Selection and Validation of Carbohydrate-utilizing Bacteria as a New Probiotic Candidate to Develop Probiotic-supplemented Thai Rice Cultivar Product

Abstract

The objectives of this study were to validate new strains of probiotics and to develop probiotic-supplemented rice products. One hundred and fifty-seven bacteria were isolated from bees, and their probiotic properties were investigated. Among these, only two strains were selected based on ability to utilize carbohydrates from rice grains. The carbohydrate-utilizing bacteria were identified as Bacillus amyloliquefaciens C11AM2 and Bacillus subtilis C12AM3 on the basis of morphological, biochemical and molecular analysis. These two probiotic candidate strains could survive in simulated gastrointestinal tract conditions involving both short and long digestion periods. From the results of the antimicrobial activity, B. amyloliquefaciens C11AM2 could inhibit growth of Vibrio cholerae and Vibrio parahaemolyticus. Both probiotic candidates did not produce virulent factors i.e. hemolysin and lecithinase. The production of probiotic-supplemented rice product revealed that the survival of probiotic strains was maintained in both encapsulated and steamed rice products, using 3 rice cultivars. The survival rates of the 2 probiotic strains were 55-60% after 2 months of storage and the products incorporating probiotic strains could be stored at 4°C for at least 2 months. This study indicated Thai rice cultivars are potential carriers of probiotic culture and are suitable for novel functional food products.