Polyphasic Characterization and Genomic Insights into an Aerobic Denitrifying Bacterium, Shewanella zhuhaiensis sp. nov., Isolated from a Tidal Flat Sediment

Abstract

A new, facultatively anaerobic, light-yellow, and rod-shaped bacterium designated as 3B26T isolated from Qi’ao Island’s tidal flat sediment was identified. Strain 3B26T can hydrolyze gelatin, aesculin, and skim milk. The major cellular fatty acids were identified as iso-C15:0, referred to as summed feature 3, and C16:0; the polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, and phospholipid; and the quinones contained Q-7, Q-8, MK-7, and MMK7. The genomic size of strain 3B26T was 4,682,650 bp, and its genomic DNA G + C content was 54.8%. While a 16S rRNA gene-based phylogenetic analysis confirmed that strain 3B26T belongs to the genus Shewanella, both phylogenomic inference and genomic comparison revealed that strain 3B26T is distinguishable from its relatives, and digital DNA-DNA hybridization (dDDH) values of 24.4–62.6% and average nucleotide identities (ANIs) of 83.5–95.6% between them were below the 70% dDDH and 96% ANI thresholds for bacterial species delineation. Genomic functional analysis demonstrated that strain 3B26T possesses complete gene clusters of eicosapentaenoic acid biosynthesis and denitrification. Based on the evidence above, strain 3B26T is considered to represent a novel species of the genus Shewanella, and the name Shewanella zhuhaiensis sp. nov. (type strain 3B26T = GDMCC 1.2057T = KCTC 82339T) is proposed.