从泡菜中筛选降解胆固醇的乳酸菌

采用半选择性培养基MRS从传统食品泡菜中筛选出15株细菌,鉴定为植物乳杆菌,在MRSO-Chol培养基中对这些菌株进行体外胆固醇降解效果的研究。37℃培养24h,发现胆固醇降解量分别达到90.5,75.3和74.0μg/ml的ST1015,ST1009和ST1010三株菌,采用MRSO培养基对所有实验菌株的胆汁耐受力进行了研究,发现不同菌株之间胆汁耐受力差异显著,但胆固醇降解量和胆汁耐受力之间没有必然的联系。     

构建高效降解胆固醇的融合乳酸菌的研究——(Ⅱ)原生质体融合及融合子的筛选

芽孢杆菌T12-1与嗜热链球菌ST及嗜酸乳杆菌C3进行原生质体融合,获得两株科间融合子S-T13-37和C-T24-8,它们对培养液中的胆固醇降解率分别为54%和78%.ST、C3和T12-1原生质体的再生率分别为10.5%、8.6%和11.2%,ST与T12-1原生质体科间融合率约为4.6×10-6;C3与T12-1原生质体科间融合率约为3.8×10-6.     

降胆固醇乳酸菌对肉鸡胆固醇的影响研究

目的探讨经体外实验筛选出的降胆固醇乳酸菌对肉鸡血清胆固醇及胸肌组织、腿肌组织和肝脏组织胆固醇含量的影响。方法将肉鸡随机分为2组,对照组喂食普通饲料,实验组喂食含有DM86056菌的饲料;喂食56d后分离其血清及肝脏等组织,并应用硫酸铁铵法测定其胆固醇含量,观察对照组与实验组结果差异是否有显著性。结果对肉鸡血清、胸肌组织、腿肌组织胆固醇含量测定后,对照组与实验组结果差异有显著性（P〈0．05）,而对肝脏组织胆固醇含量测定后,对照组与实验组结果差异无显著性（P〉0．1）。结论菌株DM86056可明显降低肉鸡血清、胸肌组织、腿肌组织中胆固醇含量,而对肝脏组织胆固醇含量没有明显改变。     

乳酸菌降低血清胆固醇的研究

本文综述了乳酸菌对血清胆固醇的降低作用,并对其作用机制进行了探讨,这将有助于对乳酸菌资源的进一步开发和利用。     

乳酸菌降胆固醇作用研究现状

本文综述了国内外关于乳酸菌在体内及体外降低胆固醇的研究进展, 并对乳酸菌降胆固醇的作用机制进行了探讨, 提出目前在研究中存在的一些问题, 以期对乳酸菌的进一步开发和利用提供帮助。     

降胆固醇乳酸菌的筛选及应用的研究进展

胆固醇摄入过量带来的高脂血症、冠心病、动脉硬化等心血管疾病已经严重危害到人体健康,如何减少胆固醇摄入量、降低人体血清胆固醇水平的研究越来越受到广泛关注^[1]。美国的一项统计调查^[2]发现,高脂血症所引起的心血管疾病是目前危害人类健康,导致死亡的首要因素。而另一项最近的研究报告^[3]证实,降低血清胆固醇含量将有助于降低高脂血症患者患上心脏疾病的几率。因此,降低血清胆固醇含量将直接关系到人类的健康,也是目前国内外科学研究的热点之一。     

乳酸菌对高脂小鼠降胆固醇作用的研究

目的探讨乳酸菌对高脂小鼠降胆固醇的作用。方法对昆明小鼠饲喂高脂饲料14 d建立高脂小鼠模型,确定模型建立成功后用1株经体外实验证实具有降胆固醇效果的乳酸菌对小鼠灌胃,测定小鼠经灌胃14、28 d的脏器指数、血清胆固醇含量和肝脏胆固醇含量。结果灌胃组小鼠脏器指数明显低于高脂组小鼠,且对于血清和肝脏胆固醇含量具有明显的降低作用。结论该菌株具有降低血清胆固醇,抑制肝脏胆固醇堆积的功能,为将来利用该菌株制作出降胆固醇功能的食品或药品提供实验基础。     

一株具降胆固醇功能乳酸菌的机制研究

目的对动物双歧杆菌SQ-0001的体外环境耐受性及其降胆固醇作用进行研究。方法用邻苯二甲醛法对pH 3.0和0.3%牛胆酸钠有一定耐受性的动物双歧杆菌SQ-0001的体外降胆固醇机制进行了研究。结果动物双歧杆菌SQ-0001对pH 3.0及0.3%胆盐环境具有一定的耐受性;该菌在胆盐浓度为0.2%,培养时间为24 h时,胆固醇脱除率最高,达到91.59%;该菌降胆固醇的作用主要以吸收为主,吸收率达到63.87%,其次是降解率,为23.81%。结论动物双歧杆菌SQ-0001的环境耐受能力良好,具有很好体外降胆固醇作用,该菌株可以作为日后降胆固醇的潜在益生菌。     

具有降解胆固醇作用益生菌的研究进展

众所周之,心血管疾病现已成为全球工业国家人民的主要死亡原因,例如在美国因心血管疾病死亡的人数当中有四分之三是由动脉粥样硬化及其并发症引起的,即动脉粥样硬化、高血压和冠心病等心血管疾病已严重威胁着人类的健康,而血清胆固醇水平过高则是其主要因素之一,另外,肾病综合征、糖尿病和肝脏疾病等也被认为是高胆固醇所引起的,因此降低胆固醇水平直接关系到了人类的身体健康。益生菌的主要功能除了具有改善肠道内环境、免疫增强作用和抗肿瘤作用,许多体内及体外研究表明益生菌也具有一定的降低胆固醇作用。     

东北酸菜发酵中几株乳酸菌的筛选

从东北酸菜汁液出发,有目的地筛选到3株菌株,通过对其形态特征、菌落特征及生化特征进行分析可知,3株菌株均为乳杆菌属。对筛选到的乳杆菌属进行酸菜发酵性能研究发现,其中菌株L2在发酵24 h后,产酸量达到2.5%,酸度达到1.73 g乳酸/100 mL,且发酵无异味,口味自然,效果较好。     

Exocellular polysaccharides produced by lactic acid bacteria

Abstract The production of homopolysaccharides (dextrans, mutans) and heteropolysaccharides by lactic acid bacteria, their chemical composition, their structure and their synthesis are outlined. Mutans streptococci, which include Streptococcus mutans and S. sobrinus produce soluble and insoluble α-glucans. The latter may contain as much as 90%α-1–3 linkages and possess a marked ability to promote adherence to the smooth tooth surface causing dental plaque. Dextrans produced by Leuconostoc mesenteroides are high molecular weight α-glucans having 1–6, 1–4 and 1–3 linkages, varying from slightly to highly branched; 1–6 linkages are predominant. Emphasis is put on exopolysaccharide producing thermophilic and mesophilic lactic acid bacteria, which are important in the dairy industry. The produced polymers play a key role in the rheological behaviour and the texture of fermented milks. One of the main problems in this field is the transitory nature of the thickening trait. This instability is not yet completely understood. Controversial results exist on the sugar composition of the slime produced, but galactose and glucose have always been identified with galactose predominating in most cases.     

Evaluation of lactic acid bacteria autolysate for the supplementation of lactic acid bacteria fermentation

At the end of culture in a carbon-limited medium, i.e. the best conditions for subsequent autolysis, lactic acid bacteria were harvested and autolysed at 50 °C for 24 h. The resulting supernatant was then successfully tested as a substitute for industrial yeast extract for the supplementation of whey permeate and its conversion into lactic acid: for almost equivalent total nitrogen amounts of both supplements, the same growth and production rates were recorded.     

Genomics of lactic acid bacteria

Lactic acid bacteria (LAB) are found to occupy a variety of ecological niches including fermented foods as well as mucosal surfaces of humans and other vertebrates. This review is based on the genomic content of LAB that is responsible for the functional and ecological diversity of these bacteria. These genomes reveal an ongoing process of reductive evolution as the LAB have specialized to different nutritionally rich environments. Species-to-species variation in the number of pseudogenes as well as genes directing nutrient uptake and metabolism reflects the adaptation of LAB to food matrices and the gastrointestinal tract. Although a general trend of genome reduction was observed, certain niche-specific genes appear to be recently acquired and appear on plasmids or adjacent to prophages. Recent work has improved our understanding of the genomic content responsible for various phenotypes that continue to be discovered, as well as those that have been exploited by man for thousands of years.     

Boza, a natural source of probiotic lactic acid bacteria

Aims: To evaluate the probiotic properties of strains isolated from boza, a traditional beverage produced from cereals. Methods and Results: The strains survived low pH conditions (pH 3·0), grew well at pH 9·0 and were not inhibited by the presence of 0·3% (w/v) oxbile. Cytotoxicity levels of the bacteriocins, expressed as CC₅₀, ranged from 38 to 3776 μg ml^?1. Bacteriocin bacST284BZ revealed high activity (EC₅₀ = 735 μg ml^?1) against herpes simplex virus type 1. Growth of Mycobacterium tuberculosis was 69% repressed after 5 days in the presence of bacST194BZ. Various levels of auto‐cell aggregation and co‐aggregation with Listeria innocua LMG 13568 were observed. Adhesion of the probiotic strains to HT‐29 cells ranged from 18 to 22%. Conclusions: Boza is a rich source of probiotic lactic acid bacteria. All strains survived conditions simulating the gastrointestinal tract and produced bacteriocins active against a number of pathogens. Adherence to HT‐29 and Caco‐2 cells was within the range reported for Lactobacillus rhamnosus GG, a well‐known probiotic. In addition, the high hydrophobicity readings recorded define the strains as good probiotics. Significance and Impact of the Study: Boza contains a number of different probiotic lactic acid bacteria and could be marketed as a functional food product.     

乳酸菌的系统分类概况

乳酸菌是重要的益生菌资源,在食品、农业、化工业、医学等领域具有广阔的应用前景。目前,人们熟知的乳酸菌主要集中在乳杆菌属、双歧杆菌属、链球菌属、肠球菌属、乳球菌属、片球菌属和明串珠菌属等少数属种。为了拓宽人们对乳酸菌的认知,本文就乳酸菌的系统分类学进行阐述。在系统分类学上,乳酸菌分别隶属于厚壁菌门4纲7目18科39属653种和放线菌门2纲2目3科12属88种。最后,对乳酸菌的益生作用、安全性与有效来源、益生潜能的体外评价指标等进行简要的讨论。     

乳酸菌对真菌毒素的脱毒作用研究进展

真菌毒素广泛存在于农业产品中,对人和动物的健康构成巨大威胁。乳酸菌作为一种公认安全的微生物,在食品生物减毒方面具有巨大的应用潜力,成本低廉且不会对食品品质及生态环境造成不良影响。文章主要根据近年来国内外研究进展,阐述乳酸菌对食品和饲料中几种常见真菌毒素的脱毒作用(抑制真菌生长、毒素的吸附和降解),关注乳酸菌在生物脱毒方面的实际应用,为乳酸菌在食品保鲜领域的应用提供理论指导。     

Degradation of free and sulfur-dioxide-bound acetaldehyde by malolactic lactic acid bacteria in white wine

AIMS: Acetaldehyde is the major carbonyl compound formed during winemaking and has implications for sensory and colour qualities of wines as well as for the use of the wine preservative SO(2). The current work investigated the degradation of acetaldehyde and SO(2)-bound acetaldehyde by two commercial Oenococcus oeni starters in white wine. METHODS AND RESULTS: Wines were produced by alcoholic fermentation with commercial yeast and adjusted to pH 3.3 and 3.6. While acetaldehyde was degraded rapidly and concurrently with malic acid at both pH values, SO(2)-bound acetaldehyde caused sluggish bacterial growth. Strain differences were small. CONCLUSIONS: Efficient degradation of acetaldehyde can be achieved by commercial starters of O. oeni. According to the results, the degradation of acetaldehyde could not be separated from malolactic conversion by oenococci. While this may be desirable in white winemaking, it may be necessary to delay malolactic fermentation (MLF) in order to allow for colour development in red wines. SO(2)-bound acetaldehyde itself maybe responsible for the sluggish or stuck MLF, and thus bound SO(2) should be considered next to free SO(2) in order to evaluate malolactic fermentability. SIGNIFICANCE AND IMPACT OF THE STUDY: The current study provides new results regarding the metabolism of acetaldehyde and SO(2)-bound acetaldehyde during the MLF in white wine. The information is of significance to the wine industry and may contribute to reducing the concentration of wine preservative SO(2).     

Hydrolysis of soybean isoflavone glucosides by lactic acid bacteria

Lactobacillus delbrueckii subsp. delbrueckii KCTC 1047, grown in de Man, Rogosa and Sharpe (MRS) or soymilk media, completely hydrolyzed the isoflavone glucosides, genistin and daidzin at 50 g ml^–1, into their respective aglycones, genistein and daidzein within 30 min. Other lactic acid bacteria did not produce -glucosidase, the enzyme responsible for the hydrolysis of isoflavone glucosides, when cultured in MRS medium. Glucoside-hydrolyzing activity was induced in some lactic acid bacteria when cultured in soymilk medium. These strains hydrolyzed 70–80% of genistin into genistein and 25–40% of daidzin into daidzein.     

一株产共轭亚油酸乳酸菌的鉴定及其特性

从酸菜汁中分离筛选到一株产共轭亚油酸(CLA)能力较高的乳酸菌。经鉴定,确定为植物乳杆菌Lactobacliius plantarum。微氧条件可提高CLA的产量,催化亚油酸(LA)生成CLA的酶受着LA的诱导。37℃对细胞生长和CLA生成最为有利。对数生长期为6～12h,18h后进入稳定期。在14～22h,CLA生成量快速增加,24h时达到最高值。该菌的培养物经萃取、甲酯化后,进行了气相色谱分离,生成的CLA产物为c9/t9,c11-CLA和t10,c12-CLA异构体的混合物。