Department of Studies in Microbiology, Davangere University, Davanagere, 577002, India.
Centre for Rural Development and Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
Probiotics Antimicrob Proteins. 2019 Dec;11(4):1100-1109. doi: 10.1007/s12602-018-9479-7.
Thirty-four isolates of Lactobacillus spp. (LAB) from 34 curd samples were evaluated for their aflatoxin B (AFB) binding and probiotic properties. Upon characterization, four LAB isolates (LC3/a, LC4/c, LC/5a, and LM13/b) were found to be effective in removing AFB from culture media with a capacity of above 75%. Staining reaction, biochemical tests, pattern of sugar utilization, and 16s rRNA gene sequence analysis revealed the identity of all the four isolates as L. fermentum. All of them could tolerate acidic pH, salt, and bile, which promise the use of these probiotic bacterial isolates for human applications. These isolates showed poor hydrophobicity and higher auto-aggregation properties. All L. fermentum isolates were found susceptible to gentamycin, chloramphenicol, cefoperazone, ampicillin, and resistant to ciprofloxacin and vancomycin. Results of hemolytic and DNase activity indicated their nonpathogenic nature. Though all L. fermentum isolates found inhibiting the growth of Salmonella ebony, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, maximum inhibition was obtained with isolate LC5/a. Kinetic studies revealed that all four bacteria required a minimum of 2 h to reach stationary phase of AFB binding. AFB binding ability varied from 66 to 85.2% among these four isolates. Bile (0.4%) was significant (P ≤ 0.05) in reducing the AFB binding property of isolates LC3/a, LC4/c, and LM13/b, while increased AFB binding ability was recorded at acidic pH (2.0). AFB binding properties of isolate LC5/a were found least affected by acidic pH and bile. The findings of our study revealed the higher efficiency of L. fermentum isolate LC5/a in reducing the bioavailability of AFB1 in gut, and additionally, it improves the consumers' health by its various probiotic characters. These beneficial characters, L. fermentum isolates, promise them to use as probiotic formulations alone or in combinations with other beneficial probiotic-bacterial isolates.
从 34 个凝乳样本中评估了 34 株乳杆菌属（LAB）分离株的黄曲霉毒素 B（AFB）结合能力和益生菌特性。经过特征描述，发现 4 株 LAB 分离株（LC3/a、LC4/c、LC/5a 和 LM13/b）能够有效地从培养基中去除 AFB，去除率超过 75%。染色反应、生化试验、糖利用模式和 16s rRNA 基因序列分析表明，所有 4 株分离株均为发酵乳杆菌。它们都能耐受酸性 pH 值、盐和胆汁，这保证了这些益生菌细菌分离株可用于人类应用。这些分离株表现出较差的疏水性和更高的自聚集特性。所有发酵乳杆菌分离株均对庆大霉素、氯霉素、头孢哌酮、氨苄西林敏感，对环丙沙星和万古霉素耐药。溶血和 DNA 酶活性结果表明它们没有致病性。虽然所有发酵乳杆菌分离株都能抑制黑曲霉、金黄色葡萄球菌、大肠杆菌和铜绿假单胞菌的生长，但 LC5/a 分离株的抑制效果最强。动力学研究表明，所有 4 株细菌都需要至少 2 小时才能达到 AFB 结合的稳定期。这 4 株细菌的 AFB 结合能力在 66%到 85.2%之间有所不同。在 LC3/a、LC4/c 和 LM13/b 这 3 个分离株中，胆汁（0.4%）显著（P≤0.05）降低了它们对 AFB 的结合能力，而在酸性 pH 值（2.0）下则记录到 AFB 结合能力的增加。LC5/a 分离株的 AFB 结合能力受酸性 pH 值和胆汁的影响最小。我们的研究结果表明，发酵乳杆菌分离株 LC5/a 能更有效地降低肠道中 AFB1 的生物利用度，此外，它还通过其各种益生菌特性改善消费者的健康。这些有益特性使发酵乳杆菌分离株有望单独使用或与其他有益益生菌细菌分离株联合使用作为益生菌制剂。
