Rheinheimera aquatica sp nov., Antimicrobial Activity-Producing Bacterium Isolated from Freshwater Culture Pond

A bacterial strain designated GR5(T), previously isolated from a freshwater culture pond in Taiwan while screening for bacteria for antimicrobial compounds, was characterized using a polyphasic taxonomic approach. Strain GR5(T) was found to be Gram-negative, aerobic, greenish-yellow colored, rod-shaped, and motile by means of a single polar flagellum. Growth occurred at 10-40 degrees C (optimum, 35 degrees C), pH 7.0-8.0 (optimum pH 8.0), and with 0-2.0% NaCl (optimum, 0.5-1.0%). The major fatty acids were C-16:1 omega 7c (36.3%), C-16:0 (16.6%), C-12:0 3-OH (12.5%), and C-18:1 omega 7c (9.1%). The major respiratory quinone was Q-8, and the DNA G+C content of the genomic DNA was 51.9 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain GR5(T) belongs to the genus Rheinheimera, where its most closely related neighbors are Rheinheimera texasensis A62-14B(T) and Rheinheimera tangshanensis JA3-B52(T) with sequence similarities of 98.1% and 97.5%, respectively, and the sequence similarities to any other recognized species within Gammaproteobacteria are less than 96.5%. The mean level. of DNA DNA relatedness between strain GR5(T) and R. texasensis A62-14B(T), the strain most closely related to the isolate, was 26.5+/-7.6%. Therefore, based, on the phylogenetic and phenotypic data, strain GR5(T) should be classified as a novel species, for which the name Rheinheimera aquatica sp. nov. is proposed. The type strain is GR5(T) (=BCRC 80081(T)= LMG 25379(T)).