分离自藏灵菇的乳酸菌的益生特性

从藏灵菇中分离纯化5株乳酸菌,初步鉴定2株为嗜酸乳杆菌,3株为乳酸乳球菌。选取其中2株菌研究其益生特性。结果表明,从藏灵菇中分离出的乳酸菌具有良好的益生特性,2株乳酸菌在pH值为4～6可生长良好;耐热范围为30～60℃;胆盐耐受性为0.1%～0.5%;发酵液对金黄色葡萄球菌、沙门氏菌、大肠杆菌等肠道病原菌有抑制作用;对抗生素有不同程度的耐药性。     

Evaluation of indigenous lactic acid bacteria of raw mare milk from pastoral areas in Xinjiang,China, for potential use in probiotic fermented dairy products

In the present study 114 lactic acid bacteria strains, isolated from raw mare milks from pastoral areas for ethnic minorities in northwest China, were screened for probiotic traits, and their characteristics were compared with those of Lactobacillus rhamnosus GG, a commercial strain. Among the 114 strains identified, the most common species was Pediococcus pentosaceus (n = 52), followed by Leuconostoc lactis (n = 35), Lactobacillus helveticus (n = 7), Lactobacillus plantarum (n = 6), Lactobacillus kefiri (n = 5), Lactobacillus curvatus (n = 4), Lactobacillus paracasei (n = 3), and Lactococcus garvieae (n = 3). Based on acid and bile salt tolerance, 15 strains were further selected. All selected strains were subjected to a series of in vitro tests to assess their technological properties, including cell surface hydrophobicity (13.6–56.2%), autoaggregation ability (9.26–38.30%), coaggregation ability, and heat and lysozyme survival rates (84.74–94.01% and 80.52–99.37%, respectively). In vitro antagonism showed that Lb. plantarum (M5–19, M8–60, M8–59) exhibited the most strong inhibitory activity against 7 tested pathogens. Moreover, antibiotic resistance and hemolytic activity were investigated for safety assessment. No strain exhibited hemolytic activity, and most of the strains were sensitive to a series of 14 antibiotics of clinical importance. Ultimately, the principal component analysis of all data obtained above showed that 2 Lb. plantarum strains (M8–59, M8–60) and Lb. paracasei M1–36 exhibited the best potential for their inclusion as adjunct functional cultures in local fermented dairy products.     

Diversity of lactic acid bacteria associated with traditional fermented dairy products in Mongolia

Spontaneous milk fermentation has a long history in Mongolia, and beneficial microorganisms have been handed down from one generation to the next for use in fermented dairy products. The objective of this study was to investigate the diversity of lactic acid bacteria (LAB) communities in fermented yak, mare, goat, and cow milk products by analyzing 189 samples collected from 13 different regions in Mongolia. The LAB counts in these samples varied from 3.41 to 9.03 log cfu/mL. Fermented yak and mare milks had almost identical mean numbers of LAB, which were significantly higher than those in fermented goat milk but slightly lower than those in fermented cow milk. In total, 668 isolates were obtained from these samples using de Man, Rogosa, and Sharpe agar and M17 agar. Each isolate was considered to be presumptive LAB based on gram-positive and catalase-negative properties, and was identified at the species level by 16S rRNA gene sequencing, multiplex PCR assay, and restriction fragment length polymorphism analysis. All isolates from Mongolian dairy products were accurately identified as Enterococcus faecalis (1 strain), Enterococcus durans (3 strains), Lactobacillus brevis (3 strains), Lactobacillus buchneri (2 strains), Lactobacillus casei (16 strains), Lactobacillus delbrueckii ssp. bulgaricus (142 strains), Lactobacillus diolivorans (17 strains), Lactobacillus fermentum (42 strains), Lactobacillus helveticus (183 strains), Lactobacillus kefiri (6 strains), Lactobacillus plantarum ssp. plantarum (7 strains), Lactococcus lactis ssp. lactis (7 strains), Leuconostoc lactis (22 strains), Leuconostoc mesenteroides (21 strains), Streptococcus thermophilus (195 strains), and Weissella cibaria (1 strain). The predominant LAB were Strep. thermophilus and Lb. helveticus, which were isolated from all sampling sites. The results demonstrate that traditional fermented dairy products from different regions of Mongolia have complex compositions of LAB species. Such diversity of LAB provides useful information for further studies of probiotic strain selection and starter culture design, with regard to the industrial production of traditional fermented milk.     

益生乳酸菌对氟喹诺酮类药物耐药机制的研究进展

益生乳酸菌对抗菌药物的耐药性机制是生物医药研究的重要领域。概述了益生乳酸菌对氟喹诺酮类药物的3种耐药性机制(靶位突变、外排泵作用、质粒介导)及其可能出现的耐药机制。显示出国内关于益生乳酸菌对氟喹诺酮类药物的耐药机制研究甚少的现状,提出对益生乳酸菌的耐药机制进行全面深入的研究的重要性。     

In vitro probiotic evaluation of potential antioxidant lactic acid bacteria isolated from idli batter fermented with Piper betle leaves

Lactic acid bacteria isolated from food sources can be introduced as probiotics because of their health‐promoting and nonpathogenic characteristics. Eight lactic acid bacteria from idli batter fermented with Piper betle leaves were selected to screen the antioxidant potential and biofilm‐forming ability. Five isolates exhibited good antioxidant potential and biofilm formation and showed antagonistic activity against the pathogenic biofilm‐forming Staphylococcus aureus. Further, in vitro probiotic properties of five isolates exhibited excellent acid tolerance, bile tolerance, simulated gastrointestinal juice tolerance, auto‐aggregation and co‐aggregation and hydrophobicity and showed resistance to antibiotics such as ciprofloxacin, nalidixic acid, norfloxacin and colistin. Isolates also showed positive bile salt hydrolase activity, cholesterol assimilation, β‐galactosidase production and mucin binding ability. The isolate KJBB10 exhibited good adhesion and pathogen exclusion percentage with human colon cancer cells (HCT‐15 and HT‐29). Hence, the isolates KJBB10, KJBB56 and KJBC06 can be used as beneficial probiotic starter cultures for the formulation of functional foods.     

Effects of rare sugar D-allulose on acid production and probiotic activities of dairy lactic acid bacteria

It has recently been reported that the rare sugar d-allulose has beneficial effects, including the suppression of postprandial blood glucose elevation in humans, and can be substituted for sucrose as a low-calorie food ingredient. To examine the applications of d-allulose in the dairy industry, we investigated the effects of d-allulose on the acid production of 8 strains of yogurt starter (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) and 4 strains of lactococci, including potential probiotic candidates derived from dairy products. Acid production by 2 L. delbrueckii ssp. bulgaricus yogurt starter strains in milk was suppressed by d-allulose, but this phenomenon was also observed in some strains with another sugar (xylose), a sugar alcohol (sorbitol), or both. In contrast, among the dairy probiotic candidates, Lactococcus lactis H61, which has beneficial effects for human skin when drunk as part of fermented milk, was the only strain that showed suppression of acid production in the presence of d-allulose. Strain H61 did not metabolize d-allulose. We did not observe suppression of acid production by strain H61 with the addition of xylose or sorbitol, and xylose and sorbitol were not metabolized by strain H61. The acid production of strain H61 after culture in a constituted medium (tryptone–yeast extract–glucose broth) was also suppressed with the addition of d-allulose, but growth efficiency and sugar fermentation style were not altered. Probiotic activities—such as the angiotensin-converting enzyme inhibitory activity of H61-fermented milk and the superoxide dismutase activity of H61 cells grown in tryptone–yeast extract–glucose broth—were not affected by d-allulose. d-Allulose may suppress acid production in certain lactic acid bacteria without altering their probiotic activity. It may be useful for developing new probiotic dairy products from probiotic strains such as Lactococcus lactis H61.     

基因工程改良乳酸菌发酵剂品质的研究进展

综述了近5年来利用基因工程技术改良乳酸菌发酵剂蛋白质水解能力、产生双乙酰能力、合成胞外多糖能力、抗杂菌病源菌污染能力4个方面研究的最新进展，并简要介绍了基因食品可能存在的不安全问题及解决方法。     

浓缩型乳酸菌发酵剂的工业化生产

对乳品发酵剂工业化生产中的重要技术，诸如高活力菌体的增殖培养、发酵过程控制与分析、细胞富集和生物保存等问题进行了探讨．以期为我国进一步发展浓缩型乳酸菌发酵剂提供理论依据。     

红薯乳酸菌发酵酸奶的研制

以红薯液、牛乳为原料,发酵制得营养丰富、口味独特的红薯酸牛奶;将保加利亚乳杆菌和嗜热链球菌按1∶1的比例3%的接种量接入原料中,结果表明:红薯液与牛乳以5:5混合、发酵温度39℃、发酵时间12 h比较适宜.     

乳酸菌在发酵香肠中的应用研究

筛选出适宜发酵肉制品使用的乳酸菌发酵剂,确定了其在发酵香肠中应用的最佳工艺条件,并对应用结果进行了分析讨论。     

发酵乳制品中苯甲酸的来源及水平

论述了发酵乳制品酸牛乳、干酪中苯甲酸的来源及水平,对分析、预测发酵乳制品中苯甲酸自然形成量,并有效控制产品的安全质量提供参考。     

Probiotic potential of lactic acid bacteria from fermented Malaysian food or milk products

This study investigated the probiotic characteristics of lactic acid bacteria (LAB) isolated from 14 Malaysian fermented food or milk products. In total, 22.3% (121 of 542) of the LAB isolated from the local fermented products exhibited antibacterial activity against Micrococcus luteus. Twelve LAB that demonstrated better antibacterial activity against M. luteus as compared to a commercial strain Lactobacillus casei strain Shirota (LABPC) were selected for further characterisation. Based on 16S rRNA gene sequence, the LAB were identified as pediococci (seven) and lactobacilli (five). All 12 LAB showed bile tolerance, but only eight were acid tolerant at pH ≥ 3.0. The highest level of adhesion to HT‐29 cells was observed among the Lactobacillus sp. LAB 1 and 10. The LAB also showed antimicrobial activity against Escherichia coli and Staphylococcus aureus through the production of organic acids. LAB isolated from Malaysian fermented food and milk products, especially fermented tapioca, contains potential probiotic candidates.     

Comprehensive molecular,probiotic, and quorum-sensing characterization of anti-listerial lactic acid bacteria,and application as bioprotective in a food (milk) model

Listeria monocytogenes is a major foodborne pathogen that adversely affects the food industry. In this study, 6 anti-listerial lactic acid bacteria (LAB) isolates were screened. These anti-listerial LAB isolates were identified via 16S rRNA gene sequencing and analyzed via repetitive extragenic palindromic-PCR. Probiotic assessment of these isolates, comprising an evaluation of the antibiotic susceptibility, tolerance to lysozyme, simulated gastric and intestinal juices, and gut conditions (low pH, bile salts, and 0.4% phenol), was carried out. Most of the isolates were resistant to streptomycin, vancomycin, gentamycin, kanamycin, and ciprofloxacin. All of the isolates were negative for virulence genes, including agg, ccf, cylA, cylB, cylLL, cylLS, cylM, esp, and gelE, and hemolytic activity. Furthermore, autoinducer-2 (a quorum-sensing molecule) was detected and quantified via HPLC with fluorescence detection after derivatization with 2,3-diaminonaphthalene. Metabolites profiles of the Lactobacillus sakei D.7 and Lactobacillus plantarum I.60 were observed and presented various organic acids linked with antibacterial activity. Moreover, freeze-dried cell-free supernatants from Lb. sakei (55 mg/mL) and Lb. plantarum (40 mg/mL) showed different minimum effective concentration (MEC) against L. monocytogenes in the food model (whole milk). In summary, these anti-listerial LAB isolates do not pose a risk to consumer health, are eco-friendly, and may be promising candidates for future use as bioprotective cultures and new probiotics to control contamination by L. monocytogenes in the food and dairy industries.     

浓缩型乳酸菌发酵剂制备中几个技术关键问题的探讨

对浓缩型乳酸菌发酵剂制备中菌株的选择、菌体增殖培养、细胞浓缩分离、生物保藏等技术关键问题进行了探讨，轻期为进一步发展浓缩型乳酸菌发酵剂提供依据。     

乳酸菌发酵骨泥液的免疫调节作用研究

经口服给予小鼠不同计量的乳酸菌骨泥发酵液30d，能够明显提高小鼠的抗体生成细胞数、足跖细胞及巨噬细胞功能。由此证明，经乳酸菌发酵骨泥而成的——乳酸菌骨泥发酵液具有增强体液免疫和细胞免疫功能及巨噬细胞功能的作用。     

发酵羊乳中乳酸菌低产粘菌株的筛选

对从商业乳酸菌发酵剂分离纯化的11株保加利亚乳杆菌和11株嗜热链球菌在发酵羊乳中的粘度进行了研究。结果表明,保加利亚乳杆菌L.b-124菌株和L.b-346菌株、嗜热链球菌S.t-222菌株和S.t-346菌株具有较低的产粘能力,凝乳时间也较短;将L.b-346菌株与S.t-346菌株按杆菌和球菌1:1比例混合后在43℃下发酵羊乳时,可获得较低的发酵粘度。     

传统发酵酸牛奶中乳酸菌多态性分析

以从内蒙古呼伦贝尔市牧区采集的1份传统发酵酸牛奶样品为研究对象,对其进行乳酸菌的分离鉴定。通过传统纯培养法分离出17株菌,并对17株菌进行16SrDNA序列分析、多位点pheS序列分析和生理生化鉴定,鉴定的结果为11株乳酸乳球菌乳酸亚种、1株格式乳球菌、1株粪肠球菌、2株植物乳杆菌植物亚种及2株弯曲乳杆菌。乳酸乳球菌乳酸亚种为优势菌(占总分离菌株的64.7%)。     

乳酸菌发酵剂浓缩培养的研究

为制备高效浓缩乳酸菌发酵剂,通过综合运用复合生长培养基、缓冲盐法及化学中和法,对乳酸菌的浓缩培养进行了研究。试验结果表明,以 12％ NFM＋ 0.3％酵母膏＋ 0.1％ Tween 80作为复合生长培养基,加 0.5％ K2HPO4作为缓冲盐,接种量为 2％ (嗜热链球菌∶保加利亚乳杆菌 =1∶ 1),培养温度 42℃,培养过程用 30％ Na2CO3溶液作中和剂,将 pH值控制在 6.3,培养 6～ 7 h后,可使乳酸菌的活菌数达到 5.89× 109 mL－ 1。与普通的液体发酵剂相比,获得了显著的浓缩效果。     

发酵蓝莓乳饮料生产工艺的探讨

以蓝莓、鲜奶为主要原料制成发酵乳饮料,通过试验对稳定剂及饮料配方进行了研究,结果表明:复合稳定剂的组成为果胶(0.20%)、CMC(0.15%)、PGA(0.10%);最佳配方为蓝莓汁的添加量8%,发酵乳的添加量30%,糖的添加量8%,pH值4.0。     

植物原料乳酸菌发酵剂增菌培养的研究

对筛自泡菜的嗜酸乳杆菌S1的生长条件和增殖培养基进行了研究,优化确定了乳酸菌的培养条件和增殖培养基:起始pH值为5.5、培养温度为35℃、培养时间为12h,培养基主要组成为麦芽糖2%、牛肉膏1%、缓冲盐(NaAc∶CaCO3)0.5∶0.3。控制培养条件,结合优化培养基,可使培养液活菌数提高一个数量级达到5×109cfu/mL。