Biotransformation of compactin to pravastatin by Actinomadura sp. 2966.

Actinomadura sp. strain 2966 can effectively convert compactin to pravastatin. The degree of conversion observed was 65% to 78% of compactin added and 65% to 88% of compactin taken up, depending on the concentration of compactin and duration of the experiment. Increasing the compactin concentration resulted in a higher final pravastatin concentration especially when compactin was added intermittently. Higher glucose concentrations had no effect on the bioconversion although uptake of compactin was inhibited. The conversion was linear over 16 hours. The system requires no induction and thus appears to be different from previously studied hydroxylases from actinomycetes.

Effect of glpT and glpD mutations on expression of the phoA gene in Escherichia coli.

In vivo 31P nuclear magnetic resonance analysis of Escherichia coli cells showed that the intracellular concentration of P(i) remained constant in wild-type and in a glpT mutant strain whether the cells were grown on excess (2 mM) P(i) or sn-glycerol-3-phosphate as a phosphate source. The function of the phoA promoter (measured by beta-galactosidase activity in a phoA-lacZ fusion strain) was repressed when glpT+ cells were utilizing sn-glycerol-3-phosphate as the sole source of phosphate. These cells were devoid of alkaline phosphatase activity. However, the phoA promoter was fully active in a glpT mutant. These results indicated that the repression of the enzyme synthesis was not due to a variation in the level of cytoplasmic P(i) but was due to the P(i) excreted into the periplasm and/or to the medium.

The antimicrobial activity of the essential oil from Achillea fragrantissima.

Essential oil from Achillea fragrantissima exerted a bactericidic effect on several gram positive and gram negative bacterial strains, as well as on Candida albicans. The oil was fractionated on sillica gel columns by a gradient of ether in petrol ether (30 degrees C-40 degrees C). Two fractions which contained less polar compounds were active against C. albicans only. The fractions which contained more polar compounds inhibited the growth of all the microorganisms tested. One of these compounds was identified as terpinen-4-ol. Commercial terpinen-4-ol had a similar antimicrobial activity.

Purification and characterization of uridine and thymidine phosphorylase from Lactobacillus casei.

Uridine and thymidine phosphorylases have been purified to homogeneity from crude extracts of Lactobacillus casei. Both enzymes had an apparent molecular mass of about 80 kDa. Uridine phosphorylase consisted of four identical subunits while thymidine phosphorylase was composed of two identical ones. The sequence of 23 amino-acid residues from its N-terminal end was analyzed. Uridine phosphorylase had a Km of 5.0 x 10(-3) M for uridine and 1.24 x 10(-1) M for phosphate, while thymidine phosphorylase had a Km of 1.32 x 10(-1) M for thymidine and 1.0 x 10(-1) M for phosphate. Uridine phosphorylase was equally active with uridine and 5-methyluridine, but had a low activity towards thymidine. Its activity was inhibited competitively by 3-O-methyl-alpha D-glucopyranoside, on the other hand thymidine phosphorylase activity was not affected by this compound. Thymidine phosphorylase showed specificity towards the deoxyribosyl moiety of the substrate. In addition, it required a nonsubstituted pyrimidine moiety or one which was substituted in position 5. The pattern of the double-reciprocal plots of the initial velocities vs. the concentrations of either one of the substrates, and the product inhibition kinetics, indicated that the catalytic mechanism of both enzymatic reactions is sequential rather than Ping-Pong and that the sequence of the addition of the substrates is random (rapid equilibrium). In the case of the uridine phosphorylase-catalyzed reaction, the products are also released randomly, while in the thymidine phosphorylase-catalyzed reaction deoxyribose 1-phosphate is released after thymine.

Nucleotide pool in pho regulon mutants and alkaline phosphatase synthesis in Escherichia coli.

The intracellular nucleotide pool of Escherichia coli W3110 reproducibly changes from conditions of growth in phosphate excess to phosphate starvation, with at least two nucleotides appearing under starvation conditions and two nucleotides appearing only under excess phosphate conditions. Strains bearing a deletion of the phoA gene show the same pattern, indicating that dephosphorylation by alkaline phosphatase is not responsible for the changes. Strains with mutations in the phoU gene, which result in constitutive expression of the pho regulon, show the nucleotide pattern of phosphate-starved cells even during phosphate excess growth. These changes in nucleotides are therefore due to phoU mutation but not to alkaline phosphatase constitutivity. In fact, a phoR (phoR68) mutant strain has the patterns of the wild type in spite of being constitutive for alkaline phosphatase. That these nucleotides might be specific signals for pho regulon expression was supported by the fact that the two nucleotides appearing under phosphate starvation induced the synthesis of alkaline phosphatase in repressed permeabilized wild-type cells under conditions of phosphate excess.

Antibacterial activity of Artemisia herba-alba.

The antibacterial activity of Artemisia herba-alba was investigated. Only its essential oil was active against some Gram-positive and Gram-negative bacteria. The essential oil was fractionated by column chromatography, and these fractions were tested for antibacterial activity. The principal component of the most active fraction was santolina alcohol.

Regulation of lactate dehydrogenase synthesis in Bacillus subtilis.

The regulation of lactate dehydrogenase in Bacillus subtilis was determined under a variety of growth conditions and in mutants blocked in the citric acid cycle. The synthesis of lactate dehydrogenase increased sharply concomitantly upon the exhaustion of glucose from the medium and the onset of the stationary phase. The synthesis of lactate dehydrogenase may be under catabolite repression control. Studies with mutants blocked in the citric acid cycle showed that lactate dehydrogenase is regulated independently of either the oxidative or reductase branches of the cycle. Certain citric acid cycle mutants, e.g., aconitase or succinate dehydrogenase, exhibited very low levels of lactate dehydrogenase while others, e.g., malate dehydrogenase or isocitrate dehydrogenase, showed normal levels. A stage O sporulation mutant expressed levels of lactate dehydrogenase more than one thousand-fold higher than the low group of citric acid cycle mutants. The induction of lactate dehydrogenase was shown to be independent of the accumulation of its substrate, pyruvate.

Inhibition and stimulation of the development of the bioluminescent system in Beneckea harveyi by cyclic GMP.

The development of the luminescence system in Beneckea harveyi is controlled by cyclic nucleotides at the level of transcription. In the wild type, it is repressed by exogenously added guanosine 3':5'-cyclic monophosphate and this repression is overcome by the addition of adenosine 3':5'-cyclic monophosphate. These observations alone support a model in which these nucleotides act antagonistically. On the other hand, in a mutant requiring adenosine 3':5'-cyclic monophosphate for maximum luminescence, guanosine 3':5'-cyclic monophosphate stimulates the synthesis of the luminescence system at low concentrations and inhibits it at higher concentrations. These results are apparently not consistent with a model involving a simple antagonistic effect of guanosine 3':5'-cyclic monophosphate on the action of adenosine 3':5'-cyclic monophosphate.

beta-D-galactosidase activity in single yeast cells during cell cycle of Saccharomyces lactis.

Single Saccharomyces lactis cells taken from a random population were assayed for beta-D-galactosidase activity under a microscope equipped for fluorogenic measurements. The cells were also photographed, and enzymatic activity was correlated to the size of cell buds. A perodic pattern of enzyme synthesis was found during the cell cycle.

An adenosine 3',5'-monophosphate-requiring mutant of the luminous bacteria Beneckea harveyi.

We have isolated a mutant of the luminous bacterium Beneckea harveyi, which requires exogenous adenosine 3',5'-monophosphate (cyclic AMP) to synthesize luciferase and emit light. The mutant was pleiotropic, lacking not only the ability to luminesce, but also the capacities to form flagella and the ability to utilize a variety of carbohydrates for growth. All these deficiencies could be corrected by added cyclic AMP. The cyclic AMP-induced de novo synthesis of luciferase was possible only after autoinduction had occurred. The induction time by cyclic AMP ranged between 6 and 10 min at 27 degrees C.

Control of synthesis of malate dehydrogenase in Aerobacter aerogenes.

An inverse linear relationship was observed between the levels of l-malate dehydrogenase (MDH) and growth rates of Aerobacter aerogenes when grown under aerobic and anaerobic conditions on various substrates which served as the sole carbon and energy sources. Deviations from this linearity were found. MDH levels of cells grown aerobically on oxalacetate, l-malate, d-mannose and d-galactose, and of cells grown anaerobically on l-malate and d-mannose were higher than those expected according to this relationship. Enzyme levels of cells grown aerobically on maltose, d-glucuronate, pyruvate, and possibly melibiose and sucrose were lower than the expected ones. Experiments in which the cells were grown on a mixture of two substrates showed that substrates which gave low levels of MDH repressed the synthesis of this enzyme even in the presence of l-malate or other "high-level substrates." Repressed levels were also observed when the mixture contained l-malate together with "intermediate" or high-level substrates. Identical MDH patterns were obtained by acrylamide gel electrophoresis for all the enzymatic preparations.