BIOTECHNOLOGY LETTERS
·
2017
·Vol. 39
·期 8
·1175-1181
·
IF 1.73
Zhou Youzhi,Liu Ke,Zhang Jinsong,Chu Jianlin,He Bingfang
Objective To improve the stability of β-galactosidase from Bacillus megaterium YZ08 (BMG) in aqueous hydrophilic solvents and promote its application in the galactosylation of natural products. Results The addition of 5 mM Mg 2+ significantly enhanced the stability of BMG in aqueous hydrophilic solvents, and the half-lives of BMG in these solutions reached 56 min to 208 h, while they were only 7 min to 5.9 h without addition of Mg 2+ . Studies on the kinetic parameters in buffer solution and 30% dimethyl sulfoxide (DMSO) indicated that the affinity of BMG to 2-nitrophenyl-β- d -galactopyranoside and its catalytic efficiency ( κ
cat / K
m ) increased with the addition of Mg 2+ . Furthermore, the addition of Mg 2+ facilitated galactosylation reactions in 30% DMSO and increased product conversions by 24–41% due to the reversal of the thermodynamic equilibrium of hydrolysis. Conclusion A convenient approach was established to improve the stability of BMG in aqueous hydrophilic solvents.
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高影响因子
FOOD CHEMISTRY
·
2017
·
IF 4.529
Lingtian Wu,Shanshan Wu,Juanjuan Qiu,Chuanxue Xu,Sha Li,Hong Xu
A green process and environmentally benign process is highly desirable in the development of enzymatic catalysis. In this work, the shuttle plasmid pHA01 was constructed and the sucrose isomerase (SIase) was expressed in Bacillus subtilis WB800. The optimal nitrogen and carbon sources for SIase expression were yeast extract (15 g/L) and un-pretreated cane molasses (UCM, 20 g/L), respectively. After the UCM fed, the whole cell activity reached 5.2 U/mL in a 7.5 L fermentor. Optimum catalytic temperature and pH of whole cell were 35 °C and 5.5, respectively. Although the biologic membrane reactor (BMR) system consecutively worked for 12 batches, the sucrose conversion remained higher than 90%, indicating the BMR system had a greater operational stability. Furthermore, isomaltulose production using the BMR system with low-cost cane molasses as its substrate not only reduces the production cost and mediates environmental pollution, but also solves the genetic background problem of the non-food-grade strains.
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BIOCONTROL SCIENCE AND TECHNOLOGY
·
2017
·
IF 0.919
Xiaohua Hu,Yajie Guo,Songqing Wu,Zhaoxia Liu,Tao Fu,Ensi Shao,Carballar-Lejarazú Rebeca,Guohui Zhao,Zhipeng Huang,Ivan Gelbič,Xiong Guan,Shuangquan Zou,Lei Xu,Lingling Zhang
Bacillus thuringiensis var. israelensis (Bti) is highly pathogenic to mosquito larvae and is widely used for mosquito control. Its mosquitocidal activity however is relatively low compared to many chemical insecticides. The detoxification mechanisms in the mosquito, among other things, might neutralize the Bti activity, resulting in resistance or tolerance. We tested whether or not the detoxification mechanisms against chemical insecticides might also operate against Bti, rendering it less effective. We targeted four enzymes in Aedes aegypti larvae involved in detoxification with inhibitors that have been used in resistance studies in chemical insecticides and assayed their effects on Bti toxicity. Results revealed that phenylmethanesulphonyl fluoride (PMSF), diethyl maleate, phenobarbital (PB), and piperonyl butoxide (PBO) altered Bti toxicity to various degrees. PMSF is a serine protease inhibitor that prevents Bti digestion and improves Bti activity. PB that induces several detoxifying enzymes had two different effects depending on the method of treatment. Mortality was higher when treatment with PB was discontinuous (149%) whereas with continuous treatment it was lower (101%). PBO, a typical cytochrome P450 inhibitor, increased Bti effect (159%). The combination of discontinuous pretreatment of larvae with PB followed by PBO had a synergistic effect and showed increased activity (146%). It appears that the mechanism for Bti resistance in mosquitoes is similar to that of chemical insecticides. Our studies indicate that we may be able to increase Bti activity by inhibiting some of the detoxification systems as active as broad spectrum chemical insecticides.
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INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
·
2024
·
IF 5
Yanmei Li,Lun Luo,Wenhai Wang,Bin Hong,Yi Ma,Jufang Wang
Bacillus cereus is a prevalent foodborne pathogen that induces food poisoning symptoms such as vomiting and diarrhea. Its capacity to form spores and biofilm enables it to withstand disinfectants and antimicrobials, leading to persistent contamination during food processing. Consequently, it is necessary to develop novel and efficient antimicrobial agents to control B. cereus , its spores, and biofilms. Peptidoglycan hydrolases have emerged as a promising and eco-friendly alternative owing to their specific lytic activity against pathogenic bacteria. Here, we identified and characterized a Lysozyme-like cell wall hydrolase Lys14579, from the genome of B. cereus ATCC 14579. Recombinant Lys14579 specifically lysed B. cereus without affecting other bacteria. Lys14579 exhibited strong lytic activity against B. cereus , effectively lysing B. cereus cell within 20 min at low concentration (10 μg/mL). It also inhibited the germination of B. cereus spores and prevented biofilm formation at 12.5 μg/mL. Moreover, Lys14579 displayed good antimicrobial stability with negligible hemolysis in mouse red blood cells and no cytotoxicity against RAW264.7 cells. Notably, Lys14579 effectively inhibited B. cereus in boiled rice and minced meat in a dose-dependent manner. Furthermore, bioinformatics analysis and point mutagenesis experiments revealed that Glu-47 was the catalytic site, and Asp-57, Gln-60, Ser-61 and Glu-63 were active-site residues related with the cell wall lytic activity. Taken together, Lys14579 could be a promising biocontrol agent against vegetative cells , spores, and biofilm of B. cereus in food industry.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Zhenkun Deng,Bing Hu,Changliu He,Lihe Zhang,Xi Zhao,Xu Zhang
Understanding the biodegradation of benzotriazole compounds (BTs) is crucial for improving their removal from the environment. Experiments using activated sludge showed a 61.65 % removal rate for benzotriazole (BTA), primarily through biodegradation. Notably, microbial diversity changed significantly, especially within the class Bacilli , which increased from 0.17 % to 0.75 % over 21 days ( p < 0.05). A novel Bacillus strain, DH-12, was identified, capable of degrading over 85 % of BTA and 5-methylbenzotriazole (MBT) within 24 hours. During the degradation of three BTs, seven possible intermediates were detected. Strain DH-12 appears to use methylation and carboxylation pathways for transformation and shows aerobic dechlorination ability. Additionally, this strain helps reduce the toxicity of BTs. This research enhances our understanding of BTs biodegradation by both microbial communities and a specific bacterial strain, offering valuable insights for environmental biotransformation strategies.
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Foods
·
2025
·Vol. 14
·期 3
·525
·
IF 5.1
Rongrong Yu,Rongxue Sun,Ning Jiang,Bin Zhang,Cheng Wang,Qianyuan Liu,Zhiqiang Li,Xingna Wang
Crab roe sauce (CRS) is prone to spoilage due to microbial contamination. Therefore, this study aimed to investigate the inhibitory effects and mechanisms of a mixed bio-preservative (0.025% ε-polylysine hydrochloride (ε-PL) + 0.01% nisin (NS) + 0.01% tea polyphenols (TPs)) on the specific spoilage bacteria (SSB) in CRS. First, the SSB in CRS were isolated and identified by 16S rRNA sequencing. Two isolates were selected as representative strains based on their enzymatic spoilage potential and spoilage capability in CRS. By comparing the inhibition zones, ε-PL, NS, and TPs were selected from five conventional bio-preservatives (ε-PL, NS, TPs, grape seed extract (GSE), and rosemary extract (RE)) to prepare the mixed bio-preservative. The results showed that the minimum inhibitory concentration (MIC) of the mixed bio-preservative againstBacillus pumilusandBacillus subtiliswas 56.3 µg/mL. The growth curves and cell viability tests revealed that the mixed bio-preservative reduced the viability of both strains. The conductivity, alkaline phosphatase activity, and nucleic acid and soluble protein leakage indicated that the mixed bio-preservative disrupted the integrity of the cell walls and membranes of the two isolates in a concentration-dependent manner. Scanning electron microscopy further confirmed the damage to the cell membranes of the two isolates by the mixed bio-preservative. Overall, the mixed bio-preservative exhibited excellently inhibitory effects on the SSB and could be a promising method for the preservation of CRS.
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JOURNAL OF FOOD SCIENCE
·
2025
·Vol. 90
·期 8
·e70466
·
IF 3.4
Li Ran,Yongjun Wu,Jing Jin,Lincheng Zhang,Cen Li,Shuoqiu Tong,Feng Wen,ZhongHui Mou
The globalization of food culture has driven the growth of the flavor market, with Bacillus subtilis- fermented soybean products widely used as traditional Asian condiments due to their distinctive soy sauce-like aroma. However, the molecular mechanism underlying aroma formation remains incompletely understood. Building on previous systematic multi-omics studies, this study identifies a key role for l -threonine catabolism in regulating pyrazine biosynthesis. Using homologous recombination, we performed targeted knockouts of the tdh and kbl genes to generate single mutants (BJ3-2Δ tdh and BJ3-2Δ kbl ) and a double mutant (BJ3-2Δ tdh - kbl ). Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS), along with sensory evaluation, revealed that the tdh knockout drastically reduced 2,5-dimethylpyrazine (2,5-DMP) levels by 96.79%. The double knockout achieved a 97.73% reduction and completely eliminated 3-ethyl-2,5-dimethylpyrazine (EDMP). Interestingly, the kbl knockout alone enhanced 2,5-DMP production by 65.34%, and the odor activity value of EDMP increased to 10.50. Exogenous supplementation experiments confirmed that 2,5-DMP is a critical contributor to nutty, sweet, and buttery aromas, while also intensifying smoky undertones. Overall, this study elucidates the regulatory function of l -threonine catabolism in pyrazine biosynthesis, linking microbial metabolism to food flavor and offering a metabolic engineering strategy for targeted aroma modulation in fermented foods. Practical Applications This research provides valuable insights into the mechanism underlying the formation of soy sauce-like aroma, laying the foundation for optimizing 2,5-dimethylpyrazine (2,5-DMP) concentrations to fine-tune aroma profiles. These findings may support the environmentally friendly production of high-quality soy sauce-like aroma foods, potentially reducing reliance on artificial additives.
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FOOD RESEARCH INTERNATIONAL
·
2024
·
IF 7
Luyao Fan,Hongchao Dai,Wenyuan Zhou,Lei Yuan,Jia Yang,Zhenquan Yang,Xin-an Jiao
Bacillus licheniformis , a quick and strong biofilm former, is served as a persistent microbial contamination in the dairy industry. Its biofilm formation process is usually regulated by environmental factors including the divalent cation Ca 2+ . This work aims to investigate how different concentrations of Ca 2+ change biofilm-related phenotypes (bacterial motility, biofilm-forming capacity, biofilm structures, and EPS production) of dairy B . licheniformis strains. The Ca 2+ ions dependent regulation mechanism for B . licheniformis biofilm formation was further investigated by RNA-sequencing analysis. Results revealed that supplementation of Ca 2+ increased B . licheniformis biofilm formation in a dose-dependent way, and enhanced average coverage and thickness of biofilms with complex structures were observed by confocal laser scanning microscopy. Bacterial mobility of B. licheniformis was increased by the supplementation of Ca 2+ except the swarming ability at 20 mM of Ca 2+ . The addition of Ca 2+ decreased the contents of polysaccharides but promoted proteins production in EPS, and the ratio of proteins/polysaccharides content was significantly enhanced with increasing Ca 2+ concentrations. RNA-sequencing results clearly indicated the variation in regulating biofilm formation under different Ca 2+ concentrations, as 939 (671 upregulated and 268 downregulated) and 951 genes (581 upregulated and 370 downregulated) in B. licheniformis BL2-11 were induced by 10 and 20 mM of Ca 2+ , respectively. Differential genes were annotated in various KEGG pathways, including flagellar assembly, two-component system, quorum sensing, ABC transporters, and related carbohydrate and amino acid metabolism pathways. Collectively, the results unravel the significance of Ca 2+ as a biofilm-promoting signal for B. licheniformis in the dairy industry.
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Biocatalysis and Agricultural Biotechnology
·
2025
·
IF 3.8
Lingyun Yao,Qingru Huang,Huatian Wang,Tao Feng,Chuang Yu,Kun Xie,Hao Liu,Shiqing Song,Li Shao,Min Sun
The Camellia seed cake (CSC) is by-product of tea tree ( Camellia oleifera ) oil that rich in proteins and traditionally discarded or used as fertilizers, which would lead to a serious waste of the high-quality resources. In this work, Bacillus subtilis was employed to the submerged fermentation of CSC for production of potential bioactive peptides. After optimization by single-factor experiments and response surface methodology (RSM), the optimal fermentation conditions revealed to be material-to-liquid ratio of 30 g/L, inoculum volume of 19.0 %, and temperature of 35.4 °C, and the peptide production yield reached 11.68 % after RSM optimization. The amino acid composition analysis of CSC hydrolysates (CSCH) showed that CSCH was mainly composed of Tyr, Cys, Gly and Val, and 94.01 % of the peptides contained in the CSCH had a molecular weight of less than 3 kDa. In addition, the CSCH revealed strong antioxidant and tyrosinase inhibition potential in vitro, and the Lineweaver–Burk analysis indicated that CSCH exhibited a reversible competitive inhibition against the tyrosinase. Peptides were supposed to be major components that contribute to the bioactivity of CSCH due to their high contained concentration. The results demonstrated that CSCH could be developed as a new type of pure natural antioxidant and anti-tyrosinase agents used for health-promoting products, and these findings would provide useful information for better transformation and utilization of the CSC by-products.
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FOOD BIOTECHNOLOGY
·
2023
·
IF 1.8
Junxin Zhao,Maomao Ma,Zheling Zeng,Dongman Wan,Xianghui Yan,Jiaheng Xia,Ping Yu,Deming Gong
This study aimed to investigate the effect of mutating the consensus pentapeptide on the enzymatic properties and structural characteristics of Bacillus licheniformis lipase. Site-directed mutagenesis was used to construct mutants and then expressed in Escherichia coli BL21. After purification and enzyme activity analysis, only A75C and A75G retained activity. Compared to the wild-type lipase and A75G, the A75C showed higher thermostability at 40°C and better alkali resistance in pH 9.0–10.0 after incubation for 1 h. The kinetic parameters, structural characteristics and surface hydrophobicity of the lipases were determined. The results indicated that the secondary structure was hardly changed, while mutants exhibited higher activity, thermostability and hydrophobicity. Finally, the reasons for the increased enzyme activity were conducted through molecular dynamics simulation. The strategy of mutating the first residue of the lipase consensus pentapeptide may provide new insights into the enzyme engineering for industrial applications.
研究领域:
生物化学
·
酶学
·
蛋白质工程
·
分子生物学
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POLYMER INTERNATIONAL
·
2020
·Vol. 70
·期 2
·185-192
·
IF 2.574
Yuanyuan Hou,Fei Huang,Hui Yang,Hao Cong,Xi Zhang,Xiaoxu Xie,Haibo Yang,Qiuping Tong,Ning Luo,Ping Zhu,Jianzong Meng
Levansucrase (EC 2.4.1.10) catalyzes both levan polymerization and sucrose hydrolysis. Levan production by recombinant Bacillus subtilis levansucrase SacB-T305A was investigated. The maximum conversion yield (33.09%) of sucrose to levan and levan yield (115.8 g L –1 ) were obtained as 30% (wt/vol) and 40% (wt/vol) initial sucrose, respectively. Under highly acidic conditions (pH 3.5 and below), the polymerization not only shifted distinctly to high molecular weight levan but also enlarged the size of low molecular weight levan. In particular, the proportion of high molecular weight levan to total products increased to 9-fold at pH 3.5. The presence of Fe 2+ , Mg 2+ , Mn 2+ and Zn 2+ ions at common ion strength (5 mmol L –1 ) increased only the size of low molecular weight levan from about 20 kDa to about 35 kDa. Our findings provide a supplementary view about the mechanism of levan molecular weight distribution in enzymatic synthesis and offer a possibility for producing levan of different molecular weights by modulating enzymatic reaction conditions. © 2020 Society of Industrial Chemistry
研究领域:
生物化学
·
工业微生物学
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高影响因子
PROCESS BIOCHEMISTRY
·
2021
·
IF 3.757
Huabiao Miao,Rui Jiang,Nanyu Han,Yu Ma,Qian Wu,Yuelin Mu,Zunxi Huang
Amylases have been widely applied for starch saccharification in the food, paper, pharmaceutical, and textile industries. In the present study, α-amylase DL-3-4−1 from B. amyloliquefaciens was successfully expressed in B. subtilis. The enzymatic activity exhibited high stability in a pH range from 4.0 to 11.0 and moderate thermostability. Furthermore, excellent stability was observed when incubated with metal ions, detergents, inhibitors, and organic solvents. Resistance against ethanol, urea, and guanidine−HCl was also observed. More importantly, a strategy to enhance the extracellular expression of α-amylase DL-3-4−1 was developed using 173 Sec-type signal peptides (SPs) as a library based on a fast and sequence-independent method. Fourteen SPs were identified with significantly increased yields of DL-3-4−1 via a high-throughput assay. Specifically, the enzymatic activity of the α-amylase-producing strain containing the signal peptide SP5D10 (YomL) was 3.74-fold higher than that of the strain with the wild type signal peptide (87.30 U/OD). In brief, the maximum specific activity of an α-amylase-producing strain containing the YomL signal peptide was 326.45 U/OD. This is the first report of an α-amylase that exhibits ethanol, urea, and guanidine−HCl tolerance. Hence, this α-amylase represents a promising candidate for future use in industry.
研究领域:
生物技术
·
酶学
·
微生物学
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