Chang-Jin Kim

Production, characterization and application of keratinase from Streptomyces gulbargensis

A Streptomyces gulbargensis newly isolated, thermotolerant feather-degrading bacterial strain was investigated for its ability to produce keratinase enzyme. Maximum keratinolytic activity was observed at 45 degrees C and pH 9.0 at 120 h of incubation. Activity was completely stable (100%) between 30 and 45 degrees C and pH 7.0-9.0, respectively. Addition of starch to the growth medium affects the activity by means of increase in keratinase secretion. After seven days of cultivation, 10-fold increase (14.3 U ml(-1)) in keratinase activity was observed in the presence of 3g starch (per liter) of the medium. The enzyme was monomeric and had a molecular mass of 46 kDa. The enzyme activity was significantly inhibited by CaCl(2) and partly inhibited by EDTA, whereas, Na(2)SO(3) enhance the enzyme activity by 2.9 times more. In addition, native chicken feather was completely degraded at 96 h of incubation. The results obtained showed that newly isolated strain S. gulbargensis could be a useful in biotechnology in terms of valorization of keratin-containing wastes or in the leather industry.

Saccharomonospora saliphila sp. nov., a halophilic actinomycete from an Indian soil

A Gram-positive, moderately halophilic actinomycete strain, designated YIM 90502(T), was isolated from a sample of muddy soil collected from Gulbarga, Karnataka Province, India, and subjected to a polyphasic taxonomical analysis. The isolate grew optimally at 28 degrees C and in the presence of 10 % (w/v) NaCl. The isolate was characterized chemotaxonomically as having meso-diaminopimelic acid in the cell-wall peptidoglycan and galactose and arabinose as whole-cell sugars. The predominant menaquinone was MK-9(H(4)), while MK-8(H(4)) was found in smaller amounts. The phospholipids were phosphatidylinositol, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. The major fatty acids were iso-C(16 : 0) (49.2 %) and C(17 : 1)omega6c (9.1 %). The DNA G+C content of the isolate was 71.8 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that the isolate fell within the evolutionary radiation encompassed by the genus Saccharomonospora. 16S rRNA gene sequence similarity between strain YIM 90502(T) and the type strains of Saccharomonospora species ranged from 92.42 % (with Saccharomonospora xinjiangensis CCTCC AA 97021(T)) to 97.45 % (with Saccharomonospora azurea KCTC 9693(T)). Levels of DNA-DNA relatedness between strain YIM 90502(T) and S. azurea KCTC 9693(T), Saccharomonospora halophila DSM 44411(T) and Saccharomonospora paurometabolica DSM 44619(T) were 46.0, 41.0 and 42.5 %, respectively. On the basis of phenotypic, phylogenetic and genotypic data, strain YIM 90502(T) was classified in the genus Saccharomonospora as a member of a novel species, for which the name Saccharomonospora saliphila sp. nov. is proposed, with YIM 90502(T) (=KCTC 19234(T) =DSM 45087(T)) as the type strain.

Reclassification of Salegentibacter catena Ying et al. 2007 as Salinimicrobium catena gen. nov., comb. nov. and description of Salinimicrobium xinjiangense sp. nov., a halophilic bacterium isolated from Xinjiang province in China

A Gram-negative, non-motile and moderately halophilic rod-shaped bacterium, designated strain BH206(T), was isolated from a saline lake of Xinjiang province in China. The isolate showed catalase-positive and oxidase-negative reactions and did not reduce nitrate. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate was most closely related to [Salegentibacter] catena HY1(T) with 95.8 % 16S rRNA gene sequence similarity, and formed a tight phyletic group with [Salegentibacter] catena HY1(T) with a bootstrap value of 99 % within the family Flavobacteriaceae. However, strain BH206(T) and [Salegentibacter] catena HY1(T) formed a phyletic lineage distinct from other Salegentibacter species. The 16S rRNA gene sequence similarities of strain BH206(T) with other related type species were lower than 94.6 %. On the basis of physiological and molecular properties, it is clear that [Salegentibacter] catena should be reclassified in the new genus Salinimicrobium as Salinimicrobium catena gen. nov., comb. nov. (type strain HY1(T)=CGMCC 1.6101(T)=JCM 14015(T)) and that strain BH206(T) represents a novel species within the genus Salinimicrobium, for which the name Salinimicrobium xinjiangense sp. nov. is proposed. The type strain of Salinimicrobium xinjiangense is BH206(T) (=KCTC 12883(T)=DSM 19287(T)).

Aidingimonas halophila gen. nov., sp. nov., a moderately halophilic bacterium isolated from a salt lake.

Two Gram-negative, facultatively anaerobic, catalase-positive, oxidase-negative, non-motile, rod-shaped and moderately halophilic bacterial strains, designated YIM 90637(T) and BH 017, were isolated from a salt lake in Xinjiang province, north-west China, and subjected to a polyphasic taxonomic study. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two novel isolates were affiliated with the family Halomonadaceae; the two strains shared 100 % sequence similarity, but showed similarities of 94.7 % with the type strain of Modicisalibacter tunisiensis, 93.2-94.7 % with members of the genus Chromohalobacter, 93.2-95.0 % with members of the genus Halomonas and less than 92.0 % with other members of the family Halomonadaceae. However, DNA-DNA relatedness data and phenotypic properties demonstrated that strains YIM 90637(T) and BH 017 were representatives of the same species. The major fatty acids were C(19 : 0) cyclo omega8c and C(16 : 0.) The relative amount of C(19 : 0) cyclo omega8c was notably higher than that found in most species of the family Halomonadaceae for which fatty acid composition has been determined. The genomic DNA G+C content was 57.2-57.5 mol% and the only respiratory quinone was ubiquinone 9. Based on evidence from the polyphasic taxonomic study, it was concluded that the two strains should be classified as representatives of a novel species in a new genus, for which name Aidingimonas halophila gen. nov., sp. nov. is proposed; the type strain of Aidingimonas halophila is YIM 90637(T) (=KCTC 12885(T)=CCTCC AB 207002(T)).

Indole-3-acetaldehyde from Rhodococcus sp. BFI 332 inhibits Escherichia coli O157:H7 biofilm formation

Pathogenic biofilms have been associated with persistent infections due to their high resistance to antimicrobial agents. To identify nontoxic biofilm inhibitors for enterohemorrhagic Escherichia coli O157:H7, the spent media of a 4,104 Actinomycetes library was screened. The culture spent medium (1%, v/v) of plant pathogen Rhodococcus sp. BFI 332 markedly inhibited E. coli O157:H7 biofilm formation without affecting the growth of planktonic E. coli O157:H7 cells. Rhodococcus sp. BFI 332 produced significant amounts of indole-3-acetaldehyde and indole-3-acetic acid, and the former of which reduced E. coli O157:H7 biofilm formation. Global transcriptome analyses showed that indole-3-acetaldehyde most repressed two curli operons, csgBAC and csgDEFG, and induced tryptophanase (tnaAB) in E. coli O157:H7 biofilm cells. Electron microscopy showed that spent medium of Rhodococcus sp. BFI 332 and indole-3-acetaldehyde reduced curli production in E. coli O157:H7. The spent medium of Rhodococcus sp. BFI 332 also significantly reduced the biofilm formation of Staphylococcus aureus and Staphylococcus epidermidis. Overall, this study suggests that indole derivatives are present in the Actinomycetes strains and they can be used as biofilm inhibitors against pathogenic bacteria.

Gracilibacillus lacisalsi sp. nov., a halophilic Gram-positive bacterium from a salt lake in China.

Two Gram-positive, motile, rod-shaped, halophilic bacteria showing optimum growth at 5-7 % (w/v) NaCl were isolated from a salt lake, Xin-Jiang Province, China. The strains, designated BH312(T) and BH314, grew in the presence of 1-18 % (w/v) NaCl and at temperatures of 15-50 degrees C (optimum: 40 degrees C) and pH values of 5.5-10.0 (optimum: pH 7.5-8.0). The major cellular fatty acids were anteiso-C(15 : 0), iso-C(15 : 0) and anteiso-C(17 : 0). The DNA G+C content was 38.8-39.0 mol% and the predominant lipoquinone was MK-7. The major cellular phospholipids were phosphatidylglycerol, diphosphatidylglycerol and two unidentified phospholipids. Phylogenetic analyses based on 16S rRNA gene sequences showed that the isolates formed a cluster with Gracilibacillus orientalis XH-63(T) within the genus Gracilibacillus. The levels of 16S rRNA gene sequence similarity with closely related type strains were lower than 96.2 %. On the basis of phylogenetic, phenotypic and chemotaxonomic properties, the isolates represent a novel species of the genus Gracilibacillus for which the name Gracilibacillus lacisalsi sp. nov. is proposed. The type strain is BH312(T) (=KCTC 13129(T)=DSM 19029(T)).

Salinimicrobium terrae sp. nov., isolated from saline soil, and emended description of the genus Salinimicrobium

A novel yellow-pigmented, Gram-negative, slightly halophilic, catalase-positive, oxidase-negative, obligately aerobic bacterium, designated strain YIM-C338(T), was isolated from saline soil from the Qaidam Basin in north-west China. Cells were non-sporulating, non-motile, short rods, predominantly occurring singly. Coccoid bodies and slightly curved rod-shaped cells of varying length developed in older cultures. Growth occurred with 0.5-8 % (w/v) NaCl (optimally with 1-3 %, w/v), at pH 6.0-9.0 (optimally at pH 7.0) and at 4-37 degrees C (optimally at 28 degrees C). The major cellular fatty acids were C(16 : 0), C(18 : 0), C(16 : 1)omega7c, C(18 : 1)omega7c, iso-C(13 : 0) 3-OH and iso-C(15 : 1). MK-6 was the only respiratory quinone. Non-diffusible carotenoid pigments were produced. Flexirubin-type pigments were absent. The genomic DNA G+C content was 42.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM-C338(T) was a member of the genus Salinimicrobium, having sequence similarities of 97.3 and 94.0 % with respect to Salinimicrobium xinjiangense BH206(T) and Salinimicrobium catena HY1(T). The combination of the phylogenetic data, phenotypic characteristics and chemotaxonomic differences supported the view that strain YIM-C338(T) represents a novel species of the genus Salinimicrobium, for which the name Salinimicrobium terrae sp. nov. is proposed. The type strain is YIM-C338(T) (=DSM 17865(T) =CGMCC 1.6308(T)). An emended description of the genus Salinimicrobium is also provided.

Paenibacillus telluris sp. nov., a novel phosphate-solubilizing bacterium isolated from soil

A phosphate-solubilizing bacterial strain designated PS38T was isolated from farm soil. The isolate was a Gram-positive, motile, endospore-forming, rod-shaped bacterium. It grew optimally at 37°C and pH 7.5. The predominant cellular fatty acids were anteiso-C15:0, anteiso-C17:0, and iso-C16:0. The DNA G+C content was 49.5 mol% and the predominant menaquinone was MK-7. Phylogenese analyses based on 16S rRNA gene sequences showed that the strain PS38T belonged to the genus Paenibacillus and was most closely related to Paenibacillus chibensis JCM 9905T, P. barengoltzii SAFN-016T, P. timonensis 2301032T, and P. motobuensis MC10T with 96.3%, 96.0%, 95.9%, and 95.5% 16S rRNA gene sequence similarity, respectively. On the basis of morphological, chemotaxonomic, physiological, and phylogenetic properties, strain PS38T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus telluris sp. nov. is proposed. The type strain is PS38T (=KCTC 13946T =CGMCC 1.10695T).

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.

Streptomyces deccanensis sp. nov., an alkaliphilic species isolated from soil

A novel actinomycete strain, DAS-139T, was isolated from a soil sample collected from Gulbarga, Karnataka Province, India. The isolate was characterized by white to grey aerial mycelium. Long spore chains were found on the aerial mycelium and the aerial mycelium was composed of non-motile spores with hairy surfaces. The cell wall of strain DAS-139T contained ll-diaminopimelic acid isomer as the diagnostic diaminoacid indicating that the cell wall was of chemotype-I. The predominant menaquinones were MK-9(H6) (76 %), MK-9(H4) (14 %) and MK-9(H8) (10 %). Phosphatidylethanolamine was the diagnostic phospholipid. On the basis of 16S rRNA gene sequence, phenotypic and phylogenetic analyses, the novel strain was identified as a member of the genus Streptomyces. The novel strain grew optimally at 28 degrees C and pH 9.0. The G+C content of the genomic DNA was 71.8 mol%. 16S rRNA gene sequence analysis showed that the novel isolate had 99.4 % sequence similarity with Streptomyces scabiei ATCC 49173T and 99.2 % similarity with Streptomyces diastachromogenes ATCC 12309T. Furthermore, DNA-DNA hybridization with these two Streptomyces species showed 36.0 and 43.0 % relatedness, respectively. Based on these observations, strain DAS-139T is proposed to represent a novel species of the genus Streptomyces, for which the name Streptomyces deccanensis sp. nov. is proposed with the type strain DAS-139T (=KCTC 19241T=CCTCC AA 207004T).