Paraconexibacter algicola gen. nov., sp. nov., a novel actinobacterium isolated from a eutrophic lake during the end of cyanobacterial harmful algal blooms, and proposal of Paraconexibacteraceae fam. nov. in the order Solirubrobacterales

Abstract

A novel bacterium, strain Seoho-28T, was isolated from a shallow eutrophic lake during the end of cyanobacterial harmful algal blooms and was characterized taxonomically and phylogenetically. Strain Seoho-28T was a Gram-stain-negative, aerobic, rod-shaped and non-motile bacterium. The strain grew optimally with 0% NaCl and at 25-30°C on Reasoner's 2A medium. The phylogenetic analysis based on 16S rRNA gene sequences positioned the novel strain among the order Solirubrobacterales, but sequence similarities to known species were less than 94.7%. The genomic DNA G+C content of the strain Seoho-28T was 74.2mol%. Genomic comparisons of strain Seoho-28T with families in the order Solirubrobacterales were made using the Genome-to-Genome Distance Calculator, average nucleotide identity and average amino acid identity analyses (values indicated ≤14.9, ≤73.5 and ≤57.8%, respectively). Strain Seoho-28T contained C16:0-iso, C18:1 ω9c and C16:0 as major fatty acids and MK-7 (H4) as the major quinone. Strain Seoho-28T contained diphosphatidylglycerol, phosphatidylinositol and an unidentified phospholipid as major polar lipids. Meso- and ll-diaminopimelic acids were the diagnostic diamino acids in the cell-wall peptidoglycan. Based on the genotypic, chemotaxonomic and phenotypic results, strain Seoho-28T represents a novel genus and species, Paraconexibacter algicola gen. nov., sp. nov., which belongs to a new family Paraconexibacteraceae in the order Solirubrobacterales and the class Thermoleophilia. The type strain is Seoho-28T (=KCTC 39791T=JCM 31881T).