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

Microbiology and Biotechnology Letters 2020년 48권 3호 p.287 ~ 295
Le Huong Giang, Yao Zhuang, 김정아, 이세진, Meng Yu, 박지영, 김정환,
소속 상세정보
 ( Le Huong Giang ) - Gyeongsang National University Graduate School Division of Applied Life Science
 ( Yao Zhuang ) - Gyeongsang National University Graduate School Division of Applied Life Science
김정아 ( Kim Jeong-A ) - Gyeongsang National University Institute of Agriculture and Life Science
이세진 ( Lee Se-Jin ) - Gyeongsang National University Graduate School Division of Applied Life Science
 ( Meng Yu ) - Gyeongsang National University Graduate School Division of Applied Life Science
박지영 ( Park Ji-Yeong ) - Gyeongsang National University Graduate School Division of Applied Life Science
김정환 ( Kim Jeong-Hwan ) - Gyeongsang National University Graduate School Division of Applied Life Science

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.

키워드

Lactobacillus zymae; β-galactosidase; lacLM; kimchi

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