Expression of bifunctional genes encoding xylanase and β(1,3-1,4)-glucanase in Gram-positive bacteria

The xylanase and beta (1,3-1,4)-Glucanase activities encoding gene from the cellulolytic rumen anaerobe bacterium was cloned into Escherichia/Streptococcus shuttle vector for introduction into Gram-positive bacteria, including the rumen facultative anaerobe bacterium Streptococcus bovis. Activities due to the cloned gene decreased in the stationary phase in batch cultures of S. bovis, reflecting the sensitivity of the cloned enzymes to inactivation in the presence of accumulated lactic acid. Cloned gene activity was detected in the culture supernatant, indicating recognition of the cloned gene signal peptide by Gram-positive bacteria.