Yeoung Min Hwang

Mucilaginibacter defluvii sp. nov., isolated from a dye wastewater treatment facility.

A non-motile, rod-shaped bacterium, designated strain A5(T), was isolated from a dye wastewater treatment facility in the Republic of Korea. Cells were Gram-reaction-negative, aerobic, catalase-positive and oxidase-negative. The major fatty acids were C(16 : 0), C(18 : 0), iso-C(15 : 0) and summed feature 3 (C16 : 1)ω6c and/or C(16 : 1ω7c) and the major polar lipid was phosphatidylethanolamine. The strain contained MK-7 as the only isoprenoid quinone and the DNA G+C content was 41.2 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain A5(T) forms an evolutionary lineage within the radiation encompassing the members of genus Mucilaginibacter, with Mucilaginibacter lutimaris BR-3(T) as its nearest neighbour (96.6% sequence similarity). A number of phenotypic characteristics distinguished strain A5(T) from the members of the genus Mucilaginibacter. On the basis of the evidence presented in this study, strain A5(T) represents a novel species, for which the name Mucilaginibacter defluvii sp. nov. is proposed. The type strain is A5(T) ( = KCTC 23922(T) = JCM 18283(T)).

Marinivirga aestuarii gen. nov., sp. nov., a member of the family Flavobacteriaceae, isolated from marine environments, and emended descriptions of the genera Hyunsoonleella, Jejuia and Pontirhabdus and the species Hyunsoonleella jejuensis, Jejuia pallidilutea and Pontirhabdus pectinivorans.

Two orange, rod-shaped, Gram-reaction-negative, aerobic bacterial strains devoid of flagella and gliding motility, designated strains KYW371(T) and KS18 were isolated from a seawater sample and a shellfish Ruditapes philippinarum, respectively, collected from Gwangyang Bay, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two strains belonged to the family Flavobacteriaceae; and that strain KYW371(T) was most closely related to Algibacter mikhailovii LMG 23988(T) (96.7 % sequence similarity), Pontirhabdus pectinivorans JC2675(T) (96.3 %), Postechiella marina M091(T) (95.6 %) and Hyunsoonleella jejuensis CNU004(T) (95.3 %). The 16S rRNA gene sequence similarity (98.8 %) and DNA-DNA relatedness (78.1 %) between strains KYW371(T) and KS18 indicated that these two strains represented a single species. The predominant cellular fatty acids of strain KYW371(T) were iso-C15 : 1 G, iso-C15 : 0, iso-C15 : 0 3-OH and iso-C17 : 0 3-OH. Flexirubin-type pigments were absent. MK-6 was the only isoprenoid quinone and the DNA G+C content was 34.8-36.6 mol%. Data from this taxonomic study employing a polyphasic approach suggested that the isolates represent a novel species in a new genus in the family Flavobacteriaceae, for which the name Marinivirga aestuarii gen. nov., sp. nov. is proposed. The type strain is KYW371(T) ( = KCTC 23449(T) = JCM 17452(T)), and an additional strain of the species is KS18 ( = KCTC 23128 = JCM 16845). Emended descriptions of the genera Hyunsoonleella, Jejuia and Pontirhabdus and the species Hyunsoonleella jejuensis, Jejuia pallidilutea and Pontirhabdus pectinivorans are also proposed.

Algibacter aquimarinus sp. nov., isolated from a marine environment, and reclassification of Pontirhabdus pectinivorans as Algibacter pectinivorans comb. nov.

An orange-coloured, rod-shaped, Gram-reaction-negative and aerobic bacterial strain, designated KYW589(T), was isolated from seawater collected from Gwangyang Bay, Republic of Korea. The isolate required sea salts for growth. Gliding motility was observed. Flexirubin-type pigments were absent. Major cellular fatty acids (>10% of the total) were iso-C15:0, iso-C17:0 3-OH, iso-C15:1 G, C16:0, iso-C15:0 3-OH and C18:0. The main polar lipids were phosphatidylethanolamine, two unidentified aminolipids and two unidentified lipids. The predominant isoprenoid quinone was MK-6. The DNA G+C content was 38.6 ± 0.7 mol% (mean ± sd of three determinations). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain KYW589(T) belongs to the family Flavobacteriaceae, and was related to the genus Algibacter. Based on data from a study using a polyphasic taxonomic approach, it is proposed that strain KYW589(T) represents a novel species belonging to the genus Algibacter, for which the name Algibacter aquimarinus sp. nov. is proposed. The type strain is KYW589(T) (=KCTC 23928(T) =JCM 18287(T)). Reclassification of Pontirhabdus pectinivorans Yi et al. 2011 to the genus Algibacter, as Algibacter pectinivorans comb. nov. (type strain JC2675(T) =KACC 14153(T) =JCM 17107(T)), is also proposed.

Algibacter agarivorans sp. nov. and Algibacter agarilyticus sp. nov., isolated from seawater, reclassification of Marinivirga aestuarii as Algibacter aestuarii comb. nov. and emended description of the genus Algibacter.

Two yellow-pigmented, rod-shaped, non-motile, Gram-reaction-negative and aerobic bacterial strains, designated KYW560(T) and KYW563(T), were isolated from seawater collected from Gwangyang Bay, Republic of Korea. The isolates required sea salts for growth. Flexirubin-type pigments were absent. The common major cellular fatty acids (>5% of total) of the two strains were C(16:0), C(18:0), iso-C(15:0), anteiso-C(15:0), iso-C(15:1) G, iso-C(17:0) 3-OH and summed feature 3 (C(16:1)ω6c and/or C(16:1)ω7c). Strain KYW560(T) also contained iso-C(15:0) 3-OH and C(20:1)ω9c as major fatty acids. The main polar lipids were phosphatidylethanolamine, an unidentified aminolipid and two unidentified lipids. The predominant isoprenoid quinone was MK-6. The DNA G+C contents of strains KYW560(T) and KYW563(T) were 41.0 ± 0.7 and 38.3 ± 0.4 mol% (mean ± sd of three determinations), respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolates belonged to the family Flavobacteriaceae, and were related to the genus Algibacter. Based on data from this taxonomic study using a polyphasic approach, it is proposed that the isolates represent novel species of the genus Algibacter, for which the names Algibacter agarivorans sp. nov. (type strain, KYW560(T) =KCTC 23855(T) =JCM 18285(T)) and Algibacter agarilyticus sp. nov. (type strain, KYW563(T) =KCTC 23857(T) =JCM 18275(T)) are proposed. Reclassification of Marinivirga aestuarii as Algibacter aestuarii comb. nov. and emended description of the genus Algibacter are also proposed.

Sphingopyxis rigui sp. nov. and Sphingopyxis wooponensis sp. nov., isolated from wetland freshwater, and emended description of the genus Sphingopyxis.

Two yellow-pigmented, Gram-reaction-negative strains, designated 01SU5-P(T) and 03SU3-P(T), were isolated from the freshwater of Woopo wetland, Republic of Korea. Both strains were aerobic, non-motile and catalase-negative. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two isolates belong to the genus Sphingopyxis, showing the highest level of sequence similarity with respect to Sphingopyxis witflariensis W-50(T) (95.4-95.7 %). The two novel isolates shared 99.4 % sequence similarity. DNA-DNA hybridization between the isolates and the type strain of S. witflariensis clearly suggested that strains 01SU5-P(T) and 03SU3-P(T) represent two separate novel species in the genus Sphingopyxis. The two strains displayed different fingerprints after PCR analysis using the repetitive primers BOX, ERIC and REP. Several phenotypic characteristics served to differentiate these two isolates from recognized members of the genus Sphingopyxis. The data from the polyphasic study presented here indicated that strains 01SU5-P(T) and 03SU3-P(T) should be classified as representing novel species in the genus Sphingopyxis, for which the names Sphingopyxis rigui sp. nov. and Sphingopyxis wooponensis sp. nov., respectively, are proposed. The type strain of Sphingopyxis rigui sp. nov. is 01SU5-P(T) ( = KCTC 23326(T) = JCM 17509(T)) and the type strain of Sphingopyxis wooponensis sp. nov. is 03SU3-P(T) ( = KCTC 23340(T) = JCM 17547(T)).

Lutibacter agarilyticus sp. nov., a marine bacterium isolated from shallow coastal seawater.

A Gram-staining-negative, non-spore-forming, non-gliding and rod-shaped bacterial strain KYW566(T), was isolated from seawater of the Suncheon Bay, Korea, and its taxonomic position was investigated by using a polyphasic study. The cells contained MK-6 as the only respiratory quinone and contained iso-C15 : 0 (13.8 %), iso-C16 : 0 3-OH (13.1 %), anteiso-C15 : 0 (9.3 %), iso-C15 : 0 3-OH (8.7 %), iso-C15 : 1 G (6.3 %) and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) (6.0 %) as the major fatty acids. The DNA G+C content of strain KYW566(T) was 41.6 ± 0.8 mol% (mean ± sd of three determinations). A phylogenetic tree based on 16S rRNA gene sequences showed that strain KYW566(T) forms an evolutionary lineage within the radiation enclosing the members of the genus Lutibacter with Lutibacter flavus IMCC1507(T) as its nearest neighbour (96.7 % sequence similarity). A number of phenotypic characteristics distinguished strain KYW566(T) from described members of the genus Lutibacter. On the basis of the evidences presented in this study, strain KYW566(T) represents a novel species, for which the name Lutibacter agarilyticus sp. nov. is proposed. The type strain is KYW566(T) ( = KCTC 23842(T) = JCM 18281(T)).

Mesoflavibacter aestuarii sp. nov., a zeaxanthin-producing marine bacterium isolated from seawater

An orange, rod-shaped, Gram-reaction-negative, aerobic and gliding bacterial strain devoid of flagella, designated strain KYW614(T), was isolated from seawater collected from Gwangyang Bay, Republic of Korea. Zeaxanthin was the major carotenoid pigment produced and flexirubin-type pigments were not produced. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain KYW614(T) belonged to the family Flavobacteriaceae and it was most closely related to Mesoflavibacter zeaxanthinifaciens TD-ZX30(T) (96.5%, sequence similarity). The predominant cellular fatty acids of strain KYW614(T) were iso-C(15 : 1) G (10.5%), summed feature 3 (C(16 : 1)ω7c/C(16 : 1)ω6c; 10.0%), iso-C(15 : 0) (9.5%), C(15 : 0) (7.5%) and iso-C(17 : 0) 3-OH (7.4%). MK-6 was the only isoprenoid quinone and the DNA G+C content was 32.6 mol%. Data from a polyphasic taxonomic study suggested that the isolate represents a novel species in the genus Mesoflavibacter, for which the name Mesoflavibacter aestuarii sp. nov. is proposed. The type strain is KYW614(T) ( = KCTC 32269(T) = JCM 19524(T)).

Seasonal Variation of Bacterial Community in the Seawater of Gwangyang Bay Estimated by Amplified Ribosomal DNA Restriction Analysis

To determine the seasonal variation of bacterial community in the seawater of Gwangyang Bay, three hundred thirty six bacterial strains were isolated on February, May, July and October 2011. Amplified Ribosomal DNA Restriction Analysis (ARDRA) was used to construct the phylotyes of the isolates using the restriction endonuclease, Hae III. Diversity indices of ARDRA patterns were calculated. One hundred and one phylotypes including 40 unique pylotypes were found at the 80% similarity level. Partial 16S rRNA genes of one hundred thirty nine strains representing each phylotypes were sequenced and compared. Bacterial community composed of 4 different phyla which include Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes. Proteobacteria was the prevailing phylum in all seasons, followed by Bacteroidetes in winter, spring and autumn while Actinobacteria in summer. At the family level, Flavobacteriaceae dominated in winter and spring and Pseudoalteromonadaceae did in summer and autumn. Genera Altererythrobacter, Loktanella, Pseudoalteromonas and Vibrio were encountered in all seasons. The most diverse bacterial community was found in autumn followed by the order of spring, winter and summer.

Prevalence of Extended-spectrum β-Lactamase and Quinolone Resistance Genes in Escherichia coli Clinical Isolates and their Antibiotic Resistance

The aim of this study was to investigate the prevalence of Extended-spectrum -lactamase (ESBL) gene and quinolone resistance determinant (qnr) and the pattern of antibiotic resistance in the ESBL-producing Escherichia coli clinical isolates. The 42 ESBL-producing strains from total 274 isolates were detected using a double disk synergy test. They were isolated from various specimens, such as urine (28 strains), sputum (6 strains), pus (3 strains), wound (2 strains), blood (2 strains), and tissue (1 strain). Using the PCR with the specific primers ESBL, ESBL and qnr gene types were determined. Thirty-five strains possessed one or two ESBL genes. CTX-M-1 type was the most abundant followed by CTX-M-9 type and TEM, but SHV, CTX-M-2, and CTX-M-8 gene types were not detected. qnr gene types were detected from ten isolates in the order of qnrB4, qnrB1, and qnrS. Coexistence of ESBL and qnr genes was found. ESBL-producing isolates showed high resistance against some antibiotics, such as cefotaxmie (80.0%), levofloxacin (82.9%), and ampicillin (100%). Neither a synergy effect from the coexistence of ESBL and qnr genes on antibiotic resistance nor a correlation between the production of qnr gene and quinolone resistance were found.