- Volume 68, Issue 3, 2018

Two strains of soil bacteria, designated CA-16T and CA-161, were isolated from a sample of stream bank soil near Kyonggi University. Cells were strictly aerobic, Gram-stain-negative, catalase-negative, oxidase-positive, motile, non-spore-forming and rod-shaped. Colonies on tryptone soya agar were brownish cream in colour. Tyrosine, Tween 60 and Tween 40 were hydrolysed. The indole test was positive. Malic acid, lactic acid and valeric acid were assimilated. Phylogenetic analysis based on their 16S rRNA gene sequences revealed that strains CA-16T and CA-161 formed a lineage within the family Comamonadaceae of the class Betaproteobacteria that were distinct from various species of the genus Simplicispira . Strain CA-16T was most closely related to Simplicispira metamorpha DSM 1837T (97.86 % sequence similarity), Simplicispira limi EMB325T (97.72 %), Simplicispira psychrophila DSM 11588T (96.83 %) and Simplicispira piscis RSG39T (96.71 %). Both strains contained Q-8 as the major isoprenoid quinone. The major polar lipids of the strains were phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. The major cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C18 : 1 ω7c-11methyl, C16 : 0, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C12 : 0. The DNA G+C contents of the strains were 63.9–64.4 mol%. DNA–DNA hybridization similarities between strain CA-16T and other closest members of the genus Simplicispira ranged from 16 % to 24 %. On the basis of phenotypic, genotypic, chemotaxonomic and phylogenetic analyses, strains CA-16T and CA-161 represent a single novel species of the genus Simplicispira , for which the name Simplicispira soli sp. nov. is proposed. The type strain is CA-16T (=KEMB 9005-529T=KACC 19107T=NBRC 112689T).

An aerobic, Gram-stain-negative, rod-shaped, non-motile bacterium capable of degrading the polycyclic aromatic hydrocarbon pyrene was isolated from sediment of Pearl River and designated PrR001. 16S rRNA gene sequence analysis revealed that this strain was affiliated within the genus Defluviimonas in the family Rhodobacteraceae of the class Alphaproteobacteria and showed great similarity with the type strain Defluviimonas indica 20V17T (96.3 % similarity). The DNA G+C content of strain PrR001T was 68.3 mol%. The major cellular fatty acids comprised summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c), C19 : 0 cyclo ω8c, C18 : 0 3OH, and C18 : 0. The sole respiratory lipoquinone was ubiquinone-10. The main polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminolipid, an unidentified aminophospholipid and three unidentified phospholipids. Based on physiological, chemotaxonomic and phylogenetic analysis, strain PrR001T is suggested as a novel species in the genus Defluviimonas , for which the name Defluviimonas pyrenivorans sp. nov. is proposed. The type strain of Defluviimonas pyrenivorans is PrR001T (=CICC 24263T=KCTC 62192T).

With the advent of molecular phylogenetic methods, it has become possible to assess the bioversity of snow algae more accurately. In this study, we focused on a morphological, ultrastructural and taxonomic description of a new Chloromonas-like alga isolated from snow in the High Arctic (Svalbard). Light and transmission electron microscopy revealed broad ellipsoidal or ellipsoidal–cylindrical, occasionally spherical cells with a chloroplast without a pyrenoid, an inconspicuous eyespot and a papilla. The size difference and the aforementioned morphological traits clearly distinguished the alga from its closest counterparts within the genus Chloromonas. Moreover, we were able to cultivate the alga at both 5 and 20 °C, revealing the psychrotolerant nature of the strain. Phylogenetic analyses of the plastid rbcL and nuclear 18S rRNA gene showed that the alga is nested within a clade containing a number of psychrotolerant strains within the Chloromonadinia phylogroup (Chlorophyceae). In the rbcL phylogeny, the alga formed an independent lineage, sister to the freshwater species Chloromonas paraserbinowii. Comparisons of secondary structure models of a highly variable ITS2 rDNA marker showed support for a distinct species identity for the new strain. The ITS2 secondary structure of the new isolate differed from the closest matches ‘Chlamydomonas’ gerloffii and Choloromonas reticulata by three and five compensatory base changes, respectively. Considering the morphological and molecular differences from its closest relatives, a new psychrotolerant species from the Arctic, Choromonas arctica sp. nov., is proposed.