Fluoroacetate-metabolizing pseudomonad isolated from Dichapetalum cymosum.

A pseudomonad was isolated from the fluoroacetate-producing plant Dichapetalum cymosum (Hook) Engl. and identified as Pseudomonas cepacia. We established that this isolate was capable of growing in fluoroacetate-enriched solutions without any reduction in growth rate. Our isolate of P. cepacia was capable of defluorinating 2.69 mg of fluoroacetate per 10(9) cells per h. Fluoroacetate was degraded to CO2 at a rate of 23.53 ng/10(9) cells per h.     

Utilization of cutin by a pseudomonad isolated from soil

Summary A Pseudomonas sp., which has been isolated from orchard soil, is able to utilize cutin as a sole source of carbon. Products obtained from the culture filtrate corresponded to that obtained by alkaline hydrolysis of cutin.     

A note on a prodigiosin-producing pseudomonad isolated from a lowland river

A Gram negative, oxidase-positive, bacterium which produced prodigiosin has been isolated during a survey of freshwater chromobacteria. It forms colonies with an adherent, rubbery texture on solid media and a flocculent growth in liquid culture. The organism will not grow at temperatures above 30°C nor will it tolerate concentrations of sodium chloride in excess of 0.5%.     

Chromate reduction by a pseudomonad isolated from a site contaminated with chromated copper arsenate

A pseudomonad (CRB5) isolated from a decommissioned wood preservation site reduced toxic chromate [Cr(VI)] to an insoluble Cr(III) precipitate under aerobic and anaerobic conditions. CRB5 tolerated up to 520 mg of Cr(VI) liter(-1) and reduced chromate in the presence of copper and arsenate. Under anaerobic conditions it also reduced Co(III) and U(VI), partially internalizing each metal. Metal precipitates were also found on the surface of the outer membrane and (sometimes) on a capsule. The results showed that chromate reduction by CRB5 was mediated by a soluble enzyme that was largely contained in the cytoplasm but also found outside of the cells. The crude reductase activity in the soluble fraction showed a K(m) of 23 mg liter(-1) (437 microM) and a V(max) of 0.98 mg of Cr h(-1) mg of protein(-1) (317 nmol min(-1) mg of protein(-1)). Minor membrane-associated Cr(VI) reduction under anaerobiosis may account for anaerobic reduction of chromate under nongrowth conditions with an organic electron donor present. Chromate reduction under both aerobic and anaerobic conditions may be a detoxification strategy for the bacterium which could be exploited to bioremediate chromate-contaminated or other toxic heavy metal-contaminated environments.     

An inducible riboflavin synthetase from a pseudomonad

Riboflavin synthetase activity is induced in a strain ofPseudomonas fluorescenspulida intermediate only under conditions permitting an accumulation of compound P, a 2,4-dioxopteridine, in the medium. The effect of different amino acids and sugars on the production of compound P and riboflavin synthetase was determined. The enzyme was partially destroyed by ammonium sulphate fractionation. It is inhibited by heavy metal ions and PCMB. PCMB inhibition can be almost completely reversed by GSH.     

秦巴山区野生金荞麦的营养及有效成分研究

对秦巴山区野生金荞麦Fagopyrum cymosum营养成分和有效成分进行分析。结果表明,秦巴山区野生金荞麦营养丰富、有效成分(表儿茶素、芦丁等)含量较高。其中,粗蛋白含量较高,达20.03%,可作为高蛋白的金荞麦育种材料;金荞麦氨基酸总量为15.78%,其中必需氨基酸含量为5.54%,非必需氨基酸含量为10.24%,是一种氨基酸含量较丰富的资源植物。秦巴山区野生金荞麦可作为优良野生牧草资源与药用兼备的多用途植物,具进一步开发利用价值。     

Study on Hairy-Root Cultures of Fagopyrum cymosum

Transformed hairy root cultures of Fagopyrum cymosum (Trey.) Meisn. have been established by infecting petioles of shoots cultured in vitro with Agrobacterium rhizogenes. These hairy root cultures grew vigorously in MS hormone-free medium. They showed a 1861-fold increase in fresh weight with in 25 days, and grew faster than cell cultures of F. cymosum (only increased 26.7-fold with in the same days). The cultures were shon to synthesis dimeric procyanidin up to 4.5% (dry wt.) approximating the level of original plant. The growth rates of hairy root cultures up to 149.3 mg dry w-t/L/day in large culture vessels (3 L) and dimeric procyanidin (3.58%, dry wt.) were detected.     

Degradation of triglycerides by a pseudomonad isolated from milk: molecular analysis of a lipase-encoding gene and its expression in Escherichia coli.

Psychrotrophic lipolytic bacteria represent a significant problem in the storage of refrigerated dairy products. A lipase-encoding gene has been cloned and characterized from a highly lipolytic strain of Pseudomonas. The nucleotide sequence of the gene predicts a polypeptide of M(r) 49,905, which was identified when the gene was expressed in Escherichia coli.     

Degradation of triglycerides by a pseudomonad isolated from milk: molecular analysis of a lipase-encoding gene and its expression in Escherichia coli.

Psychrotrophic lipolytic bacteria represent a significant problem in the storage of refrigerated dairy products. A lipase-encoding gene has been cloned and characterized from a highly lipolytic strain of Pseudomonas. The nucleotide sequence of the gene predicts a polypeptide of M(r) 49,905, which was identified when the gene was expressed in Escherichia coli.     

金荞麦抗菌活性研究

目的 探讨金荞麦乙醇提取物乙酸乙酯的萃取部分（待测样品）的抑菌作用,并对此部分进行分离纯化以研究其抗菌活性的物质基础。方法 与复方板蓝根颗粒做对比,采用平皿稀释法及动物实验对待测样品进行体外及体内实验,测定其对各试验菌的最小抑菌浓度（MIC）和对肺炎链球菌感染小鼠的体内保护作用.并采用多种色谱方法对此部分进行分离纯化。结果 体外抑菌试验表明,待测样品对乙型溶血性链球菌、肺炎球菌有明显的抑制作用;体内抑菌实验表明此部分对肺炎球菌菌株所致的小鼠感染有保护作用;从该活性部分分离得到8个化合物为：反式对羟基桂皮酸甲酯（trans-p-hydroxy cinnamic methyl ester,Ⅰ）,3,4-二羟基苯甲酰胺（3,4-dihydroxy benzamide,Ⅱ）,原儿茶酸（protocatechuic acid,Ⅲ）,原儿茶酸甲酯（protocatechuic acid methyl ester,Ⅳ）,木犀草素（luteolin,V）,槲皮素（quercitrin,Ⅵ）,芸香苷（rutm,Ⅶ）,（一）-表儿茶素[（一）-epicatechin,Ⅷ]。结论 待测样品在体内及体外均有较强的抑菌活性,而具有抗菌作用的物质基础为酚酸类及黄酮类化合物。     

Purification and properties of benzoate-4-hydroxylase from a soil pseudomonad.

Benzoate-4-hydroxylase from a soil pseudomonad was isolated and purified about 50-fold. Polyacrylamide gel electrophoresis of this enzyme preparation showed one major band and one minor band. The approximate molecular weight of the enzyme was found to be 120,000. Benzoate-4-hydroxylase was most active around pH 7.2. The enzyme showed requirements for tetrahydropteridine as the cofactor and molecular oxygen as the electron acceptor. NADPH, NADH, dithiothreitol, β-mercaptoethanol, and ascorbic acid when added alone to the reaction mixture did not support the hydroxylation reaction to any significant extent. However, when these compounds were added together with tetrahydropteridine, they stimulated the hydroxylation. This stimulation is probably due to the reduction of the oxidized pteridine back to the reduced form. This enzyme was activated by Fe²⁺ and benzoate. It was observed that benzoate-4-hydroxylase could catalyze the oxidation of NADPH in the presence of benzoate,p-aminobenzoate, p-nitrobenzoate, p-chlorobenzoate, and p-methylbenzoate, with only benzoate showing maximum hydroxylation. Inhibition studies with substrate analogs and their kinetic analysis revealed that the carboxyl group is involved in binding the substrate to the enzyme at the active center. The enzyme catalyzed the conversion of 1 mol of benzoate to 1 mol of p-hydroxybenzoate with the consumption of slightly more than 1 mol of NADPH and oxygen.     

Molecular analysis of an esterase-encoding gene from a lipolytic psychrotrophic pseudomonad.

An esterase gene (estA) from a lipolytic psychotroph (Pseudomonas sp. LS107d2), was cloned in Escherichia coli and its nucleotide sequence was determined, revealing an ORF encoding a polypeptide of 389 amino acid residues, with a molecular mass of 42276 Da. Labelling of plasmid-encoded proteins with [35S]methionine, using the maxicell procedure, gave a single polypeptide of molecular mass 42 kDa, consistent with that calculated from the ORF. Colonies of E. coli cells containing estA produced a clear halo when grown on solid media containing tributyrin; no clearance was produced when cells were grown on media containing triolein. Extracts of cells containing estA also hydrolysed water-soluble nitrophenol esters, but were unable to cleave water-insoluble substrates. The preference for water-soluble substrates indicates that the gene product is an esterase.     

Purification and characterization of a secondary alcohol dehydrogenase from a pseudomonad.

Growth of Pseudomonas sp. NRRL B3266 in the presence of oleic acid resulted in the induction of two enzymes: oleate hydratase, which produced 10(R)hydroxyoctadecanoate, and hydroxyoctadecanoate dehydrogenase, which catalyzed the oxidized nicotinamide adenine dinucleotide-dependent production of 10-oxooctadecanoate. This latter enzyme was purified to homogeneity and shown to consist of two polypeptide chains of about 29,000 daltons each. The enzyme had a broad substrate specificity, catalyzing the dehydrogenation of a number of 18-carbon hydroxy fatty acids. The kinetic parameters for various 10- and 12-hydroxy fatty acids were similar (Km ca. 5 micron and Vmax ca. 50 to 200 mumol/min per mg of protein). The enzyme also catalyzed the dehydrogenation of unsubstituted secondary alcohols. The effectiveness of these alcohols as substrates was highly dependent on their hydrophobicity, the Km decreasing from 9 mM for 4-heptanol to 7 micron for 6-dodecanol. Inhibition of the enzyme by primary alcohols also showed a dependence on hydrophobicity, the Ki decreasing from 350 mM for methanol to 90 micron for decanol.