MLFE (Micrococcus luteus fibrinolytic enzyme) is a fibrinolytic enzyme produced by Micrococcus luteus ML909 strain. The promoter and signal peptide-coding sequence of ?-amylase gene from Bacillus amyloliquefaciens DC-4 was cloned and fused to the sequence coding for mature peptide of MLFE (Gen-Bank: EU232121), forming the fusion gene called amymlfe. This hybrid gene was inserted into the Escherichia coli-Bacillus subtilis shuttle plasmid vector pSUGV4 and expression plasmid pSU-AmyMLFE was constructed. After transformation with B. subtilis WB600, transformant WB600/pSU-AmyMLFE was obtained and produced clear hydrolyzed zones on fibrin plates. The fibrinolytic activity in supernatants of WB600/pSU-AmyMLFE fermented for 24 hours was tested and found to be 238 UKU/mL. The results of SDS-PAGE analysis showed that there was indeed recombinant protein in supernatants. The Western blotting showed that the molecular weight of the expressed protein was the same as expected. These results indicate that the gene, amymlfe, is successfully expressed in B. subtilis WB600.

This study aimed to explore the correlation between rhizosphere soil microorganisms of wild Arnebia euchroma and the content of medicinal components to provide guidance for the selection of the ecological planting base. The total DNA of rhizosphere soil microorganisms of wild A. euchroma was extracted, and the microbial community structure of rhizosphere soil microorganisms was analyzed by IlluminaMiseq high-throughput sequencing technology. The content of total hydroxynaphthoquinone pigment and β,β'-dimethylacrylalkannin in medicinal materials was determined by high-performance liquid chromatography(HPLC). The physicochemical pro-perties of rhizosphere soil of wild A. euchroma in main producing areas were determined, and the correlation of soil microbial abundance with index component content and soil physicochemical properties was analyzed by SPSS software. The results showed that the species composition of rhizosphere fungi and bacteria in A. euchroma from different habitats was similar at the phylum and genus levels, but their relative abundance, richness index(Chao1), and community diversity(Simpson) index were different. Correlation analysis showed that the content of available phosphorus in soil was positively correlated with the content of total hydroxynaphthoquinone pigment and β,β'-dimethylacrylalkannin, and the abundance of five fungal genera such as Solicoccozyma and six bacterial genera such as Pseudo-nocardia and Bradyrhizobium was positively correlated with the content of medicinal components in medicinal materials. The abundance of Bradyrhizobium was significantly positively correlated with the content of β,β'-dimethylacrylalkanin. The abundance of fungi such as Archaeorhizomyces was significantly positively correlated with the content of available phosphorus in rhizosphere soil, and Bradyrhizobium was significantly negatively correlated with soil pH. Therefore, the abundance of fungi and bacteria in the rhizosphere of A. euchroma has a certain correlation with the medicinal components and the physicochemical properties of the rhizosphere soil, which can provide a scientific basis for the selection of ecological planting bases in the later stage.
Rhizosphere ; Soil Microbiology ; Bacteria/genetics* ; Phosphorus ; Soil ; Boraginaceae