Kamil Isik

Production and partial characterization of extracellular peroxidase produced byStreptomyces sp. F6616 isolated in Turkey

Streptomyces sp. F6616 was found to produce higher levels of extracellular peroxidase activity (0.535 U/mL) without any inducers than other actinobacteria which are previously reported. Maximum specific peroxidase activity (6.21 U/mg of protein) was obtained after 72 h of incubation at 30°C in a minimal salt medium (pH 8.0) containing (in wt/v) 0.6% yeast extract and 0.8% ball-milled wheat straw corresponding to a C:N ratio of 4.6:1. Characterization of the peroxidase revealed that the optimal temperature for the enzyme activity, using the standard 2,4-dichlorophenol (2,4-DCP) assay was 50°C, when the enzyme reaction was performed at pH 8.0. A study of the effect of temperature on the stability of peroxidase over time, showed that the enzyme was stable at 50°C, with a half-life of 145 min, while at higher temperature the stability and activity was reduced such that at 60°C the half-life of the enzyme was 30 min. The optimum pH for the activity of the enzyme occurred between pH 9.0 and 10.0. The apparentKm andVmax values for the peroxidase preparations were determined to be 1.52 mmol/L and 1.84 U/mg protein, respectively using 2,4-DCP as a substrate. Characterization of the peroxidase activity revealed activity against 2,4-DCP, L-3,4-dihydroxyphenylalanine (L-DOPA), 2,4,5-trichlorophenol and other chlorophenols in the presence of hydrogen peroxide. However, inhibition of peroxidase activity with the addition of potassium cyanide and sodium azide, suggested the presence of heme component in the tertiary structure of the enzyme.

Streptomyces samsunensis sp. nov., a member of the Streptomyces violaceusniger clade isolated from the rhizosphere of Robinia pseudoacacia

The taxonomic position of a Streptomyces isolate, strain M1463(T), recovered from the rhizosphere of Robinia pseudoacacia was established in a polyphasic study. The organism had chemical and morphological markers that were consistent with its classification in the Streptomyces violaceusniger clade. This assignment was confirmed by 16S rRNA gene sequence data, which also showed that the strain formed a distinct subclade together with Streptomyces malaysiensis DSM 41697(T). However, the two strains were readily distinguished on the basis of DNA relatedness and phenotypic data. The combined genotypic and phenotypic data show that strain M1463(T) should be recognized as a representative of a novel species in the Streptomyces violaceusniger clade, for which the name Streptomyces samsunensis sp. nov. is proposed. The type strain of S. samsunensis is M1463(T) ( = DSM 42010(T) = NRRL B-24803(T)).

Nonomuraea muscovyensis sp. nov., isolated from soil.

A novel actinomycete, strain FMN03(T), was isolated from a soil sample collected from Yuga Zapadnaya South-West Forest Park, Moscow, Russia. The isolate had chemical and morphological properties typical of members of the genus Nonomuraea and formed a distinct 16S rRNA gene subclade with the type strains Nonomuraea roseoviolacea subsp. carminata NBRC 15903(T) and Nonomuraea roseoviolacea subsp. roseoviolacea NBRC 14098(T). The organism formed extensively branched substrate and aerial hyphae, which generated spiral chains of spores with smooth surfaces. The cell wall contained meso-diaminopimelic acid and the whole cell sugars were glucose, galactose and trace amounts of madurose, mannose and xylose. The polar lipids were phosphatidylethanolamine, hydroxyphosphatidylethanolamine, four unidentified phospholipids, four unidentified glycolipids and one unidentified lipid. The predominant menaquinone was MK-9(H4). The major fatty acids were iso-C16 : 0 2-OH, C17 : 0 10-methyl, C17 : 1 cis9 and iso-C16 : 0. Analyses of its morphological, physiological and biochemical characteristics, together with DNA-DNA relatedness data, confirmed that strain FMN03(T) is a representative of a novel species of the genus Nonomuraea, which is distinct from closely related reference strains. Strain FMN03(T) ( = DSM 45913(T) = KCTC 29233(T)) is proposed as the type strain of a novel species, for which the name Nonomuraea muscovyensis sp. nov. is proposed.

Streptomyces burgazadensis sp. nov., isolated from soil

A novel actinobacterial strain, designated Z1R7(T), was isolated from a soil sample collected from Burgazada, in the Marmara Sea (Turkey), and the strain identity was determined using a polyphasic taxonomic approach. The organism had chemotaxonomic and morphological properties consistent with its classification in the genus Streptomyces and it formed a distinct phyletic line in the 16S rRNA gene tree, together with the type strains Streptomyces specialis GW41-1564(T) (95.76 %), Streptomyces mayteni YIM 60475(T) (95.64 %), Streptomyces hainanensis YIM 47672(T) (95.53 %), Streptomyces hoynatensis S1412(T) (95.29 %), Streptomyces avicenniae MCCC 1A01535(T) (94.74 %), Streptomyces sedi YIM 65188(T) (94.59 %) and Streptomyces zhaozhouensis NEAU-LZS-5(T) (94.68 %). Chomotaxonomic data revealed that strain Z1R7(T) possesed MK-9 (H8) as the predominant menaquinone, ll-diaminopimelic acid as the diagnostic diamino acid, and galactose, glucose and ribose as whole cell sugars. Diphosphatidylglycerol, phoshphatidylethanolamine and phosphatidylinositol were the predominant polar lipids; iso-C16 : 0, anteiso-C17 : 0 and anteiso-C15 : 0 were the major fatty acids, and the genomic DNA G+C content was 69.4 mol%. On the basis of these genotypic and phenotypic data, it is proposed that isolate Z1R7(T) ( = KCTC 29434(T) = DSM 42126(T)) should be classified in the genus Streptomyces as Streptomyces burgazadensis sp. nov.