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A new actinobacterial strain, LCR6-01T, was isolated from a lichen sample collected from Chiang Rai Province, Thailand. Its taxonomic position was determined using a polyphasic approach. The strain had morphological characteristics and chemotaxonomic properties identical to those of members of the genus Streptomyces . The predominant menaquinones were MK-9(H6) and MK-9(H8). The major fatty acids were anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 0, iso-C14 : 0 and C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified phosphoglycolipid, an unidentified phospholipid and an unidentified lipid. The genomic DNA G+C content was 74.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences suggested that the strain belonged to the genus Streptomyces . The strain showed highest 16S rRNA gene sequence similarity to Streptomyces palmae TBRC 1999T (98.6 %), Streptomyces misionensis JCM 4497T (98.6 %), Streptomyces matensis JCM 4268T (98.5 %), Streptomyces althioticus KCTC 9752T (98.5 %) and Streptomyces wuyuanensis KCTC 29112T (98.4 %). DNA–DNA relatedness values among the strain and closely related Streptomyces species were below 70 %. On the basis of the phenotypic characteristics and genotypic distinctiveness, strain LCR6-01T is considered to represent a novel species of the genus Streptomyces , for which the name Streptomyces lichenis sp. nov. is proposed. The type strain is LCR6-01T (=KCTC 39908T=TISTR 2500T)

Three actinomycetes strains, designated JBL-5, JBL-14 and JBL-20T, were isolated from bamboo (Sasa borealis) litter in Damyang, Republic of Korea. Morphological, chemotaxonomic and phylogenetic analyses demonstrated that the three strains belong to the genus Streptomyces . Microscopic observation revealed that the three strains produced Spirales spore chains with smooth surfaces. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that these strains showed the highest sequence similarity to Streptomyces gelaticus NRRL B-2928T (97.8 %), Streptomyces pulveraceus LMG 20322T (97.7 %), Streptomyces intermedius NBRC 13049T (97.7 %), Streptomyces althioticus NRRL B-3981T (97.7 %) and Streptomyces matensis NBRC 12889T (97.7 %). The DNA–DNA hybridization values between strains JBL-5, JBL-14 and JBL-20T were 91.2–92.4 %, and the values between the three strains and their close phylogenetic relatives were also below 70 %. The predominant menaquinones were MK-9 (H4) and MK-9 (H6). The cell wall contained ll-diaminopimelic acid and the whole-cell sugars were arabinose and xylose. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositolmannoside, two unidentified aminolipids, three unidentified aminophospholipids, one unidentified glycolipid and one unidentified lipid. The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C14 : 0, C18 : 1 ω7c and iso-C16 : 0. The DNA G+C contents were 71.8–72.4 mol%. On the basis of phylogenetic analyses and physiological and biochemical characterization, strains JBL-5, JBL-14 and JBL-20T are considered to represent a novel species of the genus Streptomyces , for which the name Streptomyces fuscigenes sp. nov. is proposed. The type strain is JBL-20T (=KACC 18269T=NBRC 110629T).

A newly isolated strain Streptomyces sp. BG5 was investigated for the production of bioactive compounds. The strain exhibited broad-spectrum activity against an array of nine test organisms including gram-positive bacteria, gram-negative bacteria, and fungal and microalgal pathogens, along with a moderate cytotoxic response (28.9% mortality) in a microwell cytotoxicity assay against the brine shrimp Artimia salina. The morphological, physiological, and biochemical characterization of the Streptomyces sp. BG5 strongly suggested it to be a member of the genus Streptomyces. The nucleotide sequence of 16S rRNA gene (1433 pb) of the Streptomyces sp. BG5 (Gene bank accession number EU301836) exhibited high similarity (98%) with Streptomyces matensis. The large-scale fermentation of Streptomyces sp. BG5 and subsequent extraction, isolation, and purification of the crude extract afforded three pure compounds. The structures of these compounds were identified as ochromycinone (1a), emycin D (2), and 1-acetyl-β-carbolin (3), based on nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry, and by comparison with reference data from the literature.

An extracellular xylanase produced by Streptomyces matensis DW67 was purified from the culture supernatant by ammonium sulfate precipitation, ion exchange and gel filtration chromatography and characterized. The xylanase was purified to 14.5-fold to homogeneity with a recovery yield of 14.1%. The purified xylanase appeared as a single protein band on SDS-PAGE with a molecular mass of 21.2 kDa. However, it had a very low apparent molecular mass of 3.3 kDa as determined by gel filtration chromatography. The N-terminal sequence of first 15 amino acid residues was determined as ATTITTNQTGYDGMY. The optimal temperature and pH for purified xylanase was 65 °C and pH 7.0, respectively. The enzyme was stable within the pH range of 4.5–8.0 and was up to 55 °C. The xylanase showed specific activity towards different xylans and no activity towards other substrates tested. Hydrolysis of birchwood xylan by the xylanase yielded xylobiose and xylotriose as principal products. The enzyme hardly hydrolyzed xylobiose and xylotriose, but it could hydrolyze xylotetraose and xylopentaose to produce mainly xylobiose and xylotriose through transglycosylation. These unique properties of the purified xylanase make this enzyme attractive for biotechnological applications, such as bioblenching in paper and pulp industries, production of xylooligosaccharides. This is the first report of the xylanase from S. matensis.

A gene encoding an endo-β-1,3-glucanase from Streptomyces matensis ATCC 23935 (SmβG) was characterised by cloning and expressing it in Escherichiacoli. The purified enzyme produced β-1,3-glucooligosaccharides, mainly laminaripentaose, from insoluble curdlan. The optimum pH and temperature were 6.0 and 55 °C, respectively. SmβG inhibited the growth of Candida albicans, which indicates that this enzyme could be potentially used as an anti-fungal agent to control invasive Candida infections. The results suggest that SmβG may be a useful bioavailable β-1,3-glucanase.

A novel actinomycete, strain FX61T, was isolated from a saline sample collected from the Inner Mongolian Autonomous Region in China and subjected to a taxonomic study using a polyphasic approach. The predominant menaquinones were MK-9(H6), MK-9(H8) and MK-9(H4). The major fatty acids were iso-C16 : 0, anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 1 H, C16 : 0, iso-C14 : 0 and anteiso-C17 : 0. The phospholipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, two phosphatidylinositol mannosides and an unidentified phospholipid. The G+C content of the genomic DNA was 72 mol%. The 16S rRNA gene sequence of the isolate had greater than 98 % similarity with those of Streptomyces griseoincarnatus ATCC 23623T (98.2 %), Streptomyces labedae DSM 41446T (98.2 %), Streptomyces variabilis ATCC 19815T (98.2 %), Streptomyces erythrogriseus ATCC 27427T (98.2 %), Streptomyces matensis ATCC 23935T (98.2 %), Streptomyces althioticus ATCC 19724T (98.2 %) and Streptomyces luteosporeus ATCC 33049T (98.0 %), showing that the novel strain should be assigned to the genus Streptomyces . DNA–DNA hybridizations with the seven above-mentioned members of the genus Streptomyces showed 29.8, 28.5, 27.0, 25.5, 25.0, 23.5 and 22.0 % relatedness, respectively. On the basis of the phenotypic characteristics and genotypic distinctiveness, strain FX61T should be classified as a novel species of the genus Streptomyces , for which the name Streptomyces wuyuanensis sp. nov. is proposed. The type strain is FX61T ( = CGMCC 4.7042T = KCTC 29112T).

Laminaripentaose-producing β-1,3-glucanase (LPHase) from Streptomyces matensis DIC-108 uniquely catalyzes the hydrolysis of β-1,3-glucan to release laminaripentaose as the predominant product. For studying this novel enzyme, the gene of LPHase was reconstructed with polymerase chain reaction and over-expressed in Escherichia coli. The recombinant wild-type enzyme and various mutants were further purified to >90% homogeneity on an ion-exchange chromatograph. The catalysis of the recombinant LPHase is confirmed to follow a one-step single-displacement mechanism with (1)H-NMR spectrometry. To determine the amino-acid residues essential for the catalysis, more than ten residues, including five highly conserved residues--Asp(143), Glu(154), Asp(170), Asp(376) and Asp(377), were mutated. Among the mutants, E154Q, E154G, D174N and D174G significantly lost catalytic activity. Further investigation with chemical rescue using sodium azide on E154G and D174G confirmed that Glu(154) functions as the general acid whereas Asp(170) serves as the general base in a catalytic turnover. This work is the first report that provides direct information for the identification of the essential residues of GH-64 through kinetic examination.

Laminaripentaose-producing beta-1,3-glucanase (LPHase), a member of glycoside hydrolase family 64, cleaves a long-chain polysaccharide beta-1,3-glucan into specific pentasaccharide oligomers. The crystal structure of LPHase from Streptomyces matensis DIC-108 was solved to 1.62 A resolution using multiple-wavelength anomalous dispersion methods. The LPHase structure reveals a novel crescent-like fold; it consists of a barrel domain and a mixed (alpha/beta) domain, forming a wide-open groove between the two domains. The liganded crystal structure was also solved to 1.80 A, showing limited conformational changes. Within the wide groove, a laminaritetraose molecule is found to sit in an electronegatively charged central region and is proximal to several conserved residues including two carboxylates (Glu(154) and Asp(170)) and four other sugar-binding residues (Thr(156), Asn(158), Trp(163), and Thr(167)). Molecular modeling using a laminarihexaose as a substrate suggests roles for Glu(154) and Asp(170) as acid and base catalysts, respectively, whereas the side chains of Thr(156), Asn(158), and Trp(163) demarcate subsite +5. Site-directed mutagenesis of Glu(154) and Asp(170) confirms that both carboxylates are essential for catalysis. Together, our results suggest that LPHase uses a direct displacement mechanism involving Glu(154) and Asp(170) to cleave a beta-1,3-glucan into specific alpha-pentasaccharide oligomers.

New antibiotics, OS-4742 A1, A2, B1 and B2, were isolated from the culture broth of the strain OS-4742, which was designated as Streptomyces matensis subsp. vineus. These compounds have anthracycline chromophores and sugar moieties, but do not contain nitrogen. They possess antimicrobial activities against Gram-positive bacteria and antitumor activities against S-180 solid tumor on mice.

The laminaripentaose-producing β-1,3-glucanase of Streptomyces matensis is a member of the glycoside hydrolase family GH-64. We have constructed and purified a recombinant hexahistidine-tagged form of the enzyme for characterisation. The enzyme, which exists as a monomer in solution, hydrolyses β-1,3-glucan by a mechanism leading to overall inversion of the anomeric configuration. This is the first determination of the mechanism prevailing in glycoside hydrolase family GH-64 and this is the first characterisation of an ‘inverting’ β-1,3-glucanase.

Vineomycin A1 (formerly OS-4742 A1) produced by Streptomyces matensis subsp. vineus, is an antibacterial and antitumor antibiotic. The aglycon part obtained by mild hydrolysis turned out to be identical with aquayamycin, and its 13C-NMR assignment was also determined.

From a cultured broth of Streptomyces matensis A-6621, we isolated three new platelet aggregation inhibitors designated as PI-080, PI-085 and PI-087. The structures of these compounds were established by spectral and chemical methods.

Biosynthetic studies of the antibacterial and antitumor antibiotics vineomycins A1 (1) and B2 (2), produced by Streptomyces matensis subsp. vineus, were carried out by labeling experiments with [1-13C]- and [1,2-18C2]sodium acetate followed by 18C NMR spectroscopy. The results show that the benz[a]anthraquinone chromophore of 1 is derived from a decacetate metabolite with decarboxylation at the carboxyl end and that 2 is formed via C-C bond cleavage of 1. Isolation of rabelomycin from the fermentation broth of the same strain suggests a close biosynthetic relationship among the simple benz[a]anthraquinone antibiotics such as rabelomycin, tetrangomycin, aquayamycin, a C-glycosylated benz[a]anthraquinone, and vineomycins. These biosynthetic data prompted us to reconsider the previously published structure of the antibiotic SS-228Y, which has not been revised.