Yoon-ng Ju

Nocardioides sediminis sp. nov., isolated from a sediment sample

A strictly aerobic, motile, short-rod-shaped, Gram-positive-staining actinomycete strain, designated MSL-01(T), was isolated from a sediment sample from Bigeum Island of Korea. 16S rRNA gene sequence analysis revealed that the isolate MSL-01(T) belonged to the genus Nocardioides, with the highest sequence similarity to Nocardioides terrigena DS-17(T) (98.54 %), but the DNA-DNA relatedness to this type strain was 34 %. The physiological properties of strain MSL-01(T) differ from those of Nocardioides terrigena DS-17(T) and other species of Nocardioides. The diamino acid in the cell-wall peptidoglycan of strain MSL-01(T) is ll-diaminopimelic acid, the major menaquinone is MK-8(H(4)) and iso-C(16 : 0) is the major fatty acid component. The name Nocardioides sediminis sp. nov. is proposed for the novel species, with the type strain MSL-01(T) (=DSM 19263(T) =KCTC 19271(T)).

Marmoricola bigeumensis sp. nov., a member of the family Nocardioidaceae.

A Gram-positive, aerobic strain, designated MSL-05T, was isolated from a soil sample collected from Bigeum Island, Korea, and its taxonomic position was investigated using a polyphasic approach. Cells of the novel strain were coccoid and occurred singly. The novel strain grew over a wide range of NaCl concentrations (0-7 %, w/v). The optimum growth temperature and pH were 28 degrees C and 7.2, respectively. Chemotaxonomic characteristics [peptidoglycan type, meso-diaminopimelic acid; major menaquinone, MK-8(H4); predominant fatty acids, i-C16 : 0, ai-C17 : 0, C16 : 0 and i-C14 : 0; DNA G+C content of 72.9 mol%] placed this organism within the genus Marmoricola. 16S rRNA gene sequence analysis confirmed this classification, but showed that the novel strain was distinct from its nearest neighbours. Strain MSL-05T was found in the same clade as the type strains of species of the genus Marmoricola and also shared low gene sequence similarity with Marmoricola aequoreus JCM 13812T (96.91 %) and Marmoricola aurantiacus DSM 12652T (95.39 %). Based on the results of phenotypic and phylogenetic analyses, it is proposed that the new isolate should be classified as a novel species in the genus Marmoricola, for which the name Marmoricola bigeumensis sp. nov. is proposed. The type strain is MSL-05T (=KCTC 19287T=DSM 19426T).

Nocardioides koreensis sp. nov., Nocardioides bigeumensis sp. nov. and Nocardioides agariphilus sp. nov., isolated from soil from Bigeum Island, Korea.

Three Gram-positive, coccoid to rod-shaped actinobacteria, designated strains MSL-09(T), MSL-19(T) and MSL-28(T), were isolated from a soil sample collected from Bigeum Island in Korea, and were subjected to a polyphasic taxonomic analysis. All three isolates grew optimally at pH 7.5-9.0 and 28-30 degrees C. 16S rRNA gene analysis revealed that all three strains belonged to the genus Nocardioides, with strains MSL-09(T), MSL-19(T) and MSL-28(T) respectively showing the highest sequence similarity to Nocardioides aquaticus DSM 11439(T) (96.25 %), Nocardioides aquiterrae GW-9(T) (95.75 %) and Nocardioides terrigena DS-17(T) (95.61 %). Chemotaxonomically, they contain LL-2,6-diaminopimelic acid in the cell-wall peptidoglycan, MK-8(H(4)) as the predominant menaquinone and diphosphatidylglycerol, phosphatidylglycerol and some unknown lipids as the polar lipids found in the cell wall. iso-C(16 : 0) is a major fatty acid. The G+C content of the DNA was respectively 69.9, 69.3 and 69.4 mol% for strains MSL-09(T), MSL-19(T) and MSL-28(T). Based on morphological, physiological, biochemical and chemotaxonomic characters presented in this study, the three strains represent novel species of the genus Nocardioides. The names Nocardioides koreensis sp. nov. (type strain MSL-09(T) =KCTC 19272(T) =DSM 19266(T)), Nocardioides bigeumensis sp. nov. (type strain MSL-19(T) =KCTC 19290(T) =DSM 19320(T)) and Nocardioides agariphilus sp. nov. (type strain MSL-28(T) =KCTC 19276(T) =DSM 19323(T)) are proposed.

Leifsonia kribbensis sp. nov., isolated from soil

A yellow-pigmented actinobacterium, designated strain MSL-13T, was isolated from a soil sample collected from Bigeum Island, Republic of Korea, and its taxonomic position was determined by using a polyphasic approach. Strain MSL-13T showed phenotypic and chemotaxonomic properties consistent with its classification in the genus Leifsonia. 16S rRNA gene sequence analysis of strain MSL-13T with sequences from Leifsonia naganoensis DB103T, Leifsonia aquatica DSM 20146T, Leifsonia xyli subsp. cynodontis JCM 9733T, Leifsonia poae VKM Ac-1401T and Leifsonia shinshuensis DB102T revealed similarities of 96.22, 96.19, 95.77, 95.44 and 95.37 %, respectively, with differences of 39-65 nt among 1483 total nucleotides aligned. Based on differences in phenotypic and genotypic characteristics, strain MSL-13T (=KCTC 19267T =DSM 19272T) is designated as the type strain of a novel species of the genus Leifsonia, for which the name Leifsonia kribbensis sp. nov. is proposed.

Cryobacterium mesophilum sp. nov., a novel mesophilic bacterium.

A novel mesophilic, Gram-positive, cream- to pale yellow-pigmented, aerobic bacterium, designated MSL-15T, was isolated from a soil sample collected from Bigeum Island, South Korea. The cells were catalase-positive, motile and irregular rods. The diamino acid content of the cell-wall peptidoglycan was determined to be 2,4-diaminobutyric acid. Strain MSL-15T grew well between 20 and 28 degrees C, with optimum growth occurring at 25-28 degrees C. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0 and iso-C15 : 0. The genomic DNA G+C content was 70.0 mol%. A phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MSL-15T was associated with the genus Cryobacterium and exhibited 96.6 % sequence similarity to Cryobacterium psychrotolerans JCM 13925T and 94.8 % similarity to Cryobacterium psychrophilum JCM 1463T. Phenotypic, chemotaxonomic and phylogenetic data revealed that strain MSL-15T represents a novel species within the genus Cryobacterium, for which the name Cryobacterium mesophilum is proposed. The type strain is MSL-15T (=DSM 19267T=KCTC 19270T).

Leifsonia bigeumensis sp. nov., isolated from soil on Bigeum Island, Korea.

A Gram-positive, motile, mesophilic bacterium that formed yellowish-white, circular, convex, glistening colonies, strain MSL-27T, was isolated from a soil sample from Bigeum Island, Korea, and its taxonomic position was investigated by a polyphasic approach. Cells of strain MSL-27T are non-spore-forming, irregular rods, usually fragmenting into shorter rods or coccoid elements. The growth temperature and pH ranges are 20-37 degrees C and pH 6.0-12.0, with optimum growth at 28 degrees C and pH 8.0. MK-11 is the major menaquinone and dl-2,4-diaminobutyric acid is found in the cell-wall peptidoglycan. The major fatty acids are i-C16:0 (39 %), ai-C15:0 (36 %), ai-C17:0 (18 %) and i-C15:0 (2 %). The G+C content is 69.0 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain MSL-27T should be placed in the genus Leifsonia. Levels of similarity between the 16S rRNA gene sequence of strain MSL-27T and those of the type strains of the other members of the genus Leifsonia ranged from 95.8 to 96.7 %. Based on phenotypic characteristics, biochemical properties and chemotaxonomic features, strain MSL-27T (=KCTC 19268T =DSM 19322T) represents the type strain of a novel species of Leifsonia, for which the name Leifsonia bigeumensis sp. nov. is proposed.

Frigoribacterium mesophilum sp. nov., a mesophilic actinobacterium isolated from Bigeum Island, Korea

A taxonomic study was performed on strain MSL-08T, which was isolated from a soil sample collected from Bigeum Island. The novel isolate was aerobic and Gram-positive. Cells were short and motile rods. Growth temperature ranged from 20 to 28 degrees C and the pH for growth ranged from 6.5 to 12.0. The optimum growth temperature and pH were 28 degrees C and 7.3, respectively. The predominant menaquinone was MK-9. Cell wall analysis showed B-type peptidoglycan containing 2,4-diaminobutyric acid, alanine, glycine, glutamate and lysine. The diagnostic phospholipids were diphosphatidylglycerol and phosphatidylglycerol. The major fatty acids were ai-C15:0, i-C16:0, C18:1omega7c and ai-C17:0. The DNA G+C content was 67.5 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain MSL-08(T) had less than 97 % similarity to any recognized species of the genus Frigoribacterium. Frigoribacterium faeni DSM 10309T was found to be the closest neighbour (96.95 %) to the novel strain. Based on the 16S rRNA gene sequence analysis and phenotypic characteristics, it is proposed that strain MSL-08T represents a novel member of the genus Frigoribacterium for which the name Frigoribacterium mesophilum sp. nov. is proposed. The type strain is MSL-08T (=DSM 19442T=KCTC 19311T).

Rubellimicrobium mesophilum sp. nov., a mesophilic, pigmented bacterium isolated from soil

A pink- to light-reddish-pigmented, aerobic, pointed, budding, mesophilic strain designated MSL-20T was isolated from soil from Bigeum island, Korea. The isolate was Gram-negative. Cells were motile rods without flagella. The temperature and pH for growth were 20-37 degrees C (optimum 28 degrees C) and pH 7.0-11.0 (optimum pH 7.0+/-0.2). Q-10 was the predominant respiratory ubiquinone. The major fatty acids were C16:0 (37 %), C18: 1 omega7c (36 %) and 11-methyl C18:1 omega7c (12 %). Phylogenetic analysis based on the 16S rRNA gene sequence revealed that Rubellimicrobium thermophilum DSM 16684T was its closest neighbour (95.2 % similarity); the isolate had less than 97.0 % similarity to all species with validly published names. Chemotaxonomic data were determined for this isolate, including peptidoglycan type, diagnostic sugar composition, fatty acid profiles, ubiquinones and polar lipids; the results supported the affiliation of strain MSL-20T to the genus Rubellimicrobium. The DNA G+C content was 72.3 mol%. On the basis of the phenotypic, chemotaxonomic and phylogenetic data, strain MSL-20(T) represents a novel species of the genus Rubellimicrobium, for which the name Rubellimicrobium mesophilum sp. nov. is proposed. The type strain is MSL-20T (=KCTC 22012T =DSM 19309T).

Phycicoccus bigeumensis sp. nov., a mesophilic actinobacterium isolated from Bigeum Island, Korea

An actinomycete strain, designated MSL-03(T), was isolated from a soil sample collected from Bigeum Island in the Republic of Korea. The coccoid cells of the organism were Gram-positive and non-motile and did not form endospores. The colonies were yellow, small, circular with entire margins and contained meso-diaminopimelic acid as the diagnostic diamino acid in the peptidoglycan. The major menaquinone was MK-8(H4). The polar lipids detected were diphosphatidylglycerol and phosphatidylglycerol. The major fatty acids were iso-C(15 : 0), iso-C(16 : 0), C(17 : 0), anteiso-C(15 : 0), 10-methyl C(17 : 0), iso-C(14 : 0) and C(17 : 1)omega8c. The DNA G+C content was 73.4 mol%. Phylogenetic analyses based on the 16S rRNA gene sequence positioned strain MSL-03(T) in a clade comprising Phycicoccus jejuensis KSW2-15(T) and Phycicoccus dokdonensis DS-8(T). The organism showed the highest level of sequence similarity with respect to P. dokdonensis DS-8(T) (99.58 % over 1424 nt), with differences in 64 positions out of 1488. The levels of DNA-DNA relatedness with its closest neighbours (<70 %) showed that the isolate represents a distinct genomic species. On the basis of the phenotypic and genotypic results, strain MSL-03(T) represents a novel species of the genus Phycicoccus, for which the name Phycicoccus bigeumensis sp. nov. is proposed. The type strain is strain MSL-03(T) (=KCTC 19266(T) =DSM 19264(T)).

Streptomyces-derived actinomycin D inhibits biofilm formation by Staphylococcus aureus and its hemolytic activity

Abstract Staphylococcus aureus is a versatile human pathogen that produces diverse virulence factors, and its biofilm cells are difficult to eradicate due to their inherent ability to tolerate antibiotics. The anti-biofilm activities of the spent media of 252 diverse endophytic microorganisms were investigated using three S. aureus strains. An attempt was made to identify anti-biofilm compounds in active spent media and to assess their anti-hemolytic activities and hydrophobicities in order to investigate action mechanisms. Unlike other antibiotics, actinomycin D (0.5 μg ml−1) from Streptomyces parvulus significantly inhibited biofilm formation by all three S. aureus strains. Actinomycin D inhibited slime production in S. aureus and it inhibited hemolysis by S. aureus and caused S. aureus cells to become less hydrophobic, thus supporting its anti-biofilm effect. In addition, surface coatings containing actinomycin D prevented S. aureus biofilm formation on glass surfaces. Given these results, FDA-approved actinomycin D warrants further attention as a potential antivirulence agent against S. aureus infections.