Mutation breeding of high 4-androstene-3,17-dione-producing Mycobacterium neoaurum ZADF-4 by atmospheric and room temperature plasma treatment.

Steroid medication is used extensively in clinical applications and comprises a large and vital part of the pharmaceutical industry. However, the difficulty of separating 4-androstene-3,17-dione (AD) from 1,4-androstadiene-3,17-dione (ADD) restricts the application of the microbial transformation of phytosterols in the industry. A novel atmospheric and room temperature plasma (ARTP) treatment, which employs helium as the working gas, was used to generate Mycobacterium neoaurum mutants producing large amounts of AD. After treatment of cultures with ARTP, four mutants were selected using a novel screening method with a color assay. Among the mutants, M. neoaurum ZADF-4 was considered the best candidate for industrial application. When the fermentation medium contained 15 g/L phytosterols and was cultivated on a rotary shaker at 160 r/min at 30 °C for 7 d, (6.28±0.11) g/L of AD and (0.82±0.05) g/L of ADD were produced by the ZADF-4 mutant, compared with (4.83±0.13) g/L of AD and (2.34±0.06) g/L of ADD by the original strain, M. neoaurum ZAD. Compared with ZAD, the molar yield of AD increased from 48.3% to 60.3% in the ZADF-4 mutant. This result indicates that ZADF-4 may have potential for industrial production of AD.

Role of PLC-PIP2 and cAMP-PKA signal pathways in radiation-induced immune-suppressing effect.

OBJECTIVE: The purpose of the present study was to observe the changes in CD4+CD25+Nrp1+Treg cells after irradiation with different doses and explore the possible molecular mechanisms involved. METHODS: ICR mice and mouse lymphoma cell line (EL-4 cells) was used. The expressions of CD4, CD25, Nrp1, calcineurin and PKC-α were detected by flow cytometry. The expressions of TGF-ß1, IL-10, PKA and cAMP were estimated with ELISA. RESULTS: At 12 h after irradiation, the expression of Nrp1 increased significantly in 4.0 Gy group, compared with sham-irradiation group (P<0.05) in the spleen and thymus, respectively, when ICR mice received whole-body irradiation (WBI). Meanwhile the synthesis of Interleukin 10 (IL-10) and transforming growth factor-ß1 (TGF-ß1) increased significantly after high dose irradiation (HDR) (> or = 1.0 Gy). In addition, the expression of cAMP and PKA protein increased, while PKC-α, calcineurin decreased at 12h in thymus cells after 4.0 Gy X-irradiation. While TGF-ß1 was clearly inhibited when the PLC-PIP2 signal pathway was stimulated or the cAMP-PKA signal pathway was blocked after 4.0 Gy X-irradiation, this did not limit the up-regulation of CD4+CD25+Nrp1+Treg cells after ionizing radiation. CONCLUSION: These results indicated that HDR might induce CD4+CD25+Nrp1+Treg cells production and stimulate TGF-ß1 secretion by regulating signal molecules in mice.