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Liangzhi Li,Huaxing Zhang,Jiaolong Fu,Chao Hu,Yayue Zheng,Yexian Qiu 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.2
To maximize the productivity of ribitol, which is an important starting material for the production of one expensive rare sugar, L-ribose, the effects of culture medium and agitation speed on cell growth as well as on the productivity of ribitol were thoroughly investigated in a 7 L fermentor. The maximum volumetric productivity,0.322 g/L/h of ribitol, were obtained at an initial glucose concentration of 200 g/L in a batch culture. Based on the optimum glucose concentration, the ribitol yield conversed from glucose was up to 0.193 g/g when 1% yeast extract was used as a nitrogen source. When the agitation speed was maintained at 200 rpm, the ribitol concentration of 38.60 g/L was collected after 120 h of cultivation time. Additionally, the scheme of two-phase agitation and glucose infusion was employed. To begin, in the first 24 h of fermentation, a high agitation rate at 350 rpm and the initial glucose concentration of 50 g/L were applied, and the biomass concentration of 25.50 g/L was achieved at 36 h of incubation; whereas this value was observed until 60 h in the former batch fermentation methods. Then, in the second phase, with the agitation speed reduced to 150 rpm and the infusion amount of glucose controlled at 150 g/L,the yield of ribitol reached to 65.00 g/L in two-phase agitation fermentation and was 1.68 fold of that obtained in one-stage batch fermentation. To our knowledge, this study first demonstrates its significant effectiveness in improving ribitol production with the application of Trichosporonoides oedocephalis ATCC 16958.
Qian Zheng,Si Long,Zhi Chen,Jiaolong Fu,Xin Ju,Liangzhi Li 한국식품과학회 2024 Food Science and Biotechnology Vol.33 No.7
Enzymatic preparation of rare sugars as an alternative to traditional sweeteners is an effective strategy to achieve a low-calorie healthy diet. Ribose-5-phosphate isomerase B (RpiB) is a key enzyme in the non-oxidative branch of the catalytic pentose phosphate pathway. Here, we investigated the potential of Curtobacterium flaccumfaciens ZXL1 (C. flaccumfaciens ZXL1) derived RpiB (CfRpiB) in D-allose preparation. The optimal reaction conditions for recombinant CfRpiB were found experimentally to be pH 7.0, 55 °C, and no metal ions. The kinetic parameters Km, kcat, and catalytic efficiency kcat/Km were 320 mM, 4769 s−1, and 14.9 mM−1 s−1 respectively. The conversion of D-allulose by purified enzyme (1 g L−1 ) to D-allose was 13% within 1 h. In addition, homology modeling and molecular docking were used to predict the active site residues: Asp13, Asp14, Cys72, Gly73, Thr74, Gly77, Asn106, and Lys144.
( Liangzhi Li ),( Tianyi Yang ),( Weiqiang Guo ),( Xin Ju ),( Cuiying Hu ),( Bingyu Tang ),( Jiaolong Fu ),( Jingsheng Gu ),( Haiyang Zhang ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.4
The mitogen-activated protein kinase HOG1 (high-osmolarity glycerol response pathway) plays a crucial role in the response of yeast to hyperosmotic shock. Trichosporonoides oedocephalis produces large amounts of polyols (e.g., erythritol and glycerol) in a culture medium. However, the effects of HOG1 gene knockout and environmental stress on the production of these polyols have not yet been studied. In this study, a To-HOG1 null mutation was constructed in T. oedocephalis using the loxP-Kan-loxP/Cre system as replacement of the targeted genes, and the resultant mutants showed much smaller colonies than the wild-type controls. Interestingly, compared with the wild-type strains, the results of shake-flask culture showed that To-HOG1 null mutation increased erythritol production by 1.44-fold while decreasing glycerol production by 71.23%. In addition, this study investigated the effects of citric acid stress on the T. oedocephalis HOG1 null mutants and the wild-type strain. When the supplementation of citric acid in the fermentation medium was controlled at 0.3% (w/v), the concentration of erythritol produced from the wild-type and To-HOG1 knockout mutant strains improved by 18.21% and 21.65%, respectively.
Tianyi Yang,Jiaojiao Li,Liangzhi Li,Haiyang Zhang,Jing Ma,Zhi Chen,Cuiying Hu,Xin Ju,Jiaolong Fu 한국응용생명화학회 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.6
Tacrolimus (FK506), a 23-membered polyketidemacrolide with immunosuppressant activity, can be produced byStreptomyces tsukubaensis. We studied a variety of mutant strainsof S. tsukubaensis for the microbial production of FK506. Thebest strain (CZ-19) was obtained from the parent strain LLZ-1 bynitrosoguanidine mutation and 4-Aminobutyric acid (FK506precursor structure analogs) adaption. In the shake-flask experiments,titer of FK506 by CZ-19 was 532.44 mg/L, increased by 65.13%compared to that of the parent strain. Through single factorexperiments and response surface methodology, we furtheroptimized the medium for improved FK506 production by CZ-19in shake flask culture. The optimal medium for enhanced FK506production was as follows: 17.19 g/L corn starch, 21.78 g/Lglucose, 8.06 g/L peptone, and 18.98 mg/L 4-aminobutyric acid. The predicted FK506 titer was 906.49 mg/L, and the experimentaldata confirmed the validity of the model. The present studydemonstrates that S. tsukubaensis CZ-19 is a promising strain forindustrial production of FK506.
Yang, Tianyi,Li, Jiaojiao,Li, Liangzhi,Zhang, Haiyang,Ma, Jing,Chen, Zhi,Hu, Cuiying,Ju, Xin,Fu, Jiaolong 한국응용생명화학회 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.6
Tacrolimus (FK506), a 23-membered polyketide macrolide with immunosuppressant activity, can be produced by Streptomyces tsukubaensis. We studied a variety of mutant strains of S. tsukubaensis for the microbial production of FK506. The best strain (CZ-19) was obtained from the parent strain LLZ-1 by nitrosoguanidine mutation and 4-Aminobutyric acid (FK506 precursor structure analogs) adaption. In the shake-flask experiments, titer of FK506 by CZ-19 was 532.44 mg/L, increased by 65.13% compared to that of the parent strain. Through single factor experiments and response surface methodology, we further optimized the medium for improved FK506 production by CZ-19 in shake flask culture. The optimal medium for enhanced FK506 production was as follows: 17.19 g/L corn starch, 21.78 g/L glucose, 8.06 g/L peptone, and 18.98 mg/L 4-aminobutyric acid. The predicted FK506 titer was 906.49 mg/L, and the experimental data confirmed the validity of the model. The present study demonstrates that S. tsukubaensis CZ-19 is a promising strain for industrial production of FK506.
( Min Shen ),( Xin Ju ),( Xinqi Xu ),( Xuemei Yao ),( Liangzhi Li ),( Jiajia Chen ),( Cuiying Hu ),( Jiaolong Fu ),( Lishi Yan ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.7
In this study, we attempted to find new and efficient microbial enzymes for producing rare sugars. A ribose-5-phosphate isomerase B (OsRpiB) was cloned, overexpressed, and preliminarily purified successfully from a newly screened Ochrobactrum sp. CSL1, which could catalyze the isomerization reaction of rare sugars. A study of its substrate specificity showed that the cloned isomerase (OsRpiB) could effectively catalyze the conversion of L-rhamnose to L-rhamnulose, which was unconventional for RpiB. The optimal reaction conditions (50oC, pH 8.0, and 1 mM Ca<sup>2+</sup>) were obtained to maximize the potential of OsRpiB in preparing L-rhamnulose. The catalytic properties of OsRpiB, including K<sub>m</sub>, K<sub>cat</sub>, and catalytic efficiency (K<sub>cat</sub>/K<sub>m</sub>), were determined as 43.47 mM, 129.4 sec<sup>-1</sup>, and 2.98 mM/sec. The highest conversion rate of L-rhamnose under the optimized conditions by OsRpiB could reach 26% after 4.5 h. To the best of our knowledge, this is the first successful attempt of the novel biotransformation of L-rhamnose to L-rhamnulose by OsRpiB biocatalysis.