Host Genetics and Gut Microbiota

Abstract

The gut microbiota consists of hundreds to thousands of bacterial species, and is strongly associated with the well-being of the host. Its composition differs among individual hosts, being affected by environmental factors such as food and maternal inoculation. Recently, the relative impact of the host’s genetics has been uncovered in different mammal hosts. Here, we describe the effect of host genetic background on the composition of gut bacterial communities in a murine model, focusing on lactic acid bacteria (LAB) as an important group that contains a variety of strains associated with the improvement of various gut health disorders. Based on 16S-rDNA tRFLP analysis, variation was observed in fecal LAB populations of two genetic mouse lines BALB/C and C57BL/6J. Lactobacillus johnsonii, a potentially probiotic bacterium, appeared at significantly higher levels in the feces of C57BL/6J mice compared to BALB/C. The genetic inheritance of L. johnsonii levels was further tested in reciprocal crosses between the two mouse lines, where each mouse line served alternatively as the male or female parent. The two resultant groups of F1 offspring, having the same genetic content but exposed to different maternal microflora during and after birth, presented similar L. johnsonii levels, confirming that mouse genetics plays a major role in determining these levels, compared to the relatively lower maternal effect. Our findings suggest that mouse genetics has a major effect on the composition of the intestinal LAB population in general, and on the persistence of L. johnsonii in the gut in particular.