BIOTECHNOLOGY AND BIOPROCESS ENGINEERING
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2021
·Vol. 26
·期 6
·910-922
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IF 2.836
Chen Yi,Zhao Min,Hu Liyong,Wang Zeyu,Hrynsphan Dzmitry,Chen Jun
Acrylic acid has been widely used in various industrial applications but is harmful to human health and the environment. A novel and efficient degrading acrylic acid bacterium was isolated and identified as Bacillus aryabhattai CY. In this study, batch experiments were conducted to evaluate the biodegradation of acrylic acid by B. aryabhattai CY, which were immobilized in calcium-alginate beads under different conditions. The components of the alginate beads were optimized by the response surface method, and the degradation performance of the immobilized cells was determined. Relative to the free cells, experiment results showed that the immobilized cells can achieve complete degradation of 100 mg/L acrylic acid in 24 h under the optimal conditions of SA 6% (w/v), CaCl 2 1% (w/v), and immobilization time of 6 h. According to Haldane’s model, the maximum specific growth rate ( μ max ) of the free cells and immobilized cells were 0.165/h and 0.210/h, respectively. Experiment data revealed that acrylic acid showed an inhibitory effect on biodegradation by B. aryabhattai CY, especially at concentration higher than 100 mg/L. Furthermore, the reusability of the immobilized cells revealed that the acrylic acid removal rate was above 93.70% within the eight cycles. The immobilized cells also showed higher removal efficiencies in wider ranges of temperature (20°C–60°C) and pH (5.0–10.0) than the free cells. Moreover, the possible degradation intermediates were proposed during the biodegradation of acrylic acid by GC-MS analysis. Results indicated that immobilized beads might have a potential environmental implication in the purification of practical acrylic acid wastewater.
研究领域:
环境生物学
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微生物学
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DOI
高影响因子
BIOTECHNOLOGY LETTERS
·
2019
·Vol. 41
·期 10
·1223-1232
·
IF 2.154
Zhang Yin-Jun,Chen Chang-Sheng,Liu Hao-Tian,Chen Jia-Lin,Xia Ying,Wu Shi-Jin
Objective To purify an esterase which can selectively hydrolyze ( R,S )-ethyl indoline-2-carboxylate to produce ( S )-indoline-2-carboxylic acid and characterize its enzymatic properties. Results An intracellular esterase from Bacillus aryabhattai B8W22 was isolated and the purified protein was identified as a carboxylesterase by MALDI-TOF mass spectrometry. The enzyme (named BaCE) was 59.03-fold purification determined to be of approximately 35 kDa. Its specific activity was 0.574 U/mL with 20% yield. The enzyme showed maximum activity at pH 8.5 and 30 °C and was stable at 20–30 °C using p NPB as the substrate. The K m , V max , k cat and k cat /K m of the esterase were 0.52 mM, 6.39 μM/min, 26.87 min −1 and 51.67 mM/min, respectively. The esterase demonstrated high enantioselectivity toward ( S )-ethyl indoline-2-carboxylate with 96.55% e.e. p at 44.39% conversion, corresponding to an E value of 133.45. Conclusions In this study, a new esterase BaCE with an apparent molecular mass of 35 kDa was purified to homogeneity for the first time. The esterase from Bacillus aryabhattai B8W22 was isolated with a purification more than 59-fold and a yield of 20% by anion exchange chromatography and hydrophobic interaction chromatography. And its biochemical characterization were described in detail with p NPB as substrate. It displayed high enantioselectivity toward ( S )-ethyl indoline-2-carboxylate. We next plan to highly express esterase BaCE in Escherichia coli , and apply it to industrial production of ( S )-indoline-2-carboxylic acid.
研究领域:
生物化学
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酶学
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微生物学
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DOI
PubMed
高影响因子
JOURNAL OF APPLIED MICROBIOLOGY
·
2023
·
IF 4
Tang Xi,Cai Yi-Fan,Yu Xiao-Mei,Zhou Wen-Wen
AimsThis study aimed to screen a bacterial strain with high detoxifying capability for aflatoxin B1 (AFB1), verify its biotransformation efficiency, and detoxification process.Methods and resultsThree hundred and fifty samples collected from different environmental niche were screened using coumarin as the sole carbon source. HPLC was used to detect residues of AFB1, and 16S rRNA sequencing was performed on the isolated strain with highest AFB1 removal ratio for identification. The detoxified products of this strain were tested for toxicity in E. coli as well as LO2, Caco-2 and HaCaT human cell lines. HPLC-MS was applied to further confirm AFB1 removal and detoxification process.ConclusionsWe identified a strain from plant leaf designated as DT with high AFB1-detoxifying ability that is highly homologous to Bacillus aryabhattai. The optimum detoxification conditions of this strain were 37°C and pH 8.0, resulting in 82.92% removal ratio of 2 μg mL−1 AFB1 in 72 h. The detoxified products were nontoxic for E. coli and significantly less toxic for the LO2, Caco-2 and HaCaT human cell lines. HPLC-MS analysis also confirmed the significant drop of the AFB1 characteristic peak. Two possible metabolic products, C19H15O8 (m/z 371) and C19H19O8 (m/z 375), were observed by mass spectrometry. Potential biotransformation pathway was based on the cleavage of double bond in the terminal furan of AFB1. These generated components had different chemical structures with AFB1, manifesting that the attenuation of AFB1 toxicity would be attributed to the destruction of lactone structure of AFB1 during conversion process.
研究领域:
微生物学
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毒理学
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食品安全
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环境科学
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产品关联
DOI
PubMed
高影响因子
BIOORGANIC CHEMISTRY
·
2022
·
IF 5.307
Hongjun Zhang,Zeguang Cheng,Litian Wei,Xinjun Yu,Zhao Wang,Yinjun Zhang
A gene encoding an esterase from Bacillus aryabhattai (BaCE) was identified, synthesized and efficiently expressed in the Escherichia coli system. A semi-rational protein engineering was applied to further improve the enzyme’s enantioselectivity. Under the guidance of the molecular docking result, a single mutant BaCE-L86Q and a double mutant BaCE-L86Q/G284E were obtained, with its E max value 6.4 times and 13.9 times of the wild-type BaCE, respectively. The recombinant BaCEs were purified and characterized. The overwhelming E value demonstrated that BaCE-L86Q/G284E was a promising biocatalyst for the biological resolution to prepare ( S )-indoline-2-carboxylic acid.
研究领域:
生物技术
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酶学
·
蛋白质工程
✓ 已验证
DOI
PubMed
高影响因子
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