Effect of oxidative stress on viability and selected characteristics of probiotic bacteria

Abstract

Currently, probiotic bacteria dependent dairy industries are battling to keep required concentration (more than 106 cfu/ml) of anaerobic bacteria in dairy products. In most cases the concentration of live bacteria greatly reduced due to the toxic effects of environmental oxygen. It is essential to maintain a constant volume of microbes (from manufacturing process to consumer) to exert maximum health benefit. The aims of this study were to screen and select a number of oxidative resistant probiotic bacteria, to identify any differentially expressed proteins responsible for their oxidative resistant roles and the characterization of those selected bacteria by using a number of physiological responses (acid and bile tolerance, hydrophobicity, auto aggregation and coaggregation). A comparative study was also conducted using a microencapsulation technique. The screening process was conducted using a number of Lactobacillus and Bifidobacteria cultures and finally concluded with four potential probiotic strains selected (L. casei Lc1, L. rhamnosus DR-20, B. infantis 1912 and B. animalis subsp. lactis Bb12). Relative Bacterial Growth Ratio (RBGR) method was used for the entire screening process. All four probiotic strains were found to be oxidative resistant strains as expected because they were previously selected for oxygen resistance. However under both aerobic and anaerobic situations microencapsulation demonstrated slightly increased viable cells compared to the free cells samples.

Date of Award	2010
Original language	English