江米酒中凝乳酶产生菌的分离及产酶条件的优化

江米酒是我国南方的一种传统食品, 江米酒中微生物所产凝乳酶具有凝乳作用。从江米酒中分离纯化得到4株菌, 经菌落分离计数和酪蛋白平板实验研究确定产凝乳酶的优势菌为其中的霉菌, 并对该霉菌产凝乳酶条件进行了初步优化, 结果表明: 2倍浓度的PDA培养基中添加5%葡萄糖而不添加氮源是霉菌产凝乳酶的最佳培养基, 在此条件下其所产凝乳酶活力可比优化前提高144%。     

产脂酵母产脂培养条件研究及脂肪检测方法初探

目的：研究产脂酵母产脂条件及脂肪提取方法。方法：探讨了单因素如：pH、碳源、氮源、葡萄糖浓度、金属微量元素等对其产脂能力的影响,并进行了正交试验;脂肪测定方法研究,用对比分析法,并对其中的方法加以改进,采用光谱扫描以确定酵母脂肪最大吸收波长。结果：试验范围所得酵母产脂最佳条件是：接种量3%,MnCl_2 0．05%、FesO_4 0．04%、(NH_4)_2SO_4 0．3%、葡萄糖2%、pH 6．5,培养5d,45ml的发酵液其油脂的吸光度(252nm)可达2．4082;酵母脂肪最大吸收波长为252nm,在此波长下测定,获得了快速、准确的结果。结论：所得产脂条件可为进一步的开发研究打下基础。研究出的酵母脂肪测定方法,是一种快速、简便的方法,可满足产脂酵母菌种筛选和产脂条件研究的需要。     

Ultrasensitive detection of Shiga toxin 2 and its variants in Shiga toxin‐producing Escherichia coli strains by a time‐resolved fluorescence immunoassay

A rapid and sensitive two‐step time‐resolved fluorescence immunoassay (TRFIA) was developed for the detection of Shiga toxin 2 (Stx2) and its variants in Shiga toxin‐producing Escherichia coli (STEC) strains. In sandwich mode, a monoclonal antibody against Stx2 was coated on a microtiter plate as a capture antibody. A tracer antibody against Stx2 labeled with europium(III) (Eu³⁺) chelate was then used as a detector, followed by fluorescence measurements using time‐resolved fluorescence. The sensitivity of Stx2 detection was 0.038 ng/ml (dynamic range, 0.1–1000 ng/ml). The intra‐ and inter‐assay coefficients of variation of the assay were 3.2% and 3.6%, respectively. The performance of the established assay was evaluated using culture supernatants of STEC strains, and the results were compared to those of a common HRP (horseradish peroxidase) labeling immunosorbent assay. A polymerase chain reaction (PCR) for the detection of genes encoding Stx1 and Stx2 was used as the reference for comparison. Correlation between the Stx2‐specific TRFIA and PCR was calculated by the use of kappa statics, exhibiting a perfect level of agreement. The availability of the sensitive and reliable Stx2‐specific TRFIA method for quantifying Stx2 and its variants in STEC strains will complement bacteria isolation‐based platform and aid in the accurate and prompt diagnosis of STEC infections.     

不同来源仙草的氨基酸比较分析

采用盐酸水解法分析不同来源仙草的氨基酸组成及含量差异,结果表明供试仙草均含有17种氨基酸和7种必需氨基酸,氨基酸总量为4.75％～13.65％,17种氨基酸总量和7种必需氨基酸总量的高低顺序都是9＞10＞5＞8＞1 ＞6＞4＞3＞2＞7,均以9号仙草含量最高,7号仙草最低.各种氨基酸含量高低顺序相似,以谷氨酸、天门冬氨...     

高产蛹虫草菌株发酵培养基的研究

在单因素试验初步确定高产蛹虫草菌株发酵培养基的基础上,以蛹虫草茵丝体中腺苷含量为指标,进行11因素2水平Plackett—Burman试验设计试验,结合多元一次回归模型和F检验方法,筛选出发酵培养基中影响显著的组分酵母浸粉、蔗糖和维生素B1,采用旋转中心组合设计方法对这三个组分进行进一步优化,结合多元二次回归模型和响应面分析,获得高产蛹虫草菌株的最佳培养基（g／L）：蔗糖18．85、蛋白胨10、酵母浸粉18．97、KH2PO,3、MgSO4 3、维生素Bl0．235、ZnCl20．011、（NH4）2S0410。验证试验结果表明蛹虫草腺苷得率较单因素优化获得的发酵培养基提高了26．91％。     

毛霉脂肪酶的研究

从土样中分离筛选到一株脂肪酶菌株—毛霉(Mucor sp.)M₂,其优化后的培养基组成(%);黄豆粉4.0、蔗糖0.5、橄榄油1.0、硫酸铵0.1、磷酸氢二钾0.2硫酸镤0.01、pH自然。产酶最适条件：初始pH6.5、培养温度28℃、培养周期96h.该酶最适作用温度50℃、最适pH8.0、pH稳定范围为7.0～10.0,Fe²⁺、Ca²⁺、Mg²⁺、K⁺对酶有激活作用。     

蛋白酶分泌菌对重金属胁迫的反应

本文研究了Pb、zn、cu和Cd对3种蛋白酶产生菌:碱性地衣芽孢杆菌2709(Bacilluslicheniformis 2709)、中性枯草杆菌1.398(Bacillus subtilis1.398)和酸性宇佐美曲霉537(Aspergillususamii 537)生长及其酶活性的影响,并采用生长抑制皿分析(GIPA)方法针对3种菌株在Pb、zn、Cu、Cd不同胁迫浓度下的生长量进行打分,分析其耐性与抗性指标(MTC与MIC).结果表明4种重金属在超过一定临界浓度后,对3种菌株的生长和蛋白酶活性均产生了较大的抑制作用.碱性蛋白酶对4种重金属均具有较大的适应性,其次是中性蛋白酶对Zn和Cd具有一定的适应性.而酸性蛋白酶对4种重金属均表现出被抑制状态.3种菌株对Pb和Zn耐性与抗性最高(2.0 mmol/L～6.0 mmol/L),其次是对Cd也具有一定的抗性(0.5 mmol/L～0.75 mmol/L).     

氨基酸产生菌E_(65)中质粒的分离与鉴定

在棒杆菌与短杆菌中,用微量质粒分离方法筛选到一株含多种质粒的乙酰短杆菌(Brevibacterium actylicum)E_(65)菌株,该菌株具有产氨基酸特性。进一步大量制备其质粒DNA,并进行氧化绝密度梯度超离心纯化,以及电泳分析,电镜观察,并对质粒进行分离与鉴定,从而确定了每种质粒的分子量大小。     

产自Aspergillus sp.DLCS-F18的嗜酸嗜热纤维素酶及其酶学性质

纤维素酶在饲料、造纸、纺织和纤维素乙醇生产等领域有重要用途,因而备受关注.使用稻草为唯一碳源进行纤维素降解微生物的富集,从云南大理苍山地区的土壤样品中筛选获得1株纤维素降解真菌DLCS-F18,其适宜生长温度为15-40℃、pH 2.0-13.0.通过形态学和ITS rRNA分子生物学鉴定,菌株DLCS-F18被鉴定为...     

A feasibility study of an in vitro differentiation potential toward insulin-producing cells by dental tissue-derived mesenchymal stem cells

Dental tissue-derived mesenchymal stem cells have been proposed as an alternative source for mesenchymal stem cells. Here, we investigated the differentiation ability toward insulin producing cells (IPCs) of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs). These cells expressed mesenchymal stem cell surface markers and were able to differentiate toward osteogenic and adipogenic lineages. Upon 3 step-IPCs induction, hDPSCs exhibited more colony number than hPDLSCs. The mRNA upregulation of pancreatic endoderm/islet markers was noted. However, the significant increase was noted only for PDX-1, NGN-3, and INSULIN mRNA expression of hDPSCs. The hDPSCs-derived IPCs expressed PRO-INSULIN and released C-PEPTIDE upon glucose stimulation in dose-dependent manner. After IPCs induction, the Notch target, HES-1 and HEY-1, mRNA expression was markedly noted. Notch inhibition during the last induction step or throughout the protocol disturbed the ability of C-PEPTIDE release upon glucose stimulation. The results suggested that hDPSCs had better differentiation potential toward IPCs than hPDLSCs. In addition, the Notch signalling might involve in the differentiation regulation of hDPSCs into IPCs.