Insights from the Genome Annotation of Elizabethkingia anophelis from the Malaria Vector Anopheles gambiae

Abstract

Elizabethkingia anophelis is a dominant bacterial species in the gut ecosystem of the malaria vector mosquito Anopheles gambiae. We recently sequenced the genomes of two strains of E. anophelis, R26T and Ag1, isolated from different strains of A. gambiae. The two bacterial strains are identical with a few exceptions. Phylogenetically, Elizabethkingia is closer to Chryseobacterium and Riemerella than to Flavobacterium. In line with other Bacteroidetes known to utilize various polymers in their ecological niches, the E. anophelis genome contains numerous TonB dependent transporters with various substrate specificities. In addition, several genes belonging to the polysaccharide utilization system and the glycoside hydrolase family were identified that could potentially be of benefit for the mosquito carbohydrate metabolism. In agreement with previous reports of broad antibiotic resistance in E. anophelis, a large number of genes encoding efflux pumps and β-lactamases are present in the genome. The component genes of resistance-nodulation-division type efflux pumps were found to be syntenic and conserved in different taxa of Bacteroidetes. The bacterium also displays hemolytic activity and encodes several hemolysins that may participate in the digestion of erythrocytes in the mosquito gut. At the same time, the OxyR regulon and antioxidant genes could provide defense against the oxidative stress that is associated with blood digestion. The genome annotation and comparative genomic analysis revealed functional characteristics associated with the symbiotic relationship with the mosquito host.

Elizabethkingia anophelis: Molecular Manipulation and Interactions with Mosquito Hosts

“…Data presented here and by others support the idea that E. anophelis is involved in digestion of erythrocytes, which could influence mosquito fecundity. It should be noted that E. anophelis cell growth was not significantly inhibited when erythrocytes were added to M9 medium, indicating that this bacterium has evolved mechanisms to tolerate high oxidative pressures related to blood meal utilization (2).…”

“…The finding of a 6.0-fold-higher level of E. anophelis cells after the blood meal agrees with previous observations that flavobacteria dramatically increase proportionately after blood ingestion (1). Kukutla et al demonstrated that E. anophelis has hemolytic activity in vitro (2). Many genes encoding putative hemolysins and heme-degrading proteins are present in the E. anophelis genome.…”

“…lizabethkingia species have attracted much interest because of their close biologic associations with Anopheles malaria vector and Aedes dengue fever vector mosquitoes (1)(2)(3)(4)(5). Elizabethkingia was detected in diverse sources of mosquitoes (field caught, seminatural reared, and insectary reared) sampled in different regions (Africa, Europe, and North America) (1,3,4).…”

“…Together, these studies demonstrate that Elizabethkingia species impact their host mosquitoes' physiology and interactions with malaria parasites. Recently, several genomes from E. meningoseptica and E. anophelis were sequenced and annotated (2,14,15). A number of genes, such as those related to sugar transportation/utilization, blood cell lysis, and the antioxidative system, were found and provided insights into possible flavobacterial symbiotic relationships with mosquito hosts (2).…”

“…Recently, several genomes from E. meningoseptica and E. anophelis were sequenced and annotated (2,14,15). A number of genes, such as those related to sugar transportation/utilization, blood cell lysis, and the antioxidative system, were found and provided insights into possible flavobacterial symbiotic relationships with mosquito hosts (2). E. anophelis could therefore be a good model system to investigate how predominant bacteria interact with their hosts, vectored disease agents (parasites/viruses), and other associated microbes.…”