Guang-Kai Bian

Nocardia endophytica sp. nov., an endophytic actinomycete isolated from the oil-seed plant Jatropha curcas L.

A novel actinomycete, designated strain KLBMP 1256(T), was isolated from a surface-sterilized stem of the oil-seed plant Jatropha curcas L. collected from Sichuan Province, south-west China, and was characterized to determine its taxonomic position. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the isolate was closely related to members of the genus Nocardia in the family Nocardiaceae, being most closely related to Nocardia callitridis CAP 290(T) (98.4 % similarity) and Nocardia nova JCM 6044(T) (97.5 %). Levels of 16S rRNA gene sequence similarity between strain KLBMP 1256(T) and the type strains of other recognized species of the genus Nocardia were less than 97 %. Chemotaxonomic data supported the affiliation of the new isolate to the genus Nocardia. However, the novel strain could be distinguished from its closest phylogenetic neighbour, N. callitridis CAP 290(T), by a range of phenotypic properties. The combination of low DNA-DNA relatedness values and phenotypic differences from N. callitridis CAP 290(T) indicated that strain KLBMP 1256(T) represents a novel species of the genus Nocardia, for which the name Nocardia endophytica sp. nov. is proposed. The type strain is KLBMP 1256(T) ( = KCTC 19777(T)  = CCTCC AA 2010004(T)).

Modestobacter roseus sp. nov., an endophytic actinomycete isolated from the coastal halophyte Salicornia europaea Linn., and emended description of the genus Modestobacter.

A novel actinomycete, designated strain KLBMP 1279(T), was isolated from surface-sterilized roots of a coastal halophyte, Salicornia europaea Linn., collected from Jiangsu Province, in the east of China. The taxonomic status of this organism was established using a polyphasic approach. 16S rRNA gene sequence analysis indicated that strain KLBMP 1279(T) was closely related to Modestobacter marinus 42H12-1(T) (99.5% 16S rRNA gene sequence similarity), Modestobacter versicolor CP153-2(T) (98.4%) and Modestobacter multiseptatus AA-826(T) (97.5%). Chemotaxonomic characteristics were consistent with its assignment to the genus Modestobacter in that the isolate had meso-diaminopimelic acid as the diagnostic diamino acid in the cell wall, MK-9(H4) as major menaquinone and a polar lipid profile containing diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides, two unknown aminophospholipids and an unknown phospholipid. The predominant fatty acids were iso-C16:0, iso-C15:0 and C17:1ω8c. The DNA G+C content was 71.7 mol%. However, DNA-DNA hybridization assays as well as physiological and biochemical analyses differentiated strain KLBMP 1279(T) from its closest phylogenetic relatives. On the basis of phenotypic, chemotaxonomic and phylogenetic evidence, the isolate KLBMP 1279(T) represents a novel species of the genus Modestobacter, for which the name Modestobacter roseus sp. nov. is proposed; the type strain is KLBMP 1279(T) (=KCTC 19887(T)=NBRC 108673(T)=DSM 45764(T)). An emended description of the genus Modestobacter is also proposed.

Streptomyces halophytocola sp. nov., an endophytic actinomycete isolated from the surface-sterilized stems of a coastal halophyte Tamarix chinensis Lour.

A novel actinomycete, designated KLBMP 1284(T), was isolated from the surface-sterilized stems of a coastal halophyte Tamarix chinensis Lour. collected from the city of Nantong, Jiangsu Province, east China. The strain was found to have morphological and chemotaxonomic characteristics typical of members of the genus Streptomyces. Analysis of the 16S rRNA gene sequence of strain KLBMP 1284(T) revealed that the strain formed a distinct clade within the phylogenetic tree based on 16S rRNA gene sequences and the highest sequence similarity (99.43 %) was to Streptomyces sulphureus NRRL B-1627(T). 16S rRNA gene sequence similarity to other species of the genus Streptomyces was lower than 97 %. Based on DNA-DNA hybridization values and comparison of morphological and phenotypic data, KLBMP 1284(T) could be distinguished from the closest phylogenetically related species, Streptomyces sulphureus NRRL B-1627(T). Thus, based on these data, it is evident that strain KLBMP 1284(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces halophytocola sp. nov. is proposed. The type strain is KLBMP 1284(T) (= KCTC 19890(T) = NBRC 108770(T)).

Methylated actinomycin D, a novel actinomycin D analog induces apoptosis in HepG2 cells through Fas- and mitochondria-mediated pathways.

Actinomycin D (Act D), a well known of clinical antitumor drug, has been used for the treatment of some highly malignant tumors, however, the clinical application was limited by its extreme cytotoxicity. In the present study, we reported that methylated actinomycin D (mAct D), a novel actinomycin D analog isolated from Streptomyces sp. KLBMP 2541 in our previous study, could not only exert stronger inhibitory effects on several human cancer cells than Act D in dose‐ and time‐dependent manner at ng concentrations, especially on HepG2 cells, but also lower cytotoxicity in normal cells (HL‐7702). Base on these results, HepG2 cells were treated for further study to illustrate the potential mechanism of mAct D. The results of nuclei morphology examination, DNA fragmentation detection, sub‐G1 analysis, annexin V‐FITC/PI staining and activation of caspase‐3 indicated mAct D significantly induced HepG2 cells apoptosis. Semiquantitative RT‐PCR and Western blot analysis revealed that mAct D induced apoptosis in HepG2 cells through mitochondria‐dependent pathway by increasing levels of caspase‐9, Bax, Bak while decreasing levels of Bcl‐2, Bid, and Fas‐dependent pathway by increasing levels of Fas, FasL, FADD, and caspase‐8. Subsequently, pretreatment with specific inhibitor of caspase‐8 Z‐LEHD‐FMK and caspase‐9 Z‐LEHD‐FMK significantly attenuated caspase‐3 activity, the cleavage of caspase‐3 and PARP, meanwhile increased the cell viability. In addition, p53 and mitochondrial transcription factor A (mtTFA) were also upregulated. Taken together, ng concentrations mAct D induces the apoptosis of HepG2 through Fas‐ and mitochondria‐mediated pathway and presents a potential novel alternative agent for the treatment of human hepatic carcinoma.