乳酸菌代谢产物对大肠杆菌和金黄色葡萄球菌抑制作用的研究

从燕糖酸奶中分离;“乳酸蔺,研究热、酸、pH值处理等对乳酸菌代谢产物抑制大肠杆菌和金黄色葡萄球菌效果的影响。结果表明：乳酸菌发酵液的最终pH值为3．9;乳酸菌代谢产物具有良好的热稳定性以及较好的抗蛋白酶活性和抗过氧化氧酶活性;pH值处删对乳酸菌代谢产物的抑菌能力具有明显影响,pH值越低乳酸菌代谢产物的抑菌能力越强。     

Growth of Staphylococcus aureus in fermenting tempeh made from various beans and its inhibition by Lactobacillus plantarum.

In fermenting tempeh made from non-acid-soaked horsebean, pea, and soybean Staphylococcus aureus grew rapidly to a final count of 10⁸cfu.g^-1 or more, but growth was less when chickpea was used. Inoculation of the cooked beans with Lactobacillus plantarum markedly decreased S. aureus growth rate and the final count in non-acid-soaked horsebean and pea tempeh, strongly retarded growth in chickpea-, and completely inhibited growth in soybean-tempeh. Acid-soaking the beans resulted in lower S. aureus growth, and inoculation with Lb. plantarum completely inhibited it in soybean and reduced the counts in the other products to less than 10⁴cfu.g^-1. Acidity, pH and other substances produced by Lb. plantarum are believed to inhibit S. aureus in fermenting tempeh. Inoculation of beans with Lb. plantarum may be used to control S. aureus growth and enterotoxin production during commercial scale tempeh production.     

The influence of Lactobacillus plantarum culture inoculation on the fate of Staphylococcus aureus and Salmonella typhimurium in Montasio cheese.

The growth and survival of Staphylococcus aureus and Salmonella typhimurium were investigated during the manufacturing and ripening of raw milk Montasio cheese. Initial inoculated populations in the cheese milk were about 10(5) cfu/ml for S. aureus and 10(6) cfu/ml for S. typhimurium. Samples of curds and cheeses were taken during manufacturing and storage and analysed for pH and microbial populations. S. aureus increased slightly in number during the early period of ripening and attained a population of about 10(6) cfu/ml during the remaining period of storage. S. typhimurium decreased during cheesemaking and storage but persisted through 90 days. The addition of Lactobacillus plantarum culture (0.2% v/v) produced a marked reduction in populations of the test strains in 10 days of storage. Enterotoxin A was not detected in Montasio cheese even with a S. aureus population of 1.1 X 10(7) cfu/ml. L. plantarum strains were also tested by the spot method and the associative growth approach for their antagonistic activity against S. aureus and S. typhimurium. The compound excreted by L. plantarum was active only toward S. aureus. Furthermore, its activity was destroyed by protease treatment. These results indicated that while the growth of S. typhimurium is reduced by the acid production, S. aureus inhibition can be ascribed to bacteriocin production.     

Anti‐glycative and anti‐inflammatory effects of caffeic acid and ellagic acid in kidney of diabetic mice

Protective effects of caffeic acid (CA) and ellagic acid (EA) in kidney of diabetic mice were examined. CA or EA at 2.5 and 5% was mixed in diet and supplied to diabetic mice for 12 wk. Results showed that the intake of CA or EA increased renal content of these compounds, alleviated body weight loss, decreased urine output, increased plasma insulin and decreased blood glucose levels at weeks 6 and 12 (p<0.05). The intake of these compounds dose dependently reduced plasma blood urea nitrogen and elevated creatinine clearance (p<0.05). CA or EA at 5% significantly decreased the levels of plasma HbA1c, urinary glycated albumin, renal carboxymethyllysine, pentosidine, sorbitol and fructose (p<0.05), and significantly diminished renal activity of aldose reductase and sorbitol dehydrogenase, as well as suppressed renal aldose reductase mRNA expression (p<0.05). CA or EA dose dependently lowered renal levels of IL‐6, IL‐1β, tumor necrosis factor (TNF)‐α and monocyte chemoattractant protein 1 (MCP‐1) (p<0.05). Furthermore, CA or EA dose dependently down‐regulated tumor necrosis factor‐α and monocyte chemoattractant protein‐1 mRNA expression in kidney (p<0.05). Based on the observed anti‐glycative and anti‐inflammatory effects, the supplement of CA or EA might be helpful for the prevention or attenuation of diabetic kidney diseases.     

Inhibition of Staphylococcus aureus and spheroplasts of Gram-negative bacteria by an antagonistic compound produced by a strain of Lactobacillus plantarum

A strain of Lactobacillus plantarum was examined for production of an extracellular antagonistic compound. Cellfree preparations, dialyzed to remove organic acids, were used in inhibition studies which revealed that Gram-positive bacteria were sensitive. Among these, Staphylococcus aureus was chosen for further characterization of the agent. The antagonistic compound was susceptible to breakdown by proteolytic enzymes and its effect was completely lost after heat treatment at 121°C for 15 min. Ultrafiltration studies indicated that the agent had a molecular weight of over 100, 000, suggesting a complex protein-containing aggregate. The antagonistic effect was found to be highest at low pH values and S. aureus was shown to be able to adapt to the agent. Most Gram-negative bacteria were resistant to the compound. However, after their transformation to spheroplasts, which removed most of the cell envelopes, these bacteria were sensitized. The conclusion is that the antagonistic mechanism probably includes agent influence on the cell surface.     

Metabolism of ferulic acid during growth of Lactobacillus plantarum and Lactobacillus collinoides

BACKGROUND: Food‐isolated lactic acid bacteria can transform ferulic acid (FA) into several products. Since quantification of these metabolites during the different bacterial growth phases is lacking, the aim of this study was to identify and quantify conversion products of FA and to follow the kinetics of FA metabolism during growth of Lactobacillus plantarum and Lactobacillus collinoides. RESULTS: Lactobacillus plantarum and Lactobacillus collinoides were incubated in MRS broth, to which different amounts of FA were added (final concentrations of 0, 0.5, 1.5 and 3 mmol L^?1), at 30 °C until the late stationary phase. Lactobacillus plantarum metabolised FA into 4‐vinylguaiacol (4‐VG) and hydroferulic acid (HFA). Conversion to 4‐VG started simultaneously with the degradation of FA, while formation of HFA started in the mid‐exponential phase. Lactobacillus collinoides only formed 4‐VG, mainly in the stationary phase. No significant effect of the different amounts of FA was seen on the growth and fermentation characteristics of both bacteria. CONCLUSION: The results demonstrate that both bacteria are able to convert FA. However, start of conversion differs between the two strains. The different amounts of FA had no influence on the growth and fermentation characteristics of both bacteria. Copyright © 2012 Society of Chemical Industry     

益生性植物乳杆菌的体外抗氧化活性研究

对从内蒙古奶豆腐及新生儿肠道中分离的5株植物乳杆菌的抗氧化活性进行分析.将保存的5株植物乳杆菌用MRS液体培养基活化培养后,对其耐酸特性、耐胆盐特性、疏水性和抗氧化能力进行分析.结果表明,5株植物乳杆菌均具有一定的耐酸和耐胆盐特性,其中植物乳杆菌MGSHC4302能够耐受pH=2.0的酸性环境,植物乳杆菌CRFA4608、MGSHC4301和MGSHC4302能够耐受1.0％的胆盐:5株植物乳杆对二甲苯和三氯甲烷的疏水性明显好于LGG,表明这些菌株具有较好的黏附性.实验结果表明,植物乳杆菌CRFA4608和MGSHC4302对羟自由基的清除能力高于对照菌株鼠李糖乳杆菌LGG,除植物乳杆菌MGSHC4303外其他4株茵对DPPH的清除能力均高于鼠李糖乳杆菌LGG或与之相近,而植物乳杆菌MGSHC4302、MGSHC4303具有较高的超氧阴离子清除能力.综上所述,植物乳杆菌MGSHC4302可以作为今后开发具有益生性产品的潜在菌株.     

Synergistic antifungal effects of thyme essential oil and Lactobacillus plantarum cell‐free supernatant against Penicillium spp. and in situ effects

This study evaluates the synergistic antifungal effects between thyme essential oils and Lactobacillus plantarum cell‐free supernatant (LCFS) against Penicillium spp. and in situ antifungal activity in rice grains. Thyme essential oil and LCFS showed remarkable antifungal activities against Penicillium spp. with the minimum inhibitory concentration (MIC) of 40 and 80 µL/mL, respectively. The analysis of fractional inhibitory concentration (FIC) index showed the antifungal synergism between thyme essential oil and LCFS against Penicillium spp. with FIC index of 0.5. This synergism also resulted in fourfold reduction in their MICs when applied in combination. The antifungal modes of action were characterized by observing the changes in cell membrane permeability and degradation of fungal cell wall. The combination of thyme essential oil and LCFS (2 × MIC of each) showed remarkable in situ antifungal effect and completely inhibit the growth of Penicillium in rice seeds. The results suggested the possible applications of the observed synergism on actual crops.

Practical applications

Essential oils are used as preservative in food industry and high concentration of essential oil is associated with negative organoleptic characteristics. This study presented a novel approach for synergistic antifungal effects by using the combination of thyme essential oil and Lactobacillus plantarum cell‐free supernatant (LCFS) against Penicillium spp. and systematic evaluation of the antifungal effect by using fractional inhibitory concentration (FIC) index method. This approach will be a role model for future research on synergism and overcome the major drawbacks of using live bacteria and the negative effects arising from antimicrobial activities of essential oils.     

植物乳杆菌HLX37降胆固醇活性研究

HLX37是从福建南平地区农户自然发酵的酸乳中分离得到的一株植物乳杆菌,本文对该菌株的耐酸耐胆盐能力和体内外降胆固醇活性进行研究。结果表明,HLX37菌株在p H为3.0和胆盐浓度为3.0 g/L环境下培养4 h的存活率分别为59.1%±4.8%和48.2%±4.9%,且对添加胆盐的MRS+CHOL培养基中胆固醇具有良好的降解能力（24 h和48 h降解率分别达37.33%±2.55%和44.72%±2.74%）;连续灌胃HLX37发酵酸奶65 d可显著降低高胆固醇血症大鼠血清总胆固醇含量（p<0.05）,而将该酸奶灭活后,其降胆固醇效果显著下降（p<0.05）,说明HLX37活菌能够降低高胆固醇血症大鼠血清胆固醇水平。综上,HLX37菌株在体内外均显示出良好的降胆固醇活性,具有较大潜力应用于功能性发酵食品的生产中。      

植物乳杆菌胞外多糖的脱色及其体外抑瘤效应

研究大孔吸附树脂对植物乳杆菌胞外多糖的脱色工艺,并采用Cell Counting Kit-8(CCK-8)法检测植物乳杆菌胞外多糖EPS及单一组分EPS-1、EPS-2对大肠癌细胞株HT-29的体外抑瘤效应。结果表明,选择S-8树脂,树脂用量为4g/100mL,调节胞外多糖溶液的pH值为6,在25℃条件下,糖液质量浓度为2mg/mL,静态吸附4h后脱色率为72.58%,糖保留率为69.15%。植物乳杆菌胞外多糖EPS、EPS-1和EPS-2对大肠癌细胞HT-29的体外增殖均具有显著的抑制作用(P＜0.01),且呈现出良好的量效关系。     

生物转化共轭亚麻酸植物乳杆菌的筛选及特性研究

共轭亚麻酸(conjugated linolenic acid,CLNA)是一类具有抗癌、降脂减肥、抗炎等生理功能的活性物质,为了得到高产或具有生物转化CLNA性能的生物合成体系,采用GC-MS分析方法检测了31株不同来源的植物乳杆菌的脂肪酸组成,筛选得到8种可以高效转化亚麻酸至共轭亚麻酸的菌株。基于GC-MS分析结果,对其中1株高产共轭亚麻酸的植物乳杆菌CCFM261的转化特性进行了研究。结果表明,植物乳杆菌CCFM261对亚麻酸的转化率高于50%,所得产物存在3种异构体(CLNA1,CLNA2,CLNA3),大部分以游离脂肪酸的形式存在于发酵液中,总含量可达到0.186 0 mg/m L。菌体中也积累了一定量的结合状态的CLNA。产物以CLNA1和CLNA2为主,比例约为2∶1,占总共轭亚麻酸含量的90%以上。经质谱数据分析,确定CLNA1和CLNA2分别为生物活性较高的c9,t11,c15-CLNA和t9,t11,c15-CLNA。     

酸菜来源植物乳杆菌体外去除胆固醇特性

对4株酸菜来源具有潜在益生特性的植物乳杆菌降胆固醇特性进行研究.研究发现其降胆固醇能力受胆盐浓度和胆盐种类的影响,当牛胆盐的添加浓度为3g/L时,降胆固醇能力达到最高(9.67mg/g～21.32mg/g[干重]);在培养基中添加不同种类的胆盐,降胆固醇能力不同,依次为牛磺胆酸钠＞混合胆盐＞甘氨胆酸钠.其产生的游离胆酸的量与胆固醇移除能力呈正相关,且以在牛磺胆酸钠存在下最佳.     

植物乳杆菌C8的耐受性和体外降胆固醇活性研究

对一株分离自内蒙古奶豆腐中的植物乳杆菌C8进行了酸和胆汁盐耐受实验,抗生素敏感性试验以及体外胆固醇降解实验,并分析了其降胆固醇的作用机理.结果表明,C8能够耐受pH 3和高浓度胆盐(30g/L)环境;对所选10种抗生素均表现出一定的耐药性;该菌具有良好的降胆固醇活性,产生的游离胆酸的量与胆固醇移除能力呈正相关,且以在甘氨胆酸钠存在条件下最佳(5.39mmol/L).植物乳杆菌c8降胆固醇的作用机理主要是菌体细胞的表面吸附作用和胆固醇与胆盐的共沉淀作用.     

植物乳杆菌转化亚油酸为共轭亚油酸条件的研究

研究了植物乳杆菌AS1.555转化亚油酸为共轭亚油酸的条件。该菌株在MRS培养基中经0.1%(v/v)的亚油酸诱导培养后,所得的洗涤细胞具有很强的转化能力。通过单因素实验和正交实验得到植物乳杆菌转化亚油酸为共轭亚油酸的优化反应条件:反应温度30℃、反应时间48h、游离亚油酸浓度1.5%(v/v)、0.1mol/L磷酸缓冲液pH7.0。