Induction and repression of a Streptomyces lividans chitinase gene promoter in response to various carbon sources

Induction and repression of a gene for chitinase (chiA) in Streptomyces lividans was investigated using a catechol 2,3-dioxygenase gene (xylE) as the reporter gene. Of various substrates examined, expression of the promoter (PchiA) was observed after a delay when colloidal chitin or small chitin-oligosaccharides were added to the medium. N-acetylglucosamine completely repressed the chiA promoter. The duration of the delay in expression of PchiA differed with the inducer used, with chitobiose inducing the activity most rapidly. The minimum concentration of chitobiose needed for induction was 1 microM. It appears, therefore, that an efficient inducer of the gene for chitinase in S. lividans is chitobiose.     

Identification and metabolomic analysis of chemical elicitors for tacrolimus accumulation in Streptomyces tsukubaensis

Applied Microbiology and Biotechnology - Tacrolimus is a widely used immunosuppressive agent in the treatment of various clinical diseases. However, the low fermentation yield seriously limits its...     

Enhancement of tacrolimus productivity in Streptomyces tsukubaensis by the use of novel precursors for biosynthesis

In this report the optimization of biosynthesis of tacrolimus, the immunosupressant widely used in transplantology and dermatology was described. The enhancement of the productivity of Streptomyces tsukubaensis strain was achieved by development of new precursors of tacrolimus biosynthesis, which should allow to reduce the costs of the process.The enrichment of the fermentation medium in pyridine-2-carboxylic acid (picolinic acid), piperidine-2-carboxylic acid (pipecolic acid), pyridine-3-carboxylic acid (nicotinic acid) or pyridine-3-carboxylic acid amide (nicotinamide) caused significant growth of the productivity of tacrolimus: 7-fold, 6-fold, 3-fold and 5-fold, respectively. The optimum concentration of the precursors in medium was 0.0025–0.005%. The investigation of the kinetics of tacrolimus biosynthesis together with the analysis of the impact of tested compounds on the culture growth and NAD (nicotinamide adenine dinucleotide) concentration in S. tsukubaensis cells enables to put forward a hypothesis concerning the mechanism of action of tested culture medium additives. The compounds active as tacrolimus precursors (pipecolic and picolinic acids) are more effective than these active mainly as the growth promoters (nicotinamide and nicotinic acid). Nicotinamide and nicotinic acid – vitamin B₃ components – promote S. tsukubaensis growth most probably due to the stimulation of NAD/NADP biosynthesis.     

Analysis and validation of the pho regulon in the tacrolimus-producer strain Streptomyces tsukubaensis: differences with the model organism Streptomyces coelicolor

Applied Microbiology and Biotechnology - Inorganic and organic phosphate controls both primary and secondary metabolism in Streptomyces genus. Metabolism regulation by phosphate in Streptomyces...     

Glucose kinase has a regulatory role in carbon catabolite repression in Streptomyces coelicolor.

A glucose kinase (glkA) mutant of Streptomyces coelicolor A3(2) M145 was selected by the ability to grow in the presence of the nonmetabolizable glucose analog 2-deoxyglucose. In this glkA mutant, carbon catabolite repression of glycerol kinase and agarase was relieved on several carbon sources tested, even though most of these carbon sources are not metabolized via glucose kinase. This suggests that catabolite repression is not regulated by the flux through glucose kinase and that the protein itself has a regulatory role in carbon catabolite repression. A 10-fold overproduction of glucose kinase also results in relief of catabolite repression, suggesting that excess glucose kinase can titrate the repressing signal away. This could be achieved directly by competition of excess glucose kinase with its repressing form for binding sites on DNA promoter regions or indirectly by competition for binding of another regulatory protein.     

Streptomyces plicatus as a model biocontrol agent

Three hundred and seventy two isolates belonging to the genusStreptomyces were isolated and screened for chitinase production.Streptomyces plicatus was found to be the best producer. The highest chitinase production were incubated for 3 d at 30 °C on buffered culture medium (pH 8.0) containing chitin plus sucrose and calcium nitrate as carbon and nitrogen sources.S. plicatus chitinase had a highly significant inhibitory effect on spore germination, germ tube elongation and radial growth ofFusarium oxysporum f.sp.lycopersict., Altrernaria alternata andVerticillium albo-atrum, the causal organisms ofFusarium wilt, stem canker andVerticillium wilt diseases of tomato. Application ofS. plicatus to the root system of tomato plants before transplantation markedly protected tomato plants against the tested phytopathogenic fungiin vivo.     

Candida zeylanoides as a new yeast model for lipid metabolism studies: effect of nitrogen sources on fatty acid accumulation

Lipid homeostasis is well-known in oleaginous yeasts, but there are few non-oleaginous yeast models apart from Saccharomyces cerevisiae. We are proposing the non-oleaginous yeast Candida zeylanoides QU 33 as model. The aim of this study was to investigate the influence of the carbon/nitrogen ratio and the type of nitrogen source upon oil accumulation by this yeast grown on shake flask cultures. The maximum biomass was obtained in yeast extract (2.39?±?0.19 g/l), followed by peptone (2.24?±?0.05 g/l), while the highest content of microbial oil (0.35?±?0.01 g/l) and the maximum lipid yield (15.63 %) were achieved with peptone. Oleic acid was the predominant cellular fatty acid in all culture media (>32.23 %), followed by linoleic (>15.79 %) and palmitic acids (>13.47 %). The highest lipid yield using glucose and peptone was obtained at the C/N ratio of 200:1.