Laboratory of Microbial Biomolecules, School of Pharmaceutical Sciences, University of São Paulo, Rua Do Lago, 250, Cidade Universitária, São Paulo, 05508-000, Brazil.
Fishing Institute of São Paulo/Salmoniculture Experimental Station, Av. Campos Do Jordão, Residencial Horto Florestal, Campos do Jordão, São Paulo, 12460-000, Brazil.
Sci Rep. 2022 Apr 1;12(1):5530. doi: 10.1038/s41598-022-09263-0.
The conditions of aquatic environments have a great influence on the microbiota of several animals, many of which are a potential source of microorganisms of biotechnological interest. In this study, bacterial strains isolated from aquatic environments were bioprospected to determine their probiotic profile and antimicrobial effect against fish and food pathogens. Two isolates, identified via 16S rRNA sequencing as Lactococcus lactis (L1 and L2) and one as Enterococcus faecium 135 (EF), produced a bacteriocin-like antimicrobial substance (BLIS), active against Listeria monocytogenes, Salmonella Choleraesuis and Salmonella Typhimurium. Antimicrobial activity of BLIS was reduced when exposed to high temperatures and proteolytic enzymes (trypsin, pepsin, papain and pancreatin). All strains were sensitive to 7 types of antibiotics (vancomycin, clindamycin, streptomycin, gentamicin, chloramphenicol, rifampicin and ampicillin), exhibited a high rate of adherence to Caco-2 cells and expressed no hemolysin and gelatinase virulence factors. EF showed some resistance at pH 2.5 and 3.0, and L2/EF showed higher resistance to the action of bile salts. Finally, the presence of bacteriocin genes encoding for proteins, including Nisin (L1 and L2), Enterocin A, B, P, and Mundticin KS (EF) was detected. The molecular and physiological evidence suggests that the bacterial isolates in this study could be used as natural antimicrobial agents and may be considered safe for probiotic application.
水生环境条件对许多动物的微生物群有很大影响，其中许多是具有生物技术兴趣的微生物的潜在来源。在这项研究中，从水生环境中分离出的细菌菌株被生物勘探，以确定其益生菌特性和对鱼类和食品病原体的抗菌作用。通过 16S rRNA 测序鉴定的两种分离株，即乳球菌（L1 和 L2）和一种肠球菌 135（EF），产生了一种细菌素样抗菌物质（BLIS），对李斯特菌、猪霍乱沙门氏菌和鼠伤寒沙门氏菌有效。BLIS 的抗菌活性在暴露于高温和蛋白酶（胰蛋白酶、胃蛋白酶、木瓜蛋白酶和胰蛋白酶）时会降低。所有菌株均对 7 种抗生素（万古霉素、克林霉素、链霉素、庆大霉素、氯霉素、利福平、氨苄西林）敏感，对 Caco-2 细胞具有高黏附率，且不表达溶血素和明胶酶毒力因子。EF 在 pH 2.5 和 3.0 时表现出一定的耐药性，而 L2/EF 对胆盐的作用表现出更高的耐药性。最后，检测到编码包括乳链菌肽（L1 和 L2）、肠球菌素 A、B、P 和 mundticin KS（EF）在内的蛋白的细菌素基因的存在。分子和生理证据表明，本研究中的细菌分离株可用作天然抗菌剂，并且可能被认为是益生菌应用的安全选择。
