益生菌Lactobacillus casei Zhang增殖培养基的优化

Lactobacillus casei Zhang 是一株分离自传统酸马奶中的益生菌.本文研究了不同碳源、氮源、碳氮比例、微量元素及缓冲盐对 Lactobacillus casei Zhang 增殖培养的效果,并采用响应面法对优选的碳源、氮源和缓冲盐类的组成含量进行优化,得到 Lactobacillus casei Zhang 的增殖培养基为:葡萄糖20.9 g/L、大豆蛋白胨10.45 g/L、酵母粉10.45 g/L、K2HPO4 3.5 g/L、醋酸钠14.6 g/L、柠檬酸钠2.3 g/L、MgSO4·7H2O 1 g/L,MnSO4·5H2O 54 mg/L、CuSO4·5H2O 10 mg/L、吐温80为1 g/L.Lactobacillus casei Zhang 在此增殖培养基中经37℃ 18 h培养活茵数可达到4.78×109 CFU/mL,比在MRS中(4.8×108 CFU/mL)提高近10倍.     

益生菌Lactobacillus casei Zhang固态发酵条件的优化

利用一株分离自传统发酵酸马奶中的益生干酪乳杆菌（Lactobacillus casei Zhang）进行固态发酵（Solid State Fermentation,SSF）。以发酵物中的活菌数为主要指标,采用九因素四水平（L32（4^9））的正交试验优化固态发酵培养基,并在优化的培养基基础上研究不同的初始含水量及培养时间对Lactobacillus casei Zhang活菌数的影响。实验结果表明,在固态发酵培养基组成为4g豆粕、5g麸皮、0．6g乳清粉、0．3g葡萄糖、0．3g碳酸钙、0．02g硫酸铵、0．01g硫酸镁,初始含水量为55％的优化条件下,37℃发酵60h,发酵物中Lactobacillus casei Zhang活菌数可达到4．08×10^10CFU／g。     

益生菌Lactobacillus casei Zhang增殖培养基的优化

Lactobacillus casei Zhang是一株分离自传统酸马奶中的益生菌。本文研究了不同碳源、氮源、碳氮比例、微量元素及缓冲盐对Lactobacillus casei Zhang增殖培养的效果, 并采用响应面法对优选的碳源、氮源和缓冲盐类的组成含量进行优化, 得到Lactobacillus casei Zhang的增殖培养基为：葡萄糖 20.9 g/L、大豆蛋白胨10.45 g/L、酵母粉10.45 g/L、K2HPO4 3.5 g/L、醋酸钠14.6 g/L、柠檬酸钠2.3 g/L、MgSO4?7H2O 1 g/L、MnSO4?5H2O 54 mg/L、CuSO4?5H2O 10 mg/L、吐温80为1 g/L。Lactobacillus casei Zhang在此增殖培养基中经37℃18 h培养活菌数可达到4.78×109 CFU/mL, 比在MRS中(4.8×108 CFU/mL)提高近10倍。     

凝结芽胞杆菌BC01对白羽肉鸡生产性能、免疫器官指数及肠道大肠埃希菌的影响

为研究在饲料中添加凝结芽胞杆菌BC01对白羽肉鸡生产性能、免疫器官指数及肠道大肠埃希菌的影响,将240只白羽肉鸡随机分为4组,试验组1、试验组2、试验组3在饲料中添加凝结芽胞杆菌BC01的终浓度分别为1×10~8、2×10~8、3×10~8 cfu/kg,对照组日粮中不添加任何微生态制剂,饲养6周。结果显示,日粮中添加凝结芽胞杆菌BC01可显著提高肉鸡平均日增重(P0.05),显著降低料重比(P0.05),降低死淘率(P0.05),胸腺指数、法氏囊指数均显著高于对照组(P0.05),降低肠道中的大肠埃希菌数量。结果表明,日粮中添加凝结芽胞杆菌BC01,对肉鸡的生长性能有一定的促进作用,提高饲料转化率,提升肉鸡的免疫力,提高肉鸡饲养的经济价值。凝结芽胞杆菌BC01的最佳添加浓度为每公斤饲料添加2×10~8 cfu/kg。     

优化益生菌Lactobacillus casei Zhang高密度培养条件

为实现L. casei Zhang的高密度培养,在之前优化增殖培养基的基础上进一步寻求适宜该菌的培养条件。研究了不同中和剂、缓冲盐浓度、葡萄糖浓度、pH值控制、通气条件和补料分批培养对菌体在恒pH条件下发酵的影响,根据不同条件下菌体的比生长速率、菌体密度和活菌数情况,确定L. casei Zhang较适宜的高密度培养条件为：培养基葡萄糖浓度为80 g/L~100 g/L,以氨水为中和剂使pH保持5.9,采用间歇通氮气的方法保持环境厌氧,分批培养方式下37°C保温发酵10 h~12 h后,L. casei Zhang细胞干重达到7 g/L,活菌数3.5×1010 CFU/mL,比优化前提高7倍以上,能够满足益生菌制品生产要求的高菌体密度。     

山西高平市农家酸菜汁中乳酸菌的分离及鉴定

对山西高平市农家酸菜汁中乳酸菌含量和菌种进行分析研究,经分离筛选得到3株产酸能力较强的菌株,对其进行鉴定并对其生理特性进行研究。通过对其形态特征、菌落特征及生化特征进行分析可知,其中2株为植物乳杆菌(Lactobacillus plantarum),1株为短乳杆菌(Lactobacillus breris)。对筛选到的乳酸菌进行酸菜发酵性能研究发现,其中菌株L2在发酵24 h后,发酵液pH值达到3.47、酸度达到1.67 g乳酸/100 mL、菌落数达到1.37×107cfu/mL的高密度富集状态,且发酵无异味,口味自然,效果较好。     

云南泡梨中乳酸菌的分离鉴定及其应用

【背景】泡梨是云南省常见的一种腌渍水果,在云南加工食用已经有一百多年的历史,因其味道酸甜可口、风味独特而深受人们喜爱,而目前对泡梨中微生物种群的系统分析和发酵原理的研究尚未见报道。【目的】研究乳酸菌在云南泡梨中的分布及应用,阐明乳酸菌种类对泡梨发酵中风味物质的影响。【方法】从云南省4个不同地区采集12份泡梨样品,经菌落菌体形态、生理生化特性和16SrRNA基因序列分析进行菌种分离与鉴定。利用分离的乳酸菌为菌种进行泡梨的制备,采用GC-MS技术对人工接种的复合乳酸菌发酵与自然发酵泡梨进行风味物质的分析与感官评价。【结果】分离鉴定出79株植物乳杆菌(Lactobacillus plantarum)、 3株类植物乳杆菌(Lactobacillus paraplantarum)、1株戊糖乳杆菌(Lactobacillus pentosus)、1株干酪乳杆菌(Lactobacillus casei)、2株副干酪乳杆菌(Lactobacillus paracasei)和1株短乳杆菌(Lactobacillus brevis),植物乳杆菌为泡梨发酵中的优势菌。将分离所得乳酸菌用于泡梨制备的结果表明,...     

水稻秸秆低温复合菌系多样性及发酵动态

【目的】为解决中国寒冷地区水稻秸秆大面积废弃问题,加快低温地区水稻秸秆饲料转化,本文筛选了可以低温下加速秸秆发酵过程的微生物复合菌系,研究其微生物组成并跟踪其发酵动态。【方法】通过5℃下连续定向富集筛选,获得低温复合菌系。采用克隆文库方法分析复合菌系的组成。将复合菌系和商业接种剂(由Lactobacillus plantarum,Enterococcus faecium,L.salivarilus,Pediococcus acidilactici组成)分别接入稻秸进行10℃发酵。气质联机(GC-MS)测定发酵产物的同时,通过变性梯度凝胶电泳检测微生物在发酵体系的定殖情况。采用定量PCR方法追踪复合菌系组成菌在发酵过程中的动态。【结果】16S rDNA克隆文库分析结果表明复合系主要由两种微生物组成,一种属乳酸杆菌(Lactobacillus),一种属乳酸球菌(Leuconostoc)。10℃稻秸发酵结果表明,在发酵第6天接种复合菌系处理的pH已经下降到4.3,乳酸菌菌落形成单位为2.9×109CFU/g鲜样,而接种商业接种剂的处理pH为5.3,乳酸菌菌落形成单位为3.6×108 CFU/g鲜样;在发酵30 d时,接种复合菌系处理的乳酸含量为8.1 g/kg鲜样,接种商业接种剂处理的乳酸含量为2.0 g/kg鲜样。变性梯度凝胶电泳结果表明,在接种复合菌系的稻秸中,从发酵的第6天开始,检测到的微生物主要为L.sakei和Leuconostoc inhae,在整个发酵过程中,两菌一直存在;在商业接种剂处理中,发酵第6天检测到的微生物除其四种组成菌外,还包括Uncultured bacterium;而在发酵第16天和第30天,只检测到组成菌中的L.plantarum和E.faecium。定量PCR结果显示,接种复合菌系处理中,L.sakeiDNA在发酵第6天达到41.0%,在发酵第16天已达到65%,Le inhae在发酵的第6天达到整个发酵过程中的最大值(5.5%)。【结论】接种复合菌系,可以有效促进水稻秸秆的低温发酵进程。复合菌系组成菌可以定殖在发酵体系中,并占据优势。复合菌系的关键菌为L.sakei。     

枯草芽胞杆菌发酵玉米秸秆后对家蝇的饲养效果

作物秸秆是重要的农业资源,为有效利用作物秸秆,本文利用枯草芽胞杆菌发酵玉米秸秆,配制成人工饲料来饲养家蝇。从菌液加入量和发酵天数来考察对家蝇饲养效果的影响,结果表明:枯草芽胞杆菌菌液加入量为3 mL(3.2×10~(11)cfu/mL),发酵天数3d时对家蝇饲养效果较好,幼虫质量为16.91g,与不加菌液的对照组(13.30g)相比存在显著性差异(P0.05)。经过枯草芽胞杆菌发酵和家蝇幼虫处理后,玉米秸秆的纤维素、半纤维素、木质素的绝对含量都显著降低(P0.05)。经过家蝇取食后的饲料残渣,经检测,有机质等均达到国家标准。最优家蝇饲料配方为:枯草芽胞杆菌菌液加入量3mL(3.2×10~(11) cfu/mL),发酵天数3d,玉米秸秆和麦麸各125g,每250g饲料添加初孵幼虫200mg。本研究利用枯草芽胞杆菌发酵玉米秸秆,提高其营养价值,并进一步饲养家蝇,为秸秆的资源化利用和家蝇规模化饲养奠定了基础。     

喂饲Lactobacillus casei Zhang对大鼠体内脂质代谢的影响

从内蒙古锡林郭勒盟正蓝旗传统酸马奶中分离筛选到1株降胆固醇功效较好的乳杆菌Lactobacillus．casei Zhang。用Lb．casei Zhang灌胃高脂血症模型大鼠研究其对血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)的影响。结果表明:灌胃14 d后,Lb．casei Zhang热致死菌体组大鼠血清中TC浓度较对照组显著降低(P<0．01),TG浓度虽有降低但不呈显著性,同时HDL-C浓度显著升高(P<0．05);Lb．casei Zhang活菌体组大鼠血清中TC、TG浓度均有所降低,HDL-C浓度升高,但未呈显著性。灌胃28 d后,Lb．casei Zhang热致死菌体组大鼠血清中TC浓度较对照组显著降低(P<0．05),Lb．casei Zhang活菌体组TC浓度及两组TG、LDL-C浓度降低,但差异不显著,HDL-C未发生明显的改变。Lb．casei Zhang热致死菌体组和活菌体组粪便中的胆酸含量均增高,但只有热致死菌体组差异显著(P<0．05)。通过实验表明Lb．casei Zhang通过菌体对胆固醇的吸收吸附及减少肝肠循环中的胆酸来达到降血脂的功效。     

固定化植物乳杆菌的制备及其发酵条件优化

采用海藻酸钠包埋植物乳杆菌并通过测定固定化细胞发酵清液的抑菌效果,优化得到的固定化最佳工艺条件为:海藻酸钠浓度为3%,CaCl2浓度为1.5%,菌悬液体积为3.5 mL(4.0×108 cfu/mL).固定化细胞重复发酵多批次效果良好.固定化细胞发酵条件优化结果表明:最适pH为7.0,最适温度为36℃,培养基中添加0....     

Survival, growth and persistence under farm conditions of a Lactobacillus plantarum strain inoculated into liquid pig feed

AIMS: To investigate the survival and persistence of Lactobacillus plantarum REB1 in the fermentation process of liquid pig feed on a working farm in standard production conditions. METHODS AND RESULTS: Two feed types, a control diet [nonfermented liquid feed (NFLF)] and a fermented diet [fermented liquid feed (FLF)], were compared. A rifampicin-resistant mutant L. plantarum REB1-Rif was used to initiate the fermentation of the feed. Inoculation with the experimental strain was repeated one or two times per week throughout the three month growing period. Four microbial groups were followed using standard microbiological techniques, as well as pH. Lactic acid bacteria (LAB) counts were high already at the beginning in FLF, while it took nine days to reach the corresponding LAB levels in NFLF. Yeasts were stable in FLF, whereas in NFLF there were occasional high counts during the first week. The numbers of Enterobacteriaceae were low, although in NFLF they were variable. The average pH in NFLF was 4.5 and 4 in FLF. CONCLUSIONS: The inoculation of L. plantarum REB1-Rif provided a LAB population of log 9 colony forming units (CFU) ml(-1) from the first feeding day, stable numbers of yeast and pH, and a drastic reduction of Enterobacteriaceae. SIGNIFICANCE AND IMPACT OF THE STUDY: The inoculation by L. plantarum REB1-Rif offered a FLF microbiologically stable from the first week in actual production conditions.     

Trophic relationships between Saccharomyces cerevisiae and Lactobacillus plantarum and their metabolism of glucose and citrate

Glucose and citrate are two major carbon sources in fruits or fruit juices such as orange juice. Their metabolism and the microorganisms involved in their degradation were studied by inoculating with an aliquot of fermented orange juice a synthetic model medium containing glucose and citrate. At pH 3.6, their degradation led, first, to the formation of ethanol due to the activity of yeasts fermenting glucose and, eventually, to the formation of acetate resulting from the activity of lactobacilli. The yeast population always outcompeted the lactobacilli even when the fermented orange juice used as inoculum was mixed with fermented beet leaves containing a wider variety of lactic acid bacteria. The evolution of the medium remained similar between pH 3.3 and 5.0. At pH 3.0 or below, the fermentation of citrate was totally inhibited. Saccharomyces cerevisiae and Lactobacillus plantarum were identified as the only dominant microorganisms. The evolution of the model medium with the complex microbial community was successfully reconstituted with a defined coculture of S. cerevisiae and L. plantarum. The study of the fermentation of the defined model medium with a reconstituted microbial community allows us to better understand the behavior not only of fermented orange juice but also of many other fruit fermentations utilized for the production of alcoholic beverages.     

Trophic relationships between Saccharomyces cerevisiae and Lactobacillus plantarum and their metabolism of glucose and citrate.

Glucose and citrate are two major carbon sources in fruits or fruit juices such as orange juice. Their metabolism and the microorganisms involved in their degradation were studied by inoculating with an aliquot of fermented orange juice a synthetic model medium containing glucose and citrate. At pH 3.6, their degradation led, first, to the formation of ethanol due to the activity of yeasts fermenting glucose and, eventually, to the formation of acetate resulting from the activity of lactobacilli. The yeast population always outcompeted the lactobacilli even when the fermented orange juice used as inoculum was mixed with fermented beet leaves containing a wider variety of lactic acid bacteria. The evolution of the medium remained similar between pH 3.3 and 5.0. At pH 3.0 or below, the fermentation of citrate was totally inhibited. Saccharomyces cerevisiae and Lactobacillus plantarum were identified as the only dominant microorganisms. The evolution of the model medium with the complex microbial community was successfully reconstituted with a defined coculture of S. cerevisiae and L. plantarum. The study of the fermentation of the defined model medium with a reconstituted microbial community allows us to better understand the behavior not only of fermented orange juice but also of many other fruit fermentations utilized for the production of alcoholic beverages.     

Production of probiotic cabbage juice by lactic acid bacteria

Research was undertaken to determine the suitability of cabbage as a raw material for production of probiotic cabbage juice by lactic acid bacteria (Lactobacillus plantarum C3, Lactobacillus casei A4, and Lactobacillus delbrueckii D7). Cabbage juice was inoculated with a 24-h-old lactic culture and incubated at 30 degrees C. Changes in pH, acidity, sugar content, and viable cell counts during fermentation under controlled conditions were monitored. L. casei, L. delbrueckii, and L. plantarum grew well on cabbage juice and reached nearly 10x10(8) CFU/mL after 48 h of fermentation at 30 degrees C. L. casei, however, produced a smaller amount of titratable acidity expressed as lactic acid than L. delbrueckii or L. plantarum. After 4 weeks of cold storage at 4 degrees C, the viable cell counts of L. plantarum and L. delbrueckii were still 4.1x10(7) and 4.5x10(5) mL(-1), respectively. L. casei did not survive the low pH and high acidity conditions in fermented cabbage juice and lost cell viability completely after 2 weeks of cold storage at 4 degrees C. Fermented cabbage juice could serve as a healthy beverage for vegetarians and lactose-allergic consumers.     

Effect of starter culture inoculation on feed hygiene and microbial population development in fermented pig feed composed of a cereal grain mix with wet wheat distillers' grain

Aims:  Investigating the influence of an added starter culture on the properties of fermented liquid pig feed.
Methods and Results:  Diets of cereal grain blended with wet wheat distillers' grain that were either not inoculated (WWDG), inoculated with a silage starter culture at start (WWDGsc1) or at start and at each backslopping (replacement of 80% the content with fresh mixture, simulating feed outtake, WWDGsc5) were fermented for 5 days, followed by 5 days of daily backslopping. Numbers of undesirable micro-organisms (enterobacteria, moulds) were reduced in all fermentations; particularly enterobacteria in the starter culture inoculated diets. Lactobacillus plantarum present in the starter culture became dominant in diets WWDGsc1 and WWDGsc5. However, Lactobacillus panis that was dominating WWDG was also abundant in WWDGsc1 and WWDGsc5. Yeast populations were not influenced by the starter culture, with Pichia fermentans dominating all fermentations. All diets had similar chemical characteristics with the exception of a significant increase of all tested organic acids in WWDGsc5.
Conclusions:  The addition of a starter culture influences the bacterial population in fermented liquid feed, but there is also a strong impact of the flora already present in the feed ingredients. The yeast population is not influenced by adding a lactic acid bacteria (LAB) starter culture. A consortium of LAB and yeast strains adapted to the fermentation should be used as starter culture.
Significance and Impact of the Study:  The results suggest that it is possible to influence the current unpredictable and spontaneous process of feed fermentation when appropriate starter cultures are used. For this purpose, LAB and yeasts with desirable characteristics should be isolated.     

Construction of Lactobacillus plantarum strain with enhanced L-lysine yield

AIM: To enhance L-lysine secretion in Lactobacillus plantarum. METHODS AND RESULTS: An S-2-aminoethyl-L-cystein (AEC)-resistant mutant of L. plantarum was isolated, and it produced L-lysine at considerably higher level than the parent strain. Aspartokinase in the mutant has been desensitized to feedback inhibition by L-lysine. The nucleotide sequence analysis of thrA2 that codes for aspartokinase in the mutant predicted a substitution of glutamine to histidine at position 421. L-Lysine-insensitive aspartokinase, together with aspartate semialdehyde dehydrogenase, dihydrodipicolinate synthase, and dihydrodipicolinate reductase genes, was cloned from L. plantarum DNA to a shuttle vector, pRN14, and the genes were then transformed individually into the AEC-resistant mutant and the parent strain. The overexpression of the genes led to the increase in the activity of enzymes they encode in vitro. However, only the strain overexpressing aspartokinase or dihydrodipicolinate synthase produced more L-lysine. CONCLUSIONS: The desensitization of aspartokinase to L-lysine in L. plantarum led to the overproduction of L-lysine. The overexpression of L-lysine-insensitive aspartokinase or dihydrodipicolinate synthase enhanced L-lysine secretion in L. plantarum. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of the L-lysine-overproducing strain of L. plantarum in food or feed fermentation may increase the L-lysine content of fermented products.     

接种植物乳杆菌(Lactobacillus plantarum)对小规模饲料稻青贮品质的影响

【目的】研究接种植物乳杆菌对小规模饲料稻品质的影响。【方法】以自然发酵的样品为对照,接种不同来源植物乳酸菌发酵饲料稻,发酵30 d后对饲料稻的感官进行评价;通过选择性平板对饲料稻青贮中的不同微生物进行计数;并采用V-Score评价法对发酵品质进行评定。【结果】相对自然发酵的样品而言,接种植物乳杆菌的青贮样品感官评分等级达到优良;乳酸菌为优势菌株,引起腐败变质的好氧菌、霉菌、大肠杆菌等受到抑制;接种发酵的样品中乳酸含量明显增加,氨态氮的产生量为对照的1/2左右,V-Score评分为满分。【结论】供试的植物乳杆菌,尤其是从青饲料和青贮材料中分离的菌株能有效改善饲料稻青贮的品质,可考虑用作青贮饲料稻发酵剂。     

干酪乳杆菌12A碳源代谢的比较基因组学分析

【目的】在基因组学水平上,对干酪乳杆菌的碳源代谢特性及调控机制进行研究。【方法】基于BioCyc和MetaCyc数据库,利用Pathway Tools对菌株12A及7株已公布全基因序列的干酪乳杆菌进行全基因组水平的碳源代谢比较分析。【结果】全基因组比较分析结果显示,干酪乳杆菌12A可以将9种糖转运到细胞内代谢利用;可以将多种寡糖和多糖在细胞外水解成半乳糖和葡萄糖;干酪乳杆菌12A可经异型乳酸发酵或混合酸发酵途径生成乙醇及其副产物。【结论】干酪乳杆菌12A可以代谢多种类型碳源,底物选择范围宽泛,而且可以作为工业乙醇发酵的特定菌株;利用比较基因组学方法建立基因结构与细菌代谢能力的联系是可靠的。     

Enhancing Nutritional Quality of Silage by Fermentation with Lactobacillus plantarum

The present study was aimed to investigate the nutritive profiles, microbial counts and fermentation metabolites in rye, Italian rye-grass (IRG) and barley supplemented with Lactobacillus plantarum under the field condition, and its probiotic properties. After preparation of silage, the content of crude protein (CP), crude ash, acid detergent fiber (ADF), and neutral detergent fiber (NDF), microbes such as lactic acid bacteria (LAB), yeast and fungi counts, and fermentation metabolites lactic acid, acetic acid and butyric acid was assessed. Results indicated that the content of ADF and NDF were significantly varied between rye, IRG and barley mediated silages. The content of CP was increased in L. plantarum supplemented with IRG, but slightly decreased in rye and barley mediated silages. The maximum LAB count was recorded at 53.10 × 10⁷ cfu/g in rye, 16.18 × 10⁷ cfu/g in IRG and 2.63 × 10⁷ cfu/g in barley silages respectively. A considerable number of the yeasts were observed in the IRG silages than the rye silages (P < 0.05). The amount of lactic acid production is higher in L. plantarum supplemented silages as compared with control samples (P < 0.05). It was confirmed that higher amount of lactic acid produced only due to more number of LAB found in the silages. L. plantarum was able to survive at low pH and bile salt and the duodenum passage with the highest percentage of hydrophobicity. Furthermore, the strain was sensitive towards the antibiotics commonly used to maintain the microbes in food industrial setups. In conclusion, supplementation of L. plantarum is most beneficial in rye, IRG and barley silage preparations and probiotic characteristics of L. plantarum was an intrinsic feature for the application in the preparation of animal feeds and functional foods.