Growth Studies Of Potential Probiotic Lactic Acid Bacteria In Cereal — Based Substrates

ABSTRACT

In this study the growth of three lactic acid bacteria strains being Lactobacillus fernientum, Lactobacillus plantarum and Lactobacillus nantensis in cereal substrates of maize, sorghum and malt sorghum was evaluated. Organisms used for this research were isolated from Ogi (an indigenous natural fermented food) using MRS media (Merck, Germany). Preliminary identification of these organisms were done by Gram reaction, carbohydrate utilization test as well as test for the production of catalase. Molecular analysis was used to further characterize the organisms. Probiotic potential of the strains were determined using haemolysis test, bile salt and acid tolerance tests. Prior to fermentation, the pH and buffering capacity of the substrates which do affect the fermentation process were measured. The raw grains were steeped in water for 8 hours, followed by draining of the water, wet milling and sieving. The wort obtained after sieving was inoculated with the probiotic strains and allowed to ferment for 48hours at 37°C. The viable counts, pH and lactic acid concentration during and at the end of the fermentation process were determined. Lactobacillus fermentum had lower counts than those Lactobacillus plantarum and Lactobacilius nanlensis in the maize substrate while in sorghum and malt substrates the counts were higher for L. fernientum than L.piantaruni and L.nantensis. Studies showed slight pH changes in different cereal substrates with L.fermentum producing a drop from 5.8 to 5.62 in the malt medium. Bacterial counts of probiotic strains increased after 12 hours of fermentation while there was a decrease towards the end in the maize medium. L.ferrnentuni has a cell count of 6.21 log cfu/ml at 12 hours while a count of 6.13 log cfu/ml was observed at 48 hours, the case wasn't any different in the other two substrates of sorghum and malted sorghum. Data gotten from these experiments was analysed using a one-way ANOVA at (p>O.05). This research therefore suggests that malt medium is favourable for the growth of L. fermentuni than maize and sorghum while maize supported L. plantarurn and L. nantensis more. In general cereals (maize, sorghum and malt) are suitable for the growth of the three probiotic strains being L. fermenturn, L.plantarum and L. nantensis