Influence of the composition of the medium and the duration of cultivation on the growth of Actinomyces spheroides and their biosynthesis of intracellular proteases and novobiocin

The growth of Actinomyces spheroides 35 under different conditions and the biosynthesis of biomass, proteases and the antibiotic were studied with two types of growth medium: a control one and an optimized one. The rate of biomass accumulation was by 5--7 per cent higher on the latter medium than on the former one. The dynamics of accumulation was studied with novobiocin and proteases which hydrolyzed fibrin and casein. Fibrin hydrolyzing proteases were found to be synthesized under conditions that were unfavourable for the production of novobiocin. If the production of the antibiotic was supressed, the concentration of fibrinolytic proteases in the cultural broth increased almost proportionally. Such a relation has not been found for caseinolytic proteases.     

Effect of the phosphorus concentration on novobiocin formation by the producer Act. spheroides]

According to the literature data biosynthesis of novobiocin by Act. spheroides unlike other antibiotics does not practically depend on the phosphorus levels in the medium. In the present paper it is shown that production of novobiocin in natural media is sensitive to the concentration of mineral phosphorus in the medium. The optimal concentration of phosphorus for biosynthesis of novobiocin is almost within the same ranges as that for biosynthesis of streptomycin, tetracyclines and oleandomycin.     

Functional characterizations of novWUS involved in novobiocin biosynthesis from Streptomyces spheroides

NovW, novU, and novS gene products represent dTDP-4-keto-6-deoxy-D-glucose 3,5 epimarase, C-methyltransferase and dTDP-glucose-4-ketoreductase involved in noviose biosynthetic pathway, respectively. We have expressed three genes to elucidate the functions of NovW, NovU, and NovS in Escherichia coli. NovW and NovU catalyze the formation of dTDP-4-keto-6-deoxy-5-C-methyl-L-lyxo-hexose from dTDP-4-keto-6-deoxy-D-glucose. NovS reduces the product formed from the reaction of NovW with dTDP-4-keto-6-deoxy-D-glucose in the presence of NADH to result in dTDP-l-rhamnose. Furthermore, a pathway for the biosynthesis of noviose is proposed.