类泛素介导和热激响应协同提高酿酒酵母的热稳定性

通过调节类泛素和热激响应介导的酿酒酵母内部的活性蛋白质平衡,提高酵母细胞的热稳定性和乙醇发酵性能,从而达到工业生产中降低控温能耗的目的。将5个蛋白质平衡相关基因分别与调控基因FBA1p组合构建耐热元器件,并将其导入酿酒酵母Saccharomyces cerevisiaeINVSC1,通过梯度升温培养筛选得到能赋予酵母细胞较好耐热性的类泛素元器件FBA1p-atg8和热激蛋白元器件FBA1p-hsp104;其对应的工程菌S.c-ATG8和S.c-HSP104在40℃恒定培养下,OD₆₆₀值均比对照高50%以上(84h),细胞存活率分别是对照的1.64倍和3.01倍(72h),且都具有较好的细胞壁完整性及海藻糖合成量。将atg8与hsp104组合构建成双功能耐热元器件,其工程菌S.c-ATG8-HSP104在40℃恒定发酵的生长能力、细胞活力和乙醇生产能力都明显优于S.c-ATG8与S.c-HSP104。结果表明,通过类泛素介导与热激蛋白响应协同调节胞内活性蛋白质平衡可以有效地提高酿酒酵母的热稳定性。     

膳食纤维强化冻干山楂果对小鼠肠道健康的影响

本文研究了添加10%山楂膳食纤维的冻干山楂果(按质量比9:1)对小鼠肠道健康的影响。将小鼠按体重质量随机分为4组,分别为溶剂对照组和受试物1、2和4 g/(kg·d)剂量组。灌胃6周后,试验结束前连续3 d收集小鼠新鲜粪便,测定粪便质量、水分、pH值和短链脂肪酸(SCFA)含量。试验结束空腹过夜条件下测体重,处死小鼠,分离盲肠和结肠并测定质量;取盲肠和结肠内容物测定pH和盲肠酵解产物SCFA的含量;测定盲肠和结肠内容物中的双歧杆菌、肠杆菌、肠球菌、乳杆菌和产气荚膜梭菌的数量。分析添加10%山楂膳食纤维的冻干山楂果对小鼠肠道健康的影响。各剂量组与溶剂对照组相比,各项检测指标存在显著性差异(p0.05),结果表明添加10%山楂膳食纤维的冻干山楂果对小鼠肠道内环境健康具有改善调节作用。     

Inflammation amplification by versican: the first mediator

The effects of inflammation may not always benefit the individual. Its amplifying nature represents a highly regulated biological program, and the inflammatory microenvironment is its essential component. Growing evidence suggests that the ECM (extracellular matrix) is important for the early steps of inflammation. Versican, a ubiquitous component of the ECM, contributes to the formation of the inflammatory response and is highly regulated by cytokines. Certain cytokines exert their initial effects on versican to alter the homeostasis of the inflammatory milieu, and inappropriate production of versican may promote the next inflammatory response. Therefore, versican could be the first step in the amplification of the inflammatory response, and ongoing research of this molecule may help to explain the pathogenesis of inflammation.     

五粮浓香型白酒窖房和曲房空气细菌相关性的初步研究

从宜宾华夏酒业窖房和曲房空气中分离得到44株细菌,对所得菌株进行了16S rDNA基因系统发育及部分酿造特性分析。窖房和曲房空气的细菌在属和种一级的相似性分别为40.0%和36.4%,且均以Bacillus cereus、Bacillus anthracis细菌为优势种,表明2个细菌群落具有一定的相似性。分离自窖房空气的菌株有20株（占95.2%）耐受7%的无水乙醇,2株菌耐受pH4.5,且分别有2株、9株能够产纤维素酶和淀粉酶;分离自曲房空气的菌株均不耐受7%的乙醇和pH4.5,产纤维素酶和淀粉酶的菌株分别有6株、3株。结果表明,经过长期的酿酒生产,曲房和窖房空气中均形成了较为稳定的细菌区系,其菌落组成与酿酒生产存在较为密切的相关性。在生产中,2个细菌群落之间存在广泛的交流。     

河西走廊啤酒大麦附生微生物区系研究

以甘肃河西走廊具有代表性的三个产地的啤酒大麦为研究对象,通过对大麦表面细菌、酵母菌和霉菌的筛查、分离纯化与鉴定,研究大麦附生微生物区系组成及其优势种群。结果显示,河西走廊啤酒大麦附生细菌数量最多,菌落总数在106～107cfu/g之间,酵母总数在104～105cfu/g之间,霉菌菌落总数因产地变化较大,数量在103～105cfu/g。通过对大麦附生微生物区系的鉴定,分离到9株优势细菌,9株优势酵母和11株霉菌,表明大麦附生菌群具有一定的多样性,并因产地不同,微生物组成呈现出一定差异。部分样品大麦中检出了产气肠杆菌(Enterobacter aerogenes)和产色葡萄球菌(Staphylococcus chromogenes)等细菌,以及一些产真菌毒素霉菌菌株,存在一定生物安全隐患。建议在制麦过程中,尤其是浸麦工段应加强洗麦,以减少原料大麦携带的有害病菌,并降低产生真菌毒素的风险。     

骆驼乳对慢性酒精性肝损伤小鼠肠道菌群的影响

目的:探究骆驼乳对慢性酒精性肝损伤小鼠肠道菌群多样性及结构的影响。将雄性C57BL/6NCr小鼠随机分为4组:对照组(Con,n=6)、模型组(Et,n=6)、骆驼乳剂量组(EtCM,n=6)和牛乳剂量组(EtNM,n=6);实验期为8周,前4周饲喂Lieber-DeCarli液体饲料(含对照),后4周在饲喂Lieber-DeCarli液体饲料的基础上,灌胃相应的乳或生理盐水。灌胃结束后,按照5 g/kg剂量一次性灌胃31.5%酒精溶液,建立NIAAA模型。检测血清LPS含量,并在无菌条件下取小鼠结肠粪便,进行16S rRNA测序,分析肠道菌群α多样性、β多样性及基于门、属水平的物种结构。血清指标结果显示,EtCM组和EtNM组小鼠血清LPS显著降低(P<0.01)。16S r RNA测序结果表明,骆驼乳和牛乳能显著提高ALD小鼠结肠肠道菌群的丰度和均匀度,更好地调整肠道菌群结构,其中骆驼乳较牛乳显示出更好的α多样性。在门水平上,骆驼乳和牛乳显著提高拟杆菌门的丰度,降低厚壁菌门的丰度。在属水平上,骆驼乳和牛乳显著提高副拟杆菌属、拟杆菌属、阿克曼菌属的丰度,降低瘤胃菌科下的未知属Ruminococcaceae_UCG-013丰度。其中,骆驼乳的有益菌丰度较牛乳高出9%。结论:骆驼乳通过改变ALD小鼠肠道菌群环境,来调节肠道菌群结构,可作为调节肠道菌群的功能性乳制品,可预防慢性ALD引起的肠道屏障功能障碍。     

应用PCR-DGGE研究液熏罗非鱼片贮藏过程中的菌相变化

采用基于PCR反应的变性梯度凝胶电泳技术(PCR-denaturing gradient gel electrophoresis,PCR-DGGE),对液熏罗非鱼片在贮藏过程中的菌相组成及变化进行分析,旨在为液熏罗非鱼的贮藏条件提供理论基础。研究结果表明:用DGGE法总共分离到13个条带,测序比对相似度在90%以上的菌种有10种,分别是:2株肠杆菌属(Enterobacter),2株梭菌(Clostridium),2株乳球菌属(Lactococcus),2株戊糖片球菌(Pediococcuspentosaceus),1株明串珠菌(Leuconostoc),以及1株假单胞菌属(Pseudomonas),乳酸菌(LAB)占所有菌株的50%。贮藏早期(2 d)和末期(7 d)的菌相较为复杂,可辨识条带10,贮藏中期(2~7 d)菌相条带表现出集中和明显的特点,可辨识条带仅在5条左右,微生物多样性减少,图谱结合测序分析表明贮藏期的优势菌种为乳酸球菌(Lactococcus)、戊糖片球菌(Pediococcuspentosaceus)和梭菌(Clostridium)。     

The IRC7 gene encodes cysteine desulphydrase activity and confers on yeast the ability to grow on cysteine as a nitrogen source

Although cysteine desulphydrase activity has been purified and characterized from Saccharomyces cerevisiae, the gene encoding this activity in vivo has never been defined. We show that the full‐length IRC7 gene, encoded by the YFR055W open reading frame, encodes a protein with cysteine desulphydrase activity. Irc7p purified to homogeneity is able to utilize l ‐cysteine as a substrate, producing pyruvate and hydrogen sulphide as products of the reaction. Purified Irc7p also utilized l ‐cystine and some other cysteine conjugates, but not l ‐cystathionine or l ‐methionine, as substrates. We further show that, in vivo, the IRC7 gene is both necessary and sufficient for yeast to grow on l ‐cysteine as a nitrogen source, and that overexpression of the gene results in increased H₂S production. Strains overexpressing IRC7 are also hypersensitive to a toxic analogue, S‐ethyl‐l ‐cysteine. While IRC7 has been identified as playing a critical role in converting cysteine conjugates to volatile thiols that are important in wine aroma, its biological role in yeast cells is likely to involve regulation of cysteine and redox homeostasis. Copyright © 2015 John Wiley & Sons, Ltd.