A Better and Cheaper Culture Medium for Isolation of Lactic Acid Bacteria from Milk and its Products

ABSTRACT: Milk and its products contain large number of Lactic acid bacteria (LAB) that are difficult to culture under laboratory conditions because of their complexity and diversity under dynamic ecosystem. MRS (de Man, Rogosa and Sharpe) medium was used to culture of LAB from milk and its products under aerobic and anaerobic conditions separately. The same samples were used to culture LAB on new Soybean culture medium (per litre) containing extract of 20 g soya nutri nuggets, 5 g yeast powder extract, 20 mL coconut milk and agar 20 g. The samples on both media were incubated at 37±1℃ for 48-72 h and examined for growth of different LAB. The cost of MRS medium available in the market ranges from U$ 50 to 100 per 500 g of which 50-60 g is used to prepare 1 litre of culture medium depending upon the manufacturer. The minimum cost of 1 litre MRS comes to U$ 5 while the cost of ingredients used in Soyanutri Jaggery Agar (SJA) medium is only 50 cents i.e. ten times cheaper than MRS and the number of colonies isolated from milk and its products were 8-10x higher than MRS medium. Jaggery (concentrated raw sugarcane juice) is available at the 5 Kg for 1U$ and easily available. 500 g of Soyanutri cost only U$ 1. Further researches are being conducted in our laboratories and it is suggested that Soyanutri Jaggery Agar medium may be used for routine culture of LAB in laboratories for the demonstration and practice for the students and also for screening of samples on large scale.