No abstract

Improvement of pristinamycin production by Streptomyces pristinaespiralis was performed by using recursive protoplast fusion and selection for improved resistance to the product antibiotic in a genome shuffling format. A 100-microg/ml pristinamycin resistant recombinant, G 4-17, was obtained after four rounds of protoplast fusion, and its production of pristinamycin reached 0.89 g/l, which was increased by 89.4% and 145.9% in comparison with that of the highest parent strain M-156 and the original strain CGMCC 0957, respectively. The subculture experiments indicated that the hereditary character of high producing S. pristinaespiralis G 4-17 was stable. It is concluded that genome shuffling improves the production of pristinamycin by enhancing product-resistance in a stepwise manner. Pristinamycin fermentation experiments by recombinant G 4-17 were carried out in a 5-l fermentor, and its production of pristinamycin reached 0.90 g/l after 60 h of fermentation.

No abstract

Effective microbial metabolic engineering is reliant on efficient gene transfer. Here we present a simple screening strategy that may be deployed to isolate rare, hypertransformable variants. The procedure was used to increase the frequency of transformation of the solvent producing organism Clostridium pasteurianum by three to four orders of magnitude.