五株乳酸菌和三株芽孢杆菌的生物学特性和功能

Biological properties and functions of five strains of lactic acid bacteria and three strains of Bacillus

摘要:

【背景】乳酸菌和芽孢杆菌是应用于生产最多的益生菌，但不同菌株间的生长特性均不相同，因此了解菌株的生物学特性具有重要意义。【目的】研究菌株的生物学特性，能合理地开发和利用菌株，以保证菌株生产应用的安全性。【方法】活化后鉴定5株乳酸菌和3株芽孢杆菌并对其形态进行观察，探究菌株的生长曲线、产酸能力及最适生长条件，测定菌株的抑菌活性和产酶性能，同时探究菌株的益生性和安全性。【结果】五株乳酸菌分别编号鉴定为干酪乳杆菌R1、副干酪乳杆菌R2、香肠乳杆菌R3、福莱乳杆菌R4和唾液乳杆菌R5；3株芽孢杆菌分别编号命名为贝莱斯芽孢杆菌Y1、枯草芽孢杆菌Y2和地衣芽孢杆菌Y3。八株菌形态结构均不相同但都为杆状，均在2–10 h为对数生长期，18–24 h为稳定期，培养24 h时乳酸菌和芽孢杆菌的活菌数均保持在10⁹和10⁸ CFU/mL，最适生长温度为37.0℃。乳酸菌具有较强的产酸能力和抑菌活性，芽孢杆菌有较强的产酶性，在人工胃液中都有较强的耐受性。八株菌都无溶血活性、无毒力基因、对抗生素都保持中度敏感以上；其中唾液乳杆菌有四环素耐药基因，但对四环素抗性为中度敏感。【结论】八株菌生长繁殖速度快，乳酸菌产酸能力和抑菌活性较强，芽孢杆菌具有较强的产酶性能，在体外具有较好的益生性和安全性，可应用于生产实践。

Abstract:

[Background] Lactic acid bacteria (LAB) and Bacillus are commonly used probiotics in production, with different growth characteristics. It is essential to understand the biological characteristics of different strains. [Objective] To study the biological characteristics of the strains, develop and utilize the strains in a reasonable way, and ensure the safety of strain application in production. [Methods] After activation, five strains of LAB and three strains of Bacillus were identified. Their morphology was observed, and the growth curve, acid production, and optimal growth conditions of the strains were investigated. Furthermore, the antimicrobial activity, enzyme production, probiotic properties, and safety of the strains were measured. [Results] The strains R1-R5 of LAB were identified as Lactobacillus casei, L. paracasei, L. farcimini, L. futsaii, and L. salivarius, respectively. The strains Y1-Y3 of Bacillus were identified as B. velezensis, B. subtilis, and B. licheniformis, respectively. The eight strains presented different morphological structures but all were rod-shaped and entered the logarithmic growth stage and platform stage after being cultured for 2-10 h and 18-24 h, respectively. After incubation for 24 h, LAB and Bacillus maintained the viable counts at 10⁹ and 10⁸ CFU/mL, respectively, and the optimal growth at 37.0℃. LAB had strong acid-producing ability and antimicrobial activity, and Bacillus had strong enzyme production. All the strains demonstrated strong tolerance in artificial gastric juice, no hemolytic activity, no virulence gene, and moderate sensitivity to antibiotics. Among them, L. salivarius carried tetracycline resistance genes, while it was moderately sensitive to tetracycline. [Conclusion] The eight strains of bacteria have fast growth and reproduction. LAB have strong acid-producing ability and antimicrobial activity, and Bacillus has strong enzyme-producing performance. With good probiotic properties and safety in vitro, the 8 strains can be applied in production.