Screening of β-galactosidase enzyme production by probiotic lactic acid bacteria isolated from raw and fermented milk

Document Type : Research article

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Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Assuit 71524, Egypt

Abstract

β-Galactosidase is a glycoside hydrolase enzyme that catalyzes the hydrolysis of terminal non-reducing β-D-galactose residues in β-D-galactosides. This study aimed to isolate β-galactosidase-producing bacteria from different types of milk. Focus on isolating lactic acid bacteria. Sixty-eight bacterial isolates were isolated from eight fermented and nonfermented camel and cow milk samples. Gram staining revealed that there were 68 gram-positive bacterial isolates (30 bacilli and 38 cocci), and all of them were catalase-negative and non-spore-forming. The rapid plate assay for the β-galactosidase enzyme showed that ten isolates are β-galactosidase-producing bacteria. The isolate MH-010 was the most potent β-galactosidase producer; phenol concentrations ranging from 0.4% to 0.6% significantly inhibited the growth of the bacterial isolate MH-010, resulting in a decrease in log10 CFU/ml. The bacterial isolates showed 96% auto-aggregation activity after 2 hours of incubation at 37 °C, a 42.8% co-aggregation ratio with Klebsiella sp., and hydrophobicity over 80%. The MH-010 isolate was identified as Enterococcus lactis and registered in GenBank under accession number (PP803411). According to the findings, the Enterococcus lactis strain can be used to produce the β-galactosidase enzyme for use in different industrial fields.

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Archives of Agriculture Sciences Journal
Volume 7, Issue 2
August 2024
Pages 36-50

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