Flavobacterium nakdongensis sp. nov., Isolated from Fresh Water during the Cyanobacterial Bloom Period

Abstract

A novel Gram-negative bacterial strain, 20NA77.7^T, was isolated from fresh water of the Nakdong River. Strain 20NA77.7^T shared the highest similarity with Flavobacterium indicum GPTSA100-9^T (97.91%) and Flavobacterium urocaniciphilum DSM 27078^T (96.24%) in the 16S rRNA gene sequence. The digital DNA-DNA hybridization and average nucleotide identity values for strain 20NA77.7^T with Flavobacterium species were below 20.8% and 77.33%, respectively. The major fatty acids of strain 20NA77.7^T were identified as iso-C_15:0, iso-C_16:0, iso-C_15:1 G, anteiso-C_15:0, iso-C_15:0 3OH, and iso-C_16:0 3OH. Strain 20NA77.7^T contained phosphatidylethanolamine, one unidentified aminolipid, and three unidentified lipids as polar lipids and menaquinone-6 as menaquinone. The polyphasic evidence supports the classification of strain 20NA77.7^T as a novel species belonging to the genus Flavobacterium, for which the name Flavobacterium nakdongensis is proposed. The type strain is 20NA77.7^T (= KCTC 102000^T = LMG 33137^T).

Keywords: Cyanobacterial bloom; Flavobacterium nakdongensis; novel species.

Fig. 1. Phylogenetic tree for strain 20NA77.7^T built by using the neighbor-joining method for 16S rRNA gene sequences.

At each branch point, bootstrap value (≥ 50%) based on 1,000 replications is noted. Filled circles at nodes indicate that the corresponding nodes were also observed in the trees built with other algorithms (NJ, ME, and ML methods). However, open circles at nodes imply that they appeared only with NJ and ML algorithms. Chryseobacterium gleum CCUG 14555^T (AM232812) was used as an outgroup. Scale bar, 0.02 nucleotide substitutions per nucleotide position.

Fig. 2. Phylogenomic tree for strain 20NA77.7^T and closely related taxa. The branch lengths are proportion to the GBDP distance formula d5.

The numbers denoted above the branch points are GBDP pseudo-bootstrap support values (> 60% from 100 replications). An average branch support was 48.6%. The tree was rooted at the midpoint.