Evaluation of Phytate-Degrading Lactobacillus Culture Administration to Broiler Chickens

Abstract

ABSTRACTProbiotics have been demonstrated to promote growth, stimulate immune responses, and improve food safety of poultry. While widely used, their effectiveness is mixed, and the mechanisms through which they contribute to poultry production are not well understood. Microbial phytases are increasingly supplemented in feed to improve digestibility and reduce antinutritive effects of phytate. The microbial origin of these exogenous enzymes suggests a potentially important mechanism of probiotic functionality. We investigated phytate degradation as a novel probiotic mechanism using recombinantLactobacilluscultures expressingBacillus subtilisphytase.B. subtilis phyAwas codon optimized for expression inLactobacillusand cloned into the expression vector pTRK882. The resulting plasmid, pTD003, was transformed intoLactobacillus acidophilus,Lactobacillus gallinarum, andLactobacillus gasseri. SDS-PAGE revealed a protein in the culture supernatants ofLactobacilluspTD003 transformants with a molecular weight similar to that of theB. subtilisphytase. Expression ofB. subtilisphytase increased phytate degradation ofL. acidophilus,L. gasseri, andL. gallinarumapproximately 4-, 10-, and 18-fold over the background activity of empty-vector transformants, respectively. Phytase-expressingL. gallinarumandL. gasseriwere administered to broiler chicks fed a phosphorus-deficient diet. Phytase-expressingL. gasseriimproved weight gain of broiler chickens to a level comparable to that for chickens fed a control diet adequate in phosphorus, demonstrating proof of principle that administration of phytate-degrading probiotic cultures can improve performance of livestock animals. This will inform future studies investigating whether probiotic cultures are able to provide both the performance benefits of feed enzymes and the animal health and food safety benefits traditionally associated with probiotics.