Streptomyces Spinosirectus sp. nov., Isolated From the Medicinal Plant Xanthium Sibiricum.

A novel actinobacterium, designated strain CRSS-Y-16T, was isolated from the healthy leaves of Xanthium sibiricum, in China and characterized by a polyphasic approach. This strain produced abundant aerial mycelia that generated rod-shaped spores with spiny surfaces. The cell wall contained LL-diaminopimelic acid. The major cellular fatty acids (>10.0%) were C16:0, iso-C16:0, and C18:1 ω9c. The predominant menaquinones were MK-9(H2) and MK-9(H4). The detected polar lipids were diphosphatidylglycerol, hydroxyl phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositolmannoside, phospholipids of unknown structure containing glucosamine and unidentified phospholipids. The genomic G+C content was 70.7%. The full-length 16S rRNA gene sequence analysis indicated that strain CRSS-Y-16T belonged to the genus Streptomyces and shared <98.7% sequence similarities with all recognized type species of the genus. Phylogenetic analysis based on 16S rRNA gene sequences showed that this strain formed a distinct branch. Phylogenomic analysis demonstrated that it was closely related to Streptomyces panaciradicis 1MR-8T. However, the clustering patterns resulting from phylogenomic tree verified that strain CRSS-Y-16T represented a novel Streptomyces species. This result was further confirmed by low average nucleotide identity and digital DNA-DNA hybridization values (87.54% and 30.1%) between them. Based on all these data, it is concluded that strain CRSS-Y-16T represents a novel Streptomyces species, for which the name Streptomyces spinosirectus sp. nov. is proposed. The type strain is CRSS-Y-16T (=MCCC 1K06950T=JCM 35007T).

Streptomyces liangshanensis sp. nov., a novel actinomycete isolated from rhizosphere soil of Fagopyrum tataricum.

A novel actinomycete strain, designated strain QMT-12T, was isolated from the rhizospheric soils of Fagopyrum tataricum and characterized using a polyphasic approach. Strain QMT-12T was found to have morphological features typical of the genus Streptomyces. The predominant fatty acids included C18:1 cis9 (35.9%), Summed feature 6 (C18:2 cis9, 12/C18:0 a or C18:0 anteiso/C18:2 c) (30.6%) and C16:0 (16.3%). The whole-cell sugars were arabinose and glucose. The whole-cell-wall amino acids included alanine, aspartate, glutamic acid, glycine and LL-diaminopimelic acid. The menaquinones were MK-9, MK-9(H2), MK-9(H4), MK-9(H6) and MK-9(H8). The diagnostic phospholipids consisted of diphosphatidyl glycerol, phosphatidylethanolamine, phosphatidyl methyl ethanolamine, phospholipids, phosphotidyl inositol, phosphotidylinositol mannosides, and phospholipids of unknown structure containing glucosamine. The full-length 16S rRNA gene sequence analysis showed that strain QMT-12T belonged to the genus Streptomyces and had 98.2, 98.1, 98.1 and ≤ 98.0% similarities to Streptomyces camponoticapitis 2H-TWYE14T, Streptomyces scopuliridis NRRL B-24574T, Streptomyces inhibens NEAU-D10T and other Streptomyces species with validly published and correct names, respectively. Phylogenetic analysis indicated that strain QMT-12T was closely related to Streptomyces inhibens NEAU-D10T. However, the average nucleotide identity value and the digital DNA-DNA hybridization value between strain QMT-12T and S. inhibens NEAU-D10T were 85.0 and 22.3%, respectively, well below 95-96% and 70% cut-off point recommended for delineating species. Based on its phenotypic and genotypic characteristics, strain QMT-12T (= CICC 11056T = JCM 33963T) represents the type strain of a novel species, for which the name Streptomyces liangshanensis sp. nov. is proposed.

[Effects of manganese on antioxidant system of manganese-hyperaccumulator Phytolacca americana L.].

A hydroponic experiment was conducted to study the growth, manganese (Mn) accumulation, lipid peroxidation, H2O2 concentration, and antioxidant system of Phytolacca americana L. exposed to different concentration Mn. With increasing Mn concentration in the medium, the plant Mn content increased significantly, and the Mn accumulation was in the sequence of leaf > stem > root. Comparing with the control, low concentration (5 mmol x L(-1)) Mn promoted the plant growth, decreased the leaf H2O2 concentration, and had less effects on the leaf malondialdehyde (MDA) content, while high concentration (> or = 10 mmol x L(-1)) Mn led to a remarkable increase of leaf H2O2 and MDA contents, indicating an evident oxidative damage occurred in leaves. The activities of ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase and the content of reduced ascorbate increased with increasing Mn concentration, while the SOD activity was inhibited significantly at 5 mmol x L(-1) of Mn but enhanced at > or = 10 mmol x L(-1) of Mn. The activities of catalase and peroxidase and the content of reduced glutathione increased at 5-10 mmol x L(-1) of Mn but dropped markedly at 20 mmol x L(-1) of Mn. All the results suggested that the Mn-induced oxidative damage and Mn accumulation might be responsible for the growth inhibition of P. americana plants at high Mn exposure, and the increase of antioxidative enzyme activities and low molecular antioxidant contents was, at least partly, contributed to the Mn tolerance and hyperaccumulation of P. americana. However, due to their different Mn concentration-dependent change modes, these antioxidants played different roles in the Mn tolerance of P. americana.