Intestinal bacteria isolated from goldfish (Carassius auratus) were identified based on 16 ribosomal RNA (rRNA) gene sequences and screened for their ability to produce N-acyl homoserine lactone (AHL), an autoinducer of the quorum sensing (QS) system. The 230 aerobes/facultative anaerobes that were isolated comprised members of the genera Aeromonas (184 isolates), Citrobacter (11), Enterobacter (2), Shewanella (28), Vagococcus (1), and Vibrio (4). Among these genera, the two most abundant species were Aeromonas veronii (163 isolates) and Shewanella xiamenensis (27). In addition, 142 obligate anaerobes consisting of Cetobacterium somerae (139 isolates), Clostridium frigidicarnis (2), and Cetobacterium sp. (1) were also isolated. One hundred seventy isolates (74.2%) belonging to the genera Aeromonas, Citrobacter, Enterobacter, Shewanella, and Vibrio produced AHL, while 155 (67.7%) and 91 (39.7%) isolates possessed the luxR and luxI gene homologs, respectively. None of the obligate anaerobes produced AHL or possessed luxRI homologs. Total viable counts ranged from 1.2 × 107 to 2.2 × 109 CFU/g, which were accounted for 0.8 to 15.2% of direct counts. Aeromonas veronii, S. xiamenensis, and C. somerae were detected from five goldfish at densities ranging from 4.0 × 106 to 1.7 × 109 CFU/g, indicating that these bacteria are dominant components of the culturable gut flora in goldfish. In addition, members of the genera Aeromonas and Shewanella appeared to communicate with each other by using the QS system to some extent when the concentration of AHL reaches a certain threshold. It is therefore suggested that bacteria with the ability to disrupt AHL secretion in intestinal environments are potential candidates for probionts for preventing opportunistic infections in freshwater fish such as goldfish.

• Klíčová slova
• AHL, Aeromonas, Cetobacterium, Quorum sensing, Shewanella, goldfish, gut flora, intestinal bacteria,
• MeSH
• acylbutyrolaktony metabolismus   MeSH
• Bacteria klasifikace   metabolismus   MeSH
• DNA bakterií chemie   genetika   MeSH
• gastrointestinální trakt mikrobiologie   MeSH
• karas zlatý mikrobiologie   MeSH
• počet mikrobiálních kolonií MeSH
• ribozomální DNA chemie   genetika   MeSH
• RNA ribozomální 16S genetika   MeSH
• sekvenční analýza DNA MeSH
• společenstvo * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acylbutyrolaktony MeSH
• DNA bakterií MeSH
• ribozomální DNA MeSH
• RNA ribozomální 16S MeSH

In this study, 99 Gram-negative rod bacteria were isolated from cooling tower water, and biofilm samples were examined for cell-to-cell signaling systems, N-acyl homoserine lactone (AHL) signal molecule types, and biofilm formation capacity. Four of 39 (10 %) strains isolated from water samples and 14 of 60 (23 %) strains isolated from biofilm samples were found to be producing a variety of AHL signal molecules. It was determined that the AHL signal molecule production ability and the biofilm formation capacity of sessile bacteria is higher than planktonic bacteria, and there was a statistically significant difference between the AHL signal molecule production of these two groups (p < 0.05). In addition, it was found that bacteria belonging to the same species isolated from cooling tower water and biofilm samples produced different types of AHL signal molecules and that there were different types of AHL signal molecules in an AHL extract of bacteria. In the present study, it was observed that different isolates of the same strains did not produce the same AHLs or did not produce AHL molecules, and bacteria known as AHL producers did not produce AHL. These findings suggest that detection of signal molecules in bacteria isolated from cooling towers may contribute to prevention of biofilm formation, elimination of communication among bacteria in water systems, and blockage of quorum-sensing controlled virulence of these bacteria.

• MeSH
• acylbutyrolaktony chemie   izolace a purifikace   metabolismus   MeSH
• biofilmy růst a vývoj   MeSH
• fyziologie bakterií * MeSH
• gramnegativní bakterie izolace a purifikace   metabolismus   MeSH
• mikrobiologie vody * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acylbutyrolaktony MeSH