ارزيابي اتصال و سم‌زدايي آفلاتوكسين M1 موجود در شير توسط لاكتوباسيلوس كازيي سويه TD2، پروبيوتيك بومي ايران در شرايط فيزيكو شيميايي مختلف

Connection, evaluation and detoxification of aflatoxin M1 in milk by Lactobacillus casei strain TD2, native probiotics in various physicochemical conditions

سابقه و هدف: آفلاتوكسين‌ها توسط آژانس بين المللي تحقيقات سرطان (IARC) به ‌عنوان عوامل سرطان‌زاي انساني طبقه‌بندي شده‌اند. ميكروارگانيسم‌هاي متعددي گزارش شده‌اند كه توانايي متصل شدن يا تخريب آفلاتوكسين‌ها را در مواد غذايي و خوراكي دارا مي‌باشند. در اين پژوهش توانايي اتصال و سم‌زدايي آفلاتوكسين M1 توسط لاكتوباسيل‌كازيي سويه‌ي TD2 پروبيوتيك بومي ايران كه توسط تاج‌آبادي و همكاران از ترخينه جدا شده مورد بررسي قرار گرفته است. روش بررسي: مقدار سم اوليه نمونه‌هاي شير تهيه شده، با كيت الايزا (Euro clone) تعيين گرديد. بعد از كشت و خالص سازي باكتري در محيط MRS Broth، به µl900 شير حاوي µl50 سم آفلاتوكسين M1 (غلظت ppb100) با pH برابر 7 و µl50 از سويه باكتري به تعداد CFU/ml 109×2 افزوده شد. بعد از h4 گرماگذاري در ?C 37 ميزان حذف آفلاتوكسين در شرايط بدون تيمار و نيز با انجام تيمار‌هاي فيزيكوشيميايي اندازه‌گيري شد. يافته‌ها: باكتري زنده به تنهايي باعث كاهش آفلاتوكسين M1 مي شود (%55.35 ± 0.7568) ولي ايجاد تخريب به‌دليل اجازه اتصال بيشتر و بهتر به آفلاتوكسين در تيمار با آنزيم ليزوزيم (%60.03 ± 0.5144) و اسيد كلريدريك M2 (%63.61 ± 0.5886) از همه بالاتر بوده و اختلاف معني‌داري بين اين‌ها مشاهده شد. نتيجه‌گيري: نتايج اين تحقيق نشان داد كه زنده ماني ميكروارگانيسم براي حذف موثر آفلاتوكسين الزامي نيست ولي باكتري تيمار اسيدي شده درصد حذف بالاتري از سم آفلاتوكسين M1 را نشان مي‌دهد. سويه مذكور با %55.35 حذف آفلاتوكسين M1 مي‌تواند به عنوان يك عامل موثر در حذف زيستي آفلاتوكسين از مواد مختلف مورد توجه قرار گيرد

Aim and Background: Contamination of foods such as milk and dairy products even with low level of Aflatoxins has side effects on human and animal health. Based on the International Agency for Research on Cancer (IARC), Aflatoxins are classified as human carcinogenic factors. Several microorganisms have been reported to have the ability to bind or destruct Aflatoxins in food and feed. Most of the scientists believe that detoxification is accomplished by physical binding between the cell wall and toxin. Purpose: the aim of this study was the investigation of Aflatoxin M1 detoxification ability of Lactobacillus casei strain TD2, native Iranian probiotic isolated from Tarkhineh by Tajabady and colleagues. Material and Methods: several samples of milk were collected from different regions of central province and the levels of their aflatoxin M1 was quantified with ELISA kit (Euro clone). The strain was subcultured in MRS Broth and 50 µl of it with 1×109 CFU/ml was inoculated in microfuges tubes containing 950 microliters of milk with aflatoxin M1 concentration about 100 ppb. After 4 hours incubation at 37°C and pH 7, the decrease in aflatoxin level was calculated. Then the detoxification abilities were determined in the same condition with different treatment such as heat (autoclaving), acid (hydrochloric acid), enzymes (lysozyme and protease) and physical (sound) treatment. By this way the effects of several factors on detoxification were examined. Results: Our result showed that this bacterium can bind to Aflatoxin M1 (% 55.35 ± 0.7568), but the destruction of it’s cell wall cause revealing of unavailable sites in cell wall and membrane components and enhance detoxification ability. Treatments with Lysozyme and hydrochloric acid 2 M resulted in higher detoxification levels, 60.03 ± 0.5144 and % 63.61 ± 0.5886, respectively. Conclusion: The results of this study showed that ther is no differences between living and non-living cells of Lactobacillus casei TD2 in Aflatoxin M1 removal. In another word, living of the cells is not essential for detoxification. Acidic treatment of the cells was resulted in the highest level of toxin removal between all of the treatment. A change in the cell wall structure is the possible reason for this observation. The percent of bacteria remove by acid treatment showing higher aflatoxin M1 may be due to changes made in the wall structure. In general it can be concluded that the strain TD2 with %55.35 removal of Aflatoxin M1, can be used in biological removal of toxin in different materials.