Aerobic Respiration in Lactic Acid Bacteria

Abstract

Lactic acid bacteria (LAB) are used as food-grade microorganisms for production of a variety of fermented milk products. They are also the most common probiotic organisms used for making functional foods. Lactic acid bacteria are well known for their fermentative metabolism wherein they convert simple carbohydrates to organic acids and other end products. Fermentation helps the bacteria to generate ATP required for various cellular activities via substrate level phosphorylation reaction. Fermentation results in incomplete oxidation of substrate and hence is an inefficient process with a low ATP yield. However, some LAB are genetically capable of activating an auxiliary respiratory metabolism in which a quinol oxidase serves as the final electron acceptor and high ATP production is achieved due to oxidative phosphorylation. The respiratory process is associated with high biomass production of LAB and more robust bacterial cells, which are essentially required for manufacture of high viability starter culture. This chapter explores LAB's current and future applications in dairy starter cultures.