Abstract High level expression of a catalase gene from Lactobacillus sake SR911 in catalase deficient Lactobacillus sp. TISTR891 and Lactobacillus plantarum TISTR850

A. Kengluecha¹, W. Noonpakdee^1*, S. Sitthimonchai¹, R. Valyasevi² and S. Panyim¹

¹Department of Biochemistry, Faculty of Science, Mahidol University, ¹National Center for Genetic
Engineering and Biotechnology, NSTDA, Ministry of Science, Technology and Environment, Thailand

(Received 22 July 1999 l Accepted 5 October 1999)

Abstract.
Catalase activity is rarely found in lactobacilli but it is a desirable characteristic for starter cultures as it prevents defects caused by hydrogen peroxide in food product. The catalase gene from Lactobacillus sake SR91II was cloned and expressed in Escherichia coli UM2, Lactobacillus sp. TISTR891 and Lactobacillus plantarumTISTR850. The Lactobacillus sp.TISTR891 and L. plantarum TISTR850 isolated from local fermented meat products were naturally devoid of catalase activity. The transformed lactobacilli were shown to decompose hydrogen peroxide and the recombinant proteins were also detected by in situ activity staining of the catalase enzyme. The catalase gene was expressed as an active enzyme in transformed Lactobacillus sp. TISTR891 by using pGKV210, a lactococcus promoter screening vector. Increase in the expression of catalase gene by about two fold was observed after cloning the gene under the strong lactococcal promotor p59 located in the expression vector pIL 1020. In transformed Lactobacillus plantarum TISTR850, catalase activity was expressed almost 6 times as that in Lactobacillus sp. TISTR891 where expression was under the control of its own promoter.

Keywords: High level expression, catalase gene, Lactobacilli