Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.923
Filtrar
1.
Gene ; 713: 143971, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31299361

RESUMO

An in silico genome analysis of the probiotic Bacillus strain FTC01 was performed. The draft genome comprises 3.9 Mb, with a G + C content of 46.6% and a total of 3941 coding sequences. The species of strain FTC01 was defined as B. velezensis during GenBank genome annotation, following the current nomenclature. Eight gene clusters involved in the synthesis of non-ribosomal lipopeptides, polyketides and bacilysin were found, as well as part of the gene cluster involved in the synthesis of cyclic lipopeptide locillomycin. The production of lipopeptides surfactin and iturin by strain FTC01 was confirmed. In addition, a gene encoding a peptidylprolyl isomerase, involved in bacterial adhesion to the host tissue, beyond twelve genes responsible for acid tolerance and several hydrolase genes were found. These characteristics may help in host colonization and maintenance and may account for the probiotic properties observed for strain FTC01.


Assuntos
Bacillus/genética , Bacillus/metabolismo , Proteínas de Bactérias/genética , Genoma Bacteriano , Metaboloma , Probióticos/metabolismo , Bacillus/crescimento & desenvolvimento , DNA Bacteriano/análise , Filogenia , Análise de Sequência de DNA/métodos
2.
World J Microbiol Biotechnol ; 35(6): 90, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31147784

RESUMO

The ability of plant growth promoting rhizobacteria (PGPR) for imparting abiotic stress tolerance to plants has been widely explored in recent years; however, the diversity and potential of these microbes have not been maximally exploited. In this study, we characterized four bacterial strains, namely, Pseudomonas aeruginosa PM389, Pseudomonas aeruginosa ZNP1, Bacillus endophyticus J13 and Bacillus tequilensis J12, for potential plant growth promoting (PGP) traits under osmotic-stress, induced by 25% polyethylene glycol (PEG) in the growth medium. Growth curve analysis was performed in LB medium with or without PEG, in order to understand the growth patterns of these bacteria under osmotic-stress. All strains were able to grow and proliferate under osmotic-stress, although their growth rate was slower than that under non-stressed conditions (LB without PEG). Bacterial secretions were analyzed for the presence of exopolysaccharides and phytohormones and it was observed that all four strains released these compounds into the media, both, under stressed and non-stressed conditions. In the Pseudomonas strains, osmotic stress caused a decrease in the levels of auxin (IAA) and cytokinin (tZ), but an increase in the levels of gibberellic acid. The Bacillus strains on the other hand showed a stress-induced increase in the levels of all three phytohormones. P. aeruginosa ZNP1 and B. endophyticus J13 exhibited increased EPS production under osmotic-stress. While osmotic stress caused a decrease in the levels of EPS in P. aeruginosa PM389, B. tequilensis J12 showed no change in EPS quantities released into the media under osmotic stress when compared to non-stressed conditions. Upon inoculating Arabidopsis thaliana seedlings with these strains individually, it was observed that all four strains were able to ameliorate the adverse effects of osmotic-stress (induced by 25% PEG in MS-Agar medium) in the plants, as evidenced by their enhanced fresh weight, dry weight and plant water content, as opposed to osmotic-stressed, non-inoculated plants.


Assuntos
Arabidopsis/microbiologia , Fenômenos Fisiológicos Bacterianos , Secas , Pressão Osmótica , Desenvolvimento Vegetal , Reguladores de Crescimento de Planta/metabolismo , Polissacarídeos Bacterianos/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Bacillus/crescimento & desenvolvimento , Bacillus/fisiologia , Bactérias/classificação , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Citocininas/metabolismo , Giberelinas/metabolismo , Ácidos Indolacéticos/metabolismo , Raízes de Plantas/microbiologia , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/fisiologia , Rizosfera , Plântula/crescimento & desenvolvimento , Microbiologia do Solo , Estresse Fisiológico/fisiologia
3.
J Microbiol Biotechnol ; 29(7): 1033-1042, 2019 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-31216789

RESUMO

Bacillus velezensis BS2 was isolated from meongge (common sea squirt) jeotgal, a Korean fermented seafood, and produces a bacteriocin, BacBS2, which strongly inhibits Listeria monocytogenes and Bacillus cereus. BacBS2 was partially purified by Q-Sepharose column chromatography after ammonium sulfate precipitation of the culture supernatant, then further purified by Sephadex G-50 column chromatography. Partially purified BacBS2 was estimated to be 6.5 kDa in size by Tricine-SDS PAGE and activity detection by gel-overlay. Enzyme treatment and FT-IR spectrum of partially purified BacBS2 confirmed its proteinaceous nature. BacBS2 was fully stable at pH 4-9, and half of activity was retained at pH 1-3. Full activity was retained after exposure to 80°C for 15 min, but half of the activity was retained upon exposure to 90°C for 15 min or 100°C for 10 min. BacBS2 inhibited L. monocytogenes by bactericidal mode of action. B. velezensis BS2 and its BacBS2 seem useful as biopreservatives for fermented foods such as jeotgal.


Assuntos
Antibacterianos/metabolismo , Bacillus/metabolismo , Bacteriocinas/isolamento & purificação , Bacteriocinas/metabolismo , Alimentos Fermentados/microbiologia , Conservantes de Alimentos/metabolismo , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Antibiose , Bacillus/crescimento & desenvolvimento , Bacillus/fisiologia , Bacillus cereus/efeitos dos fármacos , Bacteriocinas/química , Bacteriocinas/farmacologia , Meios de Cultura , Conservantes de Alimentos/química , Conservantes de Alimentos/isolamento & purificação , Conservantes de Alimentos/farmacologia , Temperatura Alta , Concentração de Íons de Hidrogênio , Listeria monocytogenes/efeitos dos fármacos , Peso Molecular , Estabilidade Proteica
4.
Chemosphere ; 232: 439-452, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158639

RESUMO

This study investigated the role of an allochthonous Gram-positive wastewater bacterium (Bacillus sp. KUJM2) selected through rigorous screening, for the removal of potentially toxic elements (PTEs; As, Cd, Cu, Ni) and promotion of plant growth under PTE-stress conditions. The dried biomass of the bacterial strain removed PTEs (5 mg L-1) from water by 90.17-94.75 and 60.4-81.41%, whereas live cells removed 87.15-91.69 and 57.5-78.8%, respectively, under single-PTE and co-contaminated conditions. When subjected to a single PTE, the bacterial production of indole-3-acetic acid (IAA) reached the maxima with Cu (67.66%) and Ni (64.33%), but Cd showed an inhibitory effect beyond 5 mg L-1 level. The multiple-PTE treatment induced IAA production only up to 5 mg L-1 beyond which inhibition ensued. Enhanced germination rate, germination index and seed production of lentil plant (Lens culinaris) under the bacterial inoculation indicated the plant growth promotion potential of the microbial strain. Lentil plants, as a result of bacterial inoculation, responded with higher shoot length (7.1-27.61%), shoot dry weight (18.22-36.3%) and seed production (19.23-29.17%) under PTE-stress conditions. The PTE uptake in lentil shoots decreased by 67.02-79.85% and 65.94-78.08%, respectively, under single- and multiple-PTE contaminated conditions. Similarly, PTE uptake was reduced in seeds up to 72.82-86.62% and 68.68-85.94%, respectively. The bacteria-mediated inhibition of PTE translocation in lentil plant was confirmed from the translocation factor of the respective PTEs. Thus, the selected bacterium (Bacillus sp. KUJM2) offered considerable potential as a PTE remediating agent, plant growth promoter and regulator of PTE translocation curtailing environmental and human health risks.


Assuntos
Bacillus/crescimento & desenvolvimento , Lens (Planta)/crescimento & desenvolvimento , Poluentes do Solo/análise , Águas Residuárias/microbiologia , Bacillus/metabolismo , Biodegradação Ambiental , Germinação/efeitos dos fármacos , Ácidos Indolacéticos/metabolismo , Lens (Planta)/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Poluentes do Solo/toxicidade
5.
Curr Microbiol ; 76(7): 855-862, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31073734

RESUMO

Bacillus velezensis strain S3-1 has a broad range of hosts and is used as a biocontrol agent and biofertilizer. However, the interaction of maize root exudates and colonization of the strain S3-1 has not yet been investigated. In our study, strain S3-1 effectively colonized both rhizosphere soil and root tissue. Collected maize root exudates significantly induced the chemotaxis, cluster movement, and biofilm formation of strain S3-1, showing increases of 1.43, 1.6, and 2.08 times, respectively, compared with the control. In addition, the components of root exudates (organic acids: citric acid, malic acid, and oxalic acid; amino acids: glycine, proline and phenylalanine; sugars: glucose, fructose, and sucrose) were tested. Each of these compounds could induce chemotactic response, swarming motility, and biofilm formation significantly. The strongest chemotactic response and swarming motility were found when malic acid was applied, but maximal ability of biofilm formation was stimulated by proline. Furthermore, we found that these compounds of root exudates stimulated the population of S3-1 adhering to the maize root surface, especially in the presence of malic acid. These results indicate that maize root exudates play an important role in the colonization of S3-1, and provide a deeper understanding of the interaction between plants and microorganisms.


Assuntos
Bacillus/crescimento & desenvolvimento , Exsudatos de Plantas/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Rizosfera , Microbiologia do Solo , Zea mays , Bacillus/metabolismo , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Quimiotaxia/efeitos dos fármacos , Interações entre Hospedeiro e Microrganismos , Locomoção/efeitos dos fármacos , Compostos Orgânicos/análise , Compostos Orgânicos/farmacologia , Exsudatos de Plantas/química , Exsudatos de Plantas/farmacologia , Raízes de Plantas/química , Zea mays/metabolismo , Zea mays/microbiologia
6.
Ecotoxicol Environ Saf ; 178: 33-42, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-30991245

RESUMO

The exchangeable sodium (Na+) in salt affected soils is a major constraint in potassium (K+) availability to plants that disturb ion transport and inhibit plant growth, adversely. Salt tolerant plant growth promoting rhizobacteria (PGPR) may regulate the Na+/K+ efflux and increase K+ uptake by the plant from the soil. Therefore, a pot study was performed to examine the effect of salt tolerant PGPR Bacillus sp. alone and in consortium, on antioxidant enzyme activity, ion uptake and potato (Solanum tuberosum L.) tuber yield in normal and salt affected soils. We observed that Bacillus sp. (strains SR-2-1 and SR-2-1/1) solubilized insoluble phosphorous and produced indole-3-acetic acid while only SR-2-1/1 produced ACC deaminase in culture medium supplemented with various concentrations of NaCl (0-6%). In the pot experiment, the consortium treatment of strains was found to increase relative leaf water contents whereas decreased the electrolyte leakage and antioxidant enzyme activity both in normal and salt affected soils. Similarly, consortium treatment decreased Na+ whereas increased K+, Ca+2, K+/Na+ and Ca+2/Na+ in plant dry matter in both soils. It has been investigated that inoculation of PGPR significantly (p < 0.05) increased plant biomass, number of tubers per plant and tuber weight as compared to un-inoculated plants in both soils. In addition, PGPR inoculation enhanced auxin production in root exudates of young potato plants and bacterial population dynamics in both soils. Na+ ion regulation (R2 = 0.95) and tuber weight (R2 = 0.90) in salt affected soil were significantly correlated with auxin production in the rhizosphere. Results of this study conferred that consortium of Bacillus strains (SR-2-1, SR-2-1/1) enhanced auxin production in the rhizosphere of potato plants and that ultimately regulated antioxidant enzyme production and uptake of Na+, K+ and Ca+2 in potato plants resulted into a higher tuber yield in both normal and salt affected soils.


Assuntos
Antioxidantes/metabolismo , Bacillus/crescimento & desenvolvimento , Plantas Tolerantes a Sal , Solo/química , Solanum tuberosum/microbiologia , Biomassa , Rizosfera , Microbiologia do Solo , Solanum tuberosum/crescimento & desenvolvimento , Solanum tuberosum/metabolismo
7.
J Appl Microbiol ; 127(1): 196-207, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30955229

RESUMO

AIMS: This study builds upon the premise that roots culture distinct bacteria at specific stages of plant growth to benefit of specific microbial services needed at that particular growth stage. Accordingly, we hypothesized that the co-inoculation of beneficial microbes with distinct properties at specific stages of plant development would enhance plant performance. METHODS AND RESULTS: The chosen microbes were Bacillus pumilus, Bacillus amyloliquefaciens, Bacillus mojavensis and Pseudomonas putida. These microbes were selected based on their specific services ranging from nutrient solubilization, root growth promotion and disease resistance, and were applied to the roots of tomato plants at specific time points when those services were needed the most by the plant. Laboratory and greenhouse studies were conducted to evaluate the effects of co-inoculation at specific stages of development compared to single microbial applications. CONCLUSION: In general, the combination of three microbes gave the highest biomass and yield without the presence of disease. Applications of three microbes showed the highest root/shoot ratio, and applications of four microbes the lowest ratio. Pseudomonas putida significantly increased fruit macronutrient and micronutrient contents. SIGNIFICANCE AND IMPACT OF THE STUDY: Our studies suggest that co-inoculation of three or four microbes is a good strategy for healthy crop production.


Assuntos
Bacillus/fisiologia , Lycopersicon esculentum/microbiologia , Nutrientes/metabolismo , Reguladores de Crescimento de Planta/fisiologia , Pseudomonas putida/fisiologia , Bacillus/crescimento & desenvolvimento , Biomassa , Resistência à Doença , Frutas/metabolismo , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/imunologia , Lycopersicon esculentum/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Brotos de Planta/crescimento & desenvolvimento , Pseudomonas putida/crescimento & desenvolvimento
8.
Food Microbiol ; 82: 436-444, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31027803

RESUMO

The control of bacterial reduction is important to maintain food safety during thermal processing. The goal of this study was to illustrate and describe variability in bacterial population behavior during thermal processing as a probability distribution based on individual cell heterogeneity regarding heat resistance. Toward this end, we performed a Monte Carlo simulation via computer, and compared and validated the simulated estimations with observed values. Weibullian fitted parameters were estimated from the kinetic survival data of Bacillus simplex during thermal treatment at 94 °C. The variability in reductions of bacterial sporular populations was illustrated using Monte Carlo simulation based on the Weibull distribution of the parameters. In particular, variabilities in viable spore counts and survival probability of the B. simplex spore population were simulated in various replicates. We also experimentally determined the changes in survival probability and distributions of survival spore counts; notably, these were successfully predicted by the Monte Carlo simulation based on the kinetic parameters. The kinetic parameter-based Monte Carlo simulation could thus successfully illustrate bacterial population behavior variability during thermal processing as a probability distribution. The simulation approach may contribute to improving food quality through risk-based processing designs and enhance risk assessment model accuracy.


Assuntos
Bacillus/crescimento & desenvolvimento , Microbiologia de Alimentos/métodos , Viabilidade Microbiana , Modelos Biológicos , Modelos Estatísticos , Esporos Bacterianos/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Qualidade dos Alimentos , Inocuidade dos Alimentos , Calefação , Cinética , Método de Monte Carlo , Medição de Risco , Termotolerância
9.
Food Microbiol ; 82: 316-324, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31027789

RESUMO

Biofilm-forming Bacillus species are often involved in contamination of dairy products and therefore present a major microbiological challenge in the field of food quality and safety. In this study, we sequenced and analyzed the genomes of milk- and non-milk-derived Bacillus strains, and evaluated their biofilm-formation potential in milk. Unlike non-dairy Bacillus isolates, the dairy-associated Bacillus strains were characterized by formation of robust submerged and air-liquid interface biofilm (pellicle) during growth in milk. Moreover, genome comparison analysis revealed notable differences in putative biofilm-associated determinants between the dairy and non-dairy Bacillus isolates, which correlated with biofilm phenotype. These results suggest that biofilm formation by Bacillus species might represent a presumable adaptation strategy to the dairy environment.


Assuntos
Adaptação Fisiológica , Bacillus/fisiologia , Biofilmes/crescimento & desenvolvimento , Leite/microbiologia , Adaptação Fisiológica/genética , Animais , Bacillus/classificação , Bacillus/genética , Bacillus/crescimento & desenvolvimento , Análise por Conglomerados , DNA Bacteriano/genética , Microbiologia de Alimentos , Genes Bacterianos/genética , Variação Genética , Genoma Bacteriano/genética , Análise de Sequência de DNA
10.
Food Microbiol ; 81: 115-120, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30910082

RESUMO

Heat treatment is the main hurdle used to eliminate spores in foods but the pH conditions which spores encounter after the treatment have a tremendous impact on the spore ability to germinate, outgrow and grow. The aim of this work was to discriminate the inactive permeable spores and the active spores in unfavorable acidic conditions, after a heat treatment. In this study, Bacillus weihenstephanensis KBAB4 was used as model micro-organism for psychrotrophic Bacillus. The spores were heat treated to inactivate 90% of the population, 12 min at 85 °C, or 2 min at 95 °C. After each treatment the spores were incubated at pH 5.50 or pH 7.40. The evolution of dormant spores, permeable spores, germinated and vegetative cells was monitored by flow cytometry using a double staining. LDS 751, stains in red all the permeable cells, and CFDA stains in green cells presenting an esterase activity. Dormant spores did not show neither red fluorescence nor green fluorescence. Permeabilized spores which did not recover metabolic activity were red fluorescent but not green fluorescent. Germinated spores (permeabilized and having an esterase activity) appeared red fluorescent and green fluorescent due to their permeability and their metabolic activity. This method allowed the differentiation of the impact of heat treatment and post-treatment incubation pH on the two first steps of germination: spore permeabilization and activity recovery. Having a better understanding of spore germination at unfavorable post-treatment pH allows a better control of spore forming bacteria in foods.


Assuntos
Bacillus/crescimento & desenvolvimento , Bacillus/metabolismo , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Bacterianos/metabolismo , Citometria de Fluxo , Fluorescência , Microbiologia de Alimentos , Temperatura Alta/efeitos adversos , Concentração de Íons de Hidrogênio , Cinética , Permeabilidade , Fatores de Tempo
11.
Soft Matter ; 15(11): 2348-2358, 2019 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-30810157

RESUMO

A series of water-soluble metal functionalized surfactants have been prepared using commercially available surfactant cetyl pyridinium chloride and transition metal salts. These complexes were characterized in the solid state by elemental analysis, FTIR, 1H NMR and thermogravimetric analysis. The interfacial surface activity and aggregation behaviour of the metallosurfactants were analysed through conductivity, surface tension and small angle neutron scattering measurements. Our results show that the presence of metal ions as co-ions along with counter ions favours micellization at a low critical micellization concentration (CMC). Small angle neutron scattering revealed that the metallomicelles are of a prolate ellipsoidal shape and exhibit strong counterion binding. This article further describes the interaction of the metallosurfactants with transport protein Bovine Serum Albumin (BSA) using different spectroscopic techniques. A spectroscopic study was used to study the binding, interaction and quenching mechanism of BSA with the metallosurfactants. Gel electrophoresis (SDS-PAGE) and circular dichroism (CD) investigated the structural and conformational changes produced in BSA due to the metallosurfactants. The results indicate that there is an alteration in the secondary structure of BSA due to the electrostatic interaction between positive head groups and metal co-ions of the metallosurfactants and negatively charged amino acids of BSA. As the concentration increases, the α-helicity of BSA decreases and all the three studied metallosurfactants gave comparable results. Finally, the in vitro cytotoxicity and antimicrobial activity of the metallosurfactants were evaluated against erythrocytes and microorganisms, which showed prominent effects related to the presence of a metal ion in metallomicelles of the hybrid surfactants.


Assuntos
Cetilpiridínio/química , Metais Pesados/química , Tensoativos/química , Bacillus/efeitos dos fármacos , Bacillus/crescimento & desenvolvimento , Cetilpiridínio/farmacologia , Eritrócitos/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/crescimento & desenvolvimento , Metais Pesados/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Soroalbumina Bovina/química , Propriedades de Superfície , Tensoativos/farmacologia
12.
J Appl Microbiol ; 127(2): 326-343, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30739384

RESUMO

Root-knot nematodes are destructive phytopathogens that damage agricultural crops globally, and there is growing interest in the use of biocontrol based on rhizobacteria such as Bacillus to combat Meloidogyne species. It is hypothesized that nematicidal activity of Bacillus can be attributed to the production of secondary metabolites and hydrolytic enzymes. Yet, few studies have characterized these metabolites and their identities remain unknown. Others are speculative or fail to elaborate on how secondary metabolites were detected or distinguished from primary metabolites. Metabolites can be classified based on their origin as either intracellular or extracellular and based on their function, as either primary or secondary. Although this classification is in general use, the boundaries are not always well defined. An understanding of the secondary metabolite and hydrolytic enzyme classification of Bacillus species will facilitate investigations aimed at bionematicide development. This review summarizes the significance of Bacillus hydrolytic enzymes and secondary metabolites in bionematicide research and provides an overview of known classifications. The importance of appropriate cultivation conditions for optimum metabolite and enzyme production is also discussed. Finally, the use of metabolomics for the detection and identification of nematicidal compounds is considered.


Assuntos
Bacillus/metabolismo , Agentes de Controle Biológico , Nematoides , Animais , Antinematódeos , Bacillus/enzimologia , Bacillus/crescimento & desenvolvimento , Meios de Cultura , Metabolômica , Metabolismo Secundário , Tylenchoidea
13.
Mater Sci Eng C Mater Biol Appl ; 96: 693-707, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30606583

RESUMO

A facile one step green synthesis of silver (AgNP), gold (AuNP) and platinum (PtNP) nanoparticles has been attempted using the rind extract of the fruit of Garcinia mangostana L. The rind of the fruit is enriched with wide varieties of natural resources which could be conveniently exploited as alternative for synthesis of nanoparticles eliminating the need for hazardous chemical methods. The formation of gold nanoparticles occurred at room temperature within a few seconds while the formation of silver and platinum nanoparticles was obtained after heating the solution for 20 min at 80 °C. Parameters such as contact time, temperature and pH were optimized to obtain the precise nanoparticles. The green synthesized nanoparticles were characterized using several state-of-the-art techniques like UV-Vis spectroscopic, FT-IR, HR-SEM and HR-TEM, XRD analyses and zeta potential measurements. Attempt has also been made to evaluate the antibacterial activity of the metal nanoparticles before and after combining with commercially used antibiotics as well as free antibiotics against human pathogenic bacteria. The bare silver nanoparticles (AgNP) showed relatively higher antibacterial activity than AuNP and PtNP and this activity was found to be more pronounced against gram negative bacteria than gram positive ones. Interestingly, all the three metal nanoparticles combined with antibiotics showed enhanced antibacterial activity against the pathogenic bacteria which suggested synergism between the nanoparticles and antibiotics. The high point of the present investigation has been that the Bacillus sp. which is highly resistant to streptomycin becomes highly susceptible to the same antibiotic when combined with gold nanoparticles. This particular observation opens up windows for the treatment of antibiotic resistant bacteria after combining with different nanoparticles under clinical set up.


Assuntos
Antibacterianos , Bacillus/crescimento & desenvolvimento , Ouro , Nanopartículas Metálicas/química , Platina , Prata , Antibacterianos/química , Antibacterianos/farmacologia , Sinergismo Farmacológico , Frutas/química , Garcinia/química , Ouro/química , Ouro/farmacologia , Platina/química , Platina/farmacologia , Prata/química , Prata/farmacologia
14.
J Microbiol Biotechnol ; 29(3): 347-356, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30661324

RESUMO

Bacillus sp. BS2 showing strong fibrinolytic activity was isolated from sea squirt (munggae) jeotgal, a traditional Korean fermented seafood. BS2 was identified as B. velezensis by molecular biological methods.B. velezensis BS2 grows well at 15% NaCl and at 10oC. When B. velezensis BS2 was cultivated in TSB broth for 96 h at 37°C, the culture showed the highest fibrinolytic activity (131.15 mU/µl) at 96 h. Three bands of 27, 35 and 60 kDa were observed from culture supernatant by SDS-PAGE, and fibrin zymography showed that the major fibrinolytic protein was the 27 kDa band. The gene (aprEBS2) encoding the major fibrinolytic protein was cloned, and overexpressed in heterologous hosts, B. subtilis WB600 and E. coli BL21 (DE3). B. subtilis transformant showed 1.5-fold higher fibrinolytic activity than B. velezensis BS2. Overproduced AprEBS2 in E. coli was purified by affinity chromatography. The optimum pH and temperature were pH 8.0 and 37°C, respectively. Km and Vmax were 0.15 mM and 39.68 µM/l/min, respectively, when N-succinyl-Ala-Ala-Pro-Phe-pNA was used as the substrate. AprEBS2 has strong α-fibrinogenase and moderate ß-fibrinogenase activity. Considering its high fibrinolytic activity, significant salt tolerance, and ability to grow at 10°C, B. velezensis BS2 can be used as a starter for jeotgal.


Assuntos
Bacillus/enzimologia , Bacillus/isolamento & purificação , Alimentos Fermentados/microbiologia , Fibrinolisina/metabolismo , Fibrinolíticos/metabolismo , Urocordados/microbiologia , Animais , Bacillus/genética , Bacillus/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clonagem Molecular , Ensaios Enzimáticos , Estabilidade Enzimática , Escherichia coli/genética , Fibrina , Fibrinogênio/metabolismo , Fibrinolisina/genética , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos/genética , Concentração de Íons de Hidrogênio , Cinética , Tolerância ao Sal , Temperatura Ambiente
15.
Prep Biochem Biotechnol ; 49(1): 64-73, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30648497

RESUMO

Transglutaminases are a class of transferases known to form isopeptide bond between glutamine and lysine residues in a protein molecule. Increasing demand for transglutaminase in food and other industries and its low productivity have compelled researchers to isolate and screen micro-organisms with potential to produce it. In the present investigation around 200 isolates were screened for extracellular secretion of microbial transglutaminase (MTGase). Isolate B4 showed enzyme activity of 1.71 ± 0.2 U/mL followed by isolate C2 which showed 1.61 ± 0.17 U/mL activity, comparable with the activity of industrially used microbial strains. Biochemical analysis along with 16S r-RNA sequencing revealed these isolates (B4 and C2) to be Bacillus nakamurai and a variant of Bacillus subtilis, respectively. Amongst the various production media screened, a medium containing starch and peptone was found best for MTGase production. Correlation between growth, enzyme production, and sugar utilization was also studied and maximum enzyme production was obtained after 48 to 60 hr. Highest MTGase titer (3.95 ± 0.03 U/mL for B4 and 2.65 ± 0.17 U/mL for C2) was obtained by optimization of parameters. The enzyme was characterized for temperature and pH optima, pH and thermal stability, and effect of metal ions, suggesting its potential use in future applications.


Assuntos
Bacillus/isolamento & purificação , Transglutaminases/biossíntese , Bacillus/classificação , Bacillus/enzimologia , Bacillus/crescimento & desenvolvimento , Metabolismo dos Carboidratos , Estabilidade Enzimática , Fermentação , Concentração de Íons de Hidrogênio , Cinética , Filogenia , Especificidade da Espécie , Temperatura Ambiente , Transglutaminases/metabolismo
16.
J Appl Microbiol ; 126(6): 1632-1642, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30609144

RESUMO

Bacillus species are widely recognized as good industrial platform strains, which can produce a variety of valuable products including enzymes and functional proteins. Bacillus expression systems gain various competitive edges over other expression systems, with respect to nontoxicity, convenience for gene modification and high yield of target proteins. Recently, a number of Bacillus expression systems have been developed, and various strategies were conducted to improve the yields of target proteins. In this review, we focused on the strategies of host strain optimization for heterologous protein production, including secretion pathway optimization, RNA and protein stability enhancement, cell growth facilitation, genome streamlining and transcriptional regulator engineering. In addition, Bacillus spore surface display and food-grade expression systems were developed to expand the application of Bacillus expression system in recent years. Finally, the challenges and prospects of Bacillus expression system were discussed regarding the recent progresses, challenges and trends in this field.


Assuntos
Bacillus/genética , Bacillus/metabolismo , Proteínas de Bactérias/metabolismo , Engenharia Genética , Microbiologia Industrial/tendências , Bacillus/química , Bacillus/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Técnicas de Visualização da Superfície Celular , Regulação Bacteriana da Expressão Gênica , Estabilidade Proteica , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Via Secretória , Esporos Bacterianos/química , Esporos Bacterianos/genética , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Bacterianos/metabolismo
17.
Biotechnol Appl Biochem ; 66(2): 192-201, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30578642

RESUMO

Limonin, a compound of highly oxidized triterpenoids, has potential functions in preventing or slowing the occurrences of many diseases. In this study, five different bacterial strains were isolated and identified from Citrus maxima (Burm.) Merr. cv. Shatian Yu. Morphological characteristics and 16S rRNA gene sequencing identified them as Bacillus spp, in which two limonin-producing endophytes named P and P9 were discovered by high-performance liquid chromatography and mass spectrometry using an inorganic salt medium and two natural media; also the production was greater in natural medium 1 (4.377 and 0.299 mg/L, respectively) than in natural medium 2 (0.159 and 0.025 mg/L, respectively). The growth and fermentation characteristics of strain P were studied, and during the liquid cultivation of Bacillus sp. P, limonin began to accumulate at the eighth hour in the inorganic salt medium, peaked at the 16th hour, and then decreased sharply. Single-factor experiments revealed that the optimum fermentation conditions for limonin production included 14-H-old cells, 15% inoculum, and 3 g/L glucose.


Assuntos
Bacillus/crescimento & desenvolvimento , Bacillus/isolamento & purificação , Citrus/microbiologia , Limoninas/biossíntese
18.
Food Microbiol ; 77: 21-25, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30297052

RESUMO

Predicting the microbial safety of food products stored in modified atmosphere packaging implies taking into account the effect of oxygen reduction on microbial growth. According to their respiratory-type, the micro-organisms are not impacted similarly by the oxygen concentration. The aim of this article was to quantify and model the oxygen effect on the growth rates of 5 bacterial species: Listeria monocytogenes and Bacillus weihenstephanensis (facultative anaerobic), Pseudomonas fluorescens (strict aerobic), Clostridium perfringens and Clostridium sporogenes (strict anaerobic). The results showed the oxygen concentration doesn't modify the behavior of both facultative anaerobic strains. The growth rate of P. fluorescens decreased with the oxygen concentration, but the effect is only noticeable when the oxygen concentration fell below 3% in the gaseous phase. Conversely, the oxygen acted as a growth inhibitor for both Clostridium species. But total inhibition is reached only for 3.26% and 6.61% respectively for C. sporogenes and C. perfringens. Two models have been fitted for both respiratory-types, the first is the Monod model considering oxygen as a substrate for growth, and the second is the classic inhibitory model based on minimal inhibitory concentration.


Assuntos
Bactérias/crescimento & desenvolvimento , Microbiologia de Alimentos , Modelos Biológicos , Oxigênio/metabolismo , Atmosfera , Bacillus/crescimento & desenvolvimento , Clostridium/crescimento & desenvolvimento , Clostridium perfringens/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Embalagem de Alimentos , Cinética , Listeria monocytogenes/crescimento & desenvolvimento , Pseudomonas fluorescens/crescimento & desenvolvimento
19.
Food Microbiol ; 78: 38-45, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30497606

RESUMO

Growth/no growth boundary models for Bacillus spores that accounted for the effects of environmental pH, water activity (aw), acetic acid, lactic acid, bacterial strain, and storage period were developed using conventional logistic regression and machine learning algorithms. Growth in tryptic soy broth at 317 conditions comprising nine levels of pH (4.0-6.5), six levels of aw (0.85-1.00), six levels of acetic acid concentrations (0-0.8%), and five levels of lactic acid concentrations (0-0.8%) was examined to confirm growth limit conditions. All models developed using logistic regression, neural network, and deep learning on the basis of obtained datasets successfully described growth/no growth boundaries of three Bacillus species. Although the logistic regression model failed to describe growth limits under some conditions, neural network and deep learning approaches enabled to determine them in such cases. The developed models were evaluated by independent experimental data of growth in tryptic soy broth and in clam soup. The deep learning model enabled better prediction of independent data with smaller probabilistic variability values than those of the logistic regression and neural network models. The deep learning procedure can be utilized for growth boundary modeling to control bacterial growth safely and flexibly.


Assuntos
Algoritmos , Bacillus/crescimento & desenvolvimento , Aprendizado Profundo , Esporos Bacterianos/crescimento & desenvolvimento , Ácido Acético/farmacologia , Bacillus/efeitos dos fármacos , Bacillus/fisiologia , Caseínas , Ácido Láctico/farmacologia , Modelos Logísticos , Hidrolisados de Proteína , Esporos Bacterianos/fisiologia , Água
20.
J Basic Microbiol ; 59(3): 249-255, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30548881

RESUMO

Tragacanth, a highly branched carbohydrate polymer isolated from Astragalus, is one of the most commonly used gums in food industry. The primary structure of tragacanth is composed of galacturonic acid monomers connected with α 1-4 links, and it is very similar to the pectin. Tragacanth degradation by microorganisms is significant in two aspects: first, food preservation and microbial growth control due to too much use of tragacanth in the food industry, second, therapeutic and pharmaceutical potential of obtained oligosaccharides. In the present study, we report three new strains of bacteria, Acinetobacter guillouiae strain TD1, Kosakonia sacchari strain TD2, and Bacillus vallismortis strain PD1 with the capability of growing in tragacanth as an only source of carbon and energy. The evolutionary history of the isolated strains was analyzed based on 16S rRNA gene sequences in MEGA7 using the neighbor-joining method. The production of di and tri galacturonic acid due to pectinase activities of the strains were detected by thin layer chromatography (TLC) and liquid chromatography/Mass spectroscopy (LC/MS) analysis. Here is the first report of the ability to grow in tragacanth and pectinase activity monitoring in bacteria. Our results revealed that all of the isolated strains are capable of degrading pectin and tragacanth to oligo-galacturonic acids. The obtained products, which have different structures depending on the tragacanth structures and types of pectinolytic enzymes, would show therapeutic and pharmaceutical potentials.


Assuntos
Bactérias/enzimologia , Cromatografia Líquida , Espectrometria de Massas , Oligossacarídeos/análise , Poligalacturonase/metabolismo , Tragacanto/metabolismo , Acinetobacter/classificação , Acinetobacter/enzimologia , Acinetobacter/genética , Acinetobacter/crescimento & desenvolvimento , Bacillus/classificação , Bacillus/enzimologia , Bacillus/genética , Bacillus/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Enterobacteriaceae/classificação , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Enterobacteriaceae/crescimento & desenvolvimento , Estrutura Molecular , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Tragacanto/química , Águas Residuárias/microbiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA