Background: Lactic acid is an important pharmaceutical and food ingredient, which is being utilized as a monomer for the production of biodegradable poly (lactic acid). Response surface methodology involving central composite design was successfully applied to evaluate the optimized conditions for the fermentation as well as immobilization of lactic acid production. Results: Effect of different parameters such as concentration of sugar, yeast extract and CaCO3 for fermentation of lactic acid was optimized. Further this study focuses on the production of lactic acid from glucose by Lactobacillus delbrueckii immobilized in chitosan/poly ethylene glycol stabilized Ca alginate beads. The L. delbrueckii cells illustrate increased lactic acid production and improved optical purity with cells entrapped in 2 mm alginate-chitosan-PEG beads prepared from 1.5% Na-alginate. The gel beads produced lactic acid for 12 consecutive batch fermentations without marked activity loss and deformation.

Conclusion: Higher lactic acid production and lower cell leakage with improved reusability were observed with alginate-PEG beads compared with Ca-alginate & alginate-chitosan beads.