Marinagarivorans cellulosilyticus sp. nov., a cellulolytic bacterium isolated from the deep-sea off Noma-misaki, Japan

Cells from strain GE09^T, isolated from an artificially immersed nanofibrous cellulose plate in the deep sea, were Gram-stain-negative, motile, aerobic cells that could grow with cellulose as their only nutrient. Strain GE09^T was placed among members of Cellvibrionaceae, in the Gammaproteobacteria, with Marinagarivorans algicola Z1^T, a marine degrader of agar, as the closest relative (97.4 % similarity). The average nucleotide identity and digital DNA-DNA hybridization values between GE09^T and M. algicola Z1^T were 72.5 and 21.2 %, respectively. Strain GE09^T degraded cellulose, xylan and pectin, but not starch, chitin and agar. The different carbohydrate-active enzymes encoded in the genomes of strain GE09^T and M. algicola Z1^T highlights their differences in terms of target energy sources and reflects their isolation environments. The major cellular fatty acids of strain GE09^T were C_18 : 1  ω7c, C_16 : 0 and C_16 : 1  ω7c. The polar lipid profile showed phosphatidylglycerol and phosphatidylethanolamine. The major respiratory quinone was Q-8. Based on these distinct taxonomic characteristics, strain GE09^T represents a new species in the genus Marinagarivorans, for which we propose the name Marinagarivorans cellulosilyticus sp. nov. (type strain GE09^T=DSM 113420^T=JCM 35003^T).

Degradation Rates and Bacterial Community Compositions Vary among Commonly Used Bioplastic Materials in a Brackish Marine Environment

Plastic pollution threatens both terrestrial and aquatic ecosystems. As a result of the pressures of replacing oil-based materials and reducing the accumulation of litter in the environment, the use of bioplastics is increasing, despite little being known about their accurate biodegradation in natural conditions. Here, we investigated the weight attrition and degradation behavior of four different bioplastic materials compared to conventional oil-based polyethylene during a 1-year in situ incubation in the brackish Baltic Sea and in controlled 1 month biodegradation experiments in the laboratory. Bacterial communities were also investigated to verify whether putative plastic-degrading bacteria are enriched on bioplastics. Poly-l-lactic acid showed no signs of degradation, whereas poly(3-hydroxybutyrate/3-hydroxyvalerate) (PHB/HV), plasticized starch (PR), and cellulose acetate (CA) degraded completely or almost completely during 1-year in situ incubations. In accordance, bacterial taxa potentially capable of using complex carbon substrates and belonging, e.g., to class Gammaproteobacteria were significantly enriched on PHB/HV, PR, and CA. An increase in gammaproteobacterial abundance was also observed in the biodegradation experiments. The results show substantial differences in the persistence and biodegradation rates among bioplastics, thus highlighting the need for carefully selecting materials for applications with risk of becoming marine litter.

Isolation of marine xylene-utilizing bacteria and characterization of Halioxenophilus aromaticivorans gen. nov., sp. nov. and its xylene degradation gene cluster

Seven xylene-utilizing bacterial strains were isolated from seawater collected off the coast of Japan. Analysis of 16S rRNA gene sequences indicated that six isolates were most closely related to the marine bacterial genera Alteromonas, Marinobacter or Aestuariibacter. The sequence of the remaining strain, KU68FT, showed low similarity to the 16S rRNA gene sequences of known bacteria with validly published names, the most similar species being Maricurvus nonylphenolicus strain KU41ET (92.6% identity). On the basis of physiological, chemotaxonomic and phylogenetic data, strain KU68FT is suggested to represent a novel species of a new genus in the family Cellvibrionaceae of the order Cellvibrionales within the Gammaproteobacteria, for which the name Halioxenophilus aromaticivorans gen. nov., sp. nov. is proposed. The type strain of Halioxenophilus aromaticivorans is KU68FT (=JCM 19134T = KCTC 32387T). PCR and sequence analysis revealed that strain KU68FT possesses an entire set of genes encoding the enzymes for the upper xylene methyl-monooxygenase pathway, xylCMABN, resembling the gene set of the terrestrial Pseudomonas putida strain mt-2.

Rhodosalinus sediminis gen. nov., sp. nov., isolated from marine saltern

A novel Gram-stain-negative, moderately halophilic, motile, facultatively anaerobic and rod-shaped strain, designated WDN1C137^T, was isolated from a marine saltern at Wendeng, PR China. Optimal growth occurred at 40 °C, pH 7.5 and with 7.0 % (w/v) NaCl. Q-10 was the sole respiratory quinone. The major cellular fatty acids (>10.0 %) in WDN1C137^T were C18 : 1ω7c (46.2 %), cyclo C19 : 0ω8c (18.7 %) and C16 : 0 (12.3 %). The major polar lipids were phosphatidylglycerol, phosphoglycolipid, phosphatidylcholine, one unidentified glycolipid, one unidentified lipid, one unidentified aminolipid and two unidentified phospholipids. The genomic DNA G+C content was 70.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that WDN1C137^T shared the highest similarity (94.5 %) to Roseivivax jejudonensis KCTC 42110^T, followed by Roseivivax halodurans JCM 10272^T (94.2 %) and Roseivivax roseus DSM 23042^T (94.1 %). WDN1C137^T formed a separate branch from the closely related genera Roseivivax, Loktanella, Paracoccus and Cribrihabitans within the family Rhodobacteraceae, which indicated that it represented a novel genus in the phylogenetic tree. On the basis of the data from the current polyphasic study, the isolate is proposed to represent a novel species of a novel genus within the family Rhodobacteraceae, with the name Rhodosalinus sediminis gen. nov., sp. nov. The type strain of the type species is WDN1C137^T (=KCTC 52478^T=MCCC 1H00170^T).