Showing papers by "Arnold L. Demain published in 1989"
TL;DR: A cellulose degradation process using beta-glucosidase to assist the potent cellulase complex of C. thermocellum, as shown here can open the way for industrial saccharification of cellulose to glucose.
55 citations
TL;DR: Cephalosporin production by Streptomyces clavuligerus was reduced sharply by 60 mM phosphate added to a chemically-defined medium and all the four synthetases in the pathway examined were repressed by phosphate, with ACV synthetase being the main repression target and expandase the next.
Abstract: Cephalosporin production by Streptomyces clavuligerus was reduced sharply by 60 mM phosphate added to a chemically-defined medium. All the four synthetases in the pathway examined, i.e, ACV synthetase, cyclase, epimerase and expandase, were repressed by phosphate, with ACV synthetase being the main repression target and expandase the next. ACV synthetase activity was inhibited by phosphate to a lesser extent than expandase and cyclase, and this inhibition could be reversed by adding Fe2+. Fe2+ itself was inhibitory to ACV synthetase action.
34 citations
TL;DR: Repression of ACV synthetase, cyclase, and expandase appears to be the major factors contributing to the negative effect of ammonium on S. clavuligerus NRRL 3585.
Abstract: Production of cephems (predominantly cephamycin C) by Streptomyces clavuligerus grown in chemically defined medium supplemented with 120 mM NH4Cl was sharply reduced. This concentration of ammonium...
25 citations
TL;DR: Inhibition by glucose and its catabolites of ACV synthetase appears to be one of the mechanisms involved in the negative carbon source regulation of β-lactam biosynthesis.
Abstract: The high cephalosporin-producing strainCephalosporium acremonium C-10 was found to be still subject to carbon source regulation despite earlier mutations which decreased this effect. Under phosphorus source limitation, a low concentration (2.7%) and a high concentration (6.3%) of glucose or glycerol as carbon source supported similar growth rates. The high concentration of glucose or glycerol decreased β-lactam production and repressed the formation of deacetoxycephalosporin C synthase, but not of isopenicillin N synthase or δ-(l-α-aminoadipyl)-l-cysteinyl-d-valine synthetase. A high concentration of glucose also suppressed penicillin N accumulation; this suggested the existence of an enzyme inhibition effect by glucose or its catabolites. This was supported by data from a resting-cell experiment. In vitro studies showed glucose to inhibit the action of ACV synthetase in crude extracts, with more than 70% of the activity inhibited by 5 mM glucose. Glucose-6-phosphate and glyceraldehyde-3-phosphate also were inhibitory. 3-Phosphoglycerate inhibited expandase activity. Inhibition by glucose and its catabolites of ACV synthetase appears to be one of the mechanisms involved in the negative carbon source regulation of β-lactam biosynthesis.
22 citations
TL;DR: A chemically-defined medium for rapid and extensive growth of one such strain, BGSC-1S53, which is useful for the prototrophic 168 strain, a triple auxotroph of 168, and a highly debilitated (HV-2) 168 strain (BGSC 1S76) upon addition of the specific growth factors required by these strains.
Abstract: Conventional chemically-defined media were found to be inadequate for extensive batch culture growth of an asporogenous mutant of Bacillus subtilis certified as an HV-1 host for recombinant DNA We developed a chemically-defined medium for rapid and extensive growth of one such strain, BGSC-1S53 The medium contains no components requiring separate sterilization It is also useful for the prototrophic 168 strain (from which 1S53 was derived), a triple auxotroph of 168, and a highly debilitated (HV-2) 168 strain (BGSC 1S76) upon addition of the specific growth factors required by these strains Excellent growth was also obtained with W-23, a Bacillus subtilis strain unrelated to the 168 series
9 citations