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Properties of ¥x -Galactosidase from Lactobacillus zymae GU240, an Isolate from Kimchi, and Its Gene Cloning

Authors :
Jeong A Kim
Se-Jin Lee
Ji Yeong Park
Zhuang Yao
Jeong Hwan Kim
Yu Meng
Huong Giang Le
Source :
Microbiology and Biotechnology Letters. 48:287-295
Publication Year :
2020
Publisher :
Korean Society for Microbiology and Biotechnology, 2020.

Abstract

Lactobacillus zymae GU240 was previously isolated from Kimchi, a Korean fermented vegetable, as a strong GABA producer. The strain showed β-galactosidase (β-Gal) activity on MRS agar plates with X-gal. When growth and β-Gal activities of GU240 were measured using MRS (glucose, 2%, w/v) and MRSL (lactose, 2%, w/v) broths, cells were found to grow slowly in MRSL, and the β-Gal activity (36 units at 4 h) was lower than that of cells grown in MRS (94 units at 16 h). The highest OD600 value of the culture in MRS was 1.6 at 24 h at 37℃, whereas that of the culture in MRSL was 0.6 at 16 h. β-Gal activity of the culture in MRS reached the maximum (95.6 u/ml) at 16 h, decreased thereafter, and was not detected at 48 h. β-Gal activity for culture in MRSL reached its highest (36 u/ml) at 4 h and decreased gradually, but some activity (11.05 u/ ml) still remained at 72 h. The structural gene encoding β-Gal in L. zymae GU240 was cloned as a 3.1 kb fragment, and DNA sequencing confirmed the presence of complete lacLM genes. lacLM genes from L. zymae GU240 showed 98-99% homologies in nucleotide sequences with other lacLM genes from L. brevis. Reverse transcription (RT)-PCR confirmed the operon structure of lacLM. The results indicated that L. zymae GU240 might be in the process of losing the ability to grow rapidly on lactose-containing medium, such as milk, due to adaptations to plant environments, including kimchi.

Details

ISSN :
22347305 and 1598642X
Volume :
48
Database :
OpenAIRE
Journal :
Microbiology and Biotechnology Letters
Accession number :
edsair.doi...........4dda008d3ee530dbdfd05f83f12c078c
Full Text :
https://doi.org/10.4014/mbl.1912.12004