Text

theses

The digestive systems of humans and animals contain an extraordinary diversity of microbes. These microbes constitute a functional organ contributing to physiological and health processes of the host. While many of these associations are hypothesized, correlations have been made between host health and specific bacterial groups, and the details of these associations are being revealed. Members of the phylum Bacteroidetes have been correlated with the development of early infant immunity, and members of the phylum Firmicutes have been shown to provide future protection against pathogenic bacteria. Exercise has been found to impact bacterial communities in the digestive tracts of human and laboratory animals leading to increasing levels of Bacteroidetes and decreasing levels of Firmicutes. Moreover, exercise related changes in the gut microbiome (GM) were found to either provide protection against certain illness conditions or worsen the symptoms of other conditions. Moreover, some bacterial supplementations were found to increase performance in rodent models. Here, our studies tested the hypotheses that acute exercise and exercise training would alter the GM in Standardbred racehorses. To identify the bacterial communities of the GM a good choice of DNA extraction protocol should be elected to ensure getting the right results. Therefore, we modified a phenol/chloroform extraction method plus insertion of an inhibitor removal solution. The results showed that our modifications generated clean with high concentrated DNA products as was revealed by illumine Miseq. Next, we tested the hypothesis that acute intense exercise would alter the GM in horses. Eight horses were used to run on treadmill or serving as standing control. Rectal fecal samples were taken 24 hours before and after testing. Bacterial community analysis was done by sequencing the 16s rRNA (V3-V4) region via Illumina Miseq. The relative abundance of the genus Clostridium significantly decreased in the pre-training standing control trial (SC1) (P<0.05), with a concurrent decrease in the Shannon diversity index at the species level (P<0.05). At both the genus and species levels the principle coordinate analysis (PCoA) showed significant separation when the samples collected before SC1 were compared to those collected after SC1 (P<0.05). Interestingly, we found that Fusicatenibacter saccharivorans, a bacteria found to be decreased in ulcerative colitis patients, and Treponema zioleckii, a bacteria found to degrade fructan in sheep rumen, were significantly decreased when the samples collected before SC1 were compared to those collected after SC1 (P<0.05). None of the changes observed in SC1 happened in SC2 (P>0.05). Our results indicate that the relative abundance of the genus Clostridium, Fusicatenibacter saccharivorans, and Treponema zioleckii might particularly be responsive to anticipatory effects associated with watching and hearing exercise. Then, we examined the hypothesis that exercise training may alter the GM in Standardbred Racehorse. In this study, 8 horses (4 mares, 4 geldings) were exercise trained for 12 weeks, and 4 additional mares were used as a parallel seasonal control. To identify bacterial community changes over time for both groups, rectal fecal samples were collected, DNA was extracted, and the 16S rRNA gene (V3-V4) was sequenced using the IIllumina Miseq platform. The exercise training group showed significant changes in the levels of Bacteroidetes, Proteobacteria, and Spirochaetes phyla (P<0.05), while there were no changes in the gut microbiota of the seasonal control group through the three months of the study (P>0.05). Moreover, with training two genera significantly changed in their relative abundance over time, namely Clostridium and Dysgonomonas (P<0.05). Dysgonomonas spp was significantly changed in abundance during the exercise training period (P<0.05). Treponema spp. showed significant changes during the exercise training period (P<0.05). Shannon diversity index was decreased (P<0.05), in the exercise group at the beginning of the study, but then returned to pre-training levels. Principle coordinate analysis showed significant separation between time points of the exercise training group as far as the levels of genera and species (P<0.05) represented. Our results show that exercise training influences the gut microbiota especially at the beginning of training.

ETD_7537

Ph.D.

Includes bibliographical references

by Ali Hassan Daghir Janabi

doi:10.7282/T3VH5R58

ETD doctoral

The author owns the copyright to this work.