Gwang Il Jang

Pontimonas salivibrio gen. nov., sp. nov., a new member of the family Microbacteriaceae isolated from a seawater reservoir of a solar saltern.

A Gram-staining-positive, non-motile, strictly aerobic, non-spore-forming, vibrio-shaped bacterial strain, CL-TW6(T), was isolated from a reservoir seawater sample from a solar saltern in Korea. Analysis of the 16S rRNA gene sequence of strain CL-TW6(T) revealed a clear affiliation with the family Microbacteriaceae. Strain CL-TW6(T) showed the closest phylogenetic relationships with the genera Yonghaparkia and Microcella, with 16S rRNA gene sequence similarity of 94.8-95.3%. The strain grew in the presence of 1-9% sea salts, at 15-35 °C and at pH 7.0-9.0. The major cellular fatty acids of strain CL-TW6(T) were anteiso-C15:0 (32.6%), iso-C16:0 (20.4%), iso-C15:0 (13.2%) and iso-C14:0 (11.8%) and the major menaquinones were MK-9 and MK-10. Cell-wall analysis showed that the peptidoglycan of strain CL-TW6(T) contained 2,4-diaminobutyric acid, alanine, glycine and glutamic acid. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The genomic DNA G+C content of strain CL-TW6(T) was 60.0 mol%. The combined phenotypic, chemotaxonomic and phylogenetic data showed clearly that strain CL-TW6(T) could be distinguished from members of the family Microbacteriaceae with validly published names. Thus, strain CL-TW6(T) should be classified as representing a novel genus and species in the family Microbacteriaceae, for which the name Pontimonas salivibrio gen. nov., sp. nov. is proposed. The type strain of Pontimonas salivibrio is CL-TW6(T) (=KCCM 90105(T) =JCM 18206(T)).

Nitratireductor aquimarinus sp. nov., isolated from a culture of the diatom Skeletonema costatum, and emended description of the genus Nitratireductor

Two Gram-negative-staining, aerobic bacterial strains, designated CL-SC21(T) and CL-SC22, were isolated from a culture of the diatom Skeletonema costatum (Korean Marine Microalgae Culture Center, KMMCC strain B-396) established from the East Sea, Korea. The two novel strains shared 99.9 % 16S rRNA gene sequence similarity. Analysis of the 16S rRNA gene sequences showed an affiliation with the genus Nitratireductor, with the strains sharing 96.5-97.5 % similarity with the type strains of recognized species of the genus Nitratireductor and being most closely related to Nitratireductor aquibiodomus NL21(T). Phylogenetic analyses of the 16S rRNA gene sequences showed that strain CL-SC21(T) together with strain CL-SC22 belonged to the genus Nitratireductor and formed a robust clade among closely related Nitratireductor species. The polar lipids comprised phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, two unidentified aminophospholipids, an unidentified aminolipid, an unidentified phospholipid and five unidentified lipids. Ubiquinone 10 was the major quinone. The major cellular fatty acids of strains CL-SC21(T) and CL-SC22 were C(18 : 1)ω7c (70.6-72.3 %) and C(19 : 0)ω8c cyclo (10.9-11.8 %). The genomic DNA G+C contents of strains CL-SC21(T) and CL-SC22 were 56.7 and 57.1 mol%, respectively. The level of DNA-DNA relatedness between strains CL-SC21(T) and CL-SC22 was 86 % (reciprocal 91 %), indicating that the two isolates represented a single species. However, levels of DNA-DNA relatedness between N. aquibiodomus NL21(T) and strains CL-SC21(T) and CL-SC22 were 28 % (reciprocal 45 %) and 25 % (reciprocal 50 %), respectively. Phylogenetic analysis and the results of biochemical tests showed that strains CL-SC21(T) and CL-SC22 were different from all recognized species of the genus Nitratireductor. Thus, strains CL-SC21(T) and CL-SC22 represent a novel species of the genus Nitratireductor, for which the name Nitratireductor aquimarinus sp. nov. is proposed. The type strain is CL-SC21(T) ( = KCCM 90090(T) = JCM 17288(T)).

Nocardioides marinquilinus sp. nov., isolated from coastal seawater.

A Gram-stain-positive, non-motile, strictly aerobic, non-spore-forming and short rod-shaped bacterial strain, CL-GY44(T), was isolated from coastal seawater, Korea. Analysis of the 16S rRNA gene sequence of strain CL-GY44(T) revealed a clear affiliation with the genus Nocardioides. Based on phylogenetic analysis, strain CL-GY44(T) showed the closest phylogenetic relationship with Nocardioides ginsengagri BX5-10(T) and Nocardioides plantarum NCIMB 12834(T). Strain CL-GY44(T) was not able to grow in the presence of NaCl but grew with 0-5.5 % sea salts. The optimum temperature and pH for growth were 30 °C and pH 7.0. The major cellular fatty acids of strain CL-GY44(T) were C17 : 1ω6c, iso-C16 : 0, C16 : 0 and iso-C15 : 0 and the major menaquinone was MK-8(H4). The cell-wall analysis showed that strain CL-GY44(T) contained ll-diaminopimelic acid. The genomic DNA G+C content was 71.6 mol%. The combined phenotypic, chemotaxonomic and phylogenetic data showed that strain CL-GY44(T) could be clearly distinguished from members of the genus Nocardioides. Thus, strain CL-GY44(T) should be classified as representing a novel species in the genus Nocardioides, for which the name Nocardioides marinquilinus sp. nov. is proposed. The type strain is CL-GY44(T) ( = KCCM 90109(T) = JCM 18459(T)).

Gracilimonas rosea sp. nov., isolated from tropical seawater, and emended description of the genus Gracilimonas.

A Gram-staining-negative, non-motile, spore-forming, rod-shaped, marine bacterial strain, CL-KR2(T), was isolated from tropical seawater near Kosrae, an island in the Federated States of Micronesia. Analysis of the 16S rRNA gene sequence of strain CL-KR2(T) revealed a clear affiliation with the genus Gracilimonas. Based on phylogenetic analysis, strain CL-KR2(T) showed the closest phylogenetic relationship to Gracilimonas tropica CL-CB462(T), with 16S rRNA gene sequence similarity of 96.6 %. DNA-DNA relatedness between strain CL-KR2(T) and G. tropica CL-CB462(T) was 6.7 % (reciprocal 9.5 %). Strain CL-KR2(T) grew in the presence of 1-20 % sea salts and the optimal salt concentration was 3.5-5 %. The temperature and pH optima for growth were 35 °C and pH 7.5. The major cellular fatty acids (≥10.0 %) of strain CL-KR2(T) were iso-C15 : 0, summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c) and iso-C17 : 1ω9c and the only isoprenoid quinone was MK-7. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid, two unidentified glycolipids and two unidentified lipids. The genomic DNA G+C content of strain CL-KR2(T) was 43.2 mol%. The combined phenotypic, chemotaxonomic and phylogenetic data showed that strain CL-KR2(T) could be distinguished from the only member of the genus Gracilimonas with a validly published name. Thus, strain CL-KR2(T) should be assigned to a novel species in the genus Gracilimonas, for which the name Gracilimonas rosea sp. nov. is proposed. The type strain is CL-KR2(T) ( = KCCM 90206(T) = JCM 18898(T)).

Nocardioides salsibiostraticola sp. nov., isolated from biofilm formed in coastal seawater.

A Gram-staining-positive, non-motile, aerobic, non-spore-forming and short rod-shaped bacterial strain, PAMC 26527(T), was isolated from biofilm formed in coastal seawater of the Norwegian Sea. Analysis of the 16S rRNA gene sequence of strain PAMC 26527(T) revealed a clear affiliation with the genus Nocardioides. Based on phylogenetic analysis, strain PAMC 26527(T) showed the closest phylogenetic relationship with Nocardioides caricicola YC6903(T) with 16S rRNA gene sequence similarity of 96.3 %. Strain PAMC 26527(T) grew in the presence of 0-5.0 % sea salts. The optimum temperature and pH for growth were 20 °C and pH 7.5. The major cellular fatty acids of strain PAMC 26527(T) were iso-C16 : 0, C17 : 1ω8c and C18 : 1ω9c and the major isoprenoid quinone was MK-8(H4). Cell-wall analysis showed that strain PAMC 26527(T) contained LL-diaminopimelic acid. The genomic DNA G+C content was 69.3 mol%. The combined phenotypic, chemotaxonomic and phylogenetic data showed that strain PAMC 26527(T) could be clearly distinguished from recognized members of the genus Nocardioides. Thus, strain PAMC 26527(T) should be classified as representing a novel species in the genus Nocardioides, for which the name Nocardioides salsibiostraticola sp. nov. is proposed. The type strain is PAMC 26527(T) ( = KCTC 29158(T) = JCM 18743(T)).

Prokaryotic community composition in alkaline-fermented skate (Raja pulchra).

Prokaryotes were extracted from skates and fermented skates purchased from fish markets and a local manufacturer in South Korea. The prokaryotic community composition of skates and fermented skates was investigated using 16S rRNA pyrosequencing. The ranges for pH and salinity of the grinded tissue extract from fermented skates were 8.4-8.9 and 1.6-6.6%, respectively. Urea and ammonia concentrations were markedly low and high, respectively, in fermented skates compared to skates. Species richness was increased in fermented skates compared to skates. Dominant and predominant bacterial groups present in the fermented skates belonged to the phylum Firmicutes, whereas those in skates belonged to Gammaproteobacteria. The major taxa found in Firmicutes were Atopostipes (Carnobacteriaceae, Lactobacillales) and/or Tissierella (Tissierellaceae, Tissierellales). A combination of RT-PCR and pyrosequencing for active bacterial composition showed that the dominant taxa i.e., Atopostipes and Tissierella, were active in fermented skate. Those dominant taxa are possibly marine lactic acid bacteria. Marine bacteria of the taxa Lactobacillales and/or Clostridia seem to be important in alkaline fermentation of skates.

Effects of heavy rainfall on the composition of airborne bacterial communities

Wet deposition scavenges particles and particle-associated bacteria from the air column, but the impact of raindrops on various surfaces on Earth causes emission of surface-associated bacteria into the air column. Thus, after rainfall, these two mechanisms are expected to cause changes in airborne bacterial community composition (BCC). In this study, aerosol samples were collected at a suburban site in Seoul, Korea before and after three heavy rainfall events in April, May, and July 2011. BCC was investigated by pyrosequencing the 16S rRNA gene in aerosol samples. Interestingly, the relative abundance of non-spore forming Actinobacteria operational taxonomic units (OTUs) was always higher in post-rain aerosol samples. In particular, the absolute and relative abundances of airborne Propionibacteriaceae always increased after rainfall, whereas those of airborne Firmicutes, including Carnobacteriaceae and Clostridiales, consistently decreased. Marine bacterial sequences, which were temporally important in aerosol samples, also decreased after rainfall events. Further, increases in pathogen-like sequences were often observed in post-rain air samples. Rainfall events seemed to affect airborne BCCs by the combined action of the two mechanisms, with potentially adverse effects on human and plant health.