http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Detection and quantification of phenol in liquid and gas phases using a clay/dye composite
Guocheng Lv,Shiyuan Liu,Meng Liu,Libing Liao,Limei Wu,Lefu Mei,Zhaohui Li,Caofeng Pan 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.62 No.-
In this study, an organic dye lucigenin (BNMA) was successfully intercalated into the interlayer of montmorillonite (MMT) to prevent fluorescence quenching. With its enhanced fluorescent property, the composite was fabricated into solid strips for it fast and sensitive phenol detection in both liquid and gas phases. Under proper optimizations it is anticipated that the composite would show great potential for phenol determination in real world environment such as wastewater treatment industry.
Biocatalytic Production of Glucosamine from N-Acetylglucosamine by Diacetylchitobiose Deacetylase
( Zhu Jiang ),( Xueqin Lv ),( Yanfeng Liu ),( Hyun-dong Shin ),( Jianghua Li ),( Guocheng Du ),( Long Liu ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.11
Glucosamine (GlcN) is widely used in the nutraceutical and pharmaceutical industries. Currently, GlcN is mainly produced by traditional multistep chemical synthesis and acid hydrolysis, which can cause severe environmental pollution, require a long prodution period but a lower yield. The aim of this work was to develop a whole-cell biocatalytic process for the environment-friendly synthesis of glucosamine (GlcN) from N-acetylglucosamine (GlcNAc). We constructed a recombinant Escherichia coli and Bacillus subtilis strains as efficient whole-cell biocatalysts via expression of diacetylchitobiose deacetylase (Dac<sub>ph</sub>) from Pyrococcus furiosus. Although both strains were biocatalytically active, the performance of B. subtilis was better. To enhance GlcN production, optimal reaction conditions were found: B. subtilis whole-cell biocatalyst 18.6 g/l, temperature 40°C, pH 7.5, GlcNAc concentration 50 g/l and reaction time 3 h. Under the above conditions, the maximal titer of GlcN was 35.3 g/l, the molar conversion ratio was 86.8% in 3-L bioreactor. This paper shows an efficient biotransformation process for the biotechnological production of GlcN in B. subtilis that is more environmentally friendly than the traditional multistep chemical synthesis approach. The biocatalytic process described here has the advantage of less environmental pollution and thus has great potential for largescale production of GlcN in an environment-friendly manner.
( Tingting Huang ),( Xueqin Lv ),( Jianghua Li ),( Hyun-dong Shin ),( Guocheng Du ),( Long Liu ) 한국미생물 · 생명공학회 2018 Journal of microbiology and biotechnology Vol.28 No.12
Phospholipase D has great commercial value due to its transphosphatidylation products that can be used in the food and medicine industries. In order to construct a strain for use in the production of PLD, we employed a series of combinatorial strategies to increase PLD expression in Bacillus subtilis WB600. These strategies included screening of signal peptides, selection of different plasmids, and optimization of the sequences of the ribosome-binding site (RBS) and the spacer region. We found that using the signal peptide amyE results in the highest extracellular PLD activity (11.3 U/ml) and in a PLD expression level 5.27-fold higher than when the endogenous signal peptide is used. Furthermore, the strain harboring the recombinant expression plasmid pMA0911-PLD-amyE-his produced PLD with activity enhanced by 69.03% (19.1 U/ml). We then used the online tool \RBS Calculator v2.0 to optimize the sequences of the RBS and the spacer. Using the optimized sequences resulted in an increase in the enzyme activity by about 26.7% (24.2 U/ml). In addition, we found through a transfer experiment that the retention rate of the recombinant plasmid after 5 generations was still 100%. The final product, phosphatidylserine (PS), was successfully detected, with transphosphatidylation selectivity at 74.6%. This is similar to the values for the original producer.
( Haibo Yuan ),( Yanfeng Liu ),( Xueqin Lv ),( Jianghua Li ),( Guocheng Du ),( Zhongping Shi ),( Long Liu ) 한국미생물 · 생명공학회 2018 Journal of microbiology and biotechnology Vol.28 No.12
The compound 2,5-furandicarboxylic acid (FDCA), an important bio-based monomer for the production of various polymers, can be obtained from 5-hydroxymethylfurfural (HMF). However, efficient production of FDCA from HMF via biocatalysis has not been well studied. In this study, we report the identification of key genes that are involved in FDCA synthesis and then the engineering of Raoultella ornithinolytica BF60 for biocatalytic oxidation of HMF to FDCA using its resting cells. Specifically, previously unknown candidate genes, adhP3 and alkR, which were responsible for the reduction of HMF to the undesired product 2,5- bis(hydroxymethyl)furan (HMF alcohol), were identified by transcriptomic analysis. Combinatorial deletion of these two genes resulted in 85.7% reduction in HMF alcohol formation and 23.7% improvement in FDCA production (242.0 mM). Subsequently, an aldehyde dehydrogenase, AldH, which was responsible for the oxidation of the intermediate 5-formyl-2-furoic acid (FFA) to FDCA, was identified and characterized. Finally, FDCA production was further improved by overexpressing AldH, resulting in a 96.2% yield of 264.7 mM FDCA. Importantly, the identification of these key genes not only contributes to our understanding of the FDCA synthesis pathway in R. ornithinolytica BF60 but also allows for improved FDCA production efficiency. Moreover, this work is likely to provide a valuable reference for producing other furanic chemicals.
Taichi Chen,Hongzhi Xia,Shixiu Cui,Xueqin Lv,Xueliang Li,Yanfeng Liu,Jianghua Li,Guocheng Du,Long Liu 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.5
Vitamin K2 (menaquinone) is an essential vitamin existing in the daily diet, and menaquinone-7 (MK- 7) is an important form of it. In a recent work, we engineered the synthesis modules of MK-7 in Bacillus subtilis, and the strain BS20 could produce 360 mg/l MK-7 in shake flasks, while the methylerythritol phosphate (MEP) pathway, which provides the precursor isopentenyl diphosphate for MK-7 synthesis, was not engineered. In this study, we overexpressed five genes of the MEP pathway in BS20 and finally obtained a strain (BS20DFHG) with MK-7 titer of 415 mg/l in shake flasks. Next, we optimized the fermentation process parameters (initial pH, temperature and aeration) in an 8-unit parallel bioreactor system consisting of 300-ml glass vessels. Based on this, we scaled up the MK-7 production by the strain BS20DFHG in a 50-l bioreactor, and the highest MK-7 titer reached 242 mg/l. Here, we show that the engineered strain BS20DFHG may be used for the industrial production of MK-7 in the future.
High capacity ethidium bromide removal by montmorillonites
Lijuan Wang,Zhaohui Li,Xingrong Zhang,Guocheng Lv,Xisen Wang 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12
Ethidium bromide (EtBr) is commonly used as a reagent to investigate DNA and RNA bonding in biochemistry. However, it is mutagenic and toxic; thus, its removal from the waste solution is of the top priority in lab safety practice. Although many products with high EtBr removal capacities are available on the market, developing new products with low material costs and high removal capacities is still an urgent priority. As the EtBr is in a cationic form Et+ balanced by counterion Br in aqueous solution, materials with high cation exchange capacity and large specific surface area may have great potential for efficient EtBr removal, Thus, several montmorillonites (MMTs) were evaluated for their EtBr removal capacity and methods of regeneration in this study. Results showed that both external and internal surfaces of MMTs were effective sorption sites for EtBr with a capacity up to 600mg/g. And the waste-laden materials could be regenerated or safely disposed after incineration at 500 oC for 2 h. As such, further tests on optimization and manufacturing kits or devices for practical EtBr removal in routine lab practice is of engineering priority, should MMTs be further explored as an effective material for EtBr removal.