tailieunhanh - Isolation and identification of lactic acid bacteria from vegetable-growing soils in Da Lat, Lam Dong

LAB have been isolated from fermented food, milks and plants, however, a few studies of LAB from soils have been reported. This study aimed to isolate, screen and identify LAB from vegetab le-growing soils collected from Da Lat (Lam Dong province). From 33 soil samples, 25 LAB isolates were selected on MRS agar supplemented with 1CaCO3. | Trường Đại học Nông Lâm TP. Hồ Chí Minh 1 Isolation and identification of lactic acid bacteria from vegetable-growing soils in Da Lat Lam Dong Vuong V. Le Hai T. Pham Nguyen T. T. Nguyen Mai T. N. Dang Phong V. Nguyen amp Thanh T. L. Bien Department of Biotechnology Nong Lam University Ho Chi Minh City Vietnam ARTICLE INFO ABSTRACT Research Paper Lactic acid bacteria LAB have been used for decades in agri- Received December 20 2019 culture to improve soils control disease and promote plant Revised May 12 2020 growth. LAB have been isolated from fermented food milks and plants however a few studies of LAB from soils have been Accepted June 25 2020 reported. This study aimed to isolate screen and identify LAB from vegetable-growing soils collected from Da Lat Lam Dong province . From 33 soil samples 25 LAB isolates were selected on MRS agar supplemented with 1 CaCO3 . The LAB isolates formed small creamy white convex entire margin colonies and Keywords were Gram-positive catalase-negative and rod-shaped bacteria. Based on the acid-producing capacity five LAB isolates DT2 Antibacterial CT3 CC2 XL7 and S2 that produced clear zones around Antifungi colonies due to the solubilization of CaCO3 with diameters Isolation ranged from cm and mg mL acid after Lactic acid bacteria 2-day incubation at 30o C. All selected LAB isolates showed the Vegetable-growing soil capacity to inhibit the growth of Fusarium oxysporum at level 1 inhibitory rates in range of and Phytopthora sp. at level 3 inhibitory rates in range of af- ter 3 days. The isolates did not inhibit against E. coli and Staphylococcus but inhibit the growth of Bacillus spizizenii and Salmonella typhi with average inhibition diameters in range of Corresponding author mm and mm respectively after 1-day incubation. The five LAB isolates were molecularly determined Bien Thi Lan Thanh to be Lactobacillus plantarum with 97 100 similarities. Email .