بررسي الگو‌هاي مقاومت آنتي‌بيوتيكي در دو باكتري داراي پتانسيل پروبيوتيكي،Lactococcus lactis subsp. cremoris NABRII64 و Lactococcus lactis subsp. cremoris NABRII66 جدا شده از روده ماهي قزل‌آلاي رنگين‌كمان (Oncorhynchus mykiss)

Assessment of antibiotic resistance patterns in two potential probiotic bacteria, Lactococcus lactis subsp. cremoris NABRII64 and Lactococcus lactis subsp. cremoris NABRII66 isolated from rainbow trout (Oncorhynchus mykiss) intestine

هدف اين پژوهش بررسي الگو‌هاي فنوتيپي و ژنوتيپي مقاومت آنتي‌بيوتيكي دو باكتري اسيد ‌لاكتيك Lactococcus lactis subsp. cremoris (NABRII64 و NABRII66) داراي پتانسيل پروبيوتيكي جداسازي شده از روده ماهيان قزل‌آلاي رنگين‌كمان بود. الگوي حساسيت فنوتيپي سويه‌هاي مورد بررسي بر اساس حداقل غلظت بازدارندگي (MIC) نسبت به هشت آنتي‌بيوتيك رايج در پزشكي و دامپزشكي شامل آمپي‌سيلين، كانامايسين، جنتامايسين، استرپتومايسين، اريترومايسين، كليندامايسين، تتراسايكلين و كلرامفنيكل بررسي شد. پس از مقايسه مقادير MIC با مقادير استاندارد توصيه شده توسط سازمان ايمني مواد غذايي اتحاديه اروپا (EFSA)، ماهيت مقاومت فنوتيپي مشاهده شده در سويه‌هاي باكتريايي به وسيله DNA پلاسميدي از طريق واكنش زنجيره پلي‌مرازي (PCR) بررسي شد. نتايج ارزيابي فنوتيپي نشان دهنده مقاومت تتراسايكليني در هر دو سويه باكتريايي بود (mg/L4

This study aimed to investigate the phenotypic and genotypic patterns of antibiotic resistance in two potential probiotic lactic acid bacteria, Lactococcus lactis subsp. cremoris (NABRII64 and NABRII66) isolated from the rainbow trout intestine. The phenotypic susceptibility pattern of the strains was studied based on the Minimum Inhibitory Concentration (MIC) of eight most commonly used antibiotics in medicine and veterinary including ampicillin, kanamycin, gentamicin, streptomycin, erythromycin, clindamycin, tetracycline, and chloramphenicol. After comparing the MICs with standard values recommended by European Food Safety Authority (EFSA), the nature of phenotypic resistance observed in bacterial strains was investigated by polymerase chain reaction (PCR) through plasmid DNA extraction. The results of the phenotypic evaluation indicated the tetracycline resistance in both bacterial strains (MIC<4mg/L). Genotyping of antibiotic resistance genes including tet (S), tet (L), tet (M), tet (O), tet (W) and tet (K) indicated the presence of tet (S) and tet (M) resistance genes in plasmid DNA of both bacterial strains. These results exhibited the acquired resistance and the presence of two tetracycline resistance genes in the plasmid DNA of two bacterial strains, NABRII64 and NABRII66. However, further studies are required to understand the nature of the acquired resistance mechanism in the future.