The Diversity of Hind-Gut Bacterial Microbiome of House Rats and Cockroaches: An indication of Public Health Risk for Residents of Semi-urban and Urban Morogoro, Tanzania

House rats (Rattus rattus) and cockroaches (Periplaneta americana) are important reservoirs of zoonotic bacterial diseases. Understanding these animals' gut bacteria composition is crucial for monitoring and preventing infections. This study aimed to determine the hindgut bacteria composition and diversity of the two hosts sampled from Kilosa and Morogoro districts, in Tanzania. A cross-sectional study design was employed, A total of 114 house rats and 57 cockroaches were caught. The hind guts of trapped host species were dissected and pooled to obtain four pools (two pools represent the hindgut of R. rattus and P. americana from Morogoro municipal and two pools for the hindgut of R. rattus and P. americana from Kilosa district). Genomic DNA was extracted from the pooled samples which was then used in metagenomics sequencing. The observed Shannon and Chao 1 indices indicated higher bacterial species diversity in rats of the Kilosa district and cockroaches of Morogoro municipal. The microbiome diversity in Morogoro municipal was higher for cockroaches than for rats, but it was not statistically significant (p>0.05). In Kilosa district, the microbiome diversity was higher for rats than for cockroaches, but it was not statistically significant (p>0.05) Proteobacteria and Bacteroidetes were the most abundant phyla in the hindgut samples of both animals. However, abundances differed among the host species and areas sampled. Proteobacteria were the most abundant phylum from Rattus rattus from Kilosa district, P. americana and R. rattus from Morogoro municipal, comprising 48%, 41%, and 40%, respectively. Bacteroidetes were plentiful from P. americana from Kilosa district (48%). Bacterial diversity was observed to be higher for R. rattus from Kilosa district and P. americana from Morogoro municipal. Potential pathogenic bacteria were also observed; the highest relative abundance of pathogenic bacteria was observed from P. americana of Kilosa, followed by R. rattus from the Morogoro district. Therefore, this study highlights the composition of hindgut bacteria carried by P. americana and R. rattus, which gives an insight into the different bacteria carried, including the pathogenic ones. This study suggests surveillance of these pests to minimise outbreaks and transmission of zoonotic diseases. Since this study did not focus on factors influencing microbiome composition and diversity, further studies are recommended to be conducted to see the influence of those factors on the gut microbiome.