Characterising the native midgut bacteria from main African malaria vector species, Anopheles arabiensis and An. funestus
No Thumbnail Available
Date
2021
Authors
Silva, Bianca E
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Malaria predominantly affects the African continent. The dominant African malaria vectors
include mosquito species from the Anopheles gambiae complex and the Anopheles funestus
group. Mosquito midgut microbiota play essential roles in physiology and disease
transmission. Thus, if common bacteria exist amongst vector species, this could be exploited
for malaria control. Accordingly, this study characterised the native midgut bacteria of
Anopheles arabiensis (member of An. gambiae complex) and Anopheles funestus (member of
An. funestus group). Additionally, field-collected mosquitoes are routinely preserved and
transported to a laboratory for analysis and thus far, it is unknown if midgut bacteria can be
identified from preserved Anopheles. Therefore, this study also investigated if midgut bacteria
could be identified after mosquito preservation.
Midgut bacteria were identified using culture-dependent (midgut dissections, culturomics,
MALDI-TOF MS) and culture-independent techniques (midgut dissections, bacterial DNA
extraction, next generation sequencing). Bacteria were identified from colonised mosquitoes
that were fresh (non-preserved) and preserved on silica desiccant or in RNAlater™ solution.
Bacteria were also characterised from field-collected An. arabiensis from KwaZulu-Natal and
Mpumalanga.
Results show that midgut bacteria can be characterised from preserved Anopheles samples.
Aeromonas hydrophila, Elizabethkingia anophelis, Enterobacter cloacae, Herbaspirillum
huttiense, Pseudomonas grimontii, Psychrobacter species, Raoultella ornithinolytica, Serratia
oryzae, and Staphylococcus epidermidis were bacteria isolated from both vectors. Of these, S.
epidermidis was also identified in field-collected An. arabiensis, making this a promising
bacterium for future studies investigating the use of mosquito midgut bacteria for disease
control. Overall, this study characterised the common midgut bacteria between An. arabiensis
and An. funestus and discovered that midgut bacteria could be identified from preserved
Anopheles.
Description
A dissertation submitted in fulfilment of the requirements for the degree of Master of Science to the Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, 2021