Profiles of Bacterial Communities Mediating Production of Tsetse Attractive Phenols in Urine of Selected Mammals
Musonye, Harry Asena
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Animal African Trypanosomiasis (AAT) is a major constraint to livestock health and production. The disease has for years continued to contribute towards economic and developmental setback in the sub-Saharan Africa. Tsestse flies belonging to Glossina species are the main vectors for transmission. They are attracted to livestock and wildlife hosts where they feed on blood meal contaminated by trypanosomes, the disease causing parasites. Host ageing urine has been shown to be the source of phenolic blend attractive to the tsetse. The identities and ability of bacteria to mediate production of these phenols has however, not been well investigated. This study aimed at profiling bacterial communities mediating production of tsetse attractive phenols in mammalian urine. Urine samples were collected from, disease free, African buffalo (Syncerus caffer), domestic cattle (Bos taurus) and eland (Taurotragus oryx) at Kongoni Game Valley Ranch in Nakuru County and Kenyatta University in Nairobi County. Urine samples collected for each animal species were aseptically pooled together. Each animal urine sample was then divided into two portions; 400 ml portions were used for fresh urine analysis while the other 400 ml portions were left open to age at ambient conditions. Bacteriological and phenols analysis was carried out on the ageing urine portions at 4 days ageing interval for 24 days. Morphological and biochemical analyses of bacterial isolates from fresh urine tentatively revealed presence of Proteus spp., Enterobacter spp Serratia spp., Klebsiella spp., Stapylococcus spp., Streptococcus spp. and Enteroccoccus spp. Bacterial counts were significantly different across ageing intervals in each of the urine samples of the study animals (p≤0.0001). Highest (9.40×107 CFU/ml) and lowest (4.36×105 CFU/ml) bacterial counts were observed in urine samples of cattle (day 20) and eland (fresh) respectively. Bacteriological analysis of ageing urine revealed ninteen morpholically different isolates. On subjecting the isolates to PAST software for morphological diversity, Shannon Weiner (H) showed highest diversity index at days twelve and sixteen, both at 2.639 and lowest diversity index in fresh urine, at 1.099. GC-Phenols analysis of ageing urine extracts showed a total of nine volatile phenols: P-cresol, o-cresol, m-cresol, phenol, 3-ethylphenol, 3-propylphenol, 2-methyloxyphenol, 4-ethylphenol and 4-propylphenol. There was important qualitative difference among ageing intervals for these phenols in all the urine samples. Phenols concentrations in urine extracts of the animals were statistically different, at P≤0.05, across ageing intervals. The concentration increased with ageing urine up to day 20 and depreciated at day 24. Comparison between animals, ageing intervals and their interaction revealed significant difference in amount of phenols emitted across days (P≤0.0001). Statistical comparison of specific phenols concentration among animals showed no significant difference at P≤0.05. When screened for potential to mediate phenols production, 8 isolates were found positive. Morphological, biochemical and 16S rRNA gene characterization of the isolates closely resembled Enterococcus faecalis KUB3006, Psychrobacter alimentarius PAMC 27887, Streptococcus agalactiae 2603V, Morganella morganii sub.sp. morganii KT, Micrococcus luteus NCTC2665, Planococcus massiliensis strain ES2, Ochrobactrum pituitosum AA2 and Enterococcus faecalis OGIRF. This study established that some of the bacterial communities colonising mammalian urine are well characterized by certain phenols, which influence tsetse-host seeking behaviour. The study opens potential pathways of reducing attraction of tsetse to the host animals and enhancing “push-pull” models in vector control that combines the use of these bacteria.