BIOCATALYSIS AND BIOTRANSFORMATION
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2019
·
IF 1.627
Lu Dong,Yongkai Xu,Yun Zhang,Aijun Sun,Yunfeng Hu
Chiral 1-phenylethanol and its ester derivative are important chiral chemicals in diverse industries and the preparation of those optically pure enantiomers is of great importance. One bacterium, Bacillus sp. DL-2, whose extracellular proteases could efficiently asymmetrically hydrolyse (±)-1-phenylethyl acetate, was isolated from the deep sea of the Western Pacific. After the immobilization of extracellular proteases and the optimization of enzymatic reactions, (R)-1-phenylethanol was prepared with the enantiomeric excess (e.e.) being 97% and the yield being 41%, respectively. The optimal resolution reaction condition for the preparation of (R)-1-phenylethanol using immobilized extracellular proteases was found to be 5-mM (±)-1-phenylethyl acetate, 360 mg/mL immobilized extracellular proteases, pH 6.5, and 20 °C for 2 h. (S)-1-phenylethyl acetate was generated through enzymatic kinetic resolution with the e.e. being as high as 99% and the yield being 71%, respectively. The optimal resolution reaction condition for the preparation of (S)-1-phenylethyl acetate was found to be 2.5-mM (±)-1-phenylethyl acetate, 440 mg/mL immobilized extracellular proteases, pH 7.5, and 35 °C for 10 h. Our report is the first report about the kinetic resolution of (±)-1-phenylethyl acetate using proteases and the enantio-preference of the proteases was found to be the same as those of most other esterases/lipases. Also notably, the optical purity of (S)-1-phenylethyl acetate generated through kinetic resolution using the proteases of Bacillus sp. DL-2 was the highest report so far. Proteases from deep-sea Bacillus sp. DL-2 are new contributions to the biocatalyst library for the preparation of valuable chiral alcohols and chiral esters through kinetic resolution.
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PROCESS BIOCHEMISTRY
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2019
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IF 2.883
Xinyun Xu,Jiahao Wang,Ting Yu,Haohan Nian,Hui Zhang,Guangli Wang,Feng Li
Aryloxyphenoxypropionate (AOPP) herbicides with a chiral center are widely used to selectively remove annual and perennial grasses. However, the study of the enzymes involved in enantioselective degradation of AOPP herbicides is limited. A novel family VIII carboxylesterase gene, estwx , hydrolyzed the ester bond cleavage of AOPP herbicides to form the corresponding acid and alkyl side chain alcohol, was cloned from Brevundimonas sp. strain QPT-2 and overexpressed in E. coli BL21. The purified recombinant EstWX was shown to hydrolyze a wide range of AOPP herbicides with various catalytic efficiencies. The enantioselectivity assay indicated that EstWX preferentially catalyzed the hydrolysis of the R -enantiomer of AOPP herbicides. The S73, K76, Y196 together with W368 residues, especially S73 and Y196, were essential for the catalytic function of the carboxylesterase. EstWX is a promising candidate for the bioremediation of multiple AOPP herbicide-contaminated environments and for future mechanism studies on the enantioselective degradation of chiral AOPP herbicides.
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JOURNAL OF BIOTECHNOLOGY
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2019
·
IF 3.163
Xiao-Ling Tang,Nan-Nan Zhang,Guo-Yan Ye,Yu-Guo Zheng
( R )-3-amino-1-butanol is a key intermediate of Dolutegravir for the treatment of HIV/AIDS and its green and efficient biosynthesis has attracted a great deal of attention. Transaminases are currently used as promising biocatalyst for the synthesis of chiral amines. However, many transaminases have ( S )-specificity and ( R )-selective transaminases were less exploited and studied, making the production of ( R )-amines remain challenging. In this study, a novel transaminase from Actinobacteria sp. ( As -TA) was obtained and applied for the biosynthesis of ( R )-3-amino-1-butanol by transferring the amino group from isopropylamine to 4-hydroxy-2-butanone. After optimization of the reaction condition and using a substrate fed-batch strategy, the conversion of 100, 200, 300, 400 and 500 mM 4-hydroxy-2-butanone reached 100%, 94.9%, 86.1%, 76.1% and 70.9%, respectively. ( R )-3-amino-1-butanol with a maximum yield of 29.6 g/L and 99.9% e.e. value was obtained. This was the first time demonstrating the successful biosynthesis of ( R )-3-amino-1-butanol with transaminase as biocatalyst and the obtained As -TA enriched the enzyme pool of transaminase with ( R )-specificity.
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Biotechnology for Biofuels
·
2019
·Vol. 12
·期 1
·1-15
·
IF 5.452
Fang Wei,Xue Saisai,Deng Pengjun,Zhang Xuecheng,Wang Xiaotang,Xiao Yazhong,Fang Zemin
Background Starch is an inexpensive and renewable raw material for numerous industrial applications. However, most starch-based products are not cost-efficient due to high-energy input needed in traditional enzymatic starch conversion processes. Therefore, α-amylase with high efficiency to directly hydrolyze high concentration raw starches at a relatively lower temperature will have a profound impact on the efficient application of starch. Results A novel raw starch digesting α-amylase (named AmyZ1) was screened and cloned from a deep-sea bacterium Pontibacillus sp. ZY. Phylogenetic analysis showed that AmyZ1 was a member of subfamily 5 of glycoside hydrolase family 13. When expressed in Escherichia coli , the recombinant AmyZ1 showed high activity at pH 6.0–7.5 and 25–50 °C. Its optimal pH and temperature were 7.0 and 35 °C, respectively. Similar to most α-amylases, AmyZ1 activity was enhanced (2.4-fold) by 1.0 mM Ca 2+ . Its half-life time at 35 °C was also extended from about 10 min to 100 min. In comparison, AmyZ1 showed a broad substrate specificity toward raw starches, including those derived from rice, corn, and wheat. The specific activity of AmyZ1 towards raw rice starch was 12,621 ± 196 U/mg, much higher than other reported raw starch hydrolases. When used in raw starch hydrolyzing process, AmyZ1 hydrolyzed 52%, 47% and 38% of 30% (w/v) rice, corn, and wheat starch after 4 h incubation. It can also hydrolyze marine raw starch derived from Chlorella pyrenoidosa , resulting in 50.9 mg/g DW (dry weight of the biomass) of reducing sugars after 4 h incubation at 35 °C. Furthermore, when hydrolyzing raw corn starch using the combination of AmyZ1 and commercial glucoamylase, the hydrolysis rate reached 75% after 4.5 h reaction, notably higher than that obtained in existing starch-processing industries. Conclusions As a novel raw starch-digesting α-amylase with high specific activity, AmyZ1 efficiently hydrolyzed raw starches derived from both terrestrial and marine environments at near ambient temperature, suggesting its application potential in starch-based industrial processes.
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
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2018
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IF 3.974
Xiaoxin Chen,Sheng He,Xiaolu Liu,Jiye Hu
Using sequential soil and liquid culture enrichments with cyprodinil as the sole carbon source, a Gram-negative cyprodinil-degrader from cyprodinil-polluted agricultural soil was isolated. The sequencing analysis of 16 S rRNA indicated that the strain showed 99% homology to Acinetobacter sp. The strain could effectively degrade cyprodinil at the neutral condition. At the initial concentrations of 10, 20, 50, 100, 150 and 200 mg L −1 in minimal medium, cyprodinil was degraded by 10, 20, 49.3, 64.2, 57 and 24 mg L −1 within 14 days, respectively. Two metabolites (4-cyclopropyl-6-methyl-2-pyrimidpyridine amine and monohydroxylated para-substitution) were identified using high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS/MS). A biodegradation pathway involving imines hydrolysis and monohydroxyl substitution on benzene ring was proposed on basis of the identified metabolites. Acinetobacter sp. would have a potential application in bioremediation of cyprodinil-contaminated soil, and the strain might have important implications in detoxification and bioremediation of pyrimidine analogues.
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Biotechnology Journal
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2015
·Vol. 11
·期 2
·228-237
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IF 3.49
Tian Ma,Yuanjie Zhou,Xiaowei Li,Fayin Zhu,Yongbo Cheng,Yi Liu,Zixin Deng,Tiangang Liu
As a highly valued keto-carotenoid, astaxanthin is widely used in nutritional supplements and pharmaceuticals. Therefore, the demand for biosynthetic astaxanthin and improved efficiency of astaxanthin biosynthesis has driven the investigation of metabolic engineering of native astaxanthin producers and heterologous hosts. However, microbial resources for astaxanthin are limited. In this study, we found that the α-Proteobacterium Sphingomonas sp. ATCC 55669 could produce astaxanthin naturally. We used whole-genome sequencing to identify the astaxanthin biosynthetic pathway using a combined PacBio-Illumina approach. The putative astaxanthin biosynthetic pathway in Sphingomonas sp. ATCC 55669 was predicted. For further confirmation, a high-efficiency targeted engineering carotenoid synthesis platform was constructed in E. coli for identifying the functional roles of candidate genes. All genes involved in astaxanthin biosynthesis showed discrete distributions on the chromosome. Moreover, the overexpression of exogenous E. coli idi in Sphingomonas sp. ATCC 55669 increased astaxanthin production by 5.4-fold. This study described a new astaxanthin producer and provided more biosynthesis components for bioengineering of astaxanthin in the future. Graphical Limited microbial resources for astaxanthin limit its widespread applications in nutritional supplements and pharmaceuticals. Sphingomonas sp. ATCC 55669 can produce astaxanthin naturally. Whole-genome sequencing with gene functional confirmation identifies the discrete astaxanthin biosynthetic genes, and overexpressed related genes in E. coli can increase astaxanthin production. The new astaxanthin producer and biosynthesis components provide more possibilities for bioengineering of astaxanthin in the future.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
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2016
·Vol. 23
·期 12
·12019-12029
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IF 2.76
Bai Naling,Wang Sheng,Abuduaini Rexiding,Zhu Xufen,Zhao Yuhua
Nonylphenol polyethoxylates (NPEOs), although banned for decades, are still widely used in manufactories and thus affect human lives. In this study, a highly efficient NPEO-degrading bacterium, Sphingomonas sp. Y2, was isolated from sewage sludge by enrichment culture. Strain Y2 ensured the complete removal of NPEO in 48 h and degraded 99.2 % NPEO (1,000 mg L −1 ) within 30 h at a specific growth rate of 0.73 h −1 in minimum salt medium. To date, this degradation efficiency is the highest reported for NPEO metabolism by a pure bacterium under this condition. Furthermore, the application of this bacterium to wastewater treatment demonstrated that it metabolized 98.5 % NPEO (1,000 mg L −1 ) within 5 days with a specific growth rate of 2.03 day −1 . The degradation intermediates, identified as nonylphenol, short-chain NPEOs and short-chain nonylphenol polyethoxycarboxylates by high-performance liquid chromatography and gas chromatography-mass spectrometry, indicated the sequential exo-cleavage of the EO chain. Additionally, the enzymes involved in the biodegradation were inducible rather than constitutive. Considering that strain Y2 exhibits prominent biodegradation advantages in industrial wastewater treatment, it might serve as a promising potential candidate for in situ bioremediation of contamination by NPEOs and other structurally similar compounds.
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Journal of Environmental Sciences
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2016
·
IF 2.208
Xingdu Chen,Chengjian Yang,Weiwei Wang,Bizhou Ge,Jun Zhang,Yucan Liu,Yaping Nan
The biodegradation characteristic and potential metabolic pathway for removal of environmental N,N-dimethylacetamide (DMAC) by Rhodococcus sp. strain B83 was studied. Rhodococcus sp. strain B83 was isolated from the rhizosphere of a pagoda tree and proved capable of utilizing DMAC as sole source of carbon and nitrogen. Batch culture studies showed that strain B83 could tolerate up to 25 g/L DMAC and showed distinct growth on possible catabolic intermediates except for acetate. The nitrogen balance analysis revealed that approximately 71% of the initial nitrogen was converted to organic nitrogen. DMAC degradation has led to accumulation of acetate and organic nitrogen, meanwhile traces of nitrate and ammonia was build-up but without nitrite. The growth of strain B83 could be inhibited by adding exogenous acetate. By means of the assay of enzymatic degradation of DMAC, several catabolic intermediates at different intervals were observed and identified. Based on the results obtained from culture solution and enzymatic degradation assay, a detailed pathway is proposed for DMAC biodegradation.
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POWDER TECHNOLOGY
·
2017
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IF 2.942
Lanbo Li,Rui Bao,Jianhong Yi,Liang Liu,Shuai Mao
Uniform dispersion of carbon nanotube (CNT) and strong interface combination between nano‑carbon reinforcement and metal matrix are of extremely importance to fabricate CNT/metals composite by powder metallurgy method due to the hereditary effects. Therefore, in this paper, CNT/Cu composite powder was fabricated through Spray Pyrolysis (SP) to improve the dispersity and interface property . Nucleation and growth of Cu grains on the CNT surface occurred in the ultrasonic atomization of acetate (Cu(CH 3 COO) 2 ·H 2 O) solution droplets with mono-dispersed CNT. The microstructures of composite powder were investigated by TGA , Raman, XRD, FESEM and TEM analysis methods. Results show that structural integrity and purity of CNT can be enhanced by SP process at 500 °C. And CNT/Cu composite powder with uniform dispersion and good combination between CNT and Cu particles could be obtained by SP even though high composition of CNT was added. At last, the mechanisms of nucleation and growth were estimated based on the microstructure analysis .
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
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2024
·Vol. 31
·期 26
·38274-38287
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IF 0
Yang Lei,Li Yucai,Li Xiaotong,Lu Haoqi,Wang Yuchao,Meng Hongyan,Ren Yongxiang,Lan Jun
With the wide application of nanomaterials, the concentration of nanomaterials in natural water continues to increase, which poses a severe threat to the water environment. However, the influence of organic matter and nanomaterials rich in natural water on the toxic effect of algae growth is still unclear. In this study, the effects of humic acid (HA) and nano-cerium oxide (nCeO 2 ) on the physiology and transcriptome of Chlorella sp. were analyzed, and the mechanism of the toxic effect of HA on Chlorella sp. under nCeO 2 stress was revealed. Under 20–200 mg/L nCeO 2 stress, the growth of Chlorella cells was inhibited and the highest inhibition rate reached 52% within 200 mg/L nCeO 2 . The Fv/Fm and ETRmax values of Chlorella sp. decreased from 0.490 and 24.45 (20 mg/L nCeO 2 ) to 0.488 and 23.4 (100 mg/L nCeO 2 ), respectively. Under the stimulation of nCeO 2 , the level of reactive oxygen species in algal cells was increased, accompanied by lipid peroxidation and membrane damage. However, the addition of HA at concentrations of 5–10 mg/L effectively alleviated the toxic effect of nCeO 2 on Chlorella sp. Transcriptome analysis showed that 10 mg/L HA could alleviate the cellular stress at 100 mg/L nCeO 2 on Chlorella sp. by regulating genes related to photosynthesis and metabolism pathways. Moreover, the downregulation of genes (e.g., Lhca1, Lhcb1, AOC3, and AOC2) indicated that HA reduced the level of oxidative stress in Chlorella sp. These findings offer novel insights of evaluating the ecotoxicity nCeO 2 and HA in natural water environment and their impact on Chlorella sp. Graphical abstract
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ACS Sustainable Chemistry & Engineering
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2024
·
IF 7.1
Tong Zhang,Shubin Li,Lei Chen,Weiwen Zhang,Tao Sun
Cyanobacteria are known to be photoautotrophic cell factories capable of converting CO2 into valuable chemicals. The newly discovered marine cyanobacterium Synechococcus sp. PCC 11901 (hereafter PCC 11901) offers several advantages like rapid growth, high biomass, and high salinity tolerance, representing a promising chassis. To promote its application, we developed genetic toolboxes applicable to PCC 11901 in this study. First, a cobalamin (VB12)-independent chassis was constructed, allowing for cheaper cultivation. Second, genome copy numbers and transformation methods were, respectively, measured and optimized. Then, 14 neutral sites were identified and characterized within the genome PCC 11901, providing locations for genetic integration of exogenous cassettes. Subsequently, promoter libraries were developed, reaching an expression range of approximately 800 folds for constitutive promoters and an induction fold of up to approximately 400 for inducible promotors, respectively. As a proof of concept, natural production of the total lipid and phycocyanin was investigated using VB12-independent chassis, which realized an increase of 14.91% with lipid content compared with that of the wild-type strain. Further, we engineered the synthetic pathways of glucosylglycerol (GG) into PCC 11901 using the established toolboxes, reaching 590.41 ± 21.48 mg/L for GG production and self-sedimentation in photoreactors with the highest OD750 nm at 17.57 ± 0.77. Finally, the GG-producing strain grew well in seawater, reaching 324.50 ± 5.34 mg/L in shaking flask, which provided new strategies for cyanobacteria cultivation and production. Our work here made it possible to develop the fast-growing PCC 11901 as efficient carbon-neutral cell factory in the future.
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JOURNAL OF BIOTECHNOLOGY
·
2025
·
IF 3.9
Yu-Zhen Li,Qi Wang,Cheng Cheng,Chao Chen,Feng-Li Zhang,Yue Zou,Jun Li,Xin-Qing Zhao
Endophytic yeast strains are promising sources of various valuable bioactive compounds. However, studies on endophytic strains derived from lichen samples remains limited. In this study, we isolated and characterized Rhodotorula sp. Y090 from Usnea longissima and investigated its biosynthetic potential. Genome mining revealed distinct genetic features that differed from its closest relative strain R. graminis WP1. Ergothioneine (EGT) is a potent antioxidant and rare sulfur-containing histidine derivative. However, so far, the EGT biosynthetic enzymes by natural yeast strains have been limitedly studied. In this study, combining genome mining and transcriptomic analysis, genes encoding the potential enzymes for the production of EGT and xylose utilization were identified in Rhodotorula sp. Y090. Further studies demonstrated that Rhodotorula sp. Y090 was capable of producing EGT using xylose, glucose, glycerol, and sucrose as the sole carbon sources, and the highest titer reached 363.6 mg/L in shake flask culture, which is significantly higher than that of the most reported levels in the other natural yeasts. Rhodotorula sp. Y090 also exhibited a good ability of EGT export, which could facilitate cost-effective production. These findings suggest that the lichen-derived endophytic yeast Rhodotorula sp. Y090 represents a promising natural candidate for bio-production of the potent antioxidant.
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危险品化学品经营许可证（带存储）