Isolation and characterization of microbiota from the midgut Of field collected anopheles mosquitoes in some malaria Endemic areas of Ethiopia

Abstract

Anopheles mosquitoes are haematophagous insect transmitters of the several medically important diseases including the deadliest malaria. Insecticide resistance and invasive new Anopheles species are among the challenges to curb the disease, necessitating search for an alternative vector control strategy. Diverse Anopheline midgut microflora of different species from some malaria endemic areas have been considered to haveimpact on malaria parasite burden through colonization mechanisms, involving either direct Plasmodium microbiota interaction or bacterial mediated induction of mosquito immune response. Isolation and characterization of midgut microbiota from both primary and secondary malaria vectors of Ethiopia is important to investigate diversity and distribution of midgut microbiota and have better baseline information for future study. The objective of this study was to investigate cutureable midgut microbiota from field collected Anopheles species in some malaria endemic areas of Ethiopia for understanding of the role of microbes towards infection and vector control methods (IRS)and further designing alternative vector control strategy. Both primary and secondary malaria vectors of Ethiopia and larvae of Anopheles gambiae s.l were sampled for mid-gut microbial analysis from Lare, Asendabo and Batu study sites following standard entomological methods. Samples of WHO insecticide bioassayed An. gambiae s.l were also used for midgut microbiota analysis. The midgut microbiota was characterized on the basis of morphological, biochemical features. Antibiotic susceptibility status of selected bacteria was also conducted. SPSS software version 21 was used for statistical analysis. Accordingly, a total of 659 bacteria and five fungi were isolated from midgut of 115 adult Anopheles mosquitoes and15 larvae of An. gambiae s.l. Eleven (11) genera of bacteria belonging to Staphylococcous, Klebsiella, Bacillus, Eschericia, Pseudomonas, Entrobacter, Proteus, Aeromonas, Enterococcus, Micrococcus, Salmonella and five genera of fungi belonging to Penicillium, Aspergillus, Rhizopus, Curvularia, and Nigrospora were identified from the dissected Anopheles midgut samples. The dominant genera were Staphylococcus (34.74%, n=229) followed by Klebsiella (22.15%, n=123) and Pseudomonas (7.58 %, n= 47). From the inhibition zones observed, there was a significant variation between the antibiotics (p < 0.05) used for susceptibility test. Individual species displayed variable level of susceptibility to different antibiotics and there was also a difference in susceptibility level between different bacterial species. Accordingly, Eschericia coli was 100% susceptible to vancomycine, followed by Klebsiella 96.55 % susceptible to Vancomycin antbiotic susceptibility. From the current study, the diverse midgut microbiota islated from the malaria vectors of Ethiopia can serve as abase line information for further research focusing on the role of the microbiota in disease transmission so as to design an alternative microbiota-based vector control strategy