Construction of a Probiotic Lactic Acid Bacterium t hat Expresses Acid-Resistant Phytase Enzyme

Abstract

The use of genetically engineered probiotics to exp ress specific enzymes has been the subject of considerable attention in poultry indust ry because of increased nutrient availability and reduced cost of enzyme supplementa tion. Phytase enzyme is commonly added to poultry feed to improve digestibility and availability of phosphorus from plant sources. To construct a probiotic with potential of phytate degradation, phytase gene (appA) from E. coli was cloned and transformed into two probiotic bact eria Lactobacillus salivarius and Lactococcus lactis . The results showed plasmid instability, unable to express the gene. The expression of appA gene in L. lactis was analyzed by detecting specific RNA and zymography assay. Phytase enzyme was isolated f rom cellular extracts of recombinant L. lactis, showing a 46 kDa band upon the SDS-PAGE analysis. Z ymogram also confirmed the phytase activity of the 46 kDa b and corresponding to the enzyme. An enzyme activity of 4.9 U mL -1 was obtained in cell extracts of L. lactis . The growth of native and recombinant L. lactis was similar in the presence of two concentrations of ox bile. Keywords : Lactobacillus salivarus , Lactococcus lactis , Recombinant, Phytase, Poultry