A Gram-negative, yellow-pigmented bacterium capable of gliding motility, designated strain WPCB118^T, was isolated from fresh water collected from the Woopo wetland (Republic of Korea). Cells were rod-shaped and sometimes filamentous. The major fatty acids were iso-C_15 : 02-OH and/or C_16 : 1ω7c(45.6 %), C_16 : 1ω5c(18.5 %), iso-C_15 : 0(9.5 %) and C_16 : 0(8.8 %). The predominant menaquinone and polar lipid were MK-7 and phosphatidylethanolamine, respectively. The DNA G+C content was 53.3 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain WPCB118^Thad an evolutionary lineage within the radiation encompassing the members of the family ‘Flexibacteraceae’, its closest neighbour beingSpirosoma lingualeLMG 10896^T(93.7 % gene sequence similarity). Data from this polyphasic study indicated that strain WPCB118^Tcould not be assigned to any recognized species. Strain WPCB118^Trepresents a novel species of the genusSpirosoma, for which the nameSpirosoma riguisp. nov. is proposed. The type strain is WPCB118^T(=KCTC 12531^T=NBRC 101117^T).

Three bacterial isolates from air samples in Korea, designated strains 6424S-25^T, 6515J-31^T and 6424S-61^T, were characterized using a polyphasic approach. The cells were strictly aerobic, Gram-stain-negative, non-motile, non-spore-forming and rod-shaped. Phylogenetic analysis of their 16S rRNA gene sequences revealed a clear affiliation with the phylum Bacteroidetes. Strains 6424S-25^T and 6515J-31^T showed 16S rRNA gene sequence similarities of 92.7–94.8 % to type strains of recognized species of the genus Adhaeribacter and strain 6424S-61^T was closely related to Segetibacter koreensis Gsoil 664^T (93.9 % similarity). The G+C contents of the DNA of strains 6424S-25^T, 6515J-31^T and 6424S-61^T were 44.5, 43.9 and 38.4 mol%, respectively. Major fatty acids of strains 6424S-25^T and 6515J-31^T were summed feature 4 (iso-C_17 : 1 I and/or anteiso-C_17 : 1 B), iso-C_15 : 0 and C_16 : 1ω5c. The fatty acid content of strain 6424S-61^T mainly comprised iso-C_15 : 1 G and iso-C_15 : 0. Comparative analysis of phenotypic and phylogenetic traits indicated that strains 6424S-25^T and 6515J-31^T represented two novel species of the genus Adhaeribacter and that strain 6424S-61^T should be considered as a novel species of the genus Segetibacter. The names Adhaeribacter aerophilus sp. nov. (type strain 6424S-25^T =KACC 14118^T =NBRC 106134^T), Adhaeribacter aerolatus sp. nov. (type strain 6515J-31^T =KACC 14117^T =NBRC 106133^T) and Segetibacter aerophilus sp. nov. (type strain 6424S-61^T =KACC 14119^T =NBRC 106135^T) are proposed for these organisms.

The impact of orthophosphate addition on biofilm formation and water quality was studied in corrosion-resistant stainless steel (STS) pipe and corrosion-susceptible ductile cast iron (DCI) pipe using cultivation and culture-independent approaches. Sample coupons of DCI pipe and STS pipe were installed in annular reactors, which were operated for 9 months under hydraulic conditions similar to a domestic plumbing system. Addition of 5 mg/L of phosphate to the plumbing systems, under low residual chlorine conditions, promoted a more significant growth of biofilm and led to a greater rate reduction of disinfection by-products in DCI pipe than in STS pipe. While the level of THMs (trihalomethanes) increased under conditions of low biofilm concentration, the levels of HAAs (halo acetic acids) and CH (chloral hydrate) decreased in all cases in proportion to the amount of biofilm. It was also observed that chloroform, the main species of THM, was not readily decomposed biologically and decomposition was not proportional to the biofilm concentration; however, it was easily biodegraded after the addition of phosphate. Analysis of the 16S rDNA sequences of 102 biofilm isolates revealed that Proteobacteria (50%) was the most frequently detected phylum, followed by Firmicutes (10%) and Actinobacteria (2%), with 37% of the bacteria unclassified. Bradyrhizobium was the dominant genus on corroded DCI pipe, while Sphingomonas was predominant on non-corroded STS pipe. Methylobacterium and Afipia were detected only in the reactor without added phosphate. PCR-DGGE analysis showed that the diversity of species in biofilm tended to increase when phosphate was added regardless of the pipe material, indicating that phosphate addition upset the biological stability in the plumbing systems.