Conservation of the Chitin Utilization Pathway in the Vibrionaceae

Abstract

ABSTRACT Vibrionaceae are regarded as important marine chitin degraders, and attachment to chitin regulates important biological functions; yet, the degree of chitin pathway conservation in Vibrionaceae is unknown. Here, a core chitin degradation pathway is proposed based on comparison of 19 Vibrio and Photobacterium genomes with a detailed metabolic map assembled for V. cholerae from published biochemical, genomic, and transcriptomic results. Further, to assess whether chitin degradation is a conserved property of Vibrionaceae , a set of 54 strains from 32 taxa were tested for the ability to grow on various forms of chitin. All strains grew on N -acetylglucosamine (GlcNAc), the monomer of chitin. The majority of isolates grew on α (crab shell) and β (squid pen) chitin and contained chitinase A ( chiA ) genes. chiA sequencing and phylogenetic analysis suggest that this gene is a good indicator of chitin metabolism but appears subject to horizontal gene transfer and duplication. Overall, chitin metabolism appears to be a core function of Vibrionaceae , but individual pathway components exhibit dynamic evolutionary histories.