Growth analysis of lactobacillus acidophilus using different non-digestible carbohydrates

Abstract

Probiotics are live microorganisms and offer health benefits to the digestive system and used in the production of many fermented foods. Non-digestible carbohydrates are dietary fibers which cannot be digested and absorbed by the small intestine. Strains of Lactobacillus, are among the most common and popular group of probiotics and added to many dairy products and dietary supplements. Besides, Lactobacillus acidophilus can exhibit many useful benefits such as showing thermostability, maintaining the growth activity at a wide pH range, and offering strong inhibition actions against spoilage of food and pathogenic bacteria. Aims of this study are to analyse the ability of non-digestible carbohydrates to act as a carbon source in enhancing the growth activity of L. acidophilus in vitro and to determine which type of non-digestible carbohydrate sources contributed a high biomass production. L. acidophilus was grown on de Man, Rogosa and Sharpe (MRS) medium. The optical density and pH of the cell biomass produced were measured and cell dry weight was determined. The highest biomass production recorded was for barley 10.02 g. L-1 followed by yam 8.79 g. L-1, 7.17 g. L-1 for garlic, 6.81 g. L-1 for banana and 4.86 g. L-1 for sweet potato, while positive control (glucose) recorded 4.20 g. L-1 of cell biomass. The results also showed a decreasing in the pH values which indicated the formation of lactic acids in the medium after 24 h of incubation at 37°C on rotary shaker set at 200 rpm. The overall results, confirmed that L. acidophilus helps in the hydrolysis of non-digestible carbohydrates and subsequent conversion of the sugars to cell biomass and decrease the pH compared to the negative control (without carbon source). This shows that in future, production of a synbiotic products using these non-digestible carbohydrates and probiotics strains is promising to offer many benefits to human’s health.