شناسايي مولكولي و ارزيابي اثرات ضدميكروبي جدايه لاكتيكي عمده ترخينه و تركيبات شبه باكتريوسيني آن در برابر برخي از عوامل ميكروبي غذازاد

Molecular identification and evaluation of antimicrobial effects of dominant LAB isolated from Tarkhineh and its bacteriocin-like substances on some foodborne microorganisms

جداسازي و ارزيابي ويژگي­ هاي باكتري­ هاي اسيد لاكتيك از فراورده­ هاي تخميري سنتي، همواره احتمال مواجهه با جدايه ­هاي داراي قابليت­ هاي منحصر به فرد را در پي داشته است. در اين مطالعه پس از شناسايي مولكولي جدايه لاكتيكي عمده ترخينه، اثرات ضد باكتريايي و ضد قارچي جدايه مذكور و تركيبات شبه باكتريوسيني آن در برابر برخي از شاخص ­هاي ميكروبي غذازاد بر اساس روش­هاي مرجع مورد بررسي قرار گرفت.توالي­ يابي محصولات واكنش زنجيره­اي پليمراز منجر به شناسايي لاكتوكوكوس لاكتيس به عنوان جدايه لاكتيكي عمده ترخينه شد. جدايه مذكور داراي اثرات ضد باكتريايي مناسبي بود اما تفاوت معني داري (0/05

Isolation and evaluation of the characteristics of lactic acid bacteria (LAB) from traditional fermented products have always the possibility of exposure to isolates with unique capabilities.In the present study after molecular identification of dominant LAB isolated from Tarkhineh, antibacterial and antifungal effects of the isolate and its bacteriocin-like substances on some foodborne indicators were investigated in accordance with the reference methods. Sequencing results of polymerase chain reaction led to the identification of Lactococcus lactis as dominant isolate. LAB isolate had proper antibacterial effect but there was no significant difference (P<0.05) between growth inhibitory diameter of S. aureus and E. coli in present of the isolate. Furthermore, the inhibitory effect of the crude supernatant was higher than that of the neutralized and treated supernatants against studied indicator bacteria. The highest reduction in the population of S. aureus (87.91%) was also observed in the presence of crude supernatant obtained from Logarithmic growth phase. The LAB isolate had the higher antifungal effect on A. flavus rather than A. niger, but the growth rate of A. niger compared to A. flavus was remarkably (P<0.05) higher in each of the third to sixth days of incubation in the presence of bacteriocin-like substances. Based on the results of this study, Lactococcus lactis isolate and its bacteriocin-like substrates can be used as starter culture in fermented food processing, or as bio-preservative in food and pharmaceutical industries.