Expression of the \beta-(1,3-1,4)-Glucanase Gene in Streptococcus salivarius subsp. thermophilus


Abstract: The purpose of this study was the transformation and expression of the \beta -(1,3-1,4)-glucanase (lichenase) gene in Streptococcus salivarius subsp. thermophilus to create a recombinant probiotic for poultry and improve the thermostability of the lichenase enzyme. The recombinant plasmid TL1R containing the \beta -(1,3-1,4)-glucanase gene was introduced into S. salivarius subsp. thermophilus by electrotransformation. The expressing of the \beta -(1,3-1,4)-glucanase gene in S. salivarius subsp. thermophilus was confirmed on lichenan plate, SDS-PAGE, and zymogram analysis. The \beta -(1,3-1,4)-glucanase enzyme expressed by S. salivarius subsp. thermophilus cells seemed to increase its capacity for thermoresistance and so it maintained its activity at 70 ºC for 15 min. In contrast, the enzyme produced by Lactococcus lactis and Escherichia coli cells easily ceased activity when exposed to the same temperature. The enzyme expressed by all the recombinant bacteria resisted denaturation and somehow remained soluble after heat treatment from 37 to 100 ºC for 15 min.

Keywords: Streptococcus salivarius subsp. thermophilus, \beta -(1,3-1,4)-glucanase, expression, thermostability

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