A novel glucuronoxylan hydrolase produced by fermentation is safe as feed additive: toxicology and tolerance in broiler chickens.

The current study presents a safety evaluation of a novel glucuronoxylan hydrolase (EC 3.2.1.136) from Bacillus subtilis produced in Bacillus licheniformis. The glucuronoxylan hydrolase preparation did not exhibit irritative potential to the eye and skin when applied in in vitro models. The glucuronoxylan hydrolase preparation was non-mutagenic and non-clastogenic in in vitro tests. Oral administration of the glucuronoxylan hydrolase preparation to rats did not cause any adverse effect in a 90-days subchronic toxicity study. A tolerance study was performed with broiler chickens and confirmed that this glucuronoxylan hydrolase is safe for broiler chickens when fed at the maximum recommended dose, as well as at the 10 times higher dose. In conclusion, there are no safety concerns with using this novel glucuronoxylan hydrolase as a feed additive as it is toxicologically inert and the glucuronoxylan hydrolase is well tolerated by broiler chickens. The beneficial safety evaluation of glucuronoxylan hydrolase is consistent with the fact that this type of enzyme is ubiquitous in nature.

Safety evaluation of dietary levels of 25-hydroxyvitamin D3 in growing calves.

The objective of this study was to evaluate the safety of 25-OH-D3 addition to the diet of bovine calves. The investigation was conducted as a feeding experiment for 90 days. 40 calves were allotted to four groups: T1 - control group which received 30 IU vitamin D3/kg feed, and three experimental groups, which received 25-OH-D3 in increasing dosages: T2 - 25-OH-D3 at 1.7 µg/kg, T3 - 25-OH-D3 at 5.1 µg/kg and T4 - 25-OH-D3 at 8.5 µg/kg. All calves in the four groups gained weight continually: no growth depression was observed. No adverse effects of 25- OH-D3 were observed for any of the hematology and serum chemistry parameters measured or during the routine clinical examinations. Plasma 25-OH-D3 concentration was higher (p<0.05) in groups T2, T3 and T4 compared to that observed in group T1. Tissues content of 25-OH-D3 was significantly higher in in groups T2, T3 and T4 than in group T1. In the post-mortem evaluation, no adverse effects of the different 25-OH-D3 doses were observed, neither during the gross pathology nor in the histological examination. The results of this study show explicitly that there were no adverse effects of 25-OH-D3 compared to the control group, supplemented with vitamin D3.

Safety evaluation of rebaudioside A produced by fermentation.

The safety of rebaudioside A, produced fermentatively by Yarrowia lipolytica encoding the Stevia rebaudiana metabolic pathway (fermentative Reb A), is based on several elements: first, the safety of steviol glycosides has been extensively evaluated and an acceptable daily intake has been defined; second, the use of Y. lipolytica, an avirulent yeast naturally found in foods and used for multiple applications; and third the high purity of fermentative Reb A and its compliance with internationally defined specifications. A bacterial reverse mutation assay and an in vitro micronucleus test conducted with fermentative Reb A provide evidence for its absence of mutagenicity, clastogenicity and aneugenicity. The oral administration of fermentative Reb A to Sprague-Dawley rats for at least 91 days did not lead to any adverse effects at consumption levels up to 2057 mg/kg bw/day for males and 2023 mg/kg bw/day for females, which were concluded to be the No Observed Adverse Effect Levels. The results were consistent with outcomes of previous studies conducted with plant-derived rebaudioside A, suggesting similar safety profiles for fermentative and plant-derived rebaudioside A. The results of the toxicity studies reported here support the safety of rebaudioside A produced fermentatively from Y. lipolytica, as a general purpose sweetener.