■水产养殖作为主要食品部门的快速发展伴随着挑战,包括影响全世界罗非鱼养殖的疾病。由无乳链球菌引起的一种此类传染病对罗非鱼种群构成严重威胁。益生菌已成为针对无乳链球菌感染的潜在安全预防措施。然而,抗生素抗性细菌的抗菌素抗性仍然是一个令人担忧的问题,因为它可以导致抗性细菌的传播,并在鱼类和周围环境中充当抗生素抗性基因的储存库。本研究旨在鉴定能够促进罗非鱼生长的候选益生菌,对无乳链球菌感染提供抗性,没有潜在的致病性,并且没有抗生素抗性基因。随后,评估了这些益生菌候选物在罗非鱼中的表现。
■链球菌,大修道院,细菌。,巨大芽孢杆菌,枯草芽孢杆菌,和短小芽孢杆菌被检查以评估它们的抗菌特性,溶血模式,和抗生素抗性基因。我们使用了特异性引物tetA,tetB,tetd,tete,tetO,tetQ,ermB,和用于抗生素抗性基因检测的qnrS。通过在60天的维持期内以1×106菌落/mL/50g饲料的浓度在罗非鱼饲料中施用益生菌候选物来评估体内益生菌功效。在攻击测试后14天观察到对无乳链球菌感染的抗性。
■链球菌,巨大的P.,和细菌。在细菌分离物中被鉴定为有希望的益生菌候选物。另一方面,B.巨大的,B.枯草杆菌,短小芽孢杆菌携带抗性基因并表现出β溶血模式,使它们不适合作为益生菌候选人。选定的益生菌候选物(L.garvieae,巨大的P.,和细菌。)证明了增强罗非鱼生长的潜力,没有表现出致病倾向,并且没有抗生素抗性基因。补充L.garvieae和细菌。罗非鱼对无乳链球菌感染的抗性增强,而在攻击测试期后,与对照组相比,补充巨大P.
■益生菌,特别是L.Garvieae,巨大的P.,和细菌。,增强生长和抵抗无乳链球菌感染,不携带抗生素抗性基因.根据抗生素抗性基因选择益生菌候选物对于确保鱼类的安全至关重要,环境,和人类健康。
UNASSIGNED: The rapid development of aquaculture as a major food sector is accompanied by challenges, including diseases that affect tilapia farming worldwide. One such infectious disease caused by Streptococcus agalactiae poses a serious threat to tilapia populations. Probiotics have emerged as a potentially safe preventive measure against S. agalactiae infection. However, antimicrobial resistance from antibiotic-resistant bacteria remains a concern because it can lead to the spread of resistant bacteria and serve as a reservoir of antibiotic-resistant genes in fishes and the surrounding environment. This study aimed to identify candidate probiotic bacteria capable of promoting tilapia growth, providing resistance to S. agalactiae infection, devoid of potential pathogenicity, and free from antibiotic resistance genes. Subsequently, the performance of these probiotic candidates in tilapia was evaluated.
UNASSIGNED: Lactococcus garvieae, Priestia megaterium, Bacterium spp., Bacillus megaterium, Bacillus subtilis, and Bacillus pumilus were examined to assess their antibacterial properties, hemolytic patterns, and antibiotic resistance genes. We used the specific primers tetA, tetB, tetD, tetE, tetO, tetQ, ermB, and qnrS that were used for antibiotic resistance gene detection. In vivo probiotic efficacy was evaluated by administering probiotic candidates in tilapia feed at a concentration of 1 × 106 colonies/mL/50 g of feed over a 60-day maintenance period. Resistance to S. agalactiae infection was observed for 14 days after the challenge test.
UNASSIGNED: Lactococcus garvieae, P. megaterium, and Bacterium spp. were identified as promising probiotic candidates among the bacterial isolates. On the other hand, B. megaterium, B. subtilis, and B. pumilus carried resistance genes and exhibited a β hemolytic pattern, rendering them unsuitable as probiotic candidates. The selected probiotic candidates (L. garvieae, P. megaterium, and Bacterium spp.) demonstrated the potential to enhance tilapia growth, exhibited no pathogenic tendencies, and were free from antibiotic resistance genes. Supplementation with L. garvieae and Bacterium spp. enhanced tilapia resistance to S. agalactiae infection, whereas P. megaterium supplementation showed an insignificant survival rate compared with controls after the challenge test period.
UNASSIGNED: Probiotics, particularly L. garvieae, P. megaterium, and Bacterium spp., enhance growth and resistance against S. agalactiae infection, without harboring antibiotic resistance genes. Selecting probiotic candidates based on antibiotic resistance genes is essential to ensure the safety of fish, the environment, and human health.