Coculturing of Mosquito‐Microbiome Bacteria Promotes Heme Degradation in Elizabethkingia anophelis

Anopheles mosquito microbiomes are intriguing ecological niches. Within the gut, microbes adapt to oxidative stress due to heme and iron after blood meals. Although metagenomic sequencing has illuminated spatial and temporal fluxes of microbiome populations, limited data exist on microbial growth dynamics. Here, we analyze growth interactions between a dominant microbiome species, Elizabethkingia anophelis, and other Anopheles‐associated bacteria. We find E. anophelis inhibits a Pseudomonas sp. via an antimicrobial‐independent mechanism and observe biliverdins, heme degradation products, upregulated in cocultures. Purification and characterization of E. anophelis HemS demonstrates heme degradation, and we observe hemS expression is upregulated when cocultured with Pseudomonas sp. This study reveals a competitive microbial interaction between mosquito‐associated bacteria and characterizes the stimulation of heme degradation in E. anophelis when grown with Pseudomonas sp. How they survive and thrive: In vitro coculture studies of Anopheles mosquito microbiome bacteria illustrate that Elizabethkingia anophelis outcompetes a neighboring Pseudomonas species. Through a combination of metabolomics, enzymology, and growth studies, a heme‐degrading enzyme was identified in this bipartite interaction.