Characterizing the interplay of Lactic Acid Bacteria and their phages during the fermentation of milk

Divvya, Ramesh (2018) Characterizing the interplay of Lactic Acid Bacteria and their phages during the fermentation of milk. UG thesis, Azim Premji University.

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Abstract

Lactic acid bacteria are widely used as dairy starter cultures to produce fermented dairy products like cheese, yogurt etc. Some strains of Lactic acid bacteria have bacteriophages associated with them. Phage contamination is a prominent cause of fermentation failure in dairy industry. In the past, such fermentation failures have led to huge economic losses across the globe. Therefore, the relationship between bacteriophages and their bacterial hosts in the context of milk fermentation is commercially significant. In this study, the phenotypic characteristics and phage susceptibility of microbial isolates from five different brands of yogurts were examined. Growth profiles of the isolates in M9 minimal media with different sugars along with microscopic images was used to characterise them phenotypically. Two morphologically distinct strains of lactic acid bacteria putatively identified as belonging to Lactobacillus (strain 1) and Streptococcus (strain 2) genera were isolated from five brands of yogurt. To test the stability of the isolates, phages were induced using mitomycin C. It was observed that strain 1 was susceptible to phage attack whereas strain 2 was not susceptible to phage attack. It was concluded that starter cultures of some yogurts may be unstable because they can be inhibited by phages.

Item Type:	Thesis (UG)
Authors:	Divvya, Ramesh
Subjects:	Natural Sciences > Life sciences; biology
Divisions:	Azim Premji University > School of Arts and Sciences
Full Text Status:	Restricted
URI:	http://publications.azimpremjiuniversity.edu.in/id/eprint/479
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