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A Gram-stain-positive, aerobic, non-motile and mycolic-acid-containing strain, designated Y48T, was isolated from soil contaminated by crude oil located in the northern margin of the Qaidam Basin. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Y48T belongs to the genus Nocardia and is closely related to N. cummidelens DSM 44490T (99.0 % similarity), N. soli DSM 44488T (99.0 %), N. lasii 3C-HV12T (98.9 %), N. salmonicida NBRC 13393T (98.6 %), N. ignorata NBRC 108230T (98.6 %) and N. coubleae NBRC 108252T (98.6 %). The average nucleotide identity and DNA–DNA hybridization values between strain Y48T and the reference strains were 75.9–84.5 and 27.5–29.0 %, respectively, values that were below the thresholds for species delineation. Chemotaxonomic analysis indicated that the major fatty acids of strain Y48T were C16 : 0, summed feature 3 (C16 : 1 ω6c/C16 : 1 ω7c), C18 : 1 ω9c and C18 : 0 10-methyl (TBSA). The respiratory quinone was MK-8(H4, ω-cycl). The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, two glycolipids and three unidentified lipids. The cell-wall hydrolysates contained meso-diaminopimelic acid, with ribose, arabinose, glucose and galactose as whole-cell sugars. A combination of 16S rRNA gene sequence analysis, and phenotypic and chemotaxonomic characterizations demonstrated that strain Y48T represents a novel species of the genus Nocardia , for which the name Nocardia mangyaensis sp. nov. is proposed. The type strain is Y48T (=JCM 32795T=CGMCC 4.7494T).

This study investigates the biodegradation of crude oil by a mixed culture of bacteria isolated from the Qinghai-Tibet plateau using gas chromatography-mass spectrometer (GC-MS) and the gravimetric method. The results showed that a mixed culture has a stronger ability to degrade hydrocarbon than pure cultures. Once both Nocardia soli Y48 and Rhodococcus erythropolis YF28-1 (8) were present in a culture, the culture demonstrated the highest crude oil removal efficiency of almost 100% after 10 days of incubation at 20 °C. Moreover, further analysis of the degradation mechanisms used by the above strains, which revealed utilization of different n-alkane substrates, indicated the diversity of evolution and variations in different strains, as well as the importance of multiple metabolic mechanisms for alkane degradation. Therefore, it is concluded that a mixed culture of Y48 and YF28-1 (8) strains can provide a more effective method for bioremediation of hydrocarbon-contaminated soil in permafrost regions.

The plant growth promoting rhizobacterium (PGPR) strain Bacillus amyloliquefaciens GB03, an important soil-borne bacterium, was shown to promote growth and abiotic stress tolerance in Arabidopsis thaliana as well as in some crop plants. This study aimed to evaluate the effects of GB03 on salt tolerance in Codonopsis pilosula, a traditional Chinese medicinal herb that is sensitive to salinity. Twenty-day-old seedlings of C. pilosula were either inoculated with GB03 or without it (as a control). At the same time, plants were treated with NaCl (0, 50, 100, or 150 mM) for 40 days. Growth parameters, photosynthetic indexes, malondialdehyde concentration, and leaf osmotic potential were measured after treatments. The result indicated that GB03 improved plant biomass of C. pilosula under salt conditions and improved the photosynthetic capacity by increasing net photosynthetic rate and stomatal conductance and decreasing intercellular CO2 concentration under both 0 and 50 mM NaCl. The bacterium strain also decreased leaf osmotic potential and peroxidation of membrane lipids that could help the plant adapt to saline environments. This study provides insights into the application of selected bacteria in the culture of important Chinese herbal plants under mild salinity.

Codonopsis pilosula (Franch.) Nannf. is a traditional Chinese herbal medicinal plant and a low-cost succedaneum for Panax ginseng and contains various bioactivity components. In this work, we first evaluated the effects of the inoculation of the plant growth-promoting rhizobacteria Bacillus amyloliquefaciens strain GB03 on growth and metabolite accumulation of C. pilosula. The results demonstrated that application of B. amyloliquefaciens GB03 significantly improved the growth of C. pilosula compared to DH5α, Luria broth medium, and water treatment, respectively. On the other hand, we observed that the content of lobetyolin, one of the most important secondary metabolites in C. pilosula, was obviously improved by inoculation of GB03 and almost reached twice that compared to the other three treatments. In addition, some amino acids of roots were elevated by GB03, although not significantly. In conclusion, B. amyloliquefaciens GB03 could induce positive effects on the growth and further stimulate accumulation of secondary metabolites in C. pilosula.

Bacillus subtilis strain GB03 enhances growth and photosynthesis in the model plant Arabidopsis thaliana and several crop plants. In the present study, the effects of seed soaking with GB03 suspension culture and its volatile organic compounds on seed germination of Codonopsis pilosula (Franch.) Nannf. were investigated, and soil-grown C. pilosula seedlings were assayed to measure growth and photosynthetic capacity after soil inoculation with GB03. Both seed soaking with GB03 suspension culture and the presence of volatile organic compounds enhanced seed germination, especially seed germination vigour. GB03 significantly improved shoot and root length, branching, plant biomass (whole plant fresh and dry weight), leaf area and chlorophyll content in C. pilosula seedlings after 20, 40 and 60 days of soil inoculation. GB03 significantly enhanced transpiration rate, stomatal conductance and net photosynthetic rate, but decreased intercellular CO2 concentration. This study provides insight for the application of selected bacteria to improve biomass in Chinese herbal crops.