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KMID : 0545120190290111717
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Journal of Microbiology and Biotechnology
2019 Volume.29 No. 11 p.1717 ~ p.1728
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Cloning and Heterologous Expression of the β-Galactosidase Gene from Bifidobacterium longum RD47 in B. bifidum BGN4
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Park Min-Ju
Park Myeong-Soo
Ji Geun-Eog
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Abstract
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The gene encoding β-galactosidase was cloned from Bifidobacterium longum RD47 with combinations of several bifidobacterial promoters and expressed in B. bifidum BGN4. Among the recombinant bifidobacteria, BGN4+G1 showed the highest β-galactosidase level, for which the hydrolytic activity was continuously 2.5 to 4.2 times higher than that of BGN4 and 4.3 to 9.6 times higher than that of RD47. The β-galactosidase activity of BGN4+G1 was exceedingly superior to that of any of the other 35 lactic acid bacteria. When commercial whole milk and BGN4+G1 were reacted, BGN4+G1 removed nearly 50% of the lactose in the milk by the 63-h time point, and a final 61% at 93 h. These figures are about twice the lactose removal rate of conventional fermented milk. As for the reaction of commercial whole milk and crude enzyme extract from BGN4+G1, the β-galactosidase of BGN4+G1 eliminated 51% of the lactose in milk in 2 h. As shown below, we also compared the strengths and characteristics of the strong bifidobacterial promoters reported by previous studies.
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KEYWORD
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β-galactosidase, lactose hydrolysis, bifidobacteria
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