Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz 61357-831351, Iran.
Clinical Division of Fish Medicine, University of Veterinary Medicine, 1210 Vienna, Austria.
Mar Drugs. 2019 Dec 26;18(1):23. doi: 10.3390/md18010023.
Quorum quenching (QQ), the enzymatic degradation of -acyl homoserine lactones (AHLs), has been suggested as a promising strategy to control bacterial diseases. In this study, 10 AHL-degrading bacteria isolated from the intestine of barramundi were identified by 16S rDNA sequencing. They were able to degrade both short and long-chain AHLs associated with several pathogenic species (spp.) in fish, including -[(RS)-3-Hydroxybutyryl]-l-homoserine lactone (3-oh-C-HSL), -Hexanoyl-l-homoserine lactone (C-HSL), -(β-Ketocaproyl)-l-homoserine lactone (3-oxo-C-HSL), -(3-Oxodecanoyl)-l-homoserine lactone (3-oxo-C-HSL), -(3-Oxotetradecanoyl)-l-homoserine lactone (3-oxo-C-HSL). Five QQ isolates (QQIs) belonging to the and genera, showed high capacity to degrade both synthetic AHLs as well as natural AHLs produced by and using the well-diffusion method and thin-layer chromatography (TLC). The genes responsible for QQ activity, including , and were also detected. Analysis of the amino acid sequences from the predicted lactonases revealed the presence of the conserved motif HxHxDH. The selected isolates were further characterized in terms of their probiotic potentials in vitro. Based on our scoring system, QQ1 and QQ2 exhibited suitable probiotic characteristics, including the production of spore and exoenzymes, resistance to bile salts and pH, high potential to adhere on mucus, appropriate growth abilities, safety to barramundi, and sensitivity to antibiotics. These isolates, therefore, constitute new QQ probiotics that could be used to control vibriosis in .
群体感应淬灭（QQ），即酰基高丝氨酸内酯（AHLs）的酶促降解，已被认为是控制细菌疾病的一种很有前途的策略。在这项研究中，通过 16S rDNA 测序，从巴沙鱼肠道中分离出 10 株 AHL 降解细菌。它们能够降解与鱼类中几种致病性物种（ spp.）相关的短链和长链 AHLs，包括[（RS）-3-羟基丁酰基]-L-高丝氨酸内酯（3-oh-C-HSL）、-己酰基-L-高丝氨酸内酯（C-HSL）、-（β-酮己酰基）-L-高丝氨酸内酯（3-氧代-C-HSL）、-（3-氧代癸酰基）-L-高丝氨酸内酯（3-oxo-C-HSL）、-（3-氧代十四酰基）-L-高丝氨酸内酯（3-oxo-C-HSL）。属于 和 属的 5 株 QQ 分离株（QQIs），具有高能力来降解合成 AHLs 以及 和 产生的天然 AHLs，这是通过平板扩散法和薄层层析（TLC）来实现的。还检测到负责 QQ 活性的基因，包括 、 和 。从预测的内酯酶的氨基酸序列分析中，发现了保守基序 HxHxDH 的存在。所选分离株进一步在体外进行了益生菌潜力的特征分析。根据我们的评分系统，QQ1 和 QQ2 表现出合适的益生菌特性，包括孢子和外切酶的产生、胆汁盐和 pH 的抗性、高粘液附着潜力、适当的生长能力、对巴沙鱼的安全性以及对抗生素的敏感性。因此，这些分离株构成了新的 QQ 益生菌，可用于控制 的弧菌病。
