Understanding Age-Related Longitudinal Dynamics in Abundance and Diversity of Dominant Culturable Gut Lactic Acid Bacteria in Pastured Goats

Understanding gut lactic acid bacteria (LAB) in healthy hosts is an important first step in selecting potential probiotic species. To understand the dynamics of LAB in healthy goats, a cohort of thirty-seven healthy new-born goat kids was studied over a ten-month period. Total LAB was quantified using SYBR green qPCR. Seven hundred LAB isolates were characterized using microscopy, M13 RAPD genotyping and 16S rDNA sequencing. The highest and lowest LAB counts were detected at one week and ten months of age, respectively. Diverse LAB species were detected, whose identity and prevalence varied with age. The main isolates belonged to Limosilactobacillus reuteri, Limosilactibacillus fermentum, Lactobacillus johnsonni, Ligilactobacillus murinus, Ligilactobacillus salivarius, Limosilactobacillus mucosae, Lactiplantibacillus plantarum, Ligilactobacillus agilis, Lactobacillus acidophilus/amyolovolus, Pediococcus spp. and Enterococcus spp. Uniquely, L. reuteri and Pediococcus spp. were most common in pre- and peri-weaned goats, while Lactobacillus mucosae and Enterococcus spp. were predominant in goats one month and older. Based on RAPD genotyping, L. reuteri had the highest genotypic diversity, with age being a factor on the genotypes detected. This data may be relevant in the selection of age-specific probiotics for goats. The findings may also have broader implications by highlighting age as a factor for consideration in probiotic bacteria selection in other animal hosts.