Journal de microbiologie alimentaire et industrielle

Assessment of Lactic Acid Bacteria Isolated from Chakka: An Indian Fermented Dairy Product

Abstract

Mahesh M, Tushar J, Pushkar C and Sarita M

Objective: The objective of this study was to isolate, identify and characterize the lactic acid bacteria (LAB) from a domestic food (Chakka) and to evaluate their properties for application as starter cultures in fermented dairy products.
Methods: LAB were isolated using standard MRS/M17 media and characterized phenotypically and identified by 16SrDNA sequencing and Whole Genome Sequencing and their evolutionary relationships were plotted using MEGA X. Culture conditions were optimized in a shaker incubator and different media formulations using Skimmed Milk Powder, Yeast Extract, Glucose, and Casein Enzyme Hydrolysate were designed and tested. Subsequently, the isolates were grown in a 1 L bioreactor under controlled conditions to study their total viable count and the growth rates. Lactic acid production was quantified in MRS and laboratory formulated M2 media under optimized growth conditions. The recovery, quantification and total yield of exopolysaccharides (EPS) produced by the isolated strains was also done.
Results: The isolates were grouped as bacilli (C2, C4, C5, C12, and P1) and cocci(Q1, and Q2). The bacilli were identified as subspecies of Lactobacillus delbrueckii and cocci were identified as Streptococcus thermophilus. M2 media was found to be a viable alternative to standard media. Bacilli and cocci were found to produce L and D-lactic acid, respectively, and bacilli were better lactic acid producers than cocci. Similarly, bacilli were found to be better EPS producers in M2 media.
Conclusion: The results suggest of this study suggest that strains isolated from Chakka could be potential starter cultures for use in yogurt manufacturing. The critical understanding about the metabolism of these LAB would be helpful for the maintenance of strains and their exploitation as starter cultures.