Abstract
Genus Aliivibrio is known to harbor species exhibiting bioluminescence as well as pathogenic behavior affecting the fish farming industry. Current phylogenetic understanding of Aliivibrio has largely remained dormant after reclassification disentangled it from the Vibrio genus in 2007. There is growing evidence of wider diversity, but until now the lack of genomes and selective use of type strains have limited the ability to compare and classify strains firmly. In this study, a total of 143 bacterial strains, including 51 novel sequenced strains, were used to strengthen phylogenetic relationships in Aliivibrio by exploring intra-species and inter-species relations. Multilocus sequence analysis (MLSA), applying the six housekeeping genes 16S ribosomal RNA (rRNA), gapA, gyrB, pyrH, recA, and rpoA, inferred 12 clades and a singular branch in Aliivibrio. Along with four new phylogenetic clades, the MLSA resolved prior inconsistencies circumscribing Aliivibrio wodanis and formed a unique clade we propose as the novel species Aliivibrio sp. “friggae.” Furthermore, phylogenetic assessment of individual marker genes showed gyrB, pyrH, and recA superior to the 16S rRNA gene, resolving accurately for most species clades in Aliivibrio. In this study, we provide a robust phylogenetic groundwork for Aliivibrio as a reference point to classification of species.
Highlights
The family of Vibrionaceae contains a large number of bacterial species, many of which are described from marine habitats (Thompson et al, 2004)
The type strains of A. finisterrensis DSM 23419T and A. logei ATCC 29985T, and 51 additional Aliivibrio isolates were genome-sequenced for this study
A Multilocus sequence analysis (MLSA) scheme based on six concatenated genes (16S ribosomal RNA (rRNA) gene, gapA, gyrB, pyrH, recA, and rpoA) were used to infer the phylogeny and evolutionary relationships in the Aliivibrio genus
Summary
The family of Vibrionaceae contains a large number of bacterial species, many of which are described from marine habitats (Thompson et al, 2004). A comprehensive study of the family and its evolutionary history suggested a common ancestor dating back to the Devonian era some 600 million years ago (Sawabe et al, 2007). Vibrionaceae is versatile, delineated and holds 22 distinct phylogenetic clades with highly diverse species of which several are harbored within the genus Aliivibrio (Sawabe et al, 2007, 2013). The genus harbors bioluminescent bacteria that have symbiotic relationships with aquatic organisms (Bongrand and Ruby, 2019), and includes pathogens of marine animals (Hjerde et al, 2015; Kashulin et al, 2017).
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