乳酸菌计数有关问题的探讨

对社会逐渐兴起的喝乳酸菌饮料之热 ,国标虽然规定了其检验方法 ,但在实际工作中又遇到了一些乳酸菌计数的问题 ,在此谈谈我们的体会。1　培养基的问题国标提供的两种培养基 :改良 MC、改良 TJA,都是培养基有颜色 (粉红色与黄色 ) ,而长出的杆菌与球菌的颜色与之相近(红色与微白色 ) ,计数不是很方便。在实际工作中根据有关文献报道 ,我们把 TJA培养基里加入指示剂 TTC(以 10 0 ml加入1%TTC0 .2 ml) ,使培养基微黄 ,而长出的两种菌落都为红色。球菌圆凸、边缘整齐 ;杆菌为雪花状、边缘不整齐。这样既方便了计数又使结果趋于准确 ,见表…     

活性乳酸菌制品中乳酸菌计数条件的优化研究

[目的]探索一种乳酸菌计数的选择性培养基,真实反映产品中乳酸菌的数量。[方法]用涂布法和平板倾注法,在不同的培养条件对计数结果进行对比研究。[结果]在改良TJA培养基中加入硫酸多粘菌素10万IU／L和放线菌酮10mg／L(双抗-TJA培养基),双抗-TJA培养基可抑制样品中可能污染的杂菌,对乳酸菌无影响。[结论]乳酸菌计数的优化条件为：用平板涂布法,在CO2烛缸法条件下培养48h。该实验可最大限度地检出样品中的乳酸菌数量,且条件简单,方法易掌握,结果准确,易于推广使用。     

培养方式对乳酸菌计数的影响

近几年来 ,随着人民生活水平的提高 ,自身的饮食保健意识越来越强。酸奶日益受到广大消费者的喜爱。酸奶中的乳酸菌在人体肠道中能维持菌群平衡这一保健作用已为人们所认识。所以 ,酸奶中活性乳酸菌数量的多少直接影响到产品的总体质量。为了更好地提高乳酸菌数的检出率 ,我们采用了 4种培养方式进行了比较 ,现把结果报告如下。1　材料与方法1 1　试验样品　市售酸奶1 2　试验仪器　 3 7℃恒温培养箱。1 3　乳酸菌计数培养基　改良番茄琼脂培养基 (TJA)。购于北京陆桥技术有限公司。1 4　计数方法　按国标GB 4789-2 -94进行。1 5　试验方…     

活性乳酸菌制品中乳酸菌计数条件的优化研究

[目的]探索一种乳酸菌计数的选择性培养基,优化培养条件,以便真实反映产品中乳酸菌的数量。[方法]利用涂布法和平板倾注法,采用不同的培养条件对计数结果进行对比研究。[结果]于改良TJA培养基中加入硫酸多黏菌素(100000IU/L)和放线菌酮(10mg/L),以抑制样品中可能污染的杂菌,同时对乳酸菌无影响。[结论]乳酸菌计数的优化条件为:采用平板涂布法,在CO2烛缸法条件下培养48h,可最大限度地检出样品中的乳酸菌数量。该实验条件简单,方法便于掌握,结果准确,易于推广使用。     

双歧杆菌计数培养基研究

目的：选择一种适用于微生态制剂中的双歧杆菌计数培养基。方法：用改良BBL、MRS、改良TJA等选择性培养基和平板厌氧胶法对双歧杆菌进行检测，同时观察双歧杆菌和乳酸酐菌在三种培养基上生长情况。结果：在改良BBL培养基上双歧杆菌生长良好，乳酸酐菌不生长。结论：该培养基用于微生态制剂中双歧杆菌计数操作简便，有效，易于推广。     

微生态调节剂中益生菌的检测研究

目的〕为研究微生态调节剂中益生菌的检测方法。〔方法〕采用改良MRS、两层双歧琼脂、LBS、EG、改良GAM、普通营养琼脂等 6种培养基 ,使用双层琼脂培养法对 5份微生态调节剂进行双歧杆菌计数培养的比较 ,同时对 11份微生态口服液和 14份酸牛乳采用改良MRS、BS、TJA等 3种培养基 ,使用厌氧培养法 ,进行乳酸杆菌计数培养的比较。〔结果〕经统计学处理 ,显示双歧杆菌的检测以MRS琼脂为最佳。乳酸杆菌检测以TJA琼脂为佳。〔结论〕双歧杆菌、乳酸杆菌在选择较佳培养基的同时 ,以双层琼脂培养法为佳。     

乳酸菌技术培养条件的探讨

近几年来,随着人民生活水平的提高。自身的饮食保健意识越来越强。酸奶日益受到广大消费者的喜爱。酸奶中的乳酸菌在人体肠适中能维持菌群平衡这一保健作用已为人们所认识。所以,酸奶中活性乳酸菌数量的多少直接影响到产品的总体质量。为了更好的提高乳酸菌数的检出率,我们采用了四种培养方式进行了比较,现把结果报告如下:1　材料与方法1.1　试验样品　市售酸奶。1.2　试验仪器　3 7度恒温培养箱。1.3　乳酸菌计数培养基　该良番茄琼脂培养基(TJA)。购于北京陆桥技术有限公司。1.4　计数方法　按国标GB4789-2 -94进行。1.5　试验方法利时…     

乳酸菌检验培养基——改良TJA的研究

我国乳酸菌饮料，自１９８４年开始投入生产以后，发展迅速，但对该产品中乳酸菌数的测定全国还未制定出统一的检验方法。我们受全国乳酸菌乳饮料协作组委托，同南京市防疫站一起承担了国标中乳酸菌检验培养基的研究，为了探索可靠、快速、操作方便的乳酸菌计数培养基，对...     

X—Gal培养基＋PCR法快速鉴定酸奶中双歧杆菌

目的：探讨一种简易快速酸奶中双歧杆菌的鉴别方法。方法：在MRS培养基中添加一定量X—Gal（5-溴-4-氯-3-吲哚-α—D-半乳糖苷），通过对标准双歧杆菌和乳酸菌混合菌及双歧杆菌和乳酸菌发酵的酸奶进行检测，对该培养基上不同颜色的菌落提取DNA作PCR鉴定。结果：在X—Cal培养基上呈白色或浅兰色菌落经PCR鉴定为双歧杆菌，而呈深兰色菌落经PCR鉴定未出现双歧杆菌特征性条带。结论：在X—Gal培养基上双歧杆菌和乳酸菌有明显鉴别性，可用于双歧杆菌和乳酸菌混合发酵的酸乳制品菌落鉴别计数。     

乳酸菌饮料微生物污染调查

笔者对乳酸菌饮料中大肠菌群、霉菌、酵母菌 3种微生物指标 ,依据中华人民共和国国家标准方法进行检测分析 ,并着重把活性乳酸菌饮料和非活性乳酸菌饮料在上述指标上的差异及原因进行深入研究。1　材料与方法1 1　样品来源根据课题设计 ,在吉林市内批发市场及较大超市采集了吉林、黑龙江、长春、北京等 15家企业生产的 2 85件样品 ,其中活性饮料 12 0件、非活性饮料16 5件 ,供检测用。1 2　试剂与培养基革兰氏染色液 ;乳糖胆盐发酵培养基 ;伊红美蓝琼脂 ;孟加拉红培养基。1 3　器材设备吸管、试管、平皿 ,天平、酒精灯 ,显微镜 ,电热恒温培…     

3种常用封固剂制作螨标本的效果比较

目的比较3种封固剂制作螨标本玻片的效果。方法按配方配制多乙烯乳酸酚、贝氏和霍氏3种封固剂,比较它们的理化性质,并分别制作粉螨玻片标本各60张,烘干后在光学显微镜下观察制片效果,χ2检验进行统计学分析。结果多乙烯乳酸酚封固剂为淡黄色的透明液体,密度为0.99 g/ml;贝氏封固剂红棕色,密度为1.12 g/ml;霍氏封固剂颜色较贝氏稍淡,密度为1.37 g/ml。光学显微镜下,霍氏封固剂制作的粉螨标本透明度好,螨体舒展,很少出现躯体两侧发黄发焦的现象;多乙烯乳酸酚和贝氏封固剂效果欠佳。经χ2检验,三者之间差异有统计学意义（χ2=15.54,P〈0.01）,且霍氏封固剂的制片效果优于多乙烯乳酸酚（χ2=7.50,P〈0.01）和贝氏（χ2=15.70,P〈0.01）封固剂。结论霍氏封固剂制备粉螨标本玻片观察效果较好,可为高质量的螨标本制备提供参考。     

活性酸乳中乳酸菌的直接镜检计数法

目的：建立活性酸乳中乳酸菌的显微镜直接镜检计数方法。方法：将样品适当稀释后涂片染色，在显微镜下计数一定面积内定量样品中乳酸菌的数量，再根据取样量和稀释倍数计算每毫升样品所含乳酸菌总数。结果：通过与国标检测方法测得结果相比较、验证，确定该方法可快速、准确、直接地计数乳酸菌总数，省去了标准平板计数方法计数乳酸菌总数要经过72h细菌培养的漫长和繁琐。结论：更适合于实际生产监控和检测工作的快速分析鉴定的需要。     

Characterization of meningococcal serogroup B outer membrane vesicle vaccines from strain 44/76 after growth in different media

In this study, we evaluated the effect of the growth medium on the composition and immunogenicity of meningococcal outer membrane vesicle (OMV) vaccines after cultivation of the Norwegian serogroup B 44/76 vaccine strain in either Frantz’ or modified Catlin-6 media (MC.6M). Differential proteomic analysis revealed that 97% of the OMV proteins maintained the same levels in the two preparations. However, a number of differentially expressed proteins, including TdfH, OpcA, OMP NMB0088, hypothetical NMB2134, lipoprotein NMB1126/1164 and NspA, increased significantly in OMVs produced from bacteria grown in the MC.6M. Together with increased lipopolysaccharide levels, the increased expression of these proteins was associated with significantly higher serum bactericidal titres in mice immunized with the MC.6M OMV vaccine. The high resolution two-dimensional separation of the OMVs on a large-format gel across a pH range of 3–11 resolved around 2000 protein spots from which 75 proteins were identified by mass spectrometry.     

Synthesis of the cancer preventive peptide lunasin by lactic acid bacteria during sourdough fermentation

This study aimed to exploit the potential of sourdough lactic acid bacteria to release lunasin during fermentation of cereal and nonconventional flours. The peptidase activities of a large number of sourdough lactic acid bacteria were screened using synthetic substrates. Selected lactic acid bacteria were used as sourdough starters to ferment wholemeal wheat, soybean, barley, amaranth, and rye flours. Proteinase activity during fermentation was characterized by SDS-PAGE analysis of the water-soluble extracts. Albumins having molecular masses of 18 to 22 kDa, which included the size of lunasin precursors, were markedly affected by proteolysis of lactic acid bacteria. After fermentation, lunasin from the water-soluble extracts was quantified, purified, and identified through RP-HPLC and nano-LC-ESI-MS analyses. Compared to control doughs, the concentration of lunasin increased up to 2-4 times during fermentation. Lactobacillus curvatus SAL33 and Lactobacillus brevis AM7 synthesized the highest concentrations of lunasin in all the flours. Besides the presence of the entire lunasin sequence, fragments containing the immunoreactive epitope RGDDDDDDDDD were also found. This study shows that fermentation by lactic acid bacteria increased the concentration of lunasin to levels that would suggest new possibilities for the biological synthesis and for the formulation of functional foods.     

乳杆菌属30a菌株(ATCC33222)的生长特性及代谢组学采样策略

目的通过分析ATCC33222在不同培养环境下的生长曲线和pH值曲线的差异,探讨该菌的生长规律,并为产生物胺乳酸菌的代谢组学研究提供合理的采样策略。方法配制不同成分、不同pH值的培养基,分别进行菌株培养,每1～4小时取样一次并测定A600和pH值。结果乳酸菌ATCC33222菌株在不同培养条件下呈现不同的生长特性,其中pH3.5和添加壳寡糖的培养基的迟滞期较长,添加葡萄糖的培养基指数生长期时间最长。MRS培养基、添加葡萄糖的培养基和添加壳寡糖的培养基pH值曲线类似,其余3种培养基的pH值曲线各不相同。结论ATCC33222菌株可能根据生长环境和能量来源的不同,动态调节不同代谢途径,以获得最佳生长状态。在代谢组学研究中,培养基pH值推荐使用pH3.5和pH6.5两种,MRS培养基中可添加氨基酸成分,而葡萄糖成分则不是必须的。     

Lactic acid bacteria and the human gastrointestinal tract.

OBJECTIVE: This review summarises the effects of lactic acid bacteria on lactose malabsorption, bacterial/viral or antibiotic associated diarrhoea, and describes the impact of lactic acid bacteria on cancer and the fermentative products in the colon. RESULTS: Eight studies (including 78 patients) demonstrated that lactase deficient subjects absorbed lactose in yogurt better than lactose in milk, while two studies (25 patients) did not support this. Two studies (22 patients) showed that unfermented acidophilus milk was absorbed better than milk, while six studies (68 patients) found no significant differences. Addition of lactose hydrolysing enzyme, lactase, to milk improved lactose malabsorption in seven studies (131 lactose malabsorbers), while one study (10 malabsorbers) demonstrated no improvement. Lactic acid bacteria alleviated travellers' diarrhoea in one study (94 individuals) while a study including 756 individuals was borderline statistically significant. One study (50 individuals) did not find an effect of lactic acid bacteria on travellers' diarrhoea. Six studies (404 infants) demonstrated a significant effect of lactic acid bacteria on infant diarrhoea, while one study (40 infants) did not. Lactic acid bacteria moderated antibiotic associated diarrhoea in three studies (66 individuals), while two studies (117 individuals) were insignificant. CONCLUSIONS: Lactase deficient subjects benefit from a better lactose absorption after ingestion of yoghurt compared with milk and from milk added lactase, whereas ingestion of unfermented acidophilus milk does not seem to improve lactose absorption. The majority of studies support that lactic acid bacteria alleviate bacterial/viral induced diarrhoea, especially in infants, while the effect on antibiotic associated diarrhoea is less clear. Experimental studies indicate an effect of lactic bacteria on human cell cancer lines, but clinical evidence is lacking. A 'stabilising' effect of lactic acid bacteria on the colonic flora has not been documented.     

Stimulation of butyrate production by gluconic acid in batch culture of pig cecal digesta and identification of butyrate-producing bacteria

Gluconic acid reaches the large intestine to stimulate lactic acid bacteria. However, the fermentation pattern of gluconic acid has yet to be elucidated. Accordingly, we examined the fermentation properties induced by gluconic acid in the pig cecal digesta in vitro. We also tested sorbitol and glucose, substrates for which the fermentation rate and patterns are known. The gluconic acid-utilizing bacteria were further isolated from pig cecal digesta and identified to examine the effect of gluconic acid on hind gut fermentation. Gluconic acid was fermented more slowly than were the other two substrates. Gluconic acid stimulated butyrate production; the butyrate molar percentage reached 26%, which is considered a high butyrate production. The majority of gluconic acid fermenters were identified as lactic acid bacteria, such as Lactobacillus reuteri and L. mucosae, and acid-utilizing bacteria, such as Megasphaera elsdenii and Mitsuokella multiacida. The gluconic acid fermented by lactic acid bacteria, and the lactate and acetate that were produced were used to form butyrate by acid-utilizing bacteria, such as M. elsdenii. Gluconic acid may be useful as a prebiotic to stimulate butyrate production in the large intestine.     

酸乳乳酸菌数检验中不确定度的评定

目的:对酸乳中乳酸菌数不确定度的来源进行分析。方法:采用合并样品标准差的方法来评定乳酸菌数的不确定度。结果:评定结果表明酸乳中乳酸菌数检验的不确定度是测量结果对数值±0.039。结论:该批样品乳酸菌数的置信区间范围为6.2×107≤X≤7.5×107 cfu/g。     

Influences of probiotic bacteria on organic acid production by pig caecal bacteria in vitro

The mechanism of action of probiotics is largely unknown. A potential mechanism should be to increase the production of short-chain fatty acids (SCFA), known modulators of gut functions, by the bacterial ecosystem in the large intestine. The present paper reviews our recent studies in which the capacity of probiotic bacteria to increase the production of SCFA by pig caecal bacteria was investigated using batch-culture and continuous-culture techniques. All four commercial probiotic preparations and three strains of probiotic bacteria dose-dependently accelerated the net production of SCFA, succinic acid and lactic acid without changing the acid profile, and slowed the net production of NH4. Effects on organic acid production did not vary among different probiotic species. Neither probiotic preparations nor probiotic bacteria affected the organic acid production from glucose, gastric mucin, starch or lactose, or organic acids produced:added saccharide. Glucose abolished these effects of probiotic preparations. However, the capacity of probiotics to increase SCFA production was not modified by gastric mucin, starch or lactose. These results indicate that probiotic bacteria increase SCFA production by accelerating the breakdown of carbohydrates that are resistant to indigenous bacteria, and suggest that the concept of prebiotics in terms of SCFA production as a measure of probiotic function is arguable.     

简单快速筛选抑制黄曲霉生长的乳酸菌的方法

使用夹层培养基法，将乳酸菌接种于MRS琼脂与PDA琼脂之间，在PDA表面涂布一定量的霉菌孢子，28℃培养72小时后，计数霉菌菌落，即可初步判定乳酸菌是否对霉菌孢子有抑制作用，经多次重复试验，与目前常用方法相结合，可较快筛选出对黄曲霉生长有抑制作用的乳酸菌。