Safety and efficacy profile of a phytase produced by fermentation and used as a feed additive.

Enzymes can aid in optimal feed stock utilization when used as feed additives. A range of toxicological studies were performed to evaluate the safety profile of a novel phytase (phytase HM) from Citrobacter b raakii produced in Aspergillus oryzae. Phytase HM was found to be non-mutagenic and non-clastogenic in in vitro tests. Further, the phytase HM preparation did not exhibit irritative potential to the eye and skin when applied in in vitro models. A 13-week subchronic toxicity study with oral administration of phytase HM to rats did not show any adverse effects. Efficacy studies showed that the dietary supplementation of this phytase significantly improved growth performance and bone mineralization in broiler chickens and piglets fed P-deficient diets, and increased retention of phosphorus (P) and calcium (Ca), and phytate-P degradation in excreta of broiler chickens in a dose-dependent manner. In conclusion, there are no safety concerns using phytase HM as a feed additive and the phytase is well tolerated by broiler chickens and pigs. Further, phytase HM improves with high efficacy the growth performance in both broiler chickens and pigs.

A muramidase from Acremonium alcalophilum hydrolyse peptidoglycan found in the gastrointestinal tract of broiler chickens.

This study evaluates peptidoglycan hydrolysis by a microbial muramidase from the fungus Acremonium alcalophilum in vitro and in the gastrointestinal tract of broiler chickens. Peptidoglycan used for in vitro studies was derived from 5 gram-positive chicken gut isolate type strains. In vitro peptidoglycan hydrolysis was studied by three approaches: (a) helium ion microscopy to identify visual phenotypes of hydrolysis, (b) reducing end assay to quantify solubilization of peptidoglycan fragments, and (c) mass spectroscopy to estimate relative abundances of soluble substrates and reaction products. Visual effects of peptidoglycan hydrolysis could be observed by helium ion microscopy and the increase in abundance of soluble peptidoglycan due to hydrolysis was quantified by a reducing end assay. Mass spectroscopy confirmed the release of hydrolysis products and identified muropeptides from the five different peptidoglycan sources. Peptidoglycan hydrolysis in chicken crop, jejunum, and caecum samples was measured by quantifying the total and soluble muramic acid content. A significant increase in the proportion of the soluble muramic acid was observed in all three segments upon inclusion of the microbial muramidase in the diet.