Horticoccus luteus gen. nov., sp. nov., A Novel Member of the Phylum Verrucomicrobia Isolated from a Dichlorodiphenyltrichloroethane (DDT)-Contaminated Orchard Soil.

Strain KSB-15 T was isolated from an orchard soil that had been contaminated with the insecticide dichlorodiphenyltrichloroethane for about 60 years. The 16S rRNA gene sequence of this strain showed the highest sequence similarities with those of Oleiharenicola alkalitolerans NVTT (95.3%), Opitutus terrae PB90-1 T (94.8%), and Oleiharenicola lentus TWA-58 T (94.7%) among type strains, which are members of the family Opitutaceae within the phylum Verrucomicrobia. Strain KSB-15 T was an obligate aerobe, Gram-negative, non-motile, coccoid or short rod with the cellular dimensions of 0.37-0.62 µm width and 0.43-0.72 µm length. The strain grew at temperatures between 15-37 °C (optimum, 25 °C), at a pH range of 5.0-11.0 (optimum, pH 6.0), and at a NaCl concentration of 0-3% (w/v) (optimum, 0%). It contained menaquinone-7 (MK-7) as the major isoprenoid quinone (94.1%), and iso-C15:0 (34.9%) and anteiso-C15:0 (29.0%) as the two major fatty acids. The genome of strain KSB-15 T was composed of one chromosome with a total size of 4,320,198 bp, a G + C content of 64.3%, 3,393 coding genes (CDS), 14 pseudogenes, and 52 RNA genes. The OrthoANIu values, In silico DDH values and average amino acid identities between strain KSB-15 T and the members of the family Opitutaceae were 71.6 ~ 73.0%, 19.0 ~ 19.9%, and 55.9 ~ 62.0%, respectively. On the basis of our polyphasic taxonomic study, we conclude that strain KSB-15 T should be classified as a novel genus of the family Opitutaceae, for which the name Horticcoccus luteus gen. nov., sp. nov. is proposed.The type strain is KSB-15 T (= KACC 22271 T = DSM 113638 T).

Distinct Bacterial and Fungal Communities Colonizing Waste Plastic Films Buried for More Than 20 Years in Four Landfill Sites in Korea.

Plastic pollution has been recognized as a serious environmental problem, and microbial degradation of plastics is a potential, environmentally friendly solution to this. Here, we analyzed and compared microbial communities on waste plastic films (WPFs) buried for long periods at four landfill sites with those in nearby soils to identify microbes with the potential to degrade plastics. Fourier-transform infrared spectroscopy spectra of these WPFs showed that most were polyethylene and had signs of oxidation, such as carbon-carbon double bonds, carbon-oxygen single bonds, or hydrogen-oxygen single bonds, but the presence of carbonyl groups was rare. The species richness and diversity of the bacterial and fungal communities on the films were generally lower than those in nearby soils. Principal coordinate analysis of the bacterial and fungal communities showed that their overall structures were determined by their geographical locations; however, the microbial communities on the films were generally different from those in the soils. For the pulled data from the four landfill sites, the relative abundances of Bradyrhizobiaceae, Pseudarthrobacter, Myxococcales, Sphingomonas, and Spartobacteria were higher on films than in soils at the bacterial genus level. At the species level, operational taxonomic units classified as Bradyrhizobiaceae and Pseudarthrobacter in bacteria and Mortierella in fungi were enriched on the films. PICRUSt analysis showed that the predicted functions related to amino acid and carbohydrate metabolism and xenobiotic degradation were more abundant on films than in soils. These results suggest that specific microbial groups were enriched on the WPFs and may be involved in plastic degradation.