JOURNAL OF GENERAL AND APPLIED MICROBIOLOGY
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2016
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IF 1
Alei Zhang,Cong Gao,Kequan Chen,Ce Wei,Pingkai Ouyang
The pH of a microbiological culture is important for both cell growth and chitinase accumulation, but the optimal pH is not normally the same for both. The objective of this study was to investigate the effect of pH on chitinase production by Chitinolyticbacter meiyuanensis strain SYBC-H1 (ATCC BAA-2140) in a mineral medium. The results of batch culture at different pH values showed that the optimum pH for cell growth and chitinase production varied with time, although KOH produced the best results for cell growth and chitinase production, NaOH was chosen because of cost considerations. We designed a three-stage pH control strategy using NaOH as the neutralizing agent. Maximum cell growth (1.07 g dry cell weight/l) and maximum chitinase activity (13.6 U/ml) were observed after culture at 26°C for 72 h in a mineral medium. These values were greater by 129% and 162%, respectively, and the length of time to attain maximum chitinase activity was decreased by 12 h, compared with results from an earlier study (Hao et al., 2011b).
研究领域:
微生物学
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生物技术
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DOI
PubMed
高影响因子
POLYMER DEGRADATION AND STABILITY
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2021
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IF 5.03
Ning Zhou,Pengfan Yang,Jie Chen,Guoguang Wei,Chengyong Wang,Alei Zhang,Kequan Chen,Pingkai Ouyang
In this study, the effect of pretreatment with three organic solvent systems on enzymatic hydrolysis of chitin was investigated. Firstly, genes coding three chitinolytic enzymes Cm Chi1, Cm Chi4, and Cm NAGase from Chitinolyticbacter meiyuanensis SYBC-H1 were cloned and functionally expressed. Then, a cocktail capable of producing GlcNAc from chitin was formulated with 71.4% recombinant Cm Chi1, 23.8% recombinant Cm Chi4, and 4.8% recombinant Cm NAGase. Next, three organic solvent systems, including LiCl/dimethylacetamide, CaCl 2 /Methanol, and hexafluoroisopropanol were applied to treat chitin, resulting in 4.90–8.21-fold improvement of hydrolysis efficiency compared to raw chitin. The decreased crystallinity and nanofiber size structure without deacetylation, confirmed by SEM, FTIR, XRD, and EA, aided in the increased efficiency. Finally, yields of 20.97 mM, 34.50 mM, and 32.53 mM of GlcNAc with a purity of 96% were respectively obtained from 10 g/L of CLD, CHP, and CCM in 24 h.
研究领域:
生物技术
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生物化学
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材料科学
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DOI
高影响因子
BIOTECHNOLOGY LETTERS
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2022
·Vol. 44
·期 4
·623-633
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IF 2.716
Hao Zhi-kui,Li Jian-song,Wang Dan-hua,He Fei,Xue Jing-shi,Yin Liang-hong,Zheng Hua-bao
Objectives Shellfish waste is a primary source for making N -acetyl- d -glucosamine. Thus, establishing a high-efficiency and low-cost bioconversion method to produce N -acetyl- d -glucosamine directly from shellfish waste was promising.
Results A mutant C81 was obtained from Chitinolyticbacter meiyuanensis SYBC-H1 via 60 Co-γ irradiation. This mutant C81 showed the highest chitinase activity of 9.8 U/mL that was 85% higher than the parent strain. The mutant C81 exhibted improved antioxidant activities, including total antioxidant capacity, superoxide radical ability, and hydroxyl radical scavenging ability, compared to that of the parent strain. Four out of nine organic solvents increased the chitinase activity by 1.9%, 6.8%, 11.7%, and 15.8%, corresponding to methylbenzene, n-heptane, petroleum ether, and n-hexane, respectively. The biphase system composed of aqueous and hexane presented a five-fold reduction of cell viability compared to the control. Using a continuous fermentation bioconversion process, 4.2 g/L GlcNAc was produced from crayfish shell powder with a yield of 80% of the chitin content. Conclusions This study demonstrated that the mutant C81 is suitable for converting crayfish shell powder into GlcNAc in an aqueous-organic system.
研究领域:
微生物学
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生物化学
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生物工程
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DOI
PubMed
高影响因子
Biotechnology for Biofuels
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2020
·Vol. 13
·期 1
·1-14
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IF 4.815
Zhang Alei,Mo Xiaofang,Zhou Ning,Wang Yingying,Wei Guoguang,Chen Jie,Chen Kequan,Ouyang Pingkai
Background N -Acetyl glucosamine (GlcNAc) and N -Acetyl chitooligosaccharides ( N -Acetyl COSs) exhibit many biological activities, and have been widely used in the pharmaceutical, agriculture, food, and chemical industries. Particularly, higher N -Acetyl COSs with degree of polymerization from 4 to 7 ((GlcNAc) 4 –(GlcNAc) 7 ) show good antitumor and antimicrobial activity, as well as possessing strong stimulating activity toward natural killer cells. Thus, it is of great significance to discover a β- N -acetyl glucosaminidase (NAGase) that can not only produce GlcNAc, but also synthesize N -Acetyl COSs. Results The gene encoding the novel β- N -acetyl glucosaminidase, designated Cm NAGase, was cloned from Chitinolyticbacter meiyuanensis SYBC-H1. The deduced amino acid sequence of Cm NAGase contains a glycoside hydrolase family 20 catalytic module that shows low identity (12–35%) with the corresponding domain of most well-characterized NAGases. The Cm NAGase gene was highly expressed with an active form in Escherichia coli BL21 (DE3) cells. The specific activity of purified Cm NAGase toward p -nitrophenyl- N -acetyl glucosaminide ( p NP-GlcNAc) was 4878.6 U/mg of protein. Cm NAGase had a molecular mass of 92 kDa, and its optimum activity was at pH 5.4 and 40 °C. The V max , K m , K cat , and K cat / K m of Cm NAGase for p NP-GlcNAc were 16,666.67 μmol min −1 mg −1 , 0.50 μmol mL −1 , 25,555.56 s −1 , and 51,111.12 mL μmol −1 s −1 , respectively. Analysis of the hydrolysis products of N -Acetyl COSs and colloidal chitin revealed that Cm NAGase is a typical exo-acting NAGase. Particularly, Cm NAGase can synthesize higher N -Acetyl COSs ((GlcNAc) 3 –(GlcNAc) 7 ) from (GlcNAc) 2 –(GlcNAc) 6 , respectively, showed that it possesses transglycosylation activity. In addition, Cm NAGase also has reverse hydrolysis activity toward GlcNAc, synthesizing various linked GlcNAc dimers. Conclusions The observations recorded in this study that Cm NAGase is a novel NAGase with exo-acting, transglycosylation, and reverse hydrolysis activities, suggest a possible application in the production of GlcNAc or higher N -Acetyl COSs.
研究领域:
微生物学
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生物化学
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酶工程
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DOI
PubMed
高影响因子
Frontiers in Microbiology
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2022
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IF 6.064
Wang Chengyong,Chen Xueman,Zhou Ning,Chen Yan,Zhang Alei,Chen Kequan,Ouyang Pingkai
A novel multifunctional chitinase (CmChi3)-encoding gene was cloned from Chitinolyticbacter meiyuanensis and actively expressed in Escherichia coli. Sequence analysis showed that CmChi3 contains two glycoside hydrolase family 18 (GH18) catalytic domains and exhibited low identity with well-characterized chitinases. The optimum pH and temperature of purified recombinant CmChi3 were 6.0 and 50°C, respectively. CmChi3 exhibited strict substrate specificity of 4.1 U/mg toward colloidal chitin (CC) and hydrolyzed it to yield N-acetyl-D-glucosamine (GlcNAc) as the sole end product. An analysis of the hydrolysis products toward N-acetyl chitooligosaccharides (N-acetyl COSs) and CC substrates revealed that CmChi3 exhibits endochitinase, N-acetyl-β-d-glucosaminidase (NAGase), and transglycosylase (TGase) activities. Further studies revealed that the N-terminal catalytic domain of CmChi3 exhibited endo-acting and NAGase activities, while the C-terminal catalytic domain showed exo-acting and TGase activities. The hydrolytic properties and favorable environmental adaptations indicate that CmChi3 holds potential for commercial GlcNAc production from chitin.
研究领域:
生物化学
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酶学
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生物技术
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产品关联
DOI
PubMed
高影响因子
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