Showing papers by "Arnold L. Demain published in 1988"
TL;DR: This method was used to enumerate individual cell viability directly, without any prior culture, from clinically infected urine samples in about 1.5 hours for several rapidly growing pathogens, and was in agreement with much slower conventional culture methods.
Abstract: We report a new, flexible method for rapid detection and enumeration of individual microorganisms using small (e.g. 10 to 100 micron diameter) gel particles surrounded by a non-aqueous liquid with low dielectric constant. Primary samples without prior cultivation can be used. In the present study, gel microdroplets (GMDs) surrounded by an inert oil were statistically inoculated such that GMDs had a high probability of initially containing either zero or one acid-producing microorganism. Such GMDs retained dissociable metabolites produced by individual cells (or microcolonies) within the small GMD volume. The accumulated metabolic acids led to rapid changes in pH within GMDs initially occupied by one microorganism or colony forming unit (CFU), while GMDs with zero microorganisms had unchanged pH. The cumulative activity within individual GMDs was then determined using pH sensitive fluorescence indicators. This method was used to enumerate individual cell viability directly, without any prior culture, from clinically infected urine samples in about 1.5 hours for several rapidly growing pathogens, and was in agreement with much slower conventional culture methods. Because GMDs can be made readily in large numbers, and because many indicator systems can be used, GMDs used with automated measurement apparatus should have wide applicability.
58 citations
TL;DR: Previously characterized mutants of Bacillus subtilis 168 were analyzed for the accumulation of the antibiotic bacilysin in culture broths and for the presence of b Bacilysin synthetase in cell extracts, suggesting that prephenate is the primary metabolic precursor of bacallysin.
Abstract: Previously characterized mutants of Bacillus subtilis 168 were analyzed for the accumulation of the antibiotic bacilysin in culture broths and for the presence of bacilysin synthetase in cell extracts. All aro mutants tested were deficient in bacilysin biosynthesis but had synthetase activity. Mutants with lesions in tyrA and pheA produced normal levels of bacilysin, suggesting that prephenate is the primary metabolic precursor of bacilysin.
40 citations
TL;DR: A Bacillus subtilis mutant which carries a lesion in a gene specific to the synthesis of the dipeptide antibiotic bacilysin was isolated and used as the donor in PBS-1 transduction mapping experiments.
Abstract: A Bacillus subtilis mutant which carries a lesion in a gene specific to the synthesis of the dipeptide antibiotic bacilysin was isolated. A derivative strain in which transposon Tn917 had inserted near the bacilysin lesion was isolated and used as the donor in PBS-1 transduction mapping experiments. The bac-1 locus was mapped between the ctrA and sacA loci, near 90% on the standard B. subtilis 168 chromosome map.
24 citations
01 Jan 1988
23 citations
TL;DR: The present finding demonstrates that the genetic functions encoding hydrolysis of MUG and cellobiose are associated closely on the C. thermocellum chromosome, however, whether one or more protein is involved in the hydrolyzing of the two substrates remains to be determined.
22 citations
TL;DR: β-Lactam production by a high producer, Cephalosporium acremonium C-10, was reduced by high concentrations of phosphate (100 mM to 215 mM) and the optimal concentration for antibiotic production by this strain was 25 mM.
Abstract: β-Lactam production by a high producer,Cephalosporium acremonium C-10, was reduced by high concentrations of phosphate (100 mM to 215 mM). The optimal concentration for antibiotic production by this strain was 25 mM. High concentrations of phosphate did not act by increasing the rate of glucose assimilation as previously concluded (Kuenzi 1980). The three β-lactam synthetases tested, i.e., δ-(l-α-aminoadipyl)-l-cysteinyl-d-valine synthetase, cyclase and expandase, were all subject to phosphate repression as well as inhibition. The most susceptible to both kinds of regulation was the expandase.
21 citations
14 citations
TL;DR: Methionine interference in the formation of thienamycin byStreptomyces cattleya is due, to a major extent, to inhibition of enzyme activity.
Abstract: Methionine interference in the formation of thienamycin byStreptomyces cattleya is due, to a major extent, to inhibition of enzyme activity.
13 citations