Microbacterium nymphoidis sp. nov. and Microbacterium festucae sp. nov., two novel species with high plant-promoting potential isolated from wetland plants in China.

Two novel plant growth-promoting, rod-shaped, Gram-positive and non-motile rhizobacteria, W1NT and W2RT, were isolated from wetland plants Festuca elata and Nymphoides peltatum, respectively, in China. The results of the 16S rRNA sequence alignment analysis showed that they were related to Microbacterium, with the highest similarity to Microbacterium ketosireducens (98.7 %) and Microbacterium laevaniformans (98.5 %) for strain W1NT, and to Microbacterium terricola (98.1 %) and Microbacterium marinum (98.0 %) for strain W2RT. Phylogenetic analyses based on 16S rRNA gene sequences and 92 conserved concatenated proteins suggested that the two strains belong to the genus Microbacterium and were placed in two separate novel phylogenetic clades. The genome sizes of the two strains were 3.2 and 3.7 Mb, and the G+C contents were 71.7 and 68.5 mol%, respectively. The comparative genome results showed that the average nucleotide identity values between W1NT and W2RT and other species ranged from 73.5 to 83.6 %, and the digital DNA-DNA hybridization values ranged from 19.7 to 26.8 %. These two strains show physiological and biochemical features that differ from those of closely related species. Rhamnose, galactose and glucose were present in the characteristic sugar fractions of strains W1NT and W2RT. The peptidoglycan of strains W1NT and W2RT contained the amino acids ornithine, alanine and aspartic acid. C15 : 0 anteiso, C17 : 0 anteiso and C16 : 0 iso were the predominant cellular fatty acids in W1NT and W2RT. Phosphatidylglycerol and diphosphatidylglycerol are major polar lipid components. Strain W1NT not only formed bacterial biofilms but also had the ability to solubilize phosphorus and produce indole-3-acetic acid. Strain W2RT had siderophore-producing and lignin-degrading properties. Based on their genetic and phenotypic characteristics, strains W1NT and W2RT were classified as novel bacteria in the genus Microbacterium and designated as Microbacterium festucae sp. nov. (type strain W1NT=ACCC 61807T=GDMCC 1.2966T=JCM 35339T) and Microbacterium nymphoidis sp. nov. (type strain W2RT=ACCC 61808T=GDMCC 1.2967T=JCM 35340T).

Sphingomonas deserti sp. nov., isolated from Mu Us Sandy Land soil.

A Gram-stain-negative, rod-shaped bacterium, designated as strain GL-C-18T, was isolated from soil sample collected at Mu Us Sandy Land, China, and its taxonomic position was investigated using a polyphasic approach. Growth was observed in the presence of 0-1 % (w/v) NaCl (optimum, 0 %), pH 6.0-9.0 (optimum, pH 7.0-8.0) and 20-37 °C. On the basis of 16S rRNA gene sequence similarity, strain GL-C-18T belonged to the family Sphingomonadaceae and was most closely related to Sphingosinicella vermicomposti YC7378T (95.7 %), Sphingomonas oligophenolica S213T (95.0 %) and Sphingobium boeckii 301T (94.8 %). The draft genome of strain GL-C-18T was 6.09 Mb, and the G+C content was 66.0 %. The average nucleotide identity value to Sphingosinicella vermicomposti YC7378T was 83.7 %. The predominant respiratory quinone was Q-10. The major fatty acids were C18 : 1ω7c, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16:0 and C14 : 0 2OH. The main polar lipids were sphingoglycolipid, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. On the basis of chemotaxonomic, phylogenetic and phenotypic evidence, strain GL-C-18T represents a novel species of the genus Sphingomonas, for which the name Sphingomonasdeserti sp. nov. is proposed. The type strain is GL-C-18T (=ACCC 60076T=KCTC 62411T).

[Content and distribution of active components in cultivated and wild Taxus chinensis var. mairei plants].

Taxus chinensis var. mairei is an endemic and endangered plant species in China. The resources of T. chinensis var. mairei have been excessively exploited due to its anti-cancer potential, accordingly, the extant T. chinensis var. mairei population is decreasing. In this paper, ultrasonic extraction and HPLC were adopted to determine the contents of active components paclitaxel, 7-xylosyltaxol and cephalomannine in cultivated and wild T. chinensis var. mairei plants, with the content distribution of these components in different parts of the plants having grown for different years and at different slope aspects investigated. There existed obvious differences in the contents of these active components between cultivated and wild T. chinensis var. mairei plants. The paclitaxel content in the wild plants was about 0.78 times more than that in the cultivated plants, whereas the 7-xylosyltaxol and cephalomannine contents were slishtly higher in the cultivated plants. The differences in the three active components contents between different parts and tree canopies of the plants were notable, being higher in barks and upper tree canopies. Four-year old plants had comparatively higher contents of paclitaxel, 7-xylosyltaxol and cephalomannine (0.08, 0.91 and 0.32 mg x g(-1), respectively), and the plants growing at sunny slope had higher contents of the three active components, with significant differences in the paclitaxel and 7-xylosyltaxol contents and unapparent difference in the cephalomannine content of the plants at shady slope. It was suggested that the accumulation of the three active components in T. chinensis var. mairei plants were closely related to the sunshine conditions. To appropriately increase the sunshine during the artificial cultivation of T. chinensis var. mairei would be beneficial to the accumulation of the three active components in T. chinensis var. mairei plants.