乳酸菌在苹果酒酿造中的应用

乳酸菌用于苹果酒酿造中 ,可以触发苹果酸 乳酸发酵 ,通过分解苹果酸 ,产生乳酸 ,并引起其他有机酸的变化而使苹果酒的口感质量得以改善。供试的 3个乳酸菌种中 ,L3由于具有较高的苹果酸分解速率 ,发酵的苹果酒感官质量优良而成为苹果酒苹果酸 乳酸发酵的优良菌种。pH、温度、二氧化硫、酒度通过影响乳酸菌的活动而对苹果酸 乳酸发酵产生一定的影响     

广西传统发酵米粉中乳酸菌的分离鉴定

对广西传统米粉发酵液中的乳酸菌进行分离筛选,获得6株纯培养优势菌株。通过形态学鉴定及16S rDNA序列分析,结果表明其中4株乳酸菌属于戊糖片球菌(Pediococcus pentosaceus),另外2株鉴定为植物乳杆菌(Lactobacillus plantarum)。这2种乳酸菌均为对人类及动物安全的益生菌,该结果将为传统发酵米粉中有益微生物资源的挖掘和利用奠定基础。     

Characterization and Transfer of Antibiotic Resistance in Lactic Acid Bacteria from Fermented Food Products

The study provides phenotypic and molecular analyses of the antibiotic resistance in lactic acid bacteria (LAB) from fermented foods in Xi'an, China. LAB strains (n = 84) belonging to 16 species of Lactobacillus (n = 73), and Streptococcus thermophilus (n = 11) were isolated and identified by sequencing their 16S rRNA gene. All strains were susceptible to ampicillin, bacitracin, and cefsulodin, and intrinsically resistant to nalidixic acid, kanamycin, and vancomycin (except L. bulgaricus, L. acidophilus, and S. thermophilus, which were susceptible to vancomycin). Some strains had acquired resistance for penicillin (n = 2), erythromycin (n = 9), clindamycin (n = 5), and tetracycline (n = 14), while resistance to gentamycin, ciprofloxacin, streptomycin, and chloramphenicol was species dependent. Minimum inhibitory concentrations presented in this study will help to review microbiological breakpoints for some of the species of Lactobacillus. The erm(B) gene was detected from two strains of each of L. fermentum and L. vaginalis, and one strain of each of L. plantarum, L. salivarius, L. acidophilus, L. animalis, and S. thermophilus. The tet genes were identified from 12 strains of lactobacilli from traditional foods. This is the first time, the authors identified tet(S) gene from L. brevis and L. kefiri. The erm(B) gene from L. fermentum NWL24 and L. salivarius NWL33, and tet(M) gene from L. plantarum NWL22 and L. brevis NWL59 were successfully transferred to Enterococcus faecalis 181 by filter mating. It was concluded that acquired antibiotic resistance is well dispersed in fermented food products in Xi'an, China and its transferability to other genera should be monitored closely.     

中国新疆地区酸马奶中乳酸菌生物多样性研究

研究了新疆地区传统发酵酸马奶中乳酸菌的生物多样性。从30份酸马奶中分离出152株乳杆菌,采用传统分类鉴定方法对其进行鉴定。结果表明:新疆地区酸马奶中的主要乳酸菌为Lactobacillus(L.)helveticus(占总分离株的51.3%),其次为L.acidophilus(18.4%)和L.caseisubsp.pseudoplantarum(8.6%),此外,L.gasseri、L.caseisubsp.casei、L.curvatus、L.sanfrancisco、L.coryniformissubsp.coryniformis、L.brevis、L.plantrum、L.homohiechill、L.fermentum、L.dellbrueckii subsp.bulgaricu、L.ruminis、L.crispatus、L.farciminis及L.hilgardii等乳杆菌在酸马奶中也有出现,但其数量较少(1~4株),还有8株乳杆菌按目前的鉴定方法无法准确判断其归属。L.helveticus和L.acidophilu存在于所有的酸马奶样品中,L.helveticus为优势菌。     

Potentials of Exopolysaccharides from Lactic Acid Bacteria

Recent research in the area of importance of microbes has revealed the immense industrial potential of exopolysaccharides and their derivative oligosaccharides from lactic acid bacteria. However, due to lack of adequate technological knowledge, the exopolysaccharides have remained largely under exploited. In the present review, the enormous potentials of different types of exopolysaccharides from lactic acid bacteria are described. This also summarizes the recent advances in the applications of exopolysaccharides, certain problems associated with their commercial production and the remedies.     

Freon 11 Extraction of Volatile Metabolites Formed by Certain Lactic Acid Bacteria

The volatile metabolites formed by 18 lactic acid bacteria, representing three genera, were extracted from a complex medium by using a Freon 11 extraction method. The Freon extracts were then analyzed by capillary gas chromatography, and certain extracts were analyzed by gas chromatography-mass spectrometry. A total of 35 major peaks, of which 20 were positively identified, were used to differentiate between the various strains. On the basis of the results obtained, it was possible to differentiate between the members of the genera Lactobacillus, Pediococcus, and Leuconostoc, as well as between various species within the genus Leuconostoc. Of the 10 Leuconostoc oenos strains included in this study, 9 yielded similar results, but it was still possible to differentiate between the various strains. L. oenos B66 differed from the other L. oenos strains. Use of the Freon 11 extraction technique to determine volatile metabolites formed by lactic acid bacteria was shown to be highly reproducible and of great value. Furthermore, certain compounds not previously known to be formed by lactic acid bacteria were found.     

Molar Growth Yields of Certain Lactic Acid Bacteria as Influenced by Autolysis

Molar growth yields determined from batch cultures of Streptococcus diacetilactis and S. faecalis were appreciably greater at the peaks of maximal growth than after continued incubation and considerable autolysis. The higher molar growth yields were about equal to those determined in a continuous culture. Autolysis during logarithmic growth was minimal. The average Y value for adenosine triphosphate (ATP), determined by using limiting concentrations of glucose, galactose, lactose, and maltose for growing S. diacetilactis and limiting concentrations of glucose for growing S. lactis, S. cremoris, and S. faecalis, was 17.0. This is close to the Y (arginine) value of 17.8 determined with S. faecalis, but 62% greater than the generally accepted value of 10.5. Data are presented indicating that the often-used Y (ATP) value of 10.5 is erroneously low.     

Hot-Loop Test for the Determination of Carbon Dioxide Production from Glucose by Lactic Acid Bacteria

A hot-loop test was found to be more rapid, convenient, and reliable for the detection of carbon dioxide production than were conventional methods such as displacement of agar plugs and precipitation in barium hydroxide.     

Substitution of Manganese for Tomato Juice in the Cultivation of Lactic Acid Bacteria

Tomato juice was separated by chemical and physical methods into various active fractions, as measured by growth response and acid production by numerous lactic acid bacteria. Incineration of the treated extracts with little apparent loss in activity established the fact that the stimulatory component was of inorganic composition. Of the various cations tested, manganese was the only element that produced biological activity comparable to that of the original extract. Of the 71 strains of lactic acid bacteria tested, 63 strains showed a definite requirement for manganese or tomato juice.     

猪源乳酸菌产乳酸及其抑菌特性研究

研究了5株(L1、12、L3、L5和L7)分离自仔猪肠道的乳酸菌的产乳酸能力及抑菌特性。结果表明：L5菌株产乳酸的速度最快,培养液中乳酸含量最高,L5菌株培养液pH值的下降速度最快,终末pH值最低,而L1菌株产乳酸的速度最慢,培养液乳酸含量最低。5株乳酸菌对大肠杆菌K88、K99、987P、O141和大肠杆菌E1及金黄色葡萄球菌均有不同程度的抑制作用;排除酸的影响后仍有22％～53％抑菌效果;经热处理后保持有92％以上的抑菌效果;蛋白酶处理后保持85％以上的抑菌效果。     

一组鸡源乳酸菌产乳酸及其耐受特性研究*

研究了12株（K9、D17、C1、C12、D11、D14、C2、D9、K6、C21、D1和D7）分离自肉鸡肠道的乳酸菌的产乳酸能力及其中3株产酸能力强的菌株的耐受特性。12株乳酸菌产乳酸结果表明：12h内,K6产乳酸速度最快,其次为K9和C1,24h时,D17乳酸浓度最高,48h时C1终乳酸浓度最高。K9、D17和C1的耐受试验结果表明：C1菌株耐酸能力最强,pH2时,C1菌株培养3h后还能检测到活菌,D17和K9菌株培养1h后就已经检测不到活菌。在胆盐浓度0．08％-0．40％范围内,C1、D17和K9均有一定的耐受能力,随着胆盐浓度的升高,C1、D17和K9的存活数呈现缓慢的下降趋势。3株菌中D17耐热能力最强,经80％处理后仍有10^4.9／mL存活数,而K9和C1已检测不到活菌;C1对热最敏感,65℃处理后存活数由10^8／mL降为10^3／mL。     

乳酸菌食品级载体选择标记

食品级载体不依靠抗生素抗性基因作为选择标记,因而更为安全。近年来,人们已构建了多种乳酸菌的食品级克隆载体。这些食品级克隆载体是在显性选择标记和互补选择标记的基础上建立的。最近提出了第三种新的方法。该就这三种食品级载体选择标记的功能、分子机制及应用前景作了简明的介绍。     

苹果浓缩汁中嗜酸耐热菌的分离与鉴定

为了解和控制浓缩苹果汁中的嗜酸耐热菌,采用酸化的凯氏培养基对苹果浓缩汁中的耐热菌进行分离、培养和鉴定,并与标准菌株Aliyclobacillus acidoterrestris DSM3922进行了比较分析.结果表明,分离到的2株污染菌均可以在21℃～55℃温度范围及2.4～6.2的pH值范围内生长,符合脂环酸芽胞杆菌属嗜酸耐热的特点.经与标准菌株的细胞、菌落形态观察、生长条件和生理生化反应等方面的比较表明,2株分离菌与标准菌株Aliyclobacillus acidoterrestris DSM3922有明显的相似特征.     

乳酸菌细菌素的研究进展

简要介绍了乳酸菌细菌素的概念和分类,并以nisin为例对其分子结构、理化性质、抑菌范围及机制、遗传控制作了较为详尽的介绍,简要概括了乳酸菌细菌素的应用和今后的研究方向。     

乳酸菌的抗氧化作用机制

乳酸菌可以作为发酵剂、保鲜剂用于发酵食品的生产和保藏。由于无法进行呼吸产能,乳酸菌在生长过程中会面临氧化胁迫。研究表明,乳酸菌具有一定的抗氧化能力,能清除体内的活性氧分子,并使其保持相对稳定。综述了乳酸菌的抗氧化作用机制,主要从抗氧化酶、维持细胞还原状态、金属离子螯合等方面进行了介绍,以期为深入了解乳酸菌的抗氧化机制以及改善乳酸菌的环境生存能力提供一定的理论参考。     

乳酸菌肽聚糖部分免疫增强作用的研究

以小鼠为实验材料研究了肽聚糖部分免疫学活性,结果表明:小鼠腹腔注射肽聚糖后,相比对照组而言, Z8、Z17肽聚糖组巨噬细胞(MΦ)吞噬率、吞噬指数都明显提高,血清溶菌酶活性显著增强,统计学分析差异极显著(P＜0．01)。肽聚糖对鸡新城疫疫苗免疫增强效果的观察表明,与对照组相比,Z8、Z17肽聚糖组能明显提高新城疫抗体水平,并使抗体高峰水平维持时间延长。同时动物实验也表明,两个肽聚糖组间活性差异不显著,没有特异性。     

乳酸菌肽聚糖部分免疫增强作用的研究

以小鼠为实验材料研究了肽聚糖部分免疫学活性,结果表明:小鼠腹腔注射肽聚糖后,相比对照组而言, Z8、Z17肽聚糖组巨噬细胞(MΦ)吞噬率、吞噬指数都明显提高,血清溶菌酶活性显著增强,统计学分析差异极显著(P＜0．01)。肽聚糖对鸡新城疫疫苗免疫增强效果的观察表明,与对照组相比,Z8、Z17肽聚糖组能明显提高新城疫抗体水平,并使抗体高峰水平维持时间延长。同时动物实验也表明,两个肽聚糖组间活性差异不显著,没有特异性。