-bars made in this manner display the characteristic properties of the hole-mediated ferromagnetic phase, which result from good pattern isolation. Arrays of Ga1-xMnxAs dots as small as 250 nm across have been realized by this process. The second process consists of blanket hydrogenation of Ga1-xMnxAs followed by local reactivation using confined low-power pulsed-laser annealing. Conductance imaging reveals local electrical reactivation of micrometer-sized regions that accompanies the restoration of ferromagnetism. The spatial resolution achievable with this method can potentially reach <100 nm by employing near-field laser processing. The high spatial resolution attainable by hydrogenation patterning enables the development of systems with novel functionalities such as lateral spin-injection as well as the exploration of magnetization dynamics in individual and coupled structures made from this novel class of semiconductors

  1. Tunnel optical radiation in InxGa1-xN

    Science.gov (United States)

    Alexandrov, Dimiter; Skerget, Shawn

    2014-02-01

    An investigation of tunnel optical radiation in epitaxial layers of n-type InxGa1-xN grown on p-type GaN by novel plasma based migration enhanced epitaxy is presented. Experimental results of electro-luminescence spectra for InxGa1-xN/p-GaN hetero-junctions were obtained and they show two well expressed optical bands - one in range 500-540 nm and other in range 550-610 nm. An interesting detail is that each band begins and ends by sharp drops of the radiation, which nearly approach zero. A theoretical investigation of the unusual behavior of these spectra was done using LCAO electron band structure calculations. The optical ranges of these bands show that the radiation occurs in the InxGa1-xN region. In fact, substitutions of In atoms in Ga sites creates defects in the structure of InxGa1-xN and the corresponding LCAO matrix elements are found on this basis. The LCAO electron band structures are calculated considering the interactions between nearest-neighbor orbitals. Electron energy pockets are found in both the conduction and the valence bands at the Γ point of the electron band structures. Also it is found that these pockets are separated by distances, for which there is overlapping between the electron wave functions describing localized states belonging to the pockets, and as a result tunnel optical radiation can take place. This type of electron transition - between such a pocket in the conduction band and a pocket in the valence band - occurs in InxGa1-xN, causing the above described optical bands. This conclusion concurs with the fact that the shapes of these bands change with change of the applied voltage.

  2. Tunnel optical radiation in InxGa1−xN

    International Nuclear Information System (INIS)

    An investigation of tunnel optical radiation in epitaxial layers of n-type InxGa1−xN grown on p-type GaN by novel plasma based migration enhanced epitaxy is presented. Experimental results of electro-luminescence spectra for InxGa1−xN/p−GaN hetero-junctions were obtained and they show two well expressed optical bands - one in range 500-540 nm and other in range 550-610 nm. An interesting detail is that each band begins and ends by sharp drops of the radiation, which nearly approach zero. A theoretical investigation of the unusual behavior of these spectra was done using LCAO electron band structure calculations. The optical ranges of these bands show that the radiation occurs in the InxGa1−xN region. In fact, substitutions of In atoms in Ga sites creates defects in the structure of InxGa1−xN and the corresponding LCAO matrix elements are found on this basis. The LCAO electron band structures are calculated considering the interactions between nearest-neighbor orbitals. Electron energy pockets are found in both the conduction and the valence bands at the Γ point of the electron band structures. Also it is found that these pockets are separated by distances, for which there is overlapping between the electron wave functions describing localized states belonging to the pockets, and as a result tunnel optical radiation can take place. This type of electron transition - between such a pocket in the conduction band and a pocket in the valence band - occurs in InxGa1−xN, causing the above described optical bands. This conclusion concurs with the fact that the shapes of these bands change with change of the applied voltage

  3. 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.

  4. 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

  5. BacillusRegNet

    DEFF Research Database (Denmark)

    Misirli, Goksel; Hallinan, Jennifer; Röttger, Richard;

    2014-01-01

    interactions. There is a need to develop new platform technologies that can be applied to the investigation of whole-genome datasets in an efficient and cost-effective manner. One such approach is the transfer of existing knowledge from well-studied organisms to closely-related organisms. In this paper, we...... associated BacillusRegNet website (http://bacillus.ncl.ac.uk)....

  6. Controlling a three dimensional electron slab of graded AlxGa1−xN

    International Nuclear Information System (INIS)

    Polarization induced degenerate n-type doping with electron concentrations up to ∼1020 cm−3 is achieved in graded AlxGa1−xN layers (x: 0% → 37%) grown on unintentionally doped and on n-doped GaN:Si buffer/reservoir layers by metal organic vapor phase epitaxy. High resolution x-ray diffraction, transmission electron microscopy, and electron dispersive x-ray spectroscopy confirm the gradient in the composition of the AlxGa1−xN layers, while Hall effect studies reveal the formation of a three dimensional electron slab, whose conductivity can be adjusted through the GaN(:Si) buffer/reservoir

  7. 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.

  8. Photoluminescence of energetic particle-irradiated InxGa1-xN alloys

    International Nuclear Information System (INIS)

    A study of the photoluminescence characteristics of InxGa1-xN alloys in which the Fermi level is controlled by energetic particle irradiation is reported. In In-rich InxGa1-xN the photoluminescence intensity initially increases with irradiation dose before falling rapidly at high doses. This unusual trend is attributed to the high location of the average energy of the dangling-bond-type native defects (the Fermi level stabilization energy). Our calculations of the photoluminescence intensity based on the effect of the electron concentration and the minority carrier lifetime show good agreement with the experimental data. Finally the blueshift of the photoluminescence signal with increasing electron concentration is explained by the breakdown of momentum conservation due to the irradiation damage

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

    International Nuclear Information System (INIS)

    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

  10. Effect of annealing on magnetic and magnetotransport properties of Ga1-xMnxAs epilayers

    OpenAIRE

    Kuryliszyn-Kudelska, I.; Wojtowicz, T.; Liu, X; Furdyna, J. K.; Dobrowolski, W.; Domagala, J. Z.; Lusakowska, E.; Goiran, M.; Haanappel, E.; Portugall, O.

    2003-01-01

    High-field magnetic measurements performed with the use of magnetooptical Kerr effect (MOKE) in the polar configuration as well as high-field and low-field magnetotransport studies were carried out on Ga1-xMnxAs epilayers grown by low temperature molecular beam epitaxy, and subsequently annealed under various conditions. The structural investigations by means of high resolution XRD were also performed. We observe significant changes in magnetoresistivity curves, magnetization and strain intro...

  11. The double-faced DX center in AlxGa1-xAs

    International Nuclear Information System (INIS)

    New experimental data are presented, providing circumstancial evidence for a metastable character of the deep donor in AlxGa1-xAs:Si. The EMT (effective mass theory) branch of the double-well potential is well-established by PL (photoluminescence), absorption and PC (photoconductivity) measurements. The interrelation between the relaxed ('DX') and the unrelaxed branch is evidenced by PLE and ODMR results. (author) 16 refs., 6 figs

  12. Effect of annealing on magnetic and magnetotransport properties of Ga1-xMnxAs epilayers

    International Nuclear Information System (INIS)

    High-field magnetic measurements performed with the use of magnetooptical Kerr effect in the polar configuration as well as high-field and low-field magnetotransport studies were carried out on Ga1-xMnxAs epilayers grown by low-temperature molecular beam epitaxy, and subsequently annealed under various conditions. The structural investigations by means of high resolution XRD were also performed. We observe significant changes in magnetoresistivity curves, magnetization and strain introduced by the annealing

  13. 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. PMID:27161758

  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. Bacillus thuringiensis and Bacillus sphaericus biopesticides production.

    Science.gov (United States)

    el-Bendary, Magda A

    2006-01-01

    The long residual action and toxicity of the chemical insecticides have brought about serious environmental problems such as the emergence and spread of insecticide resistance in many species of vectors, mammalian toxicity, and accumulation of pesticide residues in the food chain. All these problems have highlighted the need for alternative biological control agents. Entomo-pathogenic Bacillus thuringiensis (Bt) and Bacillus sphaericus (Bs) are two safe biological control agents. They have attracted considerable interest as possible replacements for the chemical insecticides. Although microbial insecticides based on Bt and Bs are available for use, their high cost makes large-scale application impracticable in developing countries. This review focuses on the economic production of these two microorganisms by submerged fermentation and solid state fermentation using agro-industrial by-products and other wastes. PMID:16598830

  16. Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis—One Species on the Basis of Genetic Evidence

    OpenAIRE

    Helgason, Erlendur; Økstad, Ole Andreas; Dominique A. Caugant; Johansen, Henning A.; Fouet, Agnes; Mock, Michéle; Hegna, Ida; Kolstø, Anne-Brit

    2000-01-01

    Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis are members of the Bacillus cereus group of bacteria, demonstrating widely different phenotypes and pathological effects. B. anthracis causes the acute fatal disease anthrax and is a potential biological weapon due to its high toxicity. B. thuringiensis produces intracellular protein crystals toxic to a wide number of insect larvae and is the most commonly used biological pesticide worldwide. B. cereus is a probably ubiquitous so...

  17. 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...

  18. High-Temperature Hall Effect in Ga(1-x)Mn(x)As

    OpenAIRE

    Ruzmetov, D.; Scherschligt, J.; Baxter, David V.; Wojtowicz, T.; Liu, X; Sasaki, Y.; Furdyna, J. K.; Yu, K.M.; Walukiewicz, W.

    2003-01-01

    The temperature dependence of the Hall coefficient of a series of ferromagnetic Ga(1-x)Mn(x)As samples is measured in the temperature range 80K < T < 500K. We model the Hall coefficient assuming a magnetic susceptibility given by the Curie-Weiss law, a spontaneous Hall coefficient proportional to rho_xx^2(T), and including a constant diamagnetic contribution in the susceptibility. For all low resistivity samples this model provides excellent fits to the measured data up to T=380K and allows e...

  19. Effect of pressure on magnetic properties of U(Ga1-xSnx)3 alloys

    International Nuclear Information System (INIS)

    Magnetic susceptibilities, χ, of U(Ga1-xSnx)3 alloys (with x=0 and 0.45) were studied under pressures up to 2 kbar in the temperature range 64-300 K. For UGa3 the pressure dependence of the Neel temperature was found to be dTN/dP =-1.1±0.2 K/kbar. The obtained magnetovolume effect values, d ln χ/d ln V, and the results of detailed theoretical calculations of the electronic structure of UGa3 for different lattice parameters have been used to evaluate the volume dependence of the effective electron-electron interaction parameter. (orig.)

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Structural Analysis of InxGa1−xN/GaN MQWs by Different Experimental Methods

    International Nuclear Information System (INIS)

    Structural properties of InxGa1−xN/GaN multi-quantum wells (MQWs) grown on sapphire by metal organic chemical vapor deposition are investigated by synchrotron radiation x-ray diffraction (SRXRD), Rutherford backscattering/channelling (RBS/C) and high-resolution transmission electron microscopy. The sample consists of eight periods of InxGa1−xN/GaN wells of 2.1 nm thickness and 8.5 nm thickness of GaN barrier, and the results are very close, which verifies the accuracy of the three methods. The indium content in InxGa1−xN/GaN MQWs by SRXRD and RBS/C is estimated, and results are in general the same. By RBS/C random spectra, the indium atomic lattice substitution rate is 94.0%, indicating that almost all indium atoms in InxGa1−xN/GaN MQWs are at substitution, that the indium distribution of each layer in InxGa1−xN/GaN MQWs is very homogeneous and that the InxGa1−xN/GaN MQWs have a very good crystalline quality. It is not accurate to estimate indium content in InxGa1−xN/GaN MQWs by photoluminescence (PL) spectra, because the result from the PL experimental method is very different from the results by the SRXRD and RBS/C experimental methods. (cross-disciplinary physics and related areas of science and technology)

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.)

  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. Properties of (Ga1-x In x )2O3 over the whole x range.

    Science.gov (United States)

    Maccioni, M B; Ricci, F; Fiorentini, V

    2016-06-01

    Using density-functional ab initio theoretical techniques, we study (Ga1-x In x )2O3 in both its equilibrium structures (monoclinic [Formula: see text] and bixbyite) and over the whole range of composition. We establish that the alloy exhibits a large and temperature-independent miscibility gap. On the low-x side, the favored phase is isostructural with [Formula: see text]-Ga2O3; on the high-x side, it is isostructural with bixbyite In2O3. The miscibility gap opens between approximately 15% and 55% In content for the bixbyite alloy grown epitaxially on In2O3, and 15% and 85% In content for the free-standing bixbyite alloy. The gap, volume and band offsets to the parent compound also exhibit anomalies as function of x. Specifically, the offsets in epitaxial conditions are predominantly type-B staggered, but have opposite signs in the two end-of-range phases. PMID:26952634

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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...

  2. Pathogenomic Sequence Analysis of Bacillus cereus and Bacillus thuringiensis Isolates Closely Related to Bacillus anthracis

    OpenAIRE

    Han, Cliff S.; Xie, Gary; Challacombe, Jean F.; Altherr, Michael R.; Bhotika, Smriti S.; Bruce, David; Campbell, Connie S.; Campbell, Mary L.; Chen, Jin; Chertkov, Olga; Cleland, Cathy; Dimitrijevic, Mira; Doggett, Norman A.; Fawcett, John J.; Glavina, Tijana

    2006-01-01

    Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis are closely related gram-positive, spore-forming bacteria of the B. cereus sensu lato group. While independently derived strains of B. anthracis reveal conspicuous sequence homogeneity, environmental isolates of B. cereus and B. thuringiensis exhibit extensive genetic diversity. Here we report the sequencing and comparative analysis of the genomes of two members of the B. cereus group, B. thuringiensis 97-27 subsp. konkukian sero...

  3. 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

  4. Optical control of growth of AlxGa1 - xAs by organometallic molecular beam epitaxy

    Science.gov (United States)

    Aspnes, D. E.; Quinn, W. E.; Gregory, S.

    1990-12-01

    Using spectroellipsometry, we obtain information on the near-surface composition x of epitaxial AlxGa1-xAs layers during crystal growth by organometallic molecular beam epitaxy and use this information to regulate the flow of triethylaluminum to the growth surface. The resulting closed-loop control system maintains the imaginary part of the dielectric response of thick AlxGa1-xAs films constant to an equivalent compositional precision better than ±0.001 over extended periods of time.

  5. Photoelectrical and photoluminescent properties of varigap Ga(1-x)Al(x)As p-n structures

    Energy Technology Data Exchange (ETDEWEB)

    Annaev, K.; Berkeliev, A.; Bragin, E.V.; Nazarov, N.

    1984-01-01

    Optimum concentrations of the principal equilibrium holes are determined for n-GaAs-p-GaAs-p-Ga(1-x)Al(x)As structures with a thin varigap layer designed for high-efficiency photovoltaic applications. The results of the study confirm that the growth of thin epitaxial layers of Ga(1-x)Al(x)As layers on GaAs substrates using liquid capillary epitaxy results in the formation of a uniform varigap layer over the entire surface of the substrate. 6 references.

  6. 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

  7. 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

  8. 76 FR 14289 - Bacillus thuringiensis

    Science.gov (United States)

    2011-03-16

    ... AGENCY 40 CFR Part 174 Bacillus thuringiensis eCry3.1Ab Protein in Corn; Temporary Exemption From the... permissible level for residues of Bacillus thuringiensis eCry3.1Ab protein in corn. The temporary tolerance... Register of January 21, 2011 (76 FR 3885) (FRL-8855- 4), EPA issued a notice pursuant to section...

  9. 75 FR 34040 - Bacillus thuringiensis

    Science.gov (United States)

    2010-06-16

    ... AGENCY 40 CFR Part 174 Bacillus thuringiensis eCry3.1Ab Protein in Corn; Temporary Exemption from the... Bacillus thuringiensis eCry3.1Ab protein in corn under the FFDCA. The temporary tolerance exemption expires...) 305-5805. II. Background and Statutory Findings In the Federal Register of September 30, 2009 (74...

  10. 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.

  11. What is the Valence of Mn in Ga1 -xMnxN ?

    Science.gov (United States)

    Nelson, Ryky; Berlijn, Tom; Moreno, Juana; Jarrell, Mark; Ku, Wei

    2015-11-01

    We investigate the current debate on the Mn valence in Ga1 -xMnxN , a diluted magnetic semiconductor (DMS) with a potentially high Curie temperature. From a first-principles Wannier-function analysis, we unambiguously find the Mn valence to be close to 2 + (d5), but in a mixed spin configuration with average magnetic moments of 4 μB . By integrating out high-energy degrees of freedom differently, we further derive for the first time from first-principles two low-energy pictures that reflect the intrinsic dual nature of the doped holes in the DMS: (1) an effective d4 picture ideal for local physics, and (2) an effective d5 picture suitable for extended properties. In the latter, our results further reveal a few novel physical effects, and pave the way for future realistic studies of magnetism. Our study not only resolves one of the outstanding key controversies of the field, but also exemplifies the general need for multiple effective descriptions to account for the rich low-energy physics in many-body systems in general.

  12. Dynamical X-ray Diffraction from In x Ga1- x As Heterostructures with Dislocations

    Science.gov (United States)

    Rago, P. B.; Ayers, J. E.

    2013-08-01

    High-resolution x-ray diffraction is an important nondestructive tool for structural characterization of semiconductor heterostructures, and the diffraction intensity profiles contain information on the depth profiles of strain, composition, and defect densities in device heterostructures. Much of this information remains inaccessible because the lack of phase information prevents direct inversion of the rocking curves. The current practice is to use dynamical simulations in conjunction with a curve-fitting procedure to indirectly extract the profiles of strain and composition, but such dynamical simulations have been based on perfect, dislocation-free laminar crystals, which renders the analysis inapplicable to highly mismatched structures containing dislocation densities greater than about 106 cm-2. In this work we present a dynamical model for Bragg x-ray diffraction in semiconductor device structures with nonuniform composition, strain, and dislocation density, which is based on the Takagi-Taupin equation for distorted crystals and accounts for the diffuse scattering arising from the strain mosaicity and angular mosaicity associated with dislocations. We show theoretically that the x-ray diffraction profiles from In x Ga1- x As/GaAs (001) heterostructures are strongly affected by the depth distribution of the dislocation density as well as the composition and strain, so that in principle all three distributions may be obtained by the analysis of the measured diffraction profiles.

  13. The mGA1.0: A common LISP implementation of a messy genetic algorithm

    Science.gov (United States)

    Goldberg, David E.; Kerzic, Travis

    1990-01-01

    Genetic algorithms (GAs) are finding increased application in difficult search, optimization, and machine learning problems in science and engineering. Increasing demands are being placed on algorithm performance, and the remaining challenges of genetic algorithm theory and practice are becoming increasingly unavoidable. Perhaps the most difficult of these challenges is the so-called linkage problem. Messy GAs were created to overcome the linkage problem of simple genetic algorithms by combining variable-length strings, gene expression, messy operators, and a nonhomogeneous phasing of evolutionary processing. Results on a number of difficult deceptive test functions are encouraging with the mGA always finding global optima in a polynomial number of function evaluations. Theoretical and empirical studies are continuing, and a first version of a messy GA is ready for testing by others. A Common LISP implementation called mGA1.0 is documented and related to the basic principles and operators developed by Goldberg et. al. (1989, 1990). Although the code was prepared with care, it is not a general-purpose code, only a research version. Important data structures and global variations are described. Thereafter brief function descriptions are given, and sample input data are presented together with sample program output. A source listing with comments is also included.

  14. Lipopeptides from Bacillus strain AR2 inhibits biofilm formation by Candida albicans.

    Science.gov (United States)

    Rautela, Ria; Singh, Anil Kumar; Shukla, Abha; Cameotra, Swaranjit Singh

    2014-05-01

    The ability of the human fungal pathogen Candida albicans to reversibly switch between different morphological forms and establish biofilms is crucial for establishing infection. Targeting phenotypic plasticity and biofilm formation in C. albicans represents a new concept for antifungal drug discovery. The present study evaluated the influence of cyclic lipopeptide biosurfactant produced by Bacillus amyloliquefaciens strain AR2 on C. albicans biofilms. The biosurfactant was characterized as a mixture of iturin and fengycin by MALDI-TOF and amino acid analysis. The biosurfactant exhibited concentration dependent growth inhibition and fungicidal activity. The biosurfactant at sub-minimum growth inhibition concentration decreased cell surface hydrophobicity, hindered germ tube formation and reduced the mRNA expression of hyphae-specific gene HWP1 and ALS3 without exhibiting significant growth inhibition. The biosurfactants inhibited biofilm formation in the range of 46-100 % depending upon the concentration and Candida strains. The biosurfactant treatment dislodged 25-100 % of preformed biofilm from polystyrene plates. The biosurfactant retained its antifungal and antibiofilm activity even after exposure to extreme temperature. By virtue of the ability to inhibit germ tube and biofilm formation, two important traits of C. albicans involved in establishing infection, lipopeptides from strain AR2 may represent a potential candidate for developing heat stable anti-Candida drugs. PMID:24623107

  15. 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.

  16. 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.

  17. 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.

  18. Atomic-scale structure of disordered Ga1-xInxP alloys

    International Nuclear Information System (INIS)

    Extended x-ray-absorption fine-structure experiments have previously demonstrated that for each composition x, the sample average of all nearest-neighbor A-C distances in an A1-xBxC semiconductor alloy is closer to the values in the pure (x→0) AC compound than to the composition-weighted (virtual) lattice average. Such experiments do not reveal, however, the distribution of atomic positions in an alloy, so the principle displacement directions and the degrees of correlation among such atomic displacements remain unknown. Here we calculate both structural and thermodynamic properties of Ga1-xInxP alloys using an explicit occupation- and position-dependent energy functional. The latter is taken as a modified valence force field, carefully fit to structural energies determined by first-principles local-density calculations. Configurational and vibrational degrees of freedom are then treated via the continuous-space Monte Carlo approach. We find good agreement between the calculated and measured mixing enthalpy of the random alloy, nearest-neighbor bond lengths, and temperature-composition phase diagram. In addition, we predict yet unmeasured quantities such as (a) distributions, fluctuations, and moments of first- and second-neighbor bond lengths as well as bond angles, (b) radial distribution functions, (c) the dependence of short-range order on temperature, and (d) the effect of temperature on atomic displacements. Our calculations provide a detailed picture of how atoms are arranged in substitutionally random but positionally relaxed alloys, and offer an explanation for the effects of site correlations, static atomic relaxations, and dynamic vibrations on the phase-diagram and displacement maps. (Abstract Truncated)

  19. Comparative genome analysis of Bacillus cereus group genomes with Bacillus subtilis

    OpenAIRE

    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

    2005-01-01

    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-...

  20. Genotypic Diversity among Bacillus cereus and Bacillus thuringiensis Strains

    OpenAIRE

    Carlson, Cathrine Rein; Caugant, Dominique A; Kolstø, Anne-Brit

    1994-01-01

    Twenty-four strains of Bacillus cereus were analyzed by pulsed-field gel electrophoresis (PFGE) and compared with 12 Bacillus thuringiensis strains. In addition, the 36 strains were examined for variation in 15 chromosomal genes encoding enzymes (by multilocus enzyme electrophoresis [MEE]). The genome of each strain had a distinct NotI restriction enzyme digestion profile by PFGE, and the 36 strains could be assigned to 27 multilocus genotypes by MEE. However, neither PFGE nor MEE analysis co...

  1. First-principles study on electronic structure and conductivity of Sn-doped Ga1.375In0.625O3

    International Nuclear Information System (INIS)

    The structural properties, band structures and densities of states of Sn-doped Ga1.375In0.625O3 with a Sn atom substituting for the Ga atom or a Sn atom substituting for the In atom are calculated by using the first-principles method. The substitution of the Sn atom for the Ga atom in Ga1.375In0.625O3 (Ga1.25In0.625Sn0.125O3) has larger lattice parameters and stronger Sn—O ionic bonds than that of the substitutional doping of the Sn atom for the In atom in Ga1.375In0.625O3 (Ga1.375In0.5 Sn0.125O3). Results show that the Sn atom is preferentially substituted for the In atom in Sn-doped Ga1.375In0.625O3. Sn-doped Ga1.375In0.625O3 exhibits n-type metallic conductivity, and the impurity bands are mainly provided by the Sn 5s states. The optical band gap of Ga1.375In0.5Sn0.125O3 is larger than that of Ga1.25In0.625Sn0.125O3. Ga1.25In0.625Sn0.125O3 has a smaller electron effective mass and a slightly larger mobility. However, Ga1.375In0.5Sn0.125O3 has a larger relative electron number and a slightly higher conductivity. (semiconductor physics)

  2. 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.

  3. 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 were...... predicted to be essential. The vast majority of essential genes were categorized in relatively few domains of cell metabolism, with about half involved in information processing, one-fifth involved in the synthesis of cell envelope and the determination of cell shape and division, and one-tenth related to...... cell energetics. Only 4% of essential genes encode unknown functions. Most essential genes are present throughout a wide range of Bacteria, and almost 70% can also be found in Archaea and Eucarya. However, essential genes related to cell envelope, shape, division, and respiration tend to be lost from...

  4. Linear and nonlinear optical properties of GaAs/AlxGa1−xAs/GaAs/AlyGa1−yAs multi-shell spherical quantum dot

    International Nuclear Information System (INIS)

    In this work, the optical properties of GaAs/AlxGa1−xAs/GaAs/AlyGa1−yAs multi-shell quantum dot heterostructure have been studied as a function of Al doping concentrations for cases with and without a hydrogenic donor atom. It has been observed that the absorption coefficient strength and/or resonant absorption wavelength can be adjusted by changing the Al content of inner-barrier and/or outer-barrier regions. Besides, it has been shown that the donor atom has an important effect on the control of the electronic and optical properties of the structure. The results have been presented as a function of the Al contents of the inner-barrier x and outer-barrier y regions and probable physical reasons have been discussed

  5. Numerical optimization of carrier confinement characteristics in (AlxGa1-xN/AlN)SLs/GaN heterostructures

    International Nuclear Information System (INIS)

    We present numerical optimization of carrier confinement characteristics in (AlxGa1-xN/AlN)SLs/GaN heterostructures in the presence of spontaneous and piezoelectrically induced polarization effects. The calculations were made using a self-consistent solution of the Schrödinger, Poisson, potential and charge balance equations. It is found that the sheet carrier density in GaN channel increases nearly linearly with the thickness of AlN although the whole thickness and equivalent Al composition of AlxGa1-xN/AlN superlattices (SLs) barrier are kept constant. This result leads to the carrier confinement capability approaches saturation with thicknesses of AlN greater than 0.6 nm. Furthermore, the influence of carrier concentration distribution on carrier mobility was discussed. Theoretical calculations indicate that the achievement of high sheet carrier density is a trade-off with mobility.

  6. Metalorganic Vapor-Phase Epitaxial Growth and Characterization of Cubic AlxGa1-xN Alloy

    Science.gov (United States)

    Nakadaira, Atsushi; Tanaka, Hidenao

    1998-03-01

    Cubic AlxGa1-xN alloy films in the range 0≤x≤0.51 were grown on GaAs (100) substrates using low-pressure metalorganic vapor-phase epitaxy. The lattice constants of the alloys, which were estimated from the X-ray diffraction peaks, obeyed Vegard's rule. The optical quality of the alloys was improved by using triethylaluminum as the aluminum precursor. In photoluminescence measurements, AlxGa1-xN in the range x≤0.42 exhibited strong near band edge emissions, while that with x around 0.5 did not. The peak energy of the photoluminescence depended on the relationship E=3.20+1.85x in the range x≤0.42, while that around x=0.5 was less than that given by this relationship.

  7. Characteristics of p-GaAs/p-AlxGa1-xAs/si-GaAs studied by surface photovoltage

    Science.gov (United States)

    Fan, Cui; Chen, X. L.; Jiao, G. C.; Hu, C. L.; Qian, Y. S.

    2012-11-01

    A comparative study of semi-insulating GaAs substrate, p-AlxGa1-x As/ semi-insulating GaAs and p-GaAs/p-AlxGa1-xAs/ semi-insulating GaAs structure has been done using the surface photovoltage (SPV) spectroscopy in metal-insulator-semiconductor (MIS) configuration. Which space charge region (SCR) dominated contribution to SPV in a certain wavelength range was determined. The SPV signals were calculated in a similar way as the open circuit voltage of an illuminated photodiode. One-dimensional continuity equations was adopted for determine the distribution of excess minority carrier. The ideality factor of MIS configuration was investigated in air ambient. The contributions for SPV signal of different layers were discussed in detail. At last the minority carrier diffusion length of different layers and surface or interface recombination velocity were simulated.

  8. Infrared absorption by two dimensional holes in GaAs-(ALx Ga1-x)As quantum well structures

    International Nuclear Information System (INIS)

    The coefficient of infrared absorption by 2 D holes in GaAs-(ALx Ga1-x)As quantum well structures is calculated. The contributions of intra subband as well as inter subband transitions are taken into account. It is shown that, on the absorption spectrum there is a sharp peak related by inter subband transitions. With increasing of temperature this peak is not sharp. The obtained results are agreed with experiment data. (author). 7 refs., 6 figs

  9. 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...

  10. 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.

  11. Crystal structure, thermal expansion and electrical properties of GdCo0.67Ga1.33 compound

    International Nuclear Information System (INIS)

    A new ternary compound GdCo0.67Ga1.33 was synthesized and its crystal structure was determined by the Rietveld refinement of X-ray powder diffraction data. This compound crystallizes in the orthorhombic, space group Imma (No. 74) with the CeCu2 structure type, and a=0.43625(2) nm, b=0.70935(3) nm, c=0.75705(4) nm, Z=4 and Dcalc=8.207 g/cm3. The thermal expansion of GdCo0.67Ga1.33 was studied by high temperature powder X-ray diffraction technique in the temperature range of 301–598 K. The volumetric coefficient of thermal expansion, αV, can be represented by αV(T)=4.73×10−6+8.45×10−8T. The Debye temperature of GdCo0.67Ga1.33 is calculated to be ΘD=261.6 K. The electrical properties of this compound were measured between 5 and 300 K. Temperature variations of electrical resistivity suggest that magnetic ordering occurs at low temperature. The residual resistivity ratio RRR of the compound is about 1.2

  12. High purity GaAs and Al xGa 1-xAs grown by metalorganic molecular beam epitaxy

    Science.gov (United States)

    Furuhata, Naoki; Okamoto, Akihiko; Hoshino, Hitoshi

    1990-06-01

    High purity GaAs and Al xGa 1- xAs were grown by metalorganic molecular beam epitaxy (MOMBE) using metalorganic sources and arsenic (As 4). In GaAs growth using triethylgallium (TEG) and As 4, carrier concentrations depended on As 4 pressure and substrate temperatures. Below 1.5 x 10 -4 Torr As 4 pressure, the p-type carrier concentrations decreased with an increase in As 4 pressure. Above 1.5 x 10 -4 Torr As 4 pressure, the epilayer converted from p-type to n-type conductivity. Carrier concentrations decreased with a decrease in substrate temperatures. At 500°C and 1.5 x 10 -4 Torr As 4 pressure, the carrier concentration in the p-type GaAs epilayer exhibited 1.5 x 10 14 cm -3 with a room temperature mobility of 400 cm 2/V.s. Al xGa 1-xAs ( x=0.1-0. .2) was also grown using TEG, three different Al sources (triethylaluminum (TEA), trimethylaluminum (TMA) and dimethylaluminum hydride (DMAH) and As 4. Using TEG, TEA and As 4, the Al 0.15Ga 0.85As epilayer showed p-type conduction with carrier concentration of 1.2x10 15 cm -3 and mobility of 117 cm 2/V.s. This carrier concentration is the lowest value ever reported for Al xGa 1- xAs grown by MOMBE.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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...

  19. 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...

  20. Modeling the 3D In profile of In x Ga1‑x As/GaAs quantum dots

    Science.gov (United States)

    Tanaka, R. Y.; Abe, N. M.; da Silva, E. C. F.; Quivy, A. A.; Passaro, A.

    2016-06-01

    An iterative procedure, based on the finite-elements method combined with a stochastic approach, was developed to calculate the energy levels of In x Ga1‑x As/GaAs quantum dots grown by molecular-beam epitaxy. The vertical and radial In-composition profiles resulting from segregation and intermixing effects were taken into account. Two In profiles suggested in the literature were tested and compared to optical and structural data. One of them was shown to be compatible with the experimental data.

  1. 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

  2. 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.

  3. Modelling of visible and near infrared wavelength quantum well devices made of zinc-blende InxGa1-xN

    International Nuclear Information System (INIS)

    We report band offset calculations for lattice-matched and pseudomorphically strained InxGa1-xN/InyGa1-yN heterointerfaces using the model solid theory combined with ab initio calculations. From the results obtained, we have calculated the bandgap of bulk InxGa1-xN on GaN as a function of the indium composition. We have also simulated the band edges of an InxGa1-xN/GaN heterostructure. A self-consistent analysis is made to investigate the effect of strains on the interband transitions with the aim of achieving emissions at both visible and near infrared wavelengths. An attempt to explain the results obtained will be presented

  4. Growth and characterization of Al xGa 1-xN via NH 3-based metal-organic molecular beam epitaxy

    Science.gov (United States)

    Billingsley, Daniel; Henderson, Walter; Pritchett, David; Alan Doolittle, W.

    2009-02-01

    Growth and characterization of ammonia-based metal-organic molecular beam epitaxy (NH 3-MOMBE) Al xGa 1-xN epitaxial films has been conducted. Al xGa 1-xN films spanning the entire range of aluminum compositions were grown on GaN templates. This is the first reported successful growth of Al xGa 1-xN via NH 3-MOMBE, using triethylgallium (TEGa), triethylaluminum (TEAl) and ammonia (NH 3) as the precursors. These films were characterized via optical interferometry (OI), atomic force microscopy (AFM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). High-quality Al xGa 1-xN films, as inferred by XRD, are achievable in films without cracking. The catalytic effect of Al on NH 3 is found to play a major part in the growth rate of the Al xGa 1-xN films. The excessive nitrogen produced through this catalytic effect hinders the growth rate at lower Al composition while increasing the growth rate of Al xGa 1-xN ( x>0.4) films. Stress in the deposited films is found to be partially relieved through surface cracking along the direction in the film. These cracks provide dislocation gettering centers, with the dislocation pit density decreasing with increasing Al composition. A basic understanding on the factors affecting the growth of Al xGa 1-xN is determined and will become the basis for further investigations into the optimization of Al xGa 1-xN growth.

  5. Hybrid functional calculations on the band gap bowing parameters of In x Ga1‑x N

    Science.gov (United States)

    Mei, Lin; Yixu, Xu; Jianhua, Zhang; Shunqing, Wu; Zizhong, Zhu

    2016-04-01

    The electronic band structures and band gap bowing parameters of In x Ga1‑x N are studied by the first-principles method based on the density functional theory. Calculations by employing both the Heyd-Scuseria-Ernzerh of hybrid functional (HSE06) and the Perdew-Burke-Ernzerhof (PBE) one are performed. We found that the theoretical band gap bowing parameter is dependent significantly on the calculation method, especially on the exchange-correlation functional employed in the DFT calculations. The band gap of In x Ga1‑x N alloy decreases considerably when the In constituent x increases. It is the interactions of s–s and p–p orbitals between anions and cations that play significant roles in formatting the band gaps bowing. In general, the HSE06 hybrid functional could provide a good alternative to the PBE functional in calculating the band gap bowing parameters. Project supported by the National Natural Science Foundation of China (Nos. 11204257, 21233004) and the China Postdoctoral Science Foundation (No. 2012M511447).

  6. First principles total energy calculations of the structural and electronic properties of ScxGa1-xN

    International Nuclear Information System (INIS)

    Using first principles total energy calculations within the the full-potential linearized augmented plane wave (FP-LAPW) method, we have investigated the structural and electronic properties of ScxGa1-xN, with Sc concentrations varying from 0% up to 100%. In particular we have studied the relative stability of several configurations of ScxGa1-xN in wurtzite-like structures (the ground state configuration of GaN), or in rocksalt-like structures (the ground state configuration of ScN). It is found that for Sc concentrations less than ∼65%, the favored structure is a wurtzite-like one, while for Sc concentrations greater than ∼65%, the favored structure is a NaCl-like structure. It is also found that for the wurtzite-like crystals, the fundamental gap is large and direct. For the rocksalt crystals the fundamental gap is small and indirect, but with an additional larger direct gap. In agreement with the experiments of Little and Kordesch [Appl. Phys. Lett. 78, 2891 (2001)] we found a decrease of the band gap with the increase of the Sc concentration. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  7. 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

  8. 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.

  9. Draft Genome Sequences of Four Plant Probiotic Bacillus Strains.

    Science.gov (United States)

    Jeong, Haeyoung; Park, Seung-Hwan; Choi, Soo-Keun

    2016-01-01

    Here, we report the whole-genome sequences of four Bacillus strains that exhibit plant probiotic activities. Three of them are the type strains of Bacillus endophyticus, "Bacillus gaemokensis," and Bacillus trypoxylicola, and the other, Bacillus sp. strain KCTC 13219, should be reclassified into a species belonging to the genus Lysinibacillus. PMID:27174273

  10. Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice.

    Science.gov (United States)

    Shrestha, Bishnu K; Karki, Hari Sharan; Groth, Donald E; Jungkhun, Nootjarin; Ham, Jong Hyun

    2016-01-01

    Potential biological control agents for two major rice diseases, sheath blight and bacterial panicle blight, were isolated from rice plants in this study. Rice-associated bacteria (RABs) isolated from rice plants grown in the field were tested for their antagonistic activities against the rice pathogens, Rhizoctonia solani and Burkholderia glumae, which cause sheath blight and bacterial panicle blight, respectively. Twenty-nine RABs were initially screened based on their antagonistic activities against both R. solani and B. glumae. In follow-up retests, 26 RABs of the 29 RABs were confirmed to have antimicrobial activities, but the rest three RABs did not reproduce any observable antagonistic activity against R. solani or B. glumae. According to16S rDNA sequence identity, 12 of the 26 antagonistic RABs were closest to Bacillus amyloliquefaciens, while seven RABs were to B. methylotrophicus and B, subtilis, respectively. The 16S rDNA sequences of the three non-antagonistic RABs were closest to Lysinibacillus sphaericus (RAB1 and RAB12) and Lysinibacillus macroides (RAB5). The five selected RABs showing highest antimicrobial activities (RAB6, RAB9, RAB16, RAB17S, and RAB18) were closest to B. amyloliquefaciens in DNA sequence of 16S rDNA and gyrB, but to B. subtilis in that of recA. These RABs were observed to inhibit the sclerotial germination of R. solani on potato dextrose agar and the lesion development on detached rice leaves by artificial inoculation of R. solani. These antagonistic RABs also significantly suppressed the disease development of sheath blight and bacterial panicle blight in a field condition, suggesting that they can be potential biological control agents for these rice diseases. However, these antagonistic RABs showed diminished disease suppression activities in the repeated field trial conducted in the following year probably due to their reduced antagonistic activities to the pathogens during the long-term storage in -70C, suggesting that

  11. 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

  12. 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.

  13. Electronic structure of cubic ErxGa1-xN using the LSDA+U approach

    International Nuclear Information System (INIS)

    Electronic structure calculations were performed for substitutional erbium rare-earth impurity in cubic GaN using density-functional theory calculations within the LSDA+U approach (local spin-density approximation with Hubbard-U corrections). The LSDA+U method is applied to the rare-earth 4f states. The ErxGa1-xN is found to be a semiconductor, where the filled f-states are located in the valence bands and the empty ones above the conduction band edge. The filled and empty f-states are also shown to shift downwards and upwards in the valence and conduction bands, respectively, with increase in the U potentials

  14. Vacancy-type defects in InxGa1-xN alloys probed using a monoenergetic positron beam

    International Nuclear Information System (INIS)

    Native defects in InxGa1-xN grown by plasma-assisted molecular beam epitaxy were probed by a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured, and these were compared with results obtained using first-principles calculation. The defect concentration increased with increasing In composition x and reached the maximum at x = 0.44∼0.56. A clear correlation between the line-width of photoluminescence and the defect concentration was obtained. The major defect species detected by positron annihilation was identified as cation vacancies coupled with multiple nitrogen vacancies (VNs), and their introduction mechanism is discussed in terms of the strain energy due to bond-length/angle distortions and the suppression of the VN formation energy by neighboring In atoms.

  15. 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.

  16. 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.

  17. Ab initio description of the diluted magnetic semiconductor Ga1-xMnxAs: Ferromagnetism, electronic structure, and optical response

    Science.gov (United States)

    Craco, L.; Laad, M. S.; Müller-Hartmann, E.

    2003-12-01

    Motivated by a study of various experiments describing the electronic and magnetic properties of the diluted magnetic semiconductor Ga1-xMnxAs, we investigate its physical response in detail using a combination of first-principles band structure with methods based on dynamical mean field theory to incorporate strong, dynamical correlations, and intrinsic as well as extrinsic disorder in one single theoretical picture. We show how ferromagnetism is driven by double exchange (DE), in agreement with very recent observations, along with a good quantitative description of the details of the electronic structure, as probed by scanning tunneling microscopy and optical conductivity. Our results show how ferromagnetism can be driven by DE even in diluted magnetic semiconductors with small carrier concentration.

  18. GaSb quantum rings in GaAs/AlxGa1−xAs quantum wells

    International Nuclear Information System (INIS)

    We report the results of continuous and time-resolved photoluminescence measurements on type-II GaSb quantum rings embedded within GaAs/AlxGa1−xAs quantum wells. A range of samples were grown with different well widths, compensation-doping concentrations within the wells, and number of quantum-ring layers. We find that each of these variants have no discernible effect on the radiative recombination, except for the very narrowest (5 nm) quantum well. In contrast, single-particle numerical simulations of the sample predict changes in photoluminescence energy of up to 200 meV. This remarkable difference is explained by the strong Coulomb binding of electrons to rings that are multiply charged with holes. The resilience of the emission to compensation doping indicates that multiple hole occupancy of the quantum rings is required for efficient carrier recombination, regardless of whether these holes come from doping or excitation

  19. Photoelectrical properties of multilayer heterostructures CuInxGa1-xSe2/CdS

    International Nuclear Information System (INIS)

    New controlled deposition technique using pulsed channel spark ablation for producing high quality thin films of perspective solar cell components CuInxGa1-xSe2 and CdS have been elaborated. Directed energy is driven to the target for about 100 ns pulse by means of magnetically self-pinched electron beam with power density 5 108 Wt/cm2 . Two-step technology of deposition of CuIn1-xGaxSe2 polycrystalline films was developed: depositing with the help of 'e-beam ablation' process at 250 degrees Celsius and subsequent selenization at 500 degrees Celsius. The structure and optical properties of target and thin films on substrates are the same. The method of admittance spectroscopy was applied for optimization of deposition process and photovoltaic parameters. The continuous distribution of deep states has been found. Multilayer heterostructures suitable for solar cell technology are obtained. (authors)

  20. Dipole scattering by DX-d+ ion pairs in N-type Alx Ga1-xAs

    International Nuclear Information System (INIS)

    Full text. It is well known that the DX center is the dominant deep level in Alx Ga1-x As, and responsible for transport properties at low temperature. It is generally accepted that the ground state has negative charge, denoted as DX-. The possibility of correlation with positively charged donors (d+) has been taken into account lately to explain some phenomena in Alx Ga1-x As based structures. The existence of electric dipoles in n-type sample has been shown in direct bandgap (Scalvi, L.V.A. Appl. Phys. Lett. 63, 2658, 1993) as well as indirect bandgap material. The influence of monochromatic light in these dipoles (Scalvi, L.V.A. Phys. Rev. B51, 13864, 1995) has been fundamental in associating them with DX centers since the average activation energy in good agreement with the DX center binding energy (in the range 0.100-0.150 eV for the investigated aluminum composition range), and moreover, there is possibility of DX--d+ interaction. Electron scattering by these ion pairs may play a very important role in the electronic mobility of these samples at low temperature. In this work, the decay of photo-excited conductive state is simulated using dipole length distribution and the effective length for interaction, from which the ions are considered as isolated ionized impurities. Results are compared to conductance experimental data in a large range of temperature and light excitation. Theoretical curves improve significantly when DX--d+ correlations are taken into account. (author)

  1. Phase transformations in PuGa 1 at.% alloy: Study of whole reversion process following martensitic transformation

    International Nuclear Information System (INIS)

    Highlights: •Direct δ-to-α′ phase transformation at low temperatures without any γ′ phase. •Competition between direct and indirect reversion at the first stage of reversion. •Involvement of Ga diffusion associated with indirect reversion mode. •Pure-Pu β and γ phases emergence during indirect reversion with δ-phase Ga enrichment. •Reversion process of PuGa 1 at.% alloy following martensitic transformation. -- Abstract: The purpose of this work was to study PuGa 1 at.% alloy behavior from martensitic transformation to the whole reversion process. The relevant phase transformations were investigated as a function of temperature via in situ X-ray diffraction and dilatometry analyses carried out at low and high temperatures. The results show that the δ-to-α′ martensitic transformation occurring at low temperatures is direct and does not involve any intermediate γ′ phase. They also reveal that the reverse transformation of the two-phase δ + α′ alloy during heating involves two competing modes, namely direct and indirect reversion. The latter is associated with a Ga diffusion process that governs the ratio between these reversion modes. More precisely, our study demonstrates that the indirect reversion process consists of a Ga-enrichment of the remaining δ phase as well as the emergence of the β and γ phases of pure plutonium. Every stage of indirect reversion has been discussed in relation to the equilibrium phase diagram of the Pu–Ga binary system

  2. 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.

  3. Bacillus subtilis Deoxyribonucleic Acid Gyrase

    OpenAIRE

    Sugino, A; Bott, K F

    1980-01-01

    Bacillus subtilis 168 was shown to contain a deoxyribonucleic acid (DNA) gyrase activity which closely resembled those of the enzymes isolated from Escherichia coli and Micrococcus luteus in its enzymatic requirements, substrate specificity, and sensitivity to several antibiotics. The enzyme was purified from the wild type and nalidixic acid-resistant and novobiocin-resistant mutants of B. subtilis and was functionally characterized in vitro. The genetic loci nalA and novA but not novB were s...

  4. Point defects introduced by InN alloying into InxGa1−xN probed using a monoenergetic positron beam

    International Nuclear Information System (INIS)

    Native defects in InxGa1−xN (x = 0.06-0.14) grown by metal organic chemical vapor deposition were studied using a monoenergetic positron beam. Measurements of Doppler broadening spectra of the annihilation radiation as a function of incident positron energy for InxGa1−xN showed that vacancy-type defects were introduced with increasing InN composition, and the major defect species was identified as complexes between a cation vacancy and a nitrogen vacancy. The concentration of the divacancy, however, was found to be suppressed by Mg doping. The momentum distribution of electrons at the InxGa1−xN/GaN interface was close to that in defect-free GaN or InxGa1−xN, which was attributed to localization of positrons at the interface due to the built-in electric field, and to suppression of positron trapping by vacancy-type defects. We have also shown that the diffusion property of positrons is sensitive to an electric field near the InxGa1−xN/GaN interface.

  5. 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.

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

    OpenAIRE

    Annika Gillis; Jacques Mahillon

    2014-01-01

    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 inf...

  7. Quantum efficiency of transmission-mode AlxGa1-xAs/GaAs photocathodes with graded-composition and exponential-doping structure

    Science.gov (United States)

    Feng, Cheng; Zhang, Yijun; Qian, Yunsheng; Xu, Yuan; Liu, Xinxin; Jiao, Gangcheng

    2016-06-01

    A transmission-mode AlxGa1-xAs/GaAs photocathode with the combination of composition-graded AlxGa1-xAs window layer and exponential-doping GaAs emission layer is developed to maximize the cathode performance. The theoretical quantum efficiency model with this complex structure containing twofold built-in electric fields is deduced by solving the one dimensional continuity equations combined with the three-step model. By comparison of spectral characteristics of photocathodes with different composition and doping structures, and through analysis of cathode structure parameters, it is found that the twofold built-in electric fields can effectively improve photoemission performance of AlxGa1-xAs/GaAs photocathode, which is related to Al proportion variation range and thicknesses of window layer and emission layer. The quantum efficiency model would provide theoretical guidance for better design of transmission-mode graded bandgap photocathodes.

  8. 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

  9. 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.

  10. 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.

  11. High field alloy, thermoelectric, and mm wave studies of the field induced superconducting state in λ-(BETS)2FexGa1-xCl4

    International Nuclear Information System (INIS)

    Alloy studies in the π - d organic conductor λ-(BETS)2FexGa1-xCl4 have given new insight into the nature of field induced superconductivity (FISC), since the mechanism of the FISC involves cancellation of the π - d exchange field by the external field. Alloying on the FexGa1-x site allows tuning of the exchange field, thereby influencing the FISC phase boundary. A brief review of the low temperature phases are given, and new high magnetic field thermoelectric and mm wave results that probe the low temperature ground state are presented. (author)

  12. 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...

  13. 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.

  14. Plasmid-mediated transformation in Bacillus megaterium.

    OpenAIRE

    Brown, B. J.; Carlton, B C

    1980-01-01

    A transformation system was developed for Bacillus megaterium by using antibiotic resistance plasmid deoxyribonucleic acid molecules derived from Staphylococcus aureus and Bacillus cereus. Lysozyme-generated protoplasts of B. megaterium allowed uptake of plasmid deoxyribonucleic acid in the presence of polyethylene glycol. Transformants expressed the antibiotic resistance determinants present on the plasmid deoxyribonucleic acid, and reisolated plasmid deoxyribonucleic acid yielded restrictio...

  15. Physical map of the Bacillus cereus chromosome.

    OpenAIRE

    Kolstø, A B; Grønstad, A; Oppegaard, H

    1990-01-01

    A physical map of the Bacillus cereus chromosome has been constructed by aligning 11 NotI fragments, ranging in size from 200 to 1,300 kilobases. The size of the chromosome is about 5.7 megabases. This is the first Bacillus genome of which a complete physical map has been described.

  16. What sets Bacillus anthracis apart from other Bacillus species?

    Science.gov (United States)

    Kolstø, Anne-Brit; Tourasse, Nicolas J; Økstad, Ole Andreas

    2009-01-01

    Bacillus anthracis is the cause of anthrax, and two large plasmids are essential for toxicity: pXO1, which contains the toxin genes, and pXO2, which encodes a capsule. B. anthracis forms a highly monomorphic lineage within the B. cereus group, but strains of Bacillus thuringiensis and B. cereus exist that are genetically closely related to the B. anthracis cluster. During the past five years B. cereus strains that contain the pXO1 virulence plasmid were discovered, and strains with both pXO1 and pXO2 have been isolated from great apes in Africa. Therefore, the presence of pXO1 and pXO2 no longer principally separates B. anthracis from other Bacilli. The B. anthracis lineage carries a specific mutation in the global regulator PlcR, which controls the transcription of secreted virulence factors in B. cereus and B. thuringiensis. Coevolution of the B. anthracis chromosome with its plasmids may be the basis for the successful development and uniqueness of the B. anthracis lineage. PMID:19514852

  17. 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.

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

    Science.gov (United States)

    Han, Joon-Hee; Shim, Hongsik; Shin, Jong-Hwan; Kim, Kyoung Su

    2015-06-01

    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. PMID:26060435

  19. Current-perpendicular-to-plane giant magnetoresistance using Co2Fe(Ga1−xGex) Heusler alloy

    International Nuclear Information System (INIS)

    We investigated the current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) of pseudo spin valves (PSVs) using ferromagnetic (FM) Heusler alloy Co2Fe(Ga1−xGex) (x = 0, 0.5, and 1) layers and an Ag spacer layer. The FM layer with x = 0.5 gave rise to the highest MR output, ΔRA = 8.7 mΩ·μm2, at room temperature with 10 nm thick Heusler alloy layers. The MR output increased with increasing annealing temperature, Ta, with a maximum at Ta = 500 °C. Transmission electron microscopy showed no visible changes in the layered structure; however, energy dispersive x-ray analysis indicated a considerable diffusion of Ga and Ge into the other layers by annealing at Ta = 550 °C. The ΔRA dependence on the thickness of the FM layers indicated that both high bulk and interface spin asymmetries contribute to the high MR output.

  20. Metal-insulator transition in AlxGa1-xAs/GaAs heterostructures with large spacer width

    Science.gov (United States)

    Gold, A.

    1991-10-01

    Analytical results are presented for the mobility of a two-dimensional electron gas in a heterostructure with a thick spacer layer α. Due to multiple-scattering effects a metal-insulator transition occurs at a critical electron density Nc=N1/2i/(4π1/2α) (Ni is the impurity density). The transport mean free path l(t) (calculated in Born approximation) at the metal-insulator transition is l(t)c=2α. A localization criterion in terms of the renormalized single-particle mean free path l(sr) is presented: kFcl(sr)c=(1/2)1/2 (kFc is the Fermi wave number at the critical density). I compare the theoretical results with recent experimental results found in AlxGa1-xAs/GaAs heterostructures with large spacer width: 1200<α<2800 Å. Remote impurity doping and homogeneous background doping are considered. The only fitting parameter used for the theoretical results is the background doping density NB=6×1013 cm-3. My theory is in fair agreement with the experimental results.

  1. Excitonic diamagnetic shifts and linewidths in Al_xGa_1-xAs alloys in high magnetic fields

    Science.gov (United States)

    Senger, R. T.; Coli, G.; Bajaj, K. K.; Reno, J. L.; Jones, E. D.; Crooker, Scott

    2002-03-01

    We have measured both the diamagnetic shifts and the linewidths of excitonic transitions in Alx Ga_1-xAs alloys as a function of aluminum concentration and magnetic field at 1.4 K using photoluminescence spectroscopy. The aluminum composition in our samples ranged from 0 to 300 to 50 tesla. The samples were grown on GaAs substrates oriented along [001] direction using molecular beam epitaxy at 590ºC. We find that for a given value of alloy composition, both the diamagnetic shift and excitonic linewidth increase as a function of magnetic field. The observed variations of the diamagnetic shifts and excitonic linewidths with magnetic field are considerably smaller than those calculated by Lee and Bajaj [J. Appl. Phys. 73, 1788 (1993)] using a free exciton model. To explain our experimental data we propose that the excitons are localized in a very specific manner. To simulate exciton localization, we assume that the exciton reduced mass is increased and is obtained by using the alloy dependent heavy-hole mass along [001] direction treated isotropically. The calculated values of the variations of the diamagnetic shift and excitonic linewidth as a function of magnetic field obtained using this model agree very well with those reported here. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

  2. 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)

  3. 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...

  4. 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.

  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. PMID:27208660

  6. Improvement of wet-oxidized AlxGa1-xAs (x∼1) through the use of AlAs/GaAs digital alloys

    International Nuclear Information System (INIS)

    A comparison of the water vapor oxidation characteristics of AlAs, Al0.98Ga0.02As, and an AlxGa1-xAs digital alloy was performed. The AlxGa1-xAs digital alloy consists of periods of 49 monolayers of AlAs and 1 monolayer of GaAs and has an equivalent composition of x=0.98. Oxidation rates and the structural integrity of the three layers were compared. When oxidized in water vapor, the AlxGa1-xAs digital alloy and the AlAs have similar oxidation rates, both of which are twice as fast as the Al0.98Ga0.02As layer. Post-oxidation annealing of these samples at 450 degree sign C showed severe delamination at the oxide/GaAs interface in the AlAs sample while the AlxGa1-xAs digital alloy sample was not damaged. (c) 2000 American Institute of Physics

  7. 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...

  8. Multilocus enzyme electrophoresis study of Bacillus sphaericus

    Directory of Open Access Journals (Sweden)

    Viviane Zahner

    1995-02-01

    Full Text Available Multilocus enzyme electrophoresis (MLEE has been used in the study of some Bacillus species. In this work we applied MLEE and numerical analysis in the study of the Bacillus sphaericus group. B. sphaericus can be distinguished from other entomopathogenic Bacillus by a unique allele (NP-4. Within the species, all insect pathogens were recovered in the same phenetic cluster and all of these strains have the same band position (electrophoresis migration on the agarose gel (ADH-2. The entomopathogenic group of B. sphaericus seems to be a clonal population, having two widespread frequent genotypes (zymovar 59 and zymovar 119.

  9. EXAFS investigation of uranium(VI) complexes formed at Bacillus cereus and Bacillus sphaericus surfaces

    International Nuclear Information System (INIS)

    Uranium(VI) complex formation at vegetative cells and spores of Bacillus cereus and Bacillus sphaericus was studied using uranium LII-edge and LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. A comparison of the measured equatorial U-O distances and other EXAFS structural parameters of uranyl species formed at the Bacillus strains with those of the uranyl structure family indicates that the uranium is predominantly bound as uranyl complexes with phosphoryl residues. (orig.)

  10. A Randomly Amplified Polymorphic DNA Marker Specific for the Bacillus cereus Group Is Diagnostic for Bacillus anthracis

    OpenAIRE

    Daffonchio, Daniele; Borin, Sara; Frova, Giuseppe; Gallo, Romina; Mori, Elena; Fani, Renato; Sorlini, Claudia

    1999-01-01

    Aiming to develop a DNA marker specific for Bacillus anthracis and able to discriminate this species from Bacillus cereus, Bacillus thuringiensis, and Bacillus mycoides, we applied the randomly amplified polymorphic DNA (RAPD) fingerprinting technique to a collection of 101 strains of the genus Bacillus, including 61 strains of the B. cereus group. An 838-bp RAPD marker (SG-850) specific for B. cereus, B. thuringiensis, B. anthracis, and B. mycoides was identified. This fragment included a pu...

  11. Electronic structure of the Ga1-xCrxN studied by high-energy photoemission spectroscopy

    International Nuclear Information System (INIS)

    Full text: It is predicted based on hole-mediated ferromagnetism (FM) that GaMnN may have Curie temperature (Tc) higher than room temperature if doped with high hole concentration (ca 1020 cm-3 ). The hole-mediated ferromagnetism (FM) can produce reliable estimate of Tc for diluted magnetic semiconductor (DMS) such as GaMnAs due to the shallow Mn-associated energy states in the GaAs system. Since the energy states of doped transition metals exist as a deep level in a wide band semiconductor like GaN and carriers are localized in these states, different mechanisms for magnetism will play a role in GaN rather than the hole-mediated one. This conjecture is partly supported by the recent report of FM in n-type GaN doped with Cr, although the mechanism of the observed FM has not been elucidated yet. In order to get insight into the mechanism of the FM, we have studied the electronic structure of GaN doped with Cr exploiting bulk-sensitive hard X-ray photoemission spectroscopy at a photon energy of 5.95keV at SPring-8. We have observed that Cr-doping does introduce new electronic levels in the band gap and causes some change in the valence band structure. Based on the first principle calculation, the Cr-associated electronic levels in the band gap are assigned to nonbonding and anti-bonding d states, the latter of which pins the Fermi level, while the change of the valence band suggests that the Ga 4s originated states are significantly modified through hybridization with the Cr 3d orbital. The present result evidences that the Ga valence electrons are considerably modified through the interaction with second neighbor Cr atoms. Such hybridization between Ga 4s and Cr 3d may play a significant role in the observed ferromagnetism in Ga1-xCrxN

  12. 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.

  13. 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.

  14. Microbial Transformation of Quercetin by Bacillus cereus

    OpenAIRE

    Rao, Koppaka V.; Weisner, Nghe T.

    1981-01-01

    Biotransformation of quercetin was examined with a number of bacterial cultures. In the presence of a bacterial culture (Bacillus cereus), quercetin was transformed into two crystalline products, identified as protocatechuic acid and quercetin-3-glucoside (isoquercitrin).

  15. 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

  16. Bacillus cereus as a nongastrointestinal pathogen

    OpenAIRE

    Pavani G.

    2014-01-01

    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 mem...

  17. Characterization of the green band in photoluminescence spectra of heavily doped Al x Ga1‑ x N:Si with the Al content x > 0.5

    Science.gov (United States)

    Osinnykh, Igor V.; Malin, Timur V.; Plyusnin, Viktor F.; Suranov, Andrei S.; Gilinsky, Alexander M.; Zhuravlev, Konstantin S.

    2016-05-01

    We report time-resolved and temperature-dependent photoluminescence investigations of green photoluminescence in heavily doped Al x Ga1‑ x N:Si films grown by molecular beam epitaxy on sapphire substrates. The green band dominates in the photoluminescence spectra of Al x Ga1‑ x N:Si films with the Al content higher than 0.5. This band is attributed to donor–acceptor and free electron–acceptor transitions involving the same acceptor. Donor and acceptor binding energies of about 50 and 930 meV, respectively, were obtained. The donor was assigned to the Si atom on the Ga/Al site; the acceptor might be the C atom on the N site or a complex comprising a Ga/Al vacancy and a shallow donor.

  18. 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.

  19. Effect of inhomogeneous charge distribution on the cyclotron resonance in an inverted GaAs/Ga1-xAlxAs interface

    Science.gov (United States)

    Pastor, K.; Goiran, M.; Kim, D. J.; Madhukar, A.; Leotin, J.; Bouchelaghem, M.; Askenazy, S.

    1990-12-01

    Cyclotron resonance in an inverted GaAs/Ga1-xAlxAs heterostructure and/or single quantum well (GaAs is grown on a Ga1-xAlxAs-doped layer rather than vice versa) was studied in the far infrared. A large splitting was found and is attributed to inhomogeneous charge-distribution-induced coupling to the intersubband resonance. A simple model accounting for the coupling in the presence of the inhomogeneous charge at the interface has been developed. From the fit to the experimental data, the value of the average electric field gradients at the inverted interface G=1.2×109 V/cm2 was obtained.

  20. 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.

  1. The influence of growth chemistry on the MOVPE growth of GaAs and Al(x)Ga(1-x)As layers and heterostructures

    Science.gov (United States)

    Kuech, T. F.; Veuhoff, E.; Kuan, T. S.; Deline, V.; Potemski, R.

    1986-09-01

    Various combinations of triethylgallium, triethylaluminum, trimethylgallium, and trimethylaluminum have been used during the metalorganic vapor phase epitaxy (MOVPE) growth of Al(x)Ga(1-x)As in order to ascertain the influence of their growth chemistry on the properties of the resulting semiconductor layers and quantum well structures. Substantial reductions in carbon incorporation can be achieved using the ethyl-based growth chemistry. Narrow quantum well structures were demonstrated using both ethyl- and methyl-based precursors.

  2. 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.

  3. Ternary effects on the optical interface phonons in onion-like GaN/AlxGa1−xN quantum dots

    International Nuclear Information System (INIS)

    The interface optical phonons and its ternary effects in onion-like quantum dots are studied by using dielectric continuum model and the modified random-element isodisplacement model. The dispersion relations, the electron–phonon interactions and ternary effects on the interface optical phonons are calculated in the GaN/AlxGa1−xN onion-like quantum dots. The results show that aluminium concentration has important influence on the interface optical phonons and electron–phonon interactions in GaN/AlxGa1−xN onion-like quantum dots. The frequencies of interface optical phonons and electron–phonon coupling strengths change linearly with increase of aluminium concentration in high frequency range, and do not change linearly with increasing aluminium concentration in low frequency range. - Highlights: • The random-element isodisplacement model and dielectric continuum model are used. • The ternary effects on IO phonons in onion-like GaN/AlxGa1−xN QDs are studied. • The ternary effects on electron–IO phonon coupling in QDs are studied

  4. High Al-content AlxGa1-xN epilayers grown on Si substrate by plasma-assisted molecular beam epitaxy

    International Nuclear Information System (INIS)

    The microstructure and optical properties of AlxGa1-xN/GaN/AlN films on Si (1 1 1) substrate grown by plasma-assisted molecular beam epitaxy (MBE) have been studied and investigated. Reflection high energy electron diffraction (RHEED), scanning electron microscopy (SEM), high-resolution X-ray diffraction (HR-XRD), energy dispersive X-ray spectroscopy (EDS) line analysis and photoluminescence (PL) were used to investigate a reconstruction pattern, cross-section, mole fraction and crystalline quality of the heterostructure. By applying the Vegard's law, a high Al-mole fraction of AlxGa1-xN sample with value of 0.43 has been obtained and compared with EDS line analysis measurement value. PL spectrum has exhibited a sharp and intense band edge emission of GaN with the absence of yellow emission band, indicating good crystal quality of the AlxGa1-xN has been successfully grown on Si substrate.

  5. 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.

  6. Electronic structures of zigzag AlN, GaN nanoribbons and AlxGa1-xN nanoribbon heterojunctions: First-principles study

    International Nuclear Information System (INIS)

    The electronic and structural properties of zigzag aluminum nitride (AlN), gallium nitride (GaN) nanoribbons and AlxGa1-xN nanoribbon heterojunctions are investigated using the first-principles calculations. Both AlN and GaN ribbons are found to be semiconductor with an indirect band gap, which decreases monotonically with the increased ribbon width, and approaching to the gaps of their infinite two dimensional graphitic-like monolayer structures, respectively. Furthermore, the band gap of AlxGa1-xN nanoribbon heterojunctions is closely related to Al (and/or Ga) concentrations. The AlxGa1-xN nanoribbon of width n=8 shows a continuously band gap varying from about 2.2 eV-3.1 eV as x increases from 0 to 1. The large ranged tunable band gaps in such a quasi one dimension structure may open up new opportunities for these AlN/GaN based materials in future optoelectronic devices.

  7. 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.

  8. 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

  9. First-principles study of spontaneous polarization and band gap bowing in ScxAlyGa1−x−yN alloys lattice-matched to GaN

    International Nuclear Information System (INIS)

    First-principles calculations are carried out to estimate the spontaneous polarization and the band gap bowing in the ScxAlyGa1−x−yN alloys lattice-matched to GaN based on the density functional theory together with a pseudopotential plane-wave method. The results indicate nonlinear behavior of the spontaneous polarization and the band gap energies in the ScxAlyGa1−x−yN alloys similar to that in YxAlyGa1−x−yN (Shimada et al 2011 J. Appl. Phys. 110 074114). The band gap energies and the magnitude of the spontaneous polarization of ScxAlyGa1−x−yN is larger than that of YxAlyGa1−x−yN in a wide range of the mole fraction of Ga. We find that the atomic configuration of Sc affects the magnitude of the polarization in ScxAlyGa1−x−yN. Another finding is the apparent deviation from Vegard's law of the lattice constants of the ScxAlyGa1−x−yN alloys lattice-matched to GaN. (paper)

  10. Bacillus Strains Most Closely Related to Bacillus nealsonii Are Not Effectively Circumscribed within the Taxonomic Species Definition

    OpenAIRE

    Kealy Peak, K.; Kathleen E. Duncan; Luna, Vicki A.; King, Debra S.; McCarthy, Peter J.; Cannons, Andrew C.

    2011-01-01

    Bacillus strains with >99.7% 16S rRNA gene sequence similarity were characterized with DNA:DNA hybridization, cellular fatty acid (CFA) analysis, and testing of 100 phenotypic traits. When paired with the most closely related type strain, percent DNA:DNA similarities (% S) for six Bacillus strains were all far below the recommended 70% threshold value for species circumscription with Bacillus nealsonii. An apparent genomic group of four Bacillus strain pairings with 94%–70% S was contradicted...

  11. [Bacillus thuringiensis: a biotechnology model].

    Science.gov (United States)

    Sanchis, V; Lereclus, D

    1999-01-01

    This paper is on the different biotechnological approaches that have been used to improve Bacillus thuringiensis (Bt) for the control of agricultural insect pests and have contributed to the successful use of this biological control agent; it describes how a better knowledge of the high diversity of Bt strains and toxins genes together with the development of efficient host-vector systems has made it possible to overcome a number of the problems associated with Bt based insect control measures. First we present an overview of the biology of Bt and of the mode of action of its insecticidal toxins. We then describe some of the progress that has been made in furthering our knowledge of the genetics of Bt and of its insecticidal toxin genes and in the understanding of their regulation. The paper then deals with the use of recombinant DNA technology to develop new Bt strains for more effective pest control or to introduce the genes encoding partial-endotoxins directly into plants to produce insect-resistant trangenic plants. Several examples describing how biotechnology has been used to increase the production of insecticidal proteins in Bt or their persistence in the field by protecting them against UV degradation are presented and discussed. Finally, based on our knowledge of the mechanism of transposition of the Bt transposon Tn4430, we describe the construction of a new generation of recombinant strains of Bt, from which antibiotic resistance genes and other non-Bt DNA sequences were selectively eliminated, using a new generation of site-specific recombination vectors. In the future, continuing improvement of first generation products and research into new sources of resistance is essential to ensure the long-term control of insect pests. Chimeric toxins could also be produced so as to increase toxin activity or direct resistance towards a particular type of insect. The search for new insecticidal toxins, in Bt or other microorganisms, may also provide new weapons

  12. 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

  13. Aluminum Content Tunability of Structural and Optical Properties in Wide-Gap Semiconducting (AlxGa1- x)2O3

    Science.gov (United States)

    Krueger, Benjamin W.

    (AlxGa1- x)2O3 alloys have attracted renewed interest due to their potential for use in deep-ultraviolet optical devices and high-powered transistors, but realization of these technologies depends on the ability to tune the band gap and crystal phase of alloy films for specific applications. In this work, fundamental relationships between structural and optical properties of (AlxGa1-x) 2O3 were explored in a series of experiments on single-phase sintered powders produced by solution combustion synthesis, and continuous-composition-spread (CCS) thin films deposited at room temperature on silicon and sapphire by pulsed-laser deposition and post-annealed to successively higher temperatures in air, to see how crystallinity develops with alloy composition and measure the corresponding change in band gap. As the annealing temperature is raised (to a maximum of 1000°C), amorphous (AlxGa 1-x)2O3 films transition first to the metastable gamma phase, and then to the beta phase, for alloy compositions in the range 0.1 0.8. Within each phase the band gap increases steadily with Al concentration, with greater bowing in the amorphous films than crystalline films, and linear variation with no bowing in 1600°C sintered powders. No discontinuity in the band gap was observed through the beta → gamma transition, but a 0.1-0.2 eV jump to lower band gap occurs when films become amorphous. (AlxGa1-x) 2O3 films were also grown on silicon and sapphire at elevated temperature, with and without a Ga2O3 buffer layer, to determine limits on epitaxy with these two substrates and to see if films grown at high temperature exhibit similar properties as post-annealed films grown at room temperature. Epitaxial(AlxGa 1-x)2O3 CCS films on sapphire are initially [-201]-oriented on the Ga-rich side, with an in-plane epitaxial relationship Ga2O3 [201] || sapphire [2¯10] and six-fold rotational symmetry. Films with thickness greater than 100 nm start to lose their orientation by twinning on the (101

  14. 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

  15. 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.

  16. 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...

  17. 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.

  18. Global phase diagram of the magnetic field-induced organic superconductors γ-(BETS)2FexGa1-xCl4

    International Nuclear Information System (INIS)

    Organic alloys γ-(BETS)2FexGa1-xCl4 show superconductivity only under very high magnetic fields parallel to the conducting layer for x ≥ 0.47. As x decreases, the field induced superconducting phase shifts towards lower fields and a striking field-induced insulator to superconductor transition is observed below 4 T for x=0.45. We show that the overall features of the global phase diagram are well understood in terms of Jaccarino-Peter compensation mechanism. These results provide a new road map for the future design of high magnetic field superconductors. (author)

  19. 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...

  20. 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...

  1. Crystal Growth of Ca3Nb(Ga1−xAlx)3Si2O14 Piezoelectric Single Crystals with Various Al Concentrations

    OpenAIRE

    Yuui Yokota; Tetsuo Kudo; Yuji Ohashi; Andrey Medvedev; Shunsuke Kurosawa; Kei Kamada; Akira Yoshikawa

    2015-01-01

    Ca3Nb(Ga1−xAlx)3Si2O14 (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...

  2. 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.

  3. Impact of Random Dopant Fluctuations on the Electronic Properties of In(x)Ga(1-x)N/GaN Axial Nanowire Heterostructures.

    Science.gov (United States)

    Marquardt, Oliver; Geelhaar, Lutz; Brandt, Oliver

    2015-07-01

    We study the electronic properties of axial In(x)Ga(1-x)N/GaN nanowire heterostructures with randomly placed ionized donors. Our simulations are based on an eight-band k·p model and indicate large variations of both the ground state transition energy and the spatial distribution of the electron and hole charge density. We show that these variations are intrinsic to nanostructures containing ionized donors and that the presence of donors has important consequences for all nanowire-based light-emitting devices including single-photon emitters required for quantum computing and quantum cryptography. PMID:26042638

  4. 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

  5. Regulation of Polyglutamic Acid Synthesis by Glutamate in Bacillus licheniformis and Bacillus subtilis

    OpenAIRE

    Kambourova, Margarita; Tangney, Martin; Priest, Fergus G.

    2001-01-01

    The synthesis of polyglutamic acid (PGA) was repressed by exogenous glutamate in strains of Bacillus licheniformis but not in strains of Bacillus subtilis, indicating a clear difference in the regulation of synthesis of capsular slime in these two species. Although extracellular γ-glutamyltranspeptidase (GGT) activity was always present in PGA-producing cultures of B. licheniformis under various growth conditions, there was no correlation between the quantity of PGA and enzyme activity. Moreo...

  6. Evaluation of Bacillus cereus and Bacillus pumilus metabolites for anthelmintic activity

    OpenAIRE

    M L Vijaya Kumar; Thippeswamy, B.; I L Kuppust; Naveenkumar, K. J.; C K Shivakumar

    2015-01-01

    Objective: To assess the anthelmintic acivity of Bacillus cereus and Bacillus pumilus metabolites. Materials and Methods: The successive solvent extractions with petroleum ether, ethyl acetate and methanol. The solvent extracts were tested for anthelmintic activity against Pheretima posthuma at 20 mg/ml concentration. The time of paralysis and time of death of the worms was determined for all the extracts. Albendazole was taken as a standard reference and sterile water as a control. Results: ...

  7. Secondary cell wall polysaccharides in Bacillus anthracis and Bacillus cereus strains

    OpenAIRE

    Leoff, Christine

    2009-01-01

    This thesis presents a systematic comparison of cell wall carbohydrates, in particular the non classical secondary cell wall polysaccharides from closely related strains within the Bacillus cereus group. The results suggest that the cell wall glycosyl composition of the various Bacillus cereus group strains display differences that correlate with their phylogenetic relatedness. Comparative structural analysis of polysaccharide components that were released from the cell walls of the various s...

  8. Differentiation between spores of Bacillus anthracis and Bacillus cereus by a quantitative immunofluorescence technique.

    OpenAIRE

    Phillips, A. P.; Martin, K L; Broster, M G

    1983-01-01

    A quantitative immunofluorescence assay based on fiber optic microscopy was used to measure the reaction of formalized spores of Bacillus anthracis and Bacillus cereus isolates with fluorescein conjugates prepared by hyperimmunization with B. anthracis Vollum spores. The spores of 11 of the 20 B. cereus strains reacted with the anti-anthrax conjugate to such an extent that they were indistinguishable from the spores of the several B. anthracis isolates tested. However, absorption of the conju...

  9. 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

  10. 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.

  11. 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

    OpenAIRE

    Ratu SAFITRI; Bambang PRIADIE; Mia MIRANTI; Arum Widi ASTUTI

    2015-01-01

    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...

  12. 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.

  13. 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.

  14. Distribution of phenotypes among Bacillus thuringiensis strains

    Science.gov (United States)

    An extensive collection of Bacillus thuringiensis isolates from around the world were phenotypically profiled using standard biochemical tests. Six phenotypic traits occurred in 20-86% of the isolates and were useful in distinguishing isolates: production of urease (U; 20.5% of isolates), hydrolysis...

  15. Protein-Tyrosine Phosphorylation in Bacillus subtilis

    DEFF Research Database (Denmark)

    Mijakovic, Ivan; Petranovic, Dina; Bottini, N.; Deutscher, J.; Jensen, Peter Ruhdal

    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 on...

  16. Complete Genome of Bacillus subtilis Myophage Grass

    OpenAIRE

    Miller, Stanton Y.; Colquhoun, Jennifer M.; Perl, Abbey L.; Chamakura, Karthik R.; Kuty Everett, Gabriel F.

    2013-01-01

    Bacillus subtilis is a ubiquitous Gram-positive model organism. Here, we describe the complete genome of B. subtilus myophage Grass. Aside from genes encoding core proteins pertinent to the life cycle of the phage, Grass has several interesting features, including an FtsK/SpoIIIE protein.

  17. 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.

  18. 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.

  19. 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.

  20. Dielectric properties of Ba(Ga1/2Nb1/2)0.25Ti0.75O3 ceramic

    Science.gov (United States)

    Chandra, K. P.; Kulkarni, A. R.; Prasad, K.

    2016-05-01

    Lead-free perovskite Ba(Ga1/2Nb1/2)0.25Ti0.75O3 was prepared using conventional ceramic technique at 1450°C/5h in air atmosphere and characterized by X-ray diffraction, scanning electron microscopy, dielectric and impedance studies. The crystal symmetry, space group and unit cell dimensions were derived from the experimental results using FullProf software. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space groupPm3m(221). EDX and SEM studies were carried to study the quality and purity of the compound. Partial replacement of Ti4+ with pseudo-cation((Ga1/23 +Nb1/2 5 +) 4 + ) significantly reduces the dielectric constant as well as loss tangent values and improves the frequency and temperature stability of the dielectric properties and exhibited a low value of temperature coefficient of capacitance (Industries Association. Hence, this compound might be a suitable candidate for capacitor applications.

  1. Epitaxial growth of ultra-thin NbN films on AlxGa1−xN buffer-layers

    International Nuclear Information System (INIS)

    The suitability of AlxGa1−xN epilayers to deposit onto ultra-thin NbN films has been demonstrated for the first time. High quality single-crystal films with 5 nm thickness confirmed by high resolution transmission electron microscopy (HRTEM) have been deposited in a reproducible manner by means of reactive DC magnetron sputtering at elevated temperatures and exhibit critical temperatures (Tc) as high as 13.2 K and residual resistivity ratio (RRR) ∼1 on hexagonal GaN epilayers. On increasing the Al content x in the AlxGa1−xN epilayer above 20%, a gradual deterioration of Tc to 10 K was observed. Deposition of NbN on bare silicon substrates served as a reference and comparison. Excellent spatial homogeneity of the fabricated films was confirmed by R(T) measurements of patterned micro-bridges across the entire film area. The superconducting properties of these films were further characterized by critical magnetic field and critical current measurements. It is expected that the employment of GaN material as a buffer-layer for the deposition of ultra-thin NbN films will prospectively benefit terahertz electronics, particularly hot electron bolometer (HEB) mixers. (paper)

  2. 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

    2016-01-01

    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. PMID:27121446

  3. Impact of indium mole fraction on the quantum transport of ultra-scaled In x Ga1- x As double-gate Schottky MOSFET: tight-binding approach

    Science.gov (United States)

    Ahangari, Zahra

    2016-02-01

    This paper explores the impact of indium mole fraction on the electrical characteristic of In x Ga1- x As double-gate Schottky MOSFET (SBFET) in nanoscale regime. A 20-band sp 3 d 5 s * tight-binding formalism is applied to compute the bandstructure of ultra-thin body structure as a function of indium mole fraction. The injection velocity of carriers is increased as the indium mole fraction approaches to x = 1. Quantum confinement results in an increment of the effective Schottky barrier height especially for the increased values of indium mole fraction. The ultra-scaled In x Ga1- x As SBFET suffers from a low conduction band DOS in the Γ valley that results in serious degradation of the gate capacitance. The electrical characteristic of this device is considered by solving self-consistent 2D Schrődinger-Poisson equations based on non-equilibrium Green's function formalism. For channel thicknesses where the effect of quantum confinement on the gate capacitance is not dominant, shrinking the channel thickness besides increasing the indium mole fraction improves the electrical characteristic of the device. However, for the ultra-scaled structure, the indium mole fraction enhancement degrades the device performance due to the enhanced value of Schottky barrier height and low DOS.

  4. Electronic structure and magnetic properties of quaternary Heusler alloy Co2CrGa1−xGex (x=0−1)

    International Nuclear Information System (INIS)

    The electronic structure of Co-based quaternary Heusler compounds Co2CrGa1−xGex (x=0.00, 0.25, 0.50, 0.75, 1.00) are calculated by first-principles density functional theory. The substitution of Ga by Ge leads to increase in the number of valence electrons. With increasing concentration of Ge, lattice constant decreases linearly whereas bulk modulus and total magnetic moment increases. This shows that the magnetic properties of the compound are dependent on electron concentration of main group element. The calculations show that the alloys with x=0.00, 0.25, 0.50 are not true half-metallic materials whereas alloy with x=0.75, 1.00 exhibit 100% spin polarization at the Fermi level. It shows that the Fermi level can be shifted within the energy-gap to achieve 100% spin polarization. The effect of volumetric and tetragonal strain on magnetic properties is also studied. - Highlights: • We present study of electronic and magnetic properties of Co2CrGa1−xGex (x=0−1). • The Fermi level shift with change in Ge concentration. • The compounds with x=0.00, 0.25 and 0.50 have spin-polarization less than 100%. • At x=0.75 and 1.00, 100% spin-polarization is achieved. • Effect of volumetric and tetragonal strain on magnetic properties has been studied

  5. 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.

  6. Synthesis of high Al content AlxGa1−xN ternary films by pulsed laser co-ablation of GaAs and Al targets assisted by nitrogen plasma

    International Nuclear Information System (INIS)

    Highlights: • AlxGa1−xN films were synthesized by co-ablation of an Al target and a GaAs target. • Nitrogen plasma was used to assist the synthesis of AlxGa1−xN ternary films. • The AlxGa1−xN films are slightly rich in N with an Al content above 0.6. • The AlxGa1−xN films are hexagonal wurtzite in crystal structure. • The AlxGa1−xN films have an absorption edge of 260 nm and a band gap of 4.7 eV. - Abstract: We present the synthesis of AlxGa1−xN ternary films by pulsed laser co-ablation of a polycrystalline GaAs target and a metallic Al target in the environment of nitrogen plasma which provides nitrogen for the films and assists the formation of nitride films. Field emission scanning electron microscopy exposes the smooth surface appearance and dense film structure. X-ray diffraction, Fourier-transform infrared spectroscopy and Raman scattering spectroscopy reveal the hexagonal wurtzite structure. Optical characterization shows high optical transmittance with an absorption edge of about 260 nm and a band gap of 4.7 eV. Compositional analysis gives the Al content of about 0.6. The structure and optical properties of the AlxGa1−xN films are compared with those of binary GaN and AlN films synthesized by ablating GaAs or Al target with the same nitrogen plasma assistance

  7. Epidemiology of bacillus cereus implied in food contaminations

    International Nuclear Information System (INIS)

    Bacillus Cereus is an opportunistic pathogen. It is a causative agent in both gastrointestinal and in non gastrointestinal infections. In this study, 41 strains of Bacillus Cereus were isolated on Polymixin-Mannitol-Egg-Yolk Phenol red Agar (PMYPA) from foods (milk products, pasta, meat). These isolates were characterised and identified by biochemical and molecular tests. Pcr was performed for detection and characterisation of toxins genes in bacillus cereus. (author). 108 refs

  8. 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...

  9. 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

  10. 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...

  11. Insecticidal crystal proteins of Bacillus thuringiensis.

    OpenAIRE

    Höfte, H; Whiteley, H. R.

    1989-01-01

    A classification for crystal protein genes of Bacillus thuringiensis is presented. Criteria used are the insecticidal spectra and the amino acid sequences of the encoded proteins. Fourteen genes are distinguished, encoding proteins active against either Lepidoptera (cryI), Lepidoptera and Diptera (cryII), Coleoptera (cryIII), or Diptera (cryIV). One gene, cytA, encodes a general cytolytic protein and shows no structural similarities with the other genes. Toxicity studies with single purified ...

  12. First-principles calculations of the structural, electronic and optical properties of cubic BxGa1-xAs alloys

    International Nuclear Information System (INIS)

    Density functional calculations are performed to study the structural, electronic and optical properties of technologically important BxGa1-xAs ternary alloys. The calculations are based on the total-energy calculations within the full-potential augmented plane-wave (FP-LAPW) method. For exchange-correlation potential, local density approximation (LDA) and the generalized gradient approximation (GGA) have been used. The structural properties, including lattice constants, bulk modulus and their pressure derivatives, are in very good agreement with the available experimental and theoretical data. The electronic band structure, density of states for the binary compounds and their ternary alloys are given. The dielectric function and the refractive index are also calculated using different models. The obtained results compare very well with previous calculations and experimental measurements.

  13. Correlated high-resolution x-ray diffraction, photoluminescence, and atom probe tomography analysis of continuous and discontinuous InxGa1−xN quantum wells

    International Nuclear Information System (INIS)

    Atom probe tomography (APT) is used to characterize the influence of hydrogen dosing during GaN barrier growth on the indium distribution of InxGa1−xN quantum wells, and correlated micro-photoluminescence is used to measure changes in the emission spectrum and efficiency. Relative to the control growth, hydrogen dosing leads to a 50% increase in emission intensity arising from discontinuous quantum wells that are narrower, of lower indium content, and with more abrupt interfaces. Simulations of carrier distributions based on APT composition profiles indicate that the greater carrier confinement leads to an increased radiative recombination rate. Furthermore, APT analysis of quantum well profiles enables refinement of x-ray diffraction analysis for more accurate nondestructive measurements of composition

  14. Ab initio theory of native defects in alloys: application to charged N vacancies in AlxGa1-xN

    International Nuclear Information System (INIS)

    We present calculations of the electronic and atomic structures of neutral and charged nitrogen vacancies in AlxGa1-xN alloys using a combination of first-principles methods. The treatment of the alloys is based on the generalized quasichemical approach to disorder and composition effects and a cluster expansion to account for the various configurations. The point defects are modelled by supercells which are multiples of the alloy clusters. The total-energy and electronic-structure calculations are performed within the density functional theory and the local spin density approximation. We study the atomic structure, the energetics and the charge-dependent vacancy states for the different clusters versus cation numbers and for the alloys versus composition x. (author)

  15. High Real-Space Resolution Measurement of the Local Structure of Ga1-xInxAs Using X-Ray Diffraction

    International Nuclear Information System (INIS)

    High real-space resolution atomic pair distribution functions PDFs from the alloy series Ga1-xln xAs have been obtained using high-energy x-ray diffraction. The first peak in the PDF is resolved as a doublet due to the presence of two nearest neighbor bond lengths, Ga-As and In-As, as previously observed using x-ray absorption fine structure. The widths of nearest, and higher, neighbor PDF peaks are analyzed by separating the broadening due to static atom displacements from the thermal motion. The PDF peak width is 5 times larger for distant atomic neighbors than for nearest neighbors. The results are in agreement with model calculations. (c) 1999 The American Physical Society

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Bacillus cellulasensis sp. nov., isolated from marine sediment.

    Science.gov (United States)

    Mawlankar, Rahul; Thorat, Meghana N; Krishnamurthi, Srinivasan; Dastager, Syed G

    2016-01-01

    A novel bacterial strain NIO-1130(T) was isolated from sediment sample taken from Chorao Island, Goa Province, India, and subjected to a taxonomic investigation. The strain was Gram-positive, aerobic, and motile. Phylogenetic analysis based on 16S rRNA gene sequences placed the isolate within the genus Bacillus and strain NIO-1130(T) showed highest sequence similarity with Bacillus halosaccharovorans DSM 25387(T) (98.4%) and Bacillus niabensis CIP 109816(T) (98.1%), whereas other Bacillus species showed <97.0% similarity. Tree based on gyrB gene sequence revealed that strain bacillus group. The major menaquinone was MK-7 and the predominant cellular fatty acids were iso-C15:0, anteiso-C15:0, iso-C17:0, and anteiso-C17:0. The strain showed a DNA G+C content of 39.9 mol%. DNA-DNA hybridization studies revealed that strain NIO-1130(T) exhibits 70% similarity with Bacillus halosaccharovorans DSM 25387(T) and Bacillus niabensis CIP 109816(T). On the basis of physiological, biochemical, chemotaxonomic and phylogenetic analyses, we consider the isolate to represent a novel species of the genus Bacillus, for which the name Bacillus cellulasensis sp. nov., is proposed. The type strain is NIO-1130(T) (=NCIM 5461(T)=CCTCC AB 2011126(T)). PMID:26410293

  4. 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)

  5. 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.

  6. 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

  7. Chemical inhomogeneity in InxGa1-xN and ZnO. A HRTEM study on atomic scale clustering

    International Nuclear Information System (INIS)

    Nanostructuration as well as the nucleation and growth of nanoparticles pervades the development of modern materials and devices. Quantitative high resolution transmission electron microscopy (HRTEM) is currently being developed for a structural and chemical analysis at an atomic scale. It is used in this thesis to study the chemical inhomogeneity and clustering in InxGa1-xN, InN and ZnO. A methodology for reliable quantitative HRTEM is rst de ned: it necessitates a damage free sample, the avoidance of electron beam damage and the control of microscope instabilities. With these conditions satis ed, the reliability of quantitative HRTEM is demonstrated by an accurate measurement of lattice relaxation in a thin TEM sample. Clustering in an alloy can then be distinguished from a random distribution of atoms. In InxGa1-xN for instance, clustering is detected for concentrations x>0.1. The sensitivity is insufficient to determine whether clustering is present for lower concentrations. HRTEM allows to identify the amplitude and the spatial distribution of the decomposition which is attributed to a spinodal decomposition. In InN, nanometer scale metallic indium inclusions are detected. With decreasing size of the metallic clusters, the photoluminescence of the sample shifts towards the infrared. This indicates that the inclusions may be responsible for the infrared activity of InN. Finally, ZnO grown homoepitaxially on zinc-face and oxygen-face substrates is studied. The O-face epilayer is strained whereas the Zn-face epilayer is almost strain free and has a higher crystalline quality. Quantitative analysis of exit wave phases is in good agreement with simulations, but the signal to noise ratio needs to be improved for the detection of single point defects. (orig.)

  8. Genetic transformation of Bacillus strains close to bacillus subtilis and isolated from the soil

    International Nuclear Information System (INIS)

    Chromosomal and plasmid transformation was found in five out of 118 Bacillus strains, close or identical to Bacillus subtilis, and isolated from soil in Moscow or in the Moscow district. The efficiency of transformation in these strains was lower than that in derivatives of Bac. subtilis strain 168. In these strains the ability to undergo transformation was dependent on the rate of sporulation and the presence of restrictases. As in the case of Bac. subtilis 168 the strains isolated may be used as models in genetic transformation studies on Bac. subtilis

  9. Electron g-factor study in Ga1−xInxAsySb1−y–GaSb and GaSb–Ga1−xInxAsySb1−y–GaSb quaternary alloy semiconductor spherical quantum dots

    International Nuclear Information System (INIS)

    Within an interpolation scheme, we have determined the electron g-factor and the Kane interband energetic parameter of Ga1−xInxAsySb1−y–GaSb semiconductors quaternary alloy and used them to determine the electron g-factor in GaSb–Ga1−xInxAsySb1−y–GaSb spherical quantum dots (SQDs) as well as to calculate the Landau levels. In the low-dimensional systems a framework of an eight-band effective-mass model in which the contribution of the conduction remote bands and the k-vector · p-vector mixing between the conduction band Γc6 and the valence bands Γv8 and Γv7 states are considered. Our results show that the dependence of the bulk electron g-factor as a function of x can be fit with a cubic polynomial. We have established a relation between the electron g-factor and both the radius and the indium concentration in GaSb–Ga1−xInxAsySb1−y–GaSb SQDs. For these quaternary SQDs with a parabolic confining potential we have found that the difference between the electron energy levels corresponding to spin-up and spin-down states is larger (∼ 10 meV) than the corresponding states in GaAs–(Ga, Al)As quantum wells (QWs) (∼ 0.2 meV) of comparable dimensions and increases with the applied magnetic field

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. Semiautomated Metabolic Staining Assay for Bacillus cereus Emetic Toxin

    OpenAIRE

    Finlay, W. J. J.; Logan, N A; Sutherland, A. D.

    1999-01-01

    This paper describes a specific, sensitive, semiautomated, and quantitative Hep-2 cell culture-based 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for Bacillus cereus emetic toxin. Of nine Bacillus, Brevibacillus, and Paenibacillus species assessed for emetic toxin production, only B. cereus was cytotoxic.

  19. Rapid screening test for enterotoxin-producing Bacillus cereus.

    OpenAIRE

    Jackson, S G

    1993-01-01

    Culture supernatants of 30 enterotoxin-producing Bacillus cereus isolates produced a characteristic progressive destruction of McCoy cell monolayers. Enterotoxin-negative B. cereus and other group 1 Bacillus spp. caused no monolayer disruption. The McCoy cell tissue culture system appears to provide a rapid screening assay for detection of enterotoxin-producing B. cereus.

  20. Hyaluronic Acid Production in Bacillus subtilis

    OpenAIRE

    Widner, Bill; Behr, Régine; Von Dollen, Steve; Tang, Maria; Heu, Tia; Sloma, Alan; Sternberg, Dave; DeAngelis, Paul L; Paul H. Weigel; Brown, Steve

    2005-01-01

    The hasA gene from Streptococcus equisimilis, which encodes the enzyme hyaluronan synthase, has been expressed in Bacillus subtilis, resulting in the production of hyaluronic acid (HA) in the 1-MDa range. Artificial operons were assembled and tested, all of which contain the hasA gene along with one or more genes encoding enzymes involved in the synthesis of the UDP-precursor sugars that are required for HA synthesis. It was determined that the production of UDP-glucuronic acid is limiting in...

  1. Bacillus subtilis pur operon expression and regulation.

    OpenAIRE

    Ebbole, D J; Zalkin, H

    1989-01-01

    The Bacillus subtilis pur operon is a 12-gene cluster, purEKB-purC(orf)QLF-purMNH(J)-purD, organized in groups of overlapping coding units separated by intercistronic gaps. Translational fusions of Escherichia coli lacZ were constructed to purE, purC, and purM, the first gene of each group. Analyses of gene fusions integrated into the chromosomal pur operon exclude the possibility of internal promoters in intercistronic regions and support the view that transcription is from the single sigma ...

  2. 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...

  3. 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 on...... protein-tyrosine phosphorylation in this gram-positive model organism. With its two kinases, two kinase modulators, three phosphatases and at least four different tyrosine-phosphorylated substrates, B. subtilis is the bacterium with the highest number of presently known participants in the global network...

  4. Features of Bacillus cereus swarm cells.

    Science.gov (United States)

    Senesi, Sonia; Salvetti, Sara; Celandroni, Francesco; Ghelardi, Emilia

    2010-11-01

    When propagated on solid surfaces, Bacillus cereus can produce differentiated swarm cells under a wide range of growth conditions. This behavioural versatility is ecologically relevant, since it allows this bacterium to adapt swarming to environmental changes. Swarming by B. cereus is medically important: swarm cells are more virulent and particularly prone to invade host tissues. Characterisation of swarming-deficient mutants highlights that flagellar genes as well as genes governing different metabolic pathways are involved in swarm-cell differentiation. In this review, the environmental and genetic requirements for swarming and the role played by swarm cells in the virulence this pathogen exerts will be outlined. PMID:21035546

  5. 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

  6. Draft Genome Sequences of Supercritical CO[subscript 2]-Tolerant Bacteria Bacillus subterraneus MITOT1 and Bacillus cereus MIT0214

    OpenAIRE

    Peet, Kyle C.; Thompson, Janelle R.

    2015-01-01

    We report draft genome sequences of Bacillus subterraneus MITOT1 and Bacillus cereus MIT0214 isolated through enrichment of samples from geologic sequestration sites in pressurized bioreactors containing a supercritical (sc) CO[subscript 2] headspace. Their genome sequences expand the phylogenetic range of sequenced bacilli and allow characterization of molecular mechanisms of scCO[subscript 2] tolerance.

  7. Enhanced transformation efficiency of recalcitrant Bacillus cereus and Bacillus weihenstephanensis isolates upon in vitro methylation of plasmid DNA

    OpenAIRE

    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 to recalcitrant strains that carry Sau3AI restriction barriers.

  8. Identification of Bacillus cereus Group Species Associated with Food Poisoning Outbreaks in British Columbia, Canada▿

    OpenAIRE

    McIntyre, Lorraine; Bernard, Kathryn; Beniac, Daniel; Isaac-Renton, Judith L.; Naseby, David Craig

    2008-01-01

    Food poisoning laboratories identify Bacillus cereus using routine methods that may not differentiate all Bacillus cereus group species. We recharacterized Bacillus food-poisoning strains from 39 outbreaks and identified B. cereus in 23 outbreaks, B. thuringiensis in 4, B. mycoides in 1, and mixed strains of Bacillus in 11 outbreaks.

  9. 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.

  10. Pre-nitridation induced In incorporation in InxGa1−xN nanorods on Si(111) grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    We address the issue of obtaining high quality green emitting InGaN nanorods without any phase separation. Role of pre-nitridation of the Si(111) substrate and growth, temperature on the morphology, structural and optical properties of InxGa1−xN films grown by plasma assisted molecular beam epitaxy, has been studied. The nitrogen rich growth environment and surface nitridation results in the formation of vertically well-aligned single crystalline nanorods that are coalesced and isolated at 400 °C and 500 °C, respectively. In incorporation is also seen to be enhanced to ≈28% at 400 °C to yield a stable green emission, while the nanorods grown at 500 °C show blue band-edge emission. The orientation, phase separations, and optical properties characterized by Reflection High Energy Electron Diffraction, Field Emission Scanning Electron Microscopy, high resolution x-ray diffraction, x-ray photoelectron spectroscopy, and photoluminescence are corroborated to understand the underlying mechanism. The study optimizes conditions to grow high quality catalyst-free well-aligned InGaN rods on nitrided Si surface, whose band-edge emission can be tuned from blue to green by sheer control of the substrate temperature

  11. 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.

  12. 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 ...

  13. 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

  14. 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

  15. 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

  16. Binding energies of impurity states in strained wurtzite GaN/AlxGa1−xN heterojunctions with finitely thick potential barriers

    International Nuclear Information System (INIS)

    Ground state binding energies of donor impurities in a strained wurtzite GaN/AlxGa1−xN heterojunction with a potential barrier of finite thickness are investigated using a variational approach combined with a numerical computation. The built-in electric field due to the spontaneous and piezoelectric polarization, the strain modification due to the lattice mismatch near the interfaces, and the effects of ternary mixed crystals are all taken into account. It is found that the binding energies by using numerical wave functions are obviously greater than those by using variational wave functions when impurities are located in the channel near the interface of a heterojunction. Nevertheless, the binding energies using the former functions are obviously less than using the later functions when impurities are located in the channel far from an interface. The difference between our numerical method and the previous variational method is huge, showing that the former should be adopted in further work for the relevant problems. The binding energies each as a function of hydrostatic pressure are also calculated. But the change is unobvious in comparison with that obtained by the variational method

  17. Model for longitudinal-optical phonons and electron-phonon coupling in GaAs-Ga1-xAlxAs multilayer structures

    Science.gov (United States)

    Guillemot, C.; Clérot, F.

    1991-09-01

    A continuum theory is developed to investigate the properties of the long-wavelength longitudinal-optical phonons in GaAs-Ga1-xAlxAs multilayer structures and the associated electron-phonon interaction. Depending on the layer, the relative ionic displacements are related to GaAs or GaAs-type longitudinal-optical phonons and treated in the framework of the Born-Huang model, generalized to include isotropic dispersion effects in the Brillouin-zone center. For double heterostructures, a finite number of quantized confined modes is found. The interplay between the long-range Coulomb interaction, which couples the vibrations of adjacent GaAs layers, and confinement effects, which prevent the displacements of adjacent GaAs layers to overlap, is elucidated in the case of superlattices. The strength of the electron-phonon coupling in double heterostructures is reduced as compared with the electron-bulk-phonon effective coupling strength for quantum-well widths smaller than 100 Å.

  18. 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.

  19. 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

  20. Preparation of GaAs and Ga1-xAlxAs Multi-Layer Structures by Metalorganic Molecular Beam Epitaxy

    Science.gov (United States)

    Tokumitsu, Eisuke; Katoh, Toshiaki; Kimura, Ryuhei; Konagai, Makoto; Takahashi, Kiyoshi

    1986-08-01

    Metalorganic molecular beam epitaxial (MOMBE) growth of GaAs and (GaAl)As using triethylgallium (TEG) and triethylaluminum (TEA) has been studied. N-GaAs/p-GaAs multi-layer structures were prepared by applying an alternating ionization voltage to hydrogen. Single-crystal Ga1-xAlxAs ternary alloy with good surface mophology was successfully grown by introducing TEA as an Al source. The epitaxial layers typically showed p-type conduction with a carrier concentration of more than 1018 cm-3, this being due to residual carbon. A (GaAl)As/GaAs multiquantum well (MQW) heterostructure was fabricated by switching TEA and it was observed that the photoluminescence peak energies from the MQW structures were shifted to the higher energy position. Furthermore, selective growth of GaAs and (GaAl)As on a partly SiO2 masked GaAs substrate was investigated. In the MOMBE growth of (GaAl)As, polycrystalline film was deposited on the SiO2 masked region, while no deposition took place in the growth of GaAs.

  1. Epitaxial growth of InxGa1-xN alloy films on sapphire and silicon by reactive co-sputtering of GaAs and indium

    International Nuclear Information System (INIS)

    InxGa1-xN alloy films (0.2

  2. 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.

  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. Investigation of Al y Ga1‑ y N/Al0.5Ga0.5N quantum dot properties for the design of ultraviolet emitters

    Science.gov (United States)

    Brault, Julien; Matta, Samuel; Ngo, Thi-Huong; Korytov, Maxim; Rosales, Daniel; Damilano, Benjamin; Leroux, Mathieu; Vennéguès, Philippe; Khalfioui, Mohamed Al; Courville, Aimeric; Tottereau, Olivier; Massies, Jean; Gil, Bernard

    2016-05-01

    Self-assembled Al y Ga1‑ y N quantum dots (QDs), with y = 0 and 0.1, have been grown by molecular beam epitaxy on Al0.5Ga0.5N(0001) oriented layers using sapphire substrates. The QD formation has been followed in situ by reflection high energy electron diffraction (RHEED). A two- to three-dimensional (2D–3D) transition of the layer morphology is observed, characterized by a change of the RHEED pattern from streaky lines to Bragg spots. High QD densities, from 1010 up to near 1012 cm‑2, have been obtained. By decreasing the GaN QD size and incorporating Al inside the QDs, a strong variation in the photoluminescence (PL) emission has been observed, enabling to cover a large spectral range from near UV (3 eV) to UV-B (3.95 eV). By combining temperature-dependent and time-resolved PL measurements, the internal quantum efficiency of the QDs has been determined at both low and high temperatures as a function of the PL energy.

  5. In situ Eu doping into AlxGa1-xN grown by organometallic vapor phase epitaxy to improve luminescence properties

    Science.gov (United States)

    Koizumi, Atsushi; Kawabata, Kosuke; Lee, Dong-gun; Nishikawa, Atsushi; Terai, Yoshikazu; Ofuchi, Hironori; Honma, Tetsuo; Fujiwara, Yasufumi

    2015-03-01

    We have succeeded in situ Eu doping into AlxGa1-xN grown by organometallic vapor phase epitaxy and investigated the effects of the growth pressure and Al composition on the photoluminescence (PL) properties of Eu3+ ions. The intensity of red emission due to the 5D0-7F2 transition of Eu3+ ions decreased with increasing Al content in the case of growth at atmospheric pressure. The effect of the reactor pressure on the Eu concentration and Eu3+ PL properties showed that low-pressure growth is effective in increasing the Eu doping concentration and luminescence efficiency. The PL intensity increased with the Al composition and reached a maximum intensity at approximately x = 0.24. At Al compositions of higher than 0.24, X-ray absorption near-edge structure analysis revealed that the concentration of Eu2+ ions increased with increasing Al composition, leading to a reduction in the concentration of optically active Eu3+ ions.

  6. Antimicrobial Effects of Honey on Bacillus Cereus

    Directory of Open Access Journals (Sweden)

    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

    2014-05-01

    Full Text Available 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 Razavi Province and A3 of South Khorasan province (were prepared and studied in terms of chemical parameters .The antibacterial effect of honey was surveyed throughTurbidimeter using spectrometer with incubator time of 2, 4, 6, and 8hrs. the level of turbidity caused by bacterium growth was measured at different times with a wavelength of 600nm. Results: According to the study, the samples containing higher concentration of polyphenol has more antimicrobial activity. The samples of A2, A3, and A1 had the highest concentration of polyphenol, respectively. Conclusion: The results indicate the prebiotic effect of honey that can be justified by the presence of fructo-oligosacharids and vitamin B. Keywords: Honey, Bacillus Cereus, Antibacterial, Turbidimetry.

  7. 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

  8. 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

  9. 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.

  10. DNA fingerprinting of Bacillus cereus from diverse sources by restriction fragment length polymorphism analysis

    OpenAIRE

    Swarnakaran Hemalatha; Narasimhan Banu

    2010-01-01

    Bacillus cereus is an opportunistic pathogen causing food poisoning manifested by diarrhoeal or emetic syndrome. It is closely related to animal and human pathogens Bacillus anthracis and the insect pathogen Bacillus thuringiensis. In the present study, antibiotic resistance, heavy metal tolerance & molecular typing of Bacillus cereus from diverse sources such as soil, sewage water, air, fresh water, sea water and milk were studied. Bacillus cereus resistant to Penicillin (10 units/ml) an...

  11. 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 ℃ .

  12. 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℃.

  13. 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....

  14. 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.

  15. 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

  16. Structural genes encoding the thermophilic alpha-amylases of Bacillus stearothermophilus and Bacillus licheniformis.

    OpenAIRE

    Gray, G L; Mainzer, S E; Rey, M W; Lamsa, M H; Kindle, K L; Carmona, C; Requadt, C

    1986-01-01

    The genes encoding the thermostable alpha-amylases of Bacillus stearothermophilus and B. licheniformis were cloned in Escherichia coli, and their DNA sequences were determined. The coding and deduced polypeptide sequences are 59 and 62% homologous to each other, respectively. The B. stearothermophilus protein differs most significantly from that of B. licheniformis in that it possesses a 32-residue COOH-terminal tail. Transformation of E. coli with vectors containing either gene resulted in t...

  17. Bacillus thuringiensis as a surrogate for Bacillus anthracis in aerosol research.

    Science.gov (United States)

    Tufts, Jenia A M; Calfee, M Worth; Lee, Sang Don; Ryan, Shawn P

    2014-05-01

    Characterization of candidate surrogate spores prior to experimental use is critical to confirm that the surrogate characteristics are as closely similar as possible to those of the pathogenic agent of interest. This review compares the physical properties inherent to spores of Bacillus anthracis (Ba) and Bacillus thuringiensis (Bt) that impact their movement in air and interaction with surfaces, including size, shape, density, surface morphology, structure and hydrophobicity. Also evaluated is the impact of irradiation on the physical properties of both Bacillus species. Many physical features of Bt and Ba have been found to be similar and, while Bt is considered typically non-pathogenic, it is in the B. cereus group, as is Ba. When cultured and sporulated under similar conditions, both microorganisms share a similar cylindrical pellet shape, an aerodynamic diameter of approximately 1 μm (in the respirable size range), have an exosporium with a hairy nap, and have higher relative hydrophobicities than other Bacillus species. While spore size, morphology, and other physical properties can vary among strains of the same species, the variations can be due to growth/sporulation conditions and may, therefore, be controlled. Growth and sporulation conditions are likely among the most important factors that influence the representativeness of one species, or preparation, to another. All Bt spores may, therefore, not be representative of all Ba spores. Irradiated spores do not appear to be a good surrogate to predict the behavior of non-irradiated spores due to structural damage caused by the irradiation. While the use of Bt as a surrogate for Ba in aerosol testing appears to be well supported, this review does not attempt to narrow selection between Bt strains. Comparative studies should be performed to test the hypothesis that viable Ba and Bt spores will behave similarly when suspended in the air (as an aerosol) and to compare the known microscale characteristics

  18. Production of Diarrheal Enterotoxins and Other Potential Virulence Factors by Veterinary Isolates of Bacillus Species Associated with Nongastrointestinal Infections

    OpenAIRE

    Rowan, Neil J.; Caldow, George; Gemmell, Curtis G.; Hunter, Iain S.

    2003-01-01

    With the exceptions of Bacillus cereus and Bacillus anthracis, Bacillus species are generally perceived to be inconsequential. However, the relevance of other Bacillus species as food poisoning organisms and etiological agents in nongastrointestinal infections is being increasingly recognized. Eleven Bacillus species isolated from veterinary samples associated with severe nongastrointestinal infections were assessed for the presence and expression of diarrheagenic enterotoxins and other poten...

  19. Transmission electron microscopy investigation of segregation and critical floating-layer content of indium for island formation in InxGa1-xAs

    Science.gov (United States)

    Litvinov, D.; Gerthsen, D.; Rosenauer, A.; Schowalter, M.; Passow, T.; Feinäugle, P.; Hetterich, M.

    2006-10-01

    We have investigated InxGa1-xAs layers grown by molecular-beam epitaxy on GaAs(001) by transmission electron microscopy (TEM) and photoluminescence spectroscopy. InGaAs layers with In concentrations of 16, 25, and 28% and respective thicknesses of 20, 22, and 23 monolayers were deposited at 535°C . The parameters were chosen to grow layers slightly above and below the transition between the two- and three-dimensional growth mode. In-concentration profiles were obtained from high-resolution TEM images by composition evaluation by lattice fringe analysis. The measured profiles can be well described applying the segregation model of Muraki [Appl. Phys. Lett. 61, 557 (1992)]. Calculated photoluminescence peak positions on the basis of the measured concentration profiles are in good agreement with the experimental ones. Evaluating experimental In-concentration profiles it is found that the transition from the two-dimensional to the three-dimensional growth mode occurs if the indium content in the In floating layer exceeds 1.1±0.2 monolayers. The measured exponential decrease of the In concentration within the cap layer on top of the islands reveals that the In floating layer is not consumed during island formation. In addition, In0.25Ga0.75As quantum wells were grown at different temperatures between 500°C and 550°C . The evaluation of concentration profiles shows that the segregation efficiency increases from R=0.65 to R=0.83 . The strong increase of R with the growth temperature is explained by the large growth rate of 1.5ML/s . Comparison with the temperature dependence of published segregation efficiencies obtained at lower growth rates reveals increasing temperature dependence and decreasing segregation efficiency with increasing growth rate.

  20. 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

  1. Comparative research on reflection-mode GaAs photocathode with graded AlxGa1-xAs buffer layer

    Science.gov (United States)

    Chen, Liang; Shen, Yang; Zhang, Shuqin; Qian, Yunsheng; Xu, Sunan

    2015-11-01

    The graded Al compositional AlxGa1-xAs buffer layer can not only form continuous internal electric field from buffer layer to active layer but also optimize the interface properties by decreasing the misfit dislocations and stacking faults arising from lattice mismatch. By measuring the spectral response current (SRC) for two reflection-mode (r-mode) designed samples of graded and stationary Al compositional structure, we can find the special phenomenon that the graded structure had quite influence at the middle wavelength band from 550 nm to 850 nm, but not the short wavelength band from 400 nm to 550 nm, though the buffer layer can only absorb photon energy at the short wavelength band. Through the comparative research for designed samples through SPV before Cs-O activation and SRC after Cs-O activation, the graded structure can well optimize the key parameters such as LD, Ln, Sv and P. For the photon absorption lengths are relative little at the short wavelength band and relative long at the middle wavelength band, so the optimizations of key parameters have little influence on photo-excited electrons at the short wavelength band which are mainly excited from the region in active layer near surface barriers. The optimizations of key parameter, mainly the back interface recombination velocity (Sv), can have quite impact on photo-excited electrons at the middle short wavelength band which are mainly excited from the internal active layer near the back interface. This comparative research can help to well study the photo-emission theory and structure design on graded Al compositional design for r-mode GaAs photocathodes in the future research.

  2. 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

  3. 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.

  4. Pseudosecretion of Escherichia coli chloramphenicol acetyltransferase by Bacillus subtilis.

    OpenAIRE

    Le Grice, S F; Gentz, R; Bannwarth, W; Kocher, H. P.

    1987-01-01

    Bacillus subtilis harboring the vector 25RBSII secrets an Escherichia coli-derived chloramphenicol acetyltransferase into culture supernatants. The secreted enzyme lacks 18 amino acids; these are removed externally rather than during secretion.

  5. Protein engineering of cyclodextrin glycosyltransferase from Bacillus circulans strain 251

    OpenAIRE

    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. 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.

  7. 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.

  8. 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...

  9. 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.

  10. 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...

  11. 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...

  12. 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...

  13. Complete genome sequence of Bacillus thuringiensis strain HD521

    OpenAIRE

    Li, Qiao; Xu, Li Z.; Zou, Ting; Ai, Peng; Huang, Gang H.; Li, Ping; Zheng, Ai P.

    2015-01-01

    Bacillus thuringiensis is the most widely used biological pesticide in the world. It belongs to the Bacillus cereus sensu lato group, which contains six species. Among these six species, B. thuringiensis, B. anthracis, and B. cereus have a low genetic diversity. B. thuringiensis strain HD521 shows maroon colony which is different from most of the B. thuringiensis strains. Strain HD521 also displays an ability to inhibit plant sheath blight disease pathogen (Rhizoctonia solani AG1 IB) growth a...

  14. 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...

  15. 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...

  16. 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...

  17. A monograph on amylases from Bacillus spp.

    OpenAIRE

    M. K. Sarath Josh; S. Sreedevi; Prakasan Priji; K. N. Unni; S Sajith; S.Pradeep; V. N. Jisha; R. B. Smitha; Sailas Benjamin

    2013-01-01

    Owing to the production of alpha, beta and gamma amylase subtypes; starch degrading microbes, especially bacteria have an invincible role in the food, fermentation, textile and paper industries. Of them, α-amylases from Bacillus spp. have contributed tremendous advancements in bio-industry, especially in starch, detergent and pharmaceutical arena. Though general reviews are seen in literature on amylases, no focused review is available yet solely on α-amylases produced by Bacillus spp. Hence...

  18. Induction of natural competence in Bacillus cereus ATCC14579

    OpenAIRE

    Mirończuk, Aleksandra M; Kovács, Ákos T; Kuipers, Oscar P

    2008-01-01

    Summary 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 involved in natural DNA uptake in Bacillus subtiliscould be identified in B. cereus. Here, we report that B. cereus ATCC14579 can become naturally competent. When expressing the B. subtilis...

  19. The Silicon Layer Supports Acid Resistance of Bacillus cereus Spores

    OpenAIRE

    Hirota, Ryuichi; Hata, Yumehiro; Ikeda, Takeshi; Ishida, Takenori; Kuroda, Akio

    2010-01-01

    Silicon (Si) is considered to be a “quasiessential” element for most living organisms. However, silicate uptake in bacteria and its physiological functions have remained obscure. We observed that Si is deposited in a spore coat layer of nanometer-sized particles in Bacillus cereus and that the Si layer enhances acid resistance. The novel acid resistance of the spore mediated by Si encapsulation was also observed in other Bacillus strains, representing a general adaptation enhancing survival u...

  20. 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...

  1. 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...

  2. Genetic relationships between sympatric populations of Bacillus cereus and Bacillus thuringiensis, as revealed by rep-PCR genomic fingerprinting

    OpenAIRE

    Ana Paula S Peruca; Vilas-Bôas, Gislayne T.; OMN Arantes

    2008-01-01

    The bacterial strain Bacillus cereus is closely related to Bacillus thuringiensis, although any genetic relationship between the two strains is still in debate. Using rep-PCR genomic fingerprinting, we established the genetic relationships between Brazilian sympatric populations of B. cereus and B. thuringiensis simultaneously collected from two geographically separate sites. We observed the formation of both B. thuringiensis and B. cereus clusters, as well as strains of B. cereus that are mo...

  3. Expression of an endotoxin-free S-layer/allergen fusion protein in gram-positive Bacillus subtilis 1012 for the potential application as vaccines for immunotherapy of atopic allergy

    Directory of Open Access Journals (Sweden)

    Egelseer Eva

    2011-02-01

    Full Text Available Abstract Background Genetic fusion of the major birch pollen allergen (Bet v1 to bacterial surface-(S-layer proteins resulted in recombinant proteins exhibiting reduced allergenicity as well as immunomodulatory capacity. Thus, S-layer/allergen fusion proteins were considered as suitable carriers for new immunotherapeutical vaccines for treatment of Type I hypersensitivity. Up to now, endotoxin contamination of the fusion protein which occurred after isolation from the gram-negative expression host E. coli had to be removed by an expensive and time consuming procedure. In the present study, in order to achieve expression of pyrogen-free, recombinant S-layer/allergen fusion protein and to study the secretion of a protein capable to self-assemble, the S-layer/allergen fusion protein rSbpA/Bet v1 was produced in the gram-positive organism Bacillus subtilis 1012. Results The chimaeric gene encoding the S-layer protein SbpA of Lysinibacillus sphaericus CCM 2177 as well as Bet v1 was cloned and expressed in B. subtilis 1012. For that purpose, the E. coli-B. subtilis shuttle vectors pHT01 for expression in the B. subtilis cytoplasm and pHT43 for secretion of the recombinant fusion protein into the culture medium were used. As shown by western blot analysis, immediately after induction of expression, B. subtilis 1012 was able to secret rSbpA/Bet v1 mediated by the signal peptide amyQ of Bacillus amyloliquefaciens. Electron microscopical investigation of the culture medium revealed that the secreted fusion protein was able to form self-assembly products in suspension but did not recrystallize on the surface of the B. subtilis cells. The specific binding mechanism between the N-terminus of the S-layer protein and a secondary cell wall polymer (SCWP, located in the peptidoglycan-containing sacculi of Ly. sphaericus CCM 2177, could be used for isolation and purification of the secreted fusion protein from the culture medium. Immune reactivity of rSbpA/Bet v1

  4. Exciton-related nonlinear optical response and photoluminescence in dilute nitrogen InxGa1−xNyAs1−y/GaAs cylindrically shaped quantum dots

    International Nuclear Information System (INIS)

    An investigation of the effects of the dilute nitrogen contents in the exciton states of cylindrical InxGa1−xNyAs1−y/GaAs quantum dots is presented. The exciton states in the system are obtained within the effective mass theory and the band anti-crossing model. Exciton-related nonlinear optical absorption and refractive index change, as well as excitonic photoluminescence are studied with the help of the calculated exciton states. - Highlights: • Theoretical study of excitons in cylindrical InxGa1−xNyAs1−y/GaAs quantum dots. • Calculations of binding energy for different configurations of electron-hole pairs. • Nonlinear optical absorption and refractive index changes. • Dependence of photoluminescence energy transitions with several inputs

  5. Effect of InxGa1−xN ''continuously graded'' buffer layer on InGaN epilayer grown by metalorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    In this paper we report on the effect of an InxGa1−xN continuously graded buffer layer on an InGaN epilayer grown on a GaN template. In our experiment, three types of buffer layers including constant composition, continuously graded composition, and the combination of constant and continuously graded composition are used. Surface morphologies, crystalline quality, indium incorporations, and relaxation degrees of InGaN epilayers with different buffer layers are investigated. It is found that the InxGa1−xN continuously graded buffer layer is effective to improve the surface morphology, crystalline quality, and the indium incorporation of the InGaN epilayer. These superior characteristics of the continuously graded buffer layer can be attributed to the sufficient strain release and the reduction of dislocations. (condensed matter: structural, mechanical, and thermal properties)

  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. The effects of starting materials in the synthesis of (Ga(1-x)Znx)(N(1-x)O(x)) solid solution on its photocatalytic activity for overall water splitting under visible light.

    Science.gov (United States)

    Hisatomi, Takashi; Maeda, Kazuhiko; Lu, Daling; Domen, Kazunari

    2009-01-01

    The influence of starting materials on the physicochemical and photocatalytic properties of (Ga(1-x)Zn(x))(N(1-x)O(x)) were investigated in an attempt to optimize the preparation conditions. The catalyst was successfully prepared by nitriding a starting mixture of ZnO and Ga2O3. A mixture of metallic zinc and GaN, however, did not afford the desired compound. The crystallinity, surface area, composition, and absorption characteristics of the resultant (Ga(1-x)Zn(x))(N(1-x)O(x)) solid solution are found to be dependent on the morphology of ZnO but largely insensitive to the choice of Ga2O3 polymorph. The use of coarser-grained ZnO results in a coarser-grained catalyst with elevated zinc and oxygen content and reduced uniformity in composition and crystallinity. The results demonstrate the importance of selecting appropriate ZnO and Ga2O3 starting materials for maximizing the photocatalytic activity of (Ga(1-x)Zn(x))(N(1-x)O(x)) for overall water splitting under visible light. PMID:19107886

  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. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.)

  14. Bacillus subtilis Spore Inner Membrane Proteome.

    Science.gov (United States)

    Zheng, Linli; Abhyankar, Wishwas; Ouwerling, Natasja; Dekker, Henk L; van Veen, Henk; van der Wel, Nicole N; Roseboom, Winfried; de Koning, Leo J; Brul, Stanley; de Koster, Chris G

    2016-02-01

    The endospore is the dormant form of Bacillus subtilis and many other Firmicutes. By sporulation, these spore formers can survive very harsh physical and chemical conditions. Yet, they need to go through germination to return to their growing form. The spore inner membrane (IM) has been shown to play an essential role in triggering the initiation of germination. In this study, we isolated the IM of bacterial spores, in parallel with the isolation of the membrane of vegetative cells. With the use of GeLC-MS/MS, over 900 proteins were identified from the B. subtilis spore IM preparations. By bioinformatics-based membrane protein predictions, ca. one-third could be predicted to be membrane-localized. A large number of unique proteins as well as proteins common to the two membrane proteomes were identified. In addition to previously known IM proteins, a number of IM proteins were newly identified, at least some of which are likely to provide new insights into IM physiology, unveiling proteins putatively involved in spore germination machinery and hence putative germination inhibition targets. PMID:26731423

  15. 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.

  16. 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

  17. Bacillus cereus, a volatile human pathogen.

    Science.gov (United States)

    Bottone, Edward J

    2010-04-01

    Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. While B. cereus is associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal non-gastrointestinal-tract infections. The pathogenicity of B. cereus, whether intestinal or nonintestinal, is intimately associated with the production of tissue-destructive exoenzymes. Among these secreted toxins are four hemolysins, three distinct phospholipases, an emesis-inducing toxin, and proteases. The major hurdle in evaluating B. cereus when isolated from a clinical specimen is overcoming its stigma as an insignificant contaminant. Outside its notoriety in association with food poisoning and severe eye infections, this bacterium has been incriminated in a multitude of other clinical conditions such as anthrax-like progressive pneumonia, fulminant sepsis, and devastating central nervous system infections, particularly in immunosuppressed individuals, intravenous drug abusers, and neonates. Its role in nosocomial acquired bacteremia and wound infections in postsurgical patients has also been well defined, especially when intravascular devices such as catheters are inserted. Primary cutaneous infections mimicking clostridial gas gangrene induced subsequent to trauma have also been well documented. B. cereus produces a potent beta-lactamase conferring marked resistance to beta-lactam antibiotics. Antimicrobials noted to be effective in the empirical management of a B. cereus infection while awaiting antimicrobial susceptibility results for the isolate include ciprofloxacin and vancomycin. PMID:20375358

  18. 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.

  19. 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. PMID:27052865

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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 ...

  6. Phytase, Phosphatase Activity and P-Nutrition of Soybean as Influenced by Inoculation of Bacillus

    OpenAIRE

    A. Ramesh; Sushil K. Sharma; Joshi, O. P.; Khan, I. R.

    2011-01-01

    The efficiency of different Bacillus isolates on rhizosphere soil enzyme activities and P-nutrition of soybean was carried out under microcosm conditions. Significant increase in enzyme activities viz., fluorescein diacetate activity, phosphatase and phytase activity and consequent effects on P-nutrition were observed with the inoculation of Bacillus isolates over uninoculated control. Among the isolates, BD-3-1B, KHBD-6, BDKH-3, Bacillus amyloliquefacians, and Bacillus cereus were found to b...

  7. 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

  8. DETECTION OF ANTIBIOTIC-RELATED GENES FROM BACTERIAL BIOCONTROL AGENTS WITH POLYMERASE CHAIN REACTION

    Science.gov (United States)

    Pseudomonas chlororaphis PA23, Pseudomonas spp. strain DF41, and Bacillus amyloliquefaciens BS6 consistently inhibit infection of canola petals by Sclerotinia sclerotiorum in both greenhouse and field experiments. Bacillus thuringiensis BS8, Bacillus cereus L, and Bacillus mycoides S have shown sign...

  9. Malate dehydrogenases from actinomycetes: structural comparison of Thermoactinomyces enzyme with other actinomycete and Bacillus enzymes.

    OpenAIRE

    Smith, K.; Sundaram, T K; Kernick, M

    1984-01-01

    Malate dehydrogenases from bacteria belonging to the genus Thermoactinomyces are tetrameric, like those from Bacillus spp., and exhibit a high degree of structural homology to Bacillus malate dehydrogenase as judged by immunological cross-reactivity. Malate dehydrogenases from other actinomycetes are dimers and do not cross-react with antibodies to Bacillus malate dehydrogenase.

  10. 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...

  11. Complete Genome Sequence of Bacillus cereus Group Phage TsarBomba

    OpenAIRE

    Erill, Ivan; Caruso, Steven M.

    2015-01-01

    The Bacillus cereus group bacteriophage TsarBomba, a double-stranded DNA Myoviridae, was isolated from soil collected in Saratov, Russia. TsarBomba was found to be similar to Bacillus phages BCP78 and BCU4, and to have a wide host range among Bacillus cereus group species.

  12. 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

  13. Bacillus Strains Most Closely Related to Bacillus nealsonii Are Not Effectively Circumscribed within the Taxonomic Species Definition.

    Science.gov (United States)

    Peak, K Kealy; Duncan, Kathleen E; Luna, Vicki A; King, Debra S; McCarthy, Peter J; Cannons, Andrew C

    2011-01-01

    Bacillus strains with >99.7% 16S rRNA gene sequence similarity were characterized with DNA:DNA hybridization, cellular fatty acid (CFA) analysis, and testing of 100 phenotypic traits. When paired with the most closely related type strain, percent DNA:DNA similarities (% S) for six Bacillus strains were all far below the recommended 70% threshold value for species circumscription with Bacillus nealsonii. An apparent genomic group of four Bacillus strain pairings with 94%-70% S was contradicted by the failure of the strains to cluster in CFA- and phenotype-based dendrograms as well as by their differentiation with 9-13 species level discriminators such as nitrate reduction, temperature range, and acid production from carbohydrates. The novel Bacillus strains were monophyletic and very closely related based on 16S rRNA gene sequence. Coherent genomic groups were not however supported by similarly organized phenotypic clusters. Therefore, the strains were not effectively circumscribed within the taxonomic species definition. PMID:22046187

  14. 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

  15. 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.

  16. 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.

  17. 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. PMID:27031639

  18. Inactivation of Bacillus anthracis by Gamma irradiation

    Directory of Open Access Journals (Sweden)

    N. Natalia

    2013-09-01

    Full Text Available The use of Bacillus anthracis as a biological weapon heighlightened awareness of the need for validated methods for the inactivation of B. anthracis spores. Ionizing radiation is capable of causing a variety of chemical changes and biological effects on bacteria which can be due both to direct interactions with critical cell components and to indirect actions on bacteria by molecular entities formed as a result of radiolysis of other molecules in the bacterial cell. This study determined the gamma irradiation dose for inactivating B. anthracis spores and its biological effects on the bacterial characteristics. Gamma irradiation was conducted at the IRKA irradiator at the National Nuclear Energy Agency, Jakarta and cobalt-60 was used as the source of ionizing radiation (capacity of ca. 134,044 Kci. Freeze dried culture of B. anthracis in glass ampoules was irradiated using variable doses of 30, 20 and 10 KGy. Viability, biochemical and protease enzyme characteristics of B. anthracis were evaluated before and after irradiation. The ability of B. anthracis to degrade gelatin, haemoglobin and bovine immunoglobulin G was also tested. The results showed that ionizing radiation was able to inactivate or kill 11,05 x 108 cfu B. anthracis by 95.37%, 99.58% and 99.99 at respective doses of 10, 20 and 30 KGy. Bacterial spores appear to be less susceptible to irradiation than the vegetative cells, because of their specific structure. The survive spores irradiated at 30kGy shows some biochemical characteristic changes. The survivors failed to degrade methyl -D-glucopyranoside and arbutine. The ability of B. anthracis protease to degrade gelatin, haemoglobin and bovine immunoglobulin G was not affected by irradiation. These findings showed that a gamma irradiation at 30 KGy effectively inactivates B. anthracis spores without changing the protease activities.

  19. 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.

  20. 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...