一株高效降解菜籽饼粕中硫苷的枯草芽孢杆菌基因组鉴定及功能分析北大核心CSCD

为筛选可高效降解菜籽饼粕中硫苷的细菌,给硫苷降解基因工程菌的构建提供实验数据,以堆放菜籽饼粕的土壤为分离源,通过硫苷选择培养基筛选及硫苷降解率测定,获得一株硫苷降解率最大的菌株C1,采用16S rRNA基因序列进行种属鉴定,通过第3代Illumina NovaSeq PE150测序,获得其基因组完成图并进行功能注释,借助比较基因组学探究C1降解硫苷的机制。结果表明:菌株C1为枯草芽孢杆菌(Bacillus subtilis),其硫苷降解率为(68.98±4.74)%;C1菌株的基因组染色体全长为4 139 381 bp,鸟嘌呤和胞嘧啶含量为43.88%,编码区总长度占全基因组的比例为89.14%;C1菌株能编码大量的功能蛋白,主要涉及氨基酸转运与代谢;比较基因组学分析确认,C1与枯草芽孢杆菌的模式菌株(NC000964.3)共线性高,序列中未见大片段易位和倒置的区域,但C1序列中2.7 Mb处出现一个小片段的插入,2.1~2.4 Mb处出现小片段缺失,分别涵盖了2条黑芥子酶的相关基因,推测C1的硫苷降解机制为其可高效分泌黑芥子酶。C1菌株能够高效降解菜籽饼粕中的硫苷,是构建硫苷降解基因工程菌的可选材料。     

啤酒酿造用复合酶的研制

从一系列枯草芽孢杆菌（Ｂａｃｉｌｌｕｓｓｕｂｔｉｌｉｓ）和淀粉液化芽孢杆菌（Ｂａｃｉｌｌｕｓａｍｙｌｏｌｉｑｕｅｆａｃｉｅｎｓ）出发，经筛选和诱变选育，得到一株淀粉液化芽孢杆菌突变株（ＷＬ－ＢＡ－ｌ），该菌株经三角瓶摇瓶和２０Ｌ发酵后，在３０００Ｌ标准通风罐上进行试验，菌株发酵周期短，发酵液中β－葡聚糖酶约为１２０ｕ／ｍｌ，α－淀粉酶约１５０ｕ／ｍｌ，蛋白酶约１８００ｕ／ｍｌ．发酵液经压滤浓缩后制得液体酶制剂。     

Genomic and metabolomic analysis of Bacillus licheniformis with enhanced poly-γ-glutamic acid production through atmospheric and room temperature plasma mutagenesis

Poly-γ-glutamic acid is an extracellular polymeric substance with various applications owing to its valuable properties of biodegradability, flocculating activity, water solubility, and nontoxicity. However, the ability of natural strains to produce poly-γ-glutamic acid is low. Atmospheric and room temperature plasma was applied in this study to conduct mutation breeding of Bacillus licheniformis CGMCC 2876, and a mutant strain M32 with an 11% increase in poly-γ-glutamic acid was obtained. Genome resequencing analysis identified 7 nonsynonymous mutations of ppsC encoding lipopeptide synthetase associated with poly-γ-glutamic acid metabolic pathways. From molecular docking, more binding sites and higher binding energy were speculated between the mutated plipastatin synthase subunit C and glutamate, which might contribute to the higher poly-γ-glutamic acid production. Moreover, the metabolic mechanism analysis revealed that the upregulated amino acids of M32 provided substrates for glutamate and promoted the conversion between L- and D-glutamate acids. In addition, the glycolytic pathway is enhanced, leading to a better capacity for using glucose. The maximum poly-γ-glutamic acid yield of 14.08 g·L^–1 was finally reached with 30 g·L^–1 glutamate.     

酸性普鲁兰酶基因在地衣芽孢杆菌中的表达

根据Genbank公布的来源于Bacillus deramificans的普鲁兰酶基因突变体序列(AX203843)合成普鲁兰酶成熟肽基因。将该基因插入芽孢杆菌分泌型表达载体pHY-WZX,重组质粒转化地衣芽孢杆菌B60608,重组地衣芽孢杆菌实现普鲁兰酶分泌表达。对重组菌产普鲁兰酶的条件进行优化,以含2%药媒和8%甘油的培养基最适合普鲁兰酶表达。     

嗜碱性芽孢杆菌碱性纤维素酶酶系的研究

本文研究了各种碳、氮源、ｐＨ、通风量等工艺条件对嗜碱性芽孢杆菌Ｖ－５产酶酶系的影响，通过酶在表面活性剂中的实验，分析不同表面活性剂对酶系中各组分的影响，初步研究酶系与去污力的关系，认为除以内切酶为主外，酶系中另二个组分，在去污效果中的辅助作用不容忽视。     

海洋氨肽酶菌株的筛选鉴定及其酶学特性研究

从大连渤海海域海泥海水样品中分离出一株高产海洋氨肽酶(aminopeptidase)菌株YZ1-2,对其进行形态学、生理生化、分子生物学(16S rDNA)鉴定,确定该菌株为蜡样芽孢杆菌(Bacillus cereus)。并对其产海洋氨肽酶进行酶学特性研究,结果表明,最适作用温度为30 ℃;最适作用pH值为8.5;Co2+、Zn2+等能较强地激活氨肽酶的活性,Ni2+、Ca2+等对酶的抑制性较强;乙二胺四乙酸(EDTA)可以有效地抑制氨肽酶活性。     

复合酶解法制备功能性大豆多肽的研究

利用中性蛋白酶和枯草杆菌对大豆分离蛋白进行复合酶解,首先通过单因素和正交实验确定了中性蛋白酶酶解的最佳水解条件为：底物浓度4%,反应温度50℃,时间4h,pH8．5,酶用量6％,水解度(DH)可达21．46％；再经过枯草杆菌发酵36h后,水解度可迭32．06％,苦味明显降低。     

Effects of nitrogen ion irradiation on endoglucanase activity and gene mutation of Bacillus subtilis Bac01

Bacillus subtilis Bac01 was mutated by 15 keV N+ ions of 1.5×1016 cm-2.The mutant strain Bacll with high yield of endoglucanase was isolated using carboxymethylcellulose sodium and congo red indicative plates.It exhibited higher endoglucanase activitiy (381.89IU) than the original strain Bac01 (93.33IU).Two 1,500 bp endoglucanase gene fragments were obtained with PCR amplification from B.subtilis Bac01 and mutant strain Bac11.BLAST comparison result indicated that 10 nucleotides mutated.Bioinformatics methods were used to analyze the two predicted amino acid sequences,and it was found that 5 amino acid residues changed,being all in the cellulose-binding domain of endoglucanase.     

Physicochemical and Theoretical Characterization of a New Small Non-Metal Schiff Base with a Differential Antimicrobial Effect against Gram-Positive Bacteria

Searching for adequate and effective compounds displaying antimicrobial activities, especially against Gram-positive bacteria, is an important research area due to the high hospitalization and mortality rates of these bacterial infections in both the human and veterinary fields. In this work, we explored (E)-4-amino-3-((3,5-di-tert-butyl-2-hydroxybenzylidene)amino) benzoic acid (SB-1, harboring an intramolecular hydrogen bond) and (E)-2-((4-nitrobenzilidene)amino)aniline (SB-2), two Schiff bases derivatives. Results demonstrated that SB-1 showed an antibacterial activity determined by the minimal inhibitory concentration (MIC) against Staphylococcus aureus, Enterococcus faecalis, and Bacillus cereus (Gram-positive bacteria involved in human and animal diseases such as skin infections, pneumonia, diarrheal syndrome, and urinary tract infections, among others), which was similar to that shown by the classical antibiotic chloramphenicol. By contrast, this compound showed no effect against Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, and Salmonella enterica). Furthermore, we provide a comprehensive physicochemical and theoretical characterization of SB-1 (as well as several analyses for SB-2), including elemental analysis, ESMS, ¹H and ¹³C NMR (assigned by 1D and 2D techniques), DEPT, UV-Vis, FTIR, and cyclic voltammetry. We also performed a computational study through the DFT theory level, including geometry optimization, TD-DFT, NBO, and global and local reactivity analyses.     

矿化细菌Bacillus paramycoides对重金属Pb(Ⅱ)和Cd(Ⅱ)的去除及矿化特性

随着金属矿山开采和冶炼活动的增加,重金属污染问题日益严峻,微生物诱导生物矿化可有效固定重金属离子,被认为是一种重要的重金属污染环境修复工艺,对重金属污染生态修复有重要的现实意义。本研究从贵州黔西北某铅锌矿区周边土壤中分离出一株耐Pb(II)和Cd(II)菌株GS-2,经形态学特征和16S rRNA鉴定为Bacillus paramycoides,菌株GS-2对Pb(II)和Cd(II)的耐受分别高达1500和50 mg/L,对250 mg/L Pb(II)和5 mg/L Cd(II)去除率分别为99.54%和69.04%,对重金属Pb(II) 和Cd(II)（均为25 mg/L）混合去除率分别为99.73%和71.6%。SEM-EDS、FTIR和XRD结果显示,菌株通过表面的羟基、羧基、酰胺基和磷酸基团等官能团将Pb(II)和Cd(II)诱导矿化成Ca2.5Pb7.5(OH)2(PO4)6、Ca2.1Pb7.9Cl2(PO4)6、Pb3(PO4)2、Pb5(PO4)3OH、Pb9(PO4)6、Pb10(PO4)6(OH)2和Ca0.67Cd0.33CO3等晶体矿物。菌株GS-2具有较好的去除和矿化能力,对环境中Pb(II)和Cd(II)污染的生物修复具有一定应用潜力。