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1.
J Agric Food Chem ; 67(35): 9749-9756, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31415718

RESUMO

Bovine lactoferrin N-lobe plays an important key in the nonimmunological defense system. In this work, the most suitable promoter Pveg was selected and the fragment coding bovine lactoferrin N-lobe was optimized according to codon bias of Bacillus. The recombinant plasmid pMA0911-Pveg-mBLF-N was introduced into Baicillus subtilis 168 to create B. subtilis/pMA0911-Pveg-mBLF-N. The bovine lactoferrin N-lobe was highly expressed at 28 °C for 15 h. Its purified protein was obtained with 16.5 mg/L and a purity of 93.6% using ammonium sulfate precipitation, Ni-NTA, and molecular exclusion. About 200 ng/mL purified bovine lactoferrin N-lobe completely inhibited cell-growth of Escherichia coli JM109 (DE3), 70.3% of Pseudomonas aeruginosa CGMCC 1.6740, and 41.5% of Staphylococcus aureus CGMCC 1.282. To our knowledge, this is the first report about active expression, purification, and characterization of bovine lactoferrin N-lobe in safe bacterium B. subtilis, which opens an available application way in the biomedical and food industries.


Assuntos
Antibacterianos/farmacologia , Bacillus subtilis/genética , Códon/genética , Lactoferrina/genética , Regiões Promotoras Genéticas , Animais , Antibacterianos/metabolismo , Bacillus subtilis/metabolismo , Clonagem Molecular , Códon/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Expressão Gênica , Engenharia Genética , Lactoferrina/metabolismo , Lactoferrina/farmacologia , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
2.
J Agric Food Chem ; 67(33): 9314-9324, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31352776

RESUMO

Trehalose, a stable nonreducing disaccharide, protects biomolecules against environmental stress. However, trehalose production using secretory trehalose synthase (TreS) by Bacillus subtilis has not been well studied. In this study, a mutant TreS was successfully secreted and expressed in B. subtilis WB800N. The extracellular enzyme activity of TreS regulated by the P43 promoter and SPPhoD signal peptide in recombinant B. subtilis WB800N reached 23080.6 ± 1119.4 U/L in a 5-L fermenter after optimizing the culture medium, while xpF, skfA, lytC, and sdpC were knocked out. To reduce maltose consumption, malP and amyE corresponding to maltose transporters were further deleted. To simplify the trehalose production process, we invented a fermentation-coupling biocatalysis process involving recombinant bacteria fermentation to secrete TreS and simultaneous conversion of maltose to trehalose by TreS and found that the conversion rate of maltose to trehalose reached 75.5%, suggesting that this is an efficient strategy for large-scale trehalose production using recombinant B. subtilis.


Assuntos
Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Trealose/biossíntese , Bacillus subtilis/enzimologia , Bacillus subtilis/genética , Biocatálise , Fermentação , Maltose/metabolismo , Engenharia Metabólica
3.
World J Microbiol Biotechnol ; 35(8): 122, 2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31346836

RESUMO

To promote enzymatic unhairing for leather production, a new unhairing enzyme is developed. The Keratinase (kerT) gene, which is amplified from B. amyloliquefaciens TCCC11319 by PCR, is expressed in B. subtilis WB600. The recombinant KerT reduces the collagenolytic protease content as well as improving the keratinase content effectively. Therefore, the improved keratinase leads to the obviously unhairing effect, whereas the low collagenolytic protease ensures the integrity of collagen fibers in hide. It represents, the leather grain surface isn't destroyed thereby the value of finished leather can be maintained. In addition, by analyzing the properties of KerT, tits activity isn't inhibited with Na+, K+ and Ca2+ which are commonly used in leather production. The freeze-dried fermentation broth can be used directly as unhairing enzyme without addition of traditional sulfide chemicals. By evaluating the properties of unhaired hide, the results show that the collagen degradation ability of this new unhairing enzyme is slightly and it does not cause any adverse effects on the leather quality. Besides, this unhairing enzyme doesn't further degrade collagen in the time range of 8 h to 24 h, thus it is safely and easy-control in actual production. In conclusion, the enzymatic unhairing method with recombinant KerT has the potential to be more sustainable and efficient alternative than current sulphur-lime method, and it does not require the further purification thereby saving the cost.


Assuntos
Bacillus subtilis/enzimologia , Bacillus subtilis/genética , DNA Bacteriano/isolamento & purificação , Peptídeo Hidrolases/genética , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clonagem Molecular , Fragmentação do DNA , DNA Bacteriano/genética , Fermentação , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Peptídeo Hidrolases/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
4.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao ; 41(3): 307-314, 2019 Jun 30.
Artigo em Chinês | MEDLINE | ID: mdl-31282323

RESUMO

Objective To describe the microbiological characteristics of Bacillus subtilis(B. subtilis)CGMCC 12426 and determine and analyze its complete genome sequences.Methods B. subtilis strain CGMCC 12426 genomic DNA sequencing was performed on a single molecule real-time sequencing(SMRT)platform and the annotation was completed in the NCBI Prokaryotic Genomic Annotation Pipeline(pGAP).Results The complete genomic sequences of the released B. subtilis CGMCC 12426 consisted of a 4 138 265-bp circular chromosome and a 74 165-bp plasmid,which resulted in the prediction of 4581 genes including 4222 coding sequences,87 tRNAs,and 30 rRNAs(which included 5S rRNA,16S rRNA,and 23S rRNA).Conclusion The genome sequencing provided a basis for further investigations on the genetic background of B. subtilis and on the metabolic and regulatory mechanisms.


Assuntos
Bacillus subtilis/genética , Genoma Bacteriano , Plasmídeos , RNA Ribossômico 16S/genética , RNA Ribossômico 23S/genética , RNA Ribossômico 5S/genética , Análise de Sequência de DNA
5.
Nat Commun ; 10(1): 3099, 2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31308373

RESUMO

The Gram-positive bacterium Bacillus subtilis exhibits complex spatial and temporal gene expression signals. Although optogenetic tools are ideal for studying such processes, none has been engineered for this organism. Here, we port a cyanobacterial light sensor pathway comprising the green/red photoreversible two-component system CcaSR, two metabolic enzymes for production of the chromophore phycocyanobilin (PCB), and an output promoter to control transcription of a gene of interest into B. subtilis. Following an initial non-functional design, we optimize expression of pathway genes, enhance PCB production via a translational fusion of the biosynthetic enzymes, engineer a strong chimeric output promoter, and increase dynamic range with a miniaturized photosensor kinase. Our final design exhibits over 70-fold activation and rapid response dynamics, making it well-suited to studying a wide range of gene regulatory processes. In addition, the synthetic biology methods we develop to port this pathway should make B. subtilis easier to engineer in the future.


Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica/efeitos da radiação , Engenharia Metabólica/métodos , Optogenética/métodos , Fitocromo/genética , Proteínas Quinases/genética , Bacillus subtilis/genética , Proteínas de Bactérias/metabolismo , Luz , Ficobilinas/biossíntese , Ficocianina/biossíntese , Fitocromo/metabolismo , Regiões Promotoras Genéticas/efeitos da radiação , Proteínas Quinases/metabolismo
6.
Nat Commun ; 10(1): 2872, 2019 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-31253804

RESUMO

The Sec61/SecY channel allows the translocation of many proteins across the eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. In bacteria, most secretory proteins are transported post-translationally through the SecY channel by the SecA ATPase. How a polypeptide is moved through the SecA-SecY complex is poorly understood, as structural information is lacking. Here, we report an electron cryo-microscopy (cryo-EM) structure of a translocating SecA-SecY complex in a lipid environment. The translocating polypeptide chain can be traced through both SecA and SecY. In the captured transition state of ATP hydrolysis, SecA's two-helix finger is close to the polypeptide, while SecA's clamp interacts with the polypeptide in a sequence-independent manner by inducing a short ß-strand. Taking into account previous biochemical and biophysical data, our structure is consistent with a model in which the two-helix finger and clamp cooperate during the ATPase cycle to move a polypeptide through the channel.


Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Canais de Translocação SEC/metabolismo , Adenosina Trifosfatases/genética , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Microscopia Crioeletrônica , Cristalização , Escherichia coli , Geobacillus/metabolismo , Modelos Moleculares , Conformação Proteica , Transporte Proteico , Canais de Translocação SEC/genética
7.
Microbiol Res ; 223-225: 129-136, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31178045

RESUMO

Heterobasidion annosum s.s. and H. parviporum are severe pathogens of conifers causing butt rot and root rot thus reducing the economic value of timber. Here, the antifungal activity of Bacillus subtilis isolate A18 against these two Heterobasidion species was investigated. Five different culture media with different culture age were investigated to study the effect of substrate composition and culture age for metabolite production. Bacterial cultures and cell-free culture filtrates were tested for antifungal activity. Inhibition of fungal growth was analysed using the agar disc-diffusion method. MALDI-TOF and LC-HRMS analyses were used to identify the antifungal metabolites. Substrate composition and age of culture were found to be active variables with direct effect on the antifungal activity of bacterial culture extracts. High anti-fungal activity was observed when B. subtilis was cultured in PDB, SGB and LB media for four days. Mass-spectrometry analysis showed the presence of lipopeptides in culture filtrates identified as members of the surfactins, polymixins, kurstakins and fengycins. A culture filtrate containing fengycin-type lipopeptides showed the highest bioactivity against Heterobasidion species. Bacterial cultures had higher bioactivity compared to their respective cell free culture filtrates. The results of the present study suggest that B. subtilis A18 is a powerful biocontrol agent against Heterobasidion infections of tree wounds and stumps.


Assuntos
Antifúngicos/farmacologia , Bacillus subtilis/metabolismo , Basidiomycota/efeitos dos fármacos , Basidiomycota/crescimento & desenvolvimento , Agentes de Controle Biológico/metabolismo , Lipopeptídeos/antagonistas & inibidores , Lipopeptídeos/metabolismo , Antifúngicos/isolamento & purificação , Bacillus subtilis/genética , Bacillus subtilis/isolamento & purificação , Basidiomycota/patogenicidade , Agentes de Controle Biológico/isolamento & purificação , Técnicas de Cocultura , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Glucose , Lipopeptídeos/isolamento & purificação , Doenças das Plantas/microbiologia , RNA Ribossômico 16S/genética , Metabolismo Secundário , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
8.
J Basic Microbiol ; 59(8): 834-845, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31210376

RESUMO

A bacterium's ability to thrive in the presence of multiple environmental stressors simultaneously determines its resilience. We showed that activation of the SigB-controlled general stress response by mild environmental or energy stress provided significant cross-protection to subsequent lethal oxidative, disulfide and nitrosative stress in Bacillus subtilis. SigB activation is mediated via the stressosome and RsbP, the main conduits of environmental and energy stress, respectively. Cells exposed to mild environmental stress while lacking the major stressosome components RsbT or RsbRA were highly sensitive to subsequent oxidative stress, whereas rsbRB, rsbRC, rsbRD, and ytvA null mutants showed a spectrum of sensitivity, confirming their redundant roles and suggesting they could modulate the signals generated by environmental or oxidative stress. By contrast, cells encountering stationary phase stress required RsbP but not RsbT to survive subsequent oxidative stress. Interestingly, optimum cross-protection against nitrosative stress caused by sodium nitropruside required SigB but not the known regulators, RsbT and RsbP, suggesting an additional and as yet uncharacterized route of SigB activation independent of the known regulators. Together, these results provide mechanistic information on how B. subtilis promotes enhanced resistance against lethal oxidative stress during mild environmental and energy stress conditions.


Assuntos
Bacillus subtilis/fisiologia , Proteínas de Bactérias/metabolismo , Estresse Oxidativo/fisiologia , Fosfoproteínas Fosfatases/metabolismo , Fator sigma/metabolismo , Transdução de Sinais , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Deleção de Genes , Viabilidade Microbiana , Estresse Nitrosativo/fisiologia , Fosfoproteínas Fosfatases/genética , Fosfoproteínas/genética , Fosforilação , Proteínas Serina-Treonina Quinases/genética , Fator sigma/genética , Transdução de Sinais/genética
9.
Nat Commun ; 10(1): 2653, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201319

RESUMO

Ribonucleotide reductases (RNRs) use a conserved radical-based mechanism to catalyze the conversion of ribonucleotides to deoxyribonucleotides. Within the RNR family, class Ib RNRs are notable for being largely restricted to bacteria, including many pathogens, and for lacking an evolutionarily mobile ATP-cone domain that allosterically controls overall activity. In this study, we report the emergence of a distinct and unexpected mechanism of activity regulation in the sole RNR of the model organism Bacillus subtilis. Using a hypothesis-driven structural approach that combines the strengths of small-angle X-ray scattering (SAXS), crystallography, and cryo-electron microscopy (cryo-EM), we describe the reversible interconversion of six unique structures, including a flexible active tetramer and two inhibited helical filaments. These structures reveal the conformational gymnastics necessary for RNR activity and the molecular basis for its control via an evolutionarily convergent form of allostery.


Assuntos
Sítio Alostérico/genética , Proteínas de Bactérias/genética , Ribonucleotídeo Redutases/genética , Regulação Alostérica/genética , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/ultraestrutura , Microscopia Crioeletrônica , Cristalografia por Raios X , Evolução Molecular , Modelos Moleculares , Estrutura Quaternária de Proteína/genética , Ribonucleotídeo Redutases/química , Ribonucleotídeo Redutases/metabolismo , Ribonucleotídeo Redutases/ultraestrutura , Ribonucleotídeos/metabolismo , Espalhamento a Baixo Ângulo
10.
J Agric Food Chem ; 67(24): 6837-6846, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31180217

RESUMO

Mannooligosaccharides are released by mannan-degrading endo-ß-1,4-mannanase and are known as functional additives in human and animal diets. To satisfy demands for biocatalysis and bioprocessing in crowed environments, in this study, we employed a recently developed enzyme-engineering system, isopeptide bond-mediated molecular cyclization, to modify a mesophilic mannanase from Bacillus subtilis. The results revealed that the cyclized enzymes showed enhanced thermostability and ion stability and resilience to aggregation and freeze-thaw treatment by maintaining their conformational structures. Additionally, by using the SpyTag/SpyCatcher system, we generated a mannanase-xylanase bifunctional enzyme that exhibited a synergistic activity in substrate deconstruction without compromising substrate affinity. Interestingly, the dual-enzyme ring conformation was observed to be more robust than the linear enzyme but inferior to the single-enzyme ring conformation. Taken together, these findings provided new insights into the mechanisms of molecular cyclization on stability improvement and will be useful in the production of new functional oligosaccharides and feed additives.


Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/química , beta-Manosidase/química , Bacillus subtilis/química , Bacillus subtilis/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Ciclização , Estabilidade Enzimática , Temperatura Alta , Concentração de Íons de Hidrogênio , Engenharia de Proteínas , beta-Manosidase/genética , beta-Manosidase/metabolismo
11.
Microb Cell Fact ; 18(1): 100, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31159804

RESUMO

BACKGROUND: Bacillus subtilis spores have been commonly used for the surface display of various food-related or human antigens or enzymes. For successful display, the target protein needs to be fused with an anchor protein. The preferred anchored proteins are the outer-coat proteins of spores; outer-coat proteins G (CotG) and C (CotC) are commonly used. In this study, mutant trehalose synthase (V407M/K490L/R680E TreS) was displayed on the surface of B. subtilis WB800n spores using CotG and CotC individually or in combination as an anchoring protein. RESULTS: Western blotting, immunofluorescence, dot blot, and enzymatic-activity assays detected TreS on the spore surface. The TreS activity with CotC and CotG together as the anchor protein was greater than the sum of the enzymatic activities with CotC or CotG alone. The TreS displayed on the spore surface with CotC and CotG together as the anchoring protein showed elevated and stable specific activity. To ensure spore stability and prevent spore germination in the trehalose preparation system, two germination-specific lytic genes, sleB and cwlJ, were deleted from the B. subtilis WB800n genome. It was demonstrated that this deletion did not affect the growth and spore formation of B. subtilis WB800n but strongly inhibited germination of the spores during transformation. The conversion rate of trehalose from 300 g/L maltose by B. subtilis strain WB800n(ΔsleB, ΔcwlJ)/cotC-treS-cotG-treS was 74.1% at 12 h (350 U/[g maltose]), and its enzymatic activity was largely retained, with a conversion rate of 73% after four cycles. CONCLUSIONS: The spore surface display system based on food-grade B. subtilis with CotC and CotG as a combined carrier appears to be a powerful technology for TreS expression, which may be used for the biotransformation of D-maltose into D-trehalose.


Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/genética , Glucosiltransferases/genética , Esporos Bacterianos/enzimologia , Trealose/biossíntese , Bacillus subtilis/genética , Técnicas de Inativação de Genes , Esporos Bacterianos/genética
12.
Microb Cell Fact ; 18(1): 101, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31159886

RESUMO

BACKGROUND: Many fermented foods and beverages are produced through the action of complex microbial communities. Synthetic biology approaches offer the ability to genetically engineer these communities to improve the properties of these fermented foods. Soy sauce is a fermented condiment with a vast global market. Engineering members of the microbial communities responsible for soy sauce fermentation may therefore lead to the development of improved products. One important property is the colour of soy sauce, with recent evidence pointing to a consumer preference for more lightly-coloured soy sauce products for particular dishes. RESULTS: Here we show that a bacterial member of the natural soy sauce fermentation microbial community, Bacillus, can be engineered to reduce the 'browning' reaction during soy sauce production. We show that two approaches result in 'de-browning': engineered consumption of xylose, an important precursor in the browning reaction, and engineered degradation of melanoidins, the major brown pigments in soy sauce. Lastly, we show that these two strategies work synergistically using co-cultures to result in enhanced de-browning. CONCLUSIONS: Our results demonstrate the potential of using synthetic biology and metabolic engineering methods for fine-tuning the process of soy sauce fermentation and indeed for many other natural food and beverage fermentations for improved products.


Assuntos
Bacillus subtilis/metabolismo , Fermentação , Engenharia Metabólica/métodos , Polímeros/metabolismo , Alimentos de Soja , Soja/microbiologia , Xilose/metabolismo , Bacillus subtilis/genética , Técnicas de Cocultura , Microbiologia Industrial , Microbiota , Biologia Sintética , Xilose/genética
13.
Microb Cell Fact ; 18(1): 103, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31170996

RESUMO

BACKGROUND: Pseudorabies caused by pseudorabies virus (PRV) mainly infects the swine and seriously threatens the biosafety of the other animals, including humans. Since 2011, the outbreaks of PRV mutants have caused enormous economic losses in the swine industry, and traditional vaccines cannot offer enough protection. PRV can transmit by direct contact, aerosol transmission and pollutants. PRV mainly transmit through the nasal mucosa. After infecting the nasal epithelial cells, PRV can quickly infect the olfactory nerve and establish a potential infection of sensory neurons. Therefore, nasal immunity can effectively prevent viral colonization infection. Recombinant Bacillus subtilis has been widely used to deliver antigen and achieve adequate protective immune responses. RESULTS: The present study successfully constructed recombinant Bacillus subtilis (B. subtilis) expressing the dominant antigen regions of PRV gC and gD proteins (named B. subtilis-gCa and B. subtilis-gDa). Furtherly, we evaluated the immunogenicity of the two recombinant B. subtilis in mice. The mice intranasal administration with B. subtilis-gCa and B. subtilis-gDa effectively stimulated IgA and IgG immune responses, further regulated specific T lymphocytes proliferative response by IFN-γ and IL-10, and ultimately produced high titers of neutralizing antibodies against PRV infection. In particular, B. subtilis-gDa possessed more excellent immune effect than B. subtilis-gCa in mice. CONCLUSIONS: These results suggested that B. subtilis-gCa and B. subtilis-gDa could trigger high levels of mucosal and systemic immune responses and would be potential candidates for developing PRV vaccines.


Assuntos
Bacillus subtilis , Herpesvirus Suídeo 1/imunologia , Pseudorraiva/prevenção & controle , Vacinas Virais/administração & dosagem , Administração Intranasal , Animais , Bacillus subtilis/genética , Bacillus subtilis/imunologia , Feminino , Imunidade nas Mucosas , Camundongos Endogâmicos BALB C , Pseudorraiva/imunologia , Vacinas Virais/genética , Vacinas Virais/imunologia
14.
Microb Cell Fact ; 18(1): 90, 2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-31122258

RESUMO

BACKGROUND: Surfactin is a cyclic lipopeptide that is of great industrial use owing to its extraordinary surfactant power and antimicrobial, antiviral, and antitumor activities. Surfactin is synthesized by a condensation reaction in microbes, which uses fatty acids and four kinds of amino acids (L-glutamate, L-aspartate, L-leucine and L-valine) as precursors. Surfactin biosynthesis could be improved by increasing the supply of fatty acids; however, the effect of the regulation of amino acid metabolism on surfactin production was not yet clear. RESULTS: In this study, we aimed to improve surfactin production in B. subtilis by repressing the genes on the branch metabolic pathways of amino acid biosynthesis using CRISPRi technology. First, 20 genes were inhibited individually, resulting in 2.5- to 627-fold decreases in transcriptional level as determined by RT-qPCR. Among the 20 recombinant strains, 16 strains obtained higher surfactin titres than that produced by the parent BS168NU-Sd strain (the surfactin production of BS168NU-Sd with only dCas9 but no sgRNA expression was 0.17 g/L). In particular, the strains in which the yrpC, racE or murC genes were inhibited individually produced 0.54, 0.41, or 0.42 g/L surfactin, respectively. All three genes are related to the metabolism of L-glutamate, whose acylation is the first step in the surfactin condensation reaction. Furthermore, these three genes were repressed in combination, and the strain with co-inhibition of yrpC and racE produced 0.75 g/L surfactin, which was 4.69-fold higher than that of the parent strain. In addition, the inhibition of bkdAA and bkdAB, which are related to the metabolism of L-leucine and L-valine, not only improved surfactin production but also increased the proportion of the C14 isoform. CONCLUSIONS: This study, to the best of our knowledge for the first time, systematically probed the regulatory effect of increasing the supply of amino acids on surfactin production. It provided an effective strategy and a new perspective for systematic studies on surfactin and other amino acid-derived chemicals.


Assuntos
Aminoácidos , Bacillus subtilis , Lipopeptídeos , Redes e Vias Metabólicas/genética , Tensoativos/metabolismo , Aminoácidos/genética , Aminoácidos/metabolismo , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Escherichia coli/genética , Lipopeptídeos/biossíntese , Lipopeptídeos/genética
15.
Microb Cell Fact ; 18(1): 96, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31142347

RESUMO

BACKGROUND: Promoter evolution by synthetic promoter library (SPL) is a powerful approach to development of functional synthetic promoters to synthetic biology. However, it requires much tedious and time-consuming screenings because of the plethora of different variants in SPL. Actually, a large proportion of mutants in the SPL are significantly lower in strength, which contributes only to fabrication of a promoter library with a continuum of strength. Thus, to effectively obtain the evolved synthetic promoter exhibiting higher strength, it is essential to develop novel strategies to construct mutant library targeting the pivotal region rather than the arbitrary region of the template promoter. In this study, a strategy termed stepwise evolution targeting the spacer of core promoter (SETarSCoP) was established in Bacillus subtilis to effectively evolve the strength of bacterial promoter. RESULTS: The native promoter, PsrfA, from B. subtilis, which exhibits higher strength than the strong promoter P43, was set as the parental template. According to the comparison of conservation of the spacer sequences between - 35 box and - 10 box among a set of strong and weak native promoter, it revealed that 7-bp sequence immediately upstream of the - 10 box featured in the regulation of promoter strength. Based on the conservative feature, two rounds of consecutive evolution were performed targeting the hot region of PsrfA. In the first round, a primary promoter mutation library (pPML) was constructed by mutagenesis targeting the 3-bp sequence immediately upstream of the - 10 box of the PsrfA. Subsequently, four evolved mutants from pPML were selected to construction of four secondary promoter mutation libraries (sPMLs) based on mutagenesis of the 4-bp sequence upstream of the first-round target. After the consecutive two-step evolution, the mutant PBH4 was identified and verified to be a highly evolved synthetic promoter. The strength of PBH4 was higher than PsrfA by approximately 3 times. Moreover, PBH4 also exhibited broad suitability for different cargo proteins, such as ß-glucuronidase and nattokinase. The proof-of-principle test showed that SETarSCoP successfully evolved both constitutive and inducible promoters. CONCLUSION: Comparing with the commonly used SPL strategy, SETarSCoP facilitates the evolution process to obtain strength-evolved synthetic bacterial promoter through fabrication and screening of small-scale mutation libraries. This strategy will be a promising method to evolve diverse bacterial promoters to expand the toolbox for synthetic biology.


Assuntos
Bacillus subtilis/genética , Evolução Molecular Direcionada/métodos , Regiões Promotoras Genéticas , Biblioteca Gênica , Mutagênese/genética , Mutação , Biologia Sintética/métodos
16.
J Agric Food Chem ; 67(22): 6263-6274, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31088055

RESUMO

The development of commercial poly-γ-glutamic acid (γ-PGA) production by glutamate-dependent strains requires understanding the glutamate dependence mechanism in the strains. Here, we first systematically analyzed the response pattern of Bacillus subtilis to glutamate addition by comparative transcriptomics. Glutamate addition induced great changes in intracellular metabolite concentrations and significantly upregulated genes involved in the central metabolic pathways. Subsequent gene overexpression experiments revealed that only the enhancement of glutamate synthesis pathway successfully led to γ-PGA accumulation without glutamate addition, indicating the key role of intracellular glutamate for γ-PGA synthesis in glutamate-dependent strains. Finally, by a combination of metabolic engineering targets, the γ-PGA titer reached 10.21 ± 0.42 g/L without glutamate addition. Exogenous glutamate further enhanced the γ-PGA yield (35.52 ± 0.26 g/L) and productivity (0.74 g/(L h)) in shake-flask fermentation. This work provides insights into the glutamate dependence mechanism in B. subtilis and reveals potential molecular targets for increasing economical γ-PGA production.


Assuntos
Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Ácido Glutâmico/metabolismo , Ácido Poliglutâmico/análogos & derivados , Proteínas de Bactérias/metabolismo , Meios de Cultura/metabolismo , Perfilação da Expressão Gênica , Ácido Poliglutâmico/biossíntese
17.
J Photochem Photobiol B ; 194: 119-127, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30953913

RESUMO

'Go green' has also been implied to nanotechnology by harbouring eco-benign principle for a cleaner production of silver nanoparticles (AgNPs). This was achieved using a nitrate reducing Bacillus subtilis L1 (KT266579.1) inhabiting rhizosphere soil under optimized laboratory conditions, highlighting on its antibacterial modus operandi. Nano-characteristics and antimicrobial mechanism were investigated using spectroscopic and electron microscopic studies. Spectroscopic and microscopic characterization revealed typical surface plasmon resonance (SPR) with λmax 420 nm showing mean particle size of ~28.30 nm and spherical shaped nanoparticles. Antimicrobial susceptibility pattern of clinically important pathogens (n = 15) exposed to AgNPs at 10 µg, 15 µg and 20 µg/mL for 18 h was found significant in a dose dependent fashion. Electron and atomic force microscopic (AFM) studies have demonstrated the typical bactericidal effect of AgNPs (<25 µg/mL) associated with 'pitting effect', cell shrinkage and increase in surface roughness. The EDX spectrum of the control and treated bacteria showed the intrusion of AgNPs inside the bacterial cells endorsing the event of bacterial paralysis. DNA fragmentation assay demonstrated significant DNA damage in the form of smear, indicative of genotoxicity at ≤32 µg and ≤16 µg/mL of AgNPs respectively for Gram positive and negative strains in <12 h. These results suggest that AgNPs possess excellent antimicrobial activity, providing a potential lead for developing a broad spectrum antibacterial agent and extending its therapeutic modalities targeting antibiotic resistant strains at gene level.


Assuntos
Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Bioengenharia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Nanopartículas Metálicas , Prata/metabolismo , Prata/farmacologia , Antibacterianos/biossíntese , Antibacterianos/química , Antibacterianos/farmacologia , Análise Custo-Benefício , Fragmentação do DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Concentração de Íons de Hidrogênio , Imagem Molecular , Prata/química , Temperatura Ambiente
18.
Genes Genet Syst ; 94(2): 71-80, 2019 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-30971625

RESUMO

In Bacillus subtilis, extracytoplasmic function (ECF) sigma factors are activated by reduction of phosphatidylglycerol (PG) content, absence of glucolipids, or absence of lipoteichoic acid (LTA). LTA is synthesized by polymerization of the glycerophosphate moiety of PG onto diglucosyldiacylglycerol (DGlcDG), a major glucolipid in B. subtilis, in the plasma membrane. Thus, reduction of PG content or absence of glucolipids might cause some changes in LTA, and hence we investigated whether reduction of PG content or absence of glucolipids induces the activation of ECF sigma factors independently from an ensuing change in LTA. Disruption of ugtP, responsible for glucolipid synthesis, in cells lacking LTA caused an additive increase of activation levels of σM, σX, σV and σY (3.1-, 2.2-, 2.1- and 1.4-fold, respectively), relative to their activation levels in cells lacking LTA alone. Reduction of PG content (by repressing Pspac-pgsA) in the cells lacking LTA caused an additive increase of activation levels of σM, σW and σV (2.3-, 1.9- and 2.2-fold, respectively). These results suggested that absence of glucolipids or reduction of PG alone, not the possible secondary alteration in LTA, leads to changes that affect the regulation systems of some ECF sigma factors in the plasma membrane.


Assuntos
Bacillus subtilis/genética , Proteínas de Bactérias/metabolismo , Fator sigma/metabolismo , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Glicolipídeos/metabolismo , Lipopolissacarídeos/metabolismo , Fosfatidilgliceróis/metabolismo , Fator sigma/genética , Ácidos Teicoicos/metabolismo
19.
Nat Commun ; 10(1): 1919, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-31015472

RESUMO

Bacteria of the genera Pseudomonas and Bacillus can promote plant growth and protect plants from pathogens. However, the interactions between these plant-beneficial bacteria are understudied. Here, we explore the interaction between Bacillus subtilis 3610 and Pseudomonas chlororaphis PCL1606. We show that the extracellular matrix protects B. subtilis colonies from infiltration by P. chlororaphis. The absence of extracellular matrix results in increased fluidity and loss of structure of the B. subtilis colony. The P. chlororaphis type VI secretion system (T6SS) is activated upon contact with B. subtilis cells, and stimulates B. subtilis sporulation. Furthermore, we find that B. subtilis sporulation observed prior to direct contact with P. chlororaphis is mediated by histidine kinases KinA and KinB. Finally, we demonstrate the importance of the extracellular matrix and the T6SS in modulating the coexistence of the two species on melon plant leaves and seeds.


Assuntos
Bacillus subtilis/genética , Cucurbitaceae/microbiologia , Matriz Extracelular/metabolismo , Regulação Bacteriana da Expressão Gênica , Interações Microbianas/genética , Pseudomonas chlororaphis/genética , Bacillus subtilis/crescimento & desenvolvimento , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Contagem de Colônia Microbiana , Fosfotransferases/genética , Fosfotransferases/metabolismo , Folhas de Planta/microbiologia , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Pseudomonas chlororaphis/crescimento & desenvolvimento , Pseudomonas chlororaphis/metabolismo , Sementes/microbiologia , Esporos Bacterianos/genética , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Bacterianos/metabolismo , Simbiose/fisiologia , Sistemas de Secreção Tipo VI/genética , Sistemas de Secreção Tipo VI/metabolismo
20.
J Microbiol Biotechnol ; 29(5): 749-757, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-30955259

RESUMO

Nitrilase is a valuable type of hydrolase that catalyzes nitriles into carboxylic acid and ammonia. Its applications, however, are severely restricted by the harsh conditions of industrial reaction processes. To solve this problem, a nitrilase from Acidovorax facilis 72W was inserted into an Escherichia coli-Bacillus subtilis shuttle vector for spore surface display. Western blot, enzyme activity measurements and flow cytometric analysis results all indicated a successful spore surface display of the CotB-nit fusion protein. In addition, the optimal catalytic pH value and temperature of the displayed nitrilase were determined to be 7.0 and 50°C, respectively. Moreover, results of reusability tests revealed that 64% of the initial activity of the displayed nitrilase was still retained at the 10th cycle. Furthermore, hydrolysis efficiency of upscale production of cyanocarboxylic acid was significantly higher in the displayed nitrilase-treated group than in the free group expressed by E. coli (pET-28a-nit). Generally, the display of A. facilis 72W nitrilase on the spore surface of Bacillus subtilis may be a useful method for immobilization of enzyme and consequent biocatalytic stabilization.


Assuntos
Aminoidrolases/genética , Aminoidrolases/metabolismo , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Comamonadaceae/enzimologia , Esporos Bacterianos/genética , Esporos Bacterianos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Comamonadaceae/genética , Estabilidade Enzimática , Enzimas Imobilizadas/genética , Enzimas Imobilizadas/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Vetores Genéticos , Concentração de Íons de Hidrogênio , Imobilização/métodos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Temperatura Ambiente , Fatores de Tempo
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