Within barrier facilities, autoclaved diet and bedding are used for husbandry of laboratory rodents. Bacillus spp. are ubiquitous in nature and some of them are known as probiotics. Inactivation of the Bacillus spores and reduction of the diet nutritional value due to autoclavation could be especially critical for immunodeficient mice. We studied the effect of the autoclaved and non-autoclaved diets on the reproductive performance and the age of prolapse manifestation in Muc2-/- mice with impaired gut barrier function and, therefore, sensitive to change of microbiota. We found that the non-autoclaved diet led to enhancement of the fertility index of Muc2-/- and Muc2+/- female mice. The non-autoclaved diet affected the prolapse of Muc2-/- mice that occurred later in comparison with females eating the autoclaved diet. We showed that Bacillus spp. was present in the non-autoclaved diet and feces of mice on the non-autoclaved diet. Bacterial strains of the non-autoclaved diet and feces belonged to B. amyloliquefaciens, B. thuringiensis, B. subtilis, Lysinibacillus macrolides, B. cereus, and other representatives of Bacillus spp. Moreover, autoclavation of the diet affected on the percent of the blood and spleen immune cells, the bacterial composition of the intestine, and increased the level of methionine in the thigh muscle of mice. Enhanced reproductive performance and delayed prolapse manifestation in Muc2-/- mice could be due to improved digestion, as Bacillus spp. from diet and feces had enzymatic activity.
Keywords: Bacillus spp.; Muc2−/− mice; autoclaved diet; mice; model of inflammatory bowel disease; reproductive performance.