Studies on Metabolism of Pyrrolidone Carboxylic Acid in Bacteria

The present investigation is concerned with l-glutamic acid production in the presence of pyrrolidone carboxylic acid and glucose in Bacillus megaterium st. 6126. This strain does not grow on dl-pyrrolidone carboxylic acid (dl-PCA)¹⁾ as the sole source of carbon and nitrogen. The optimal concentration of yeast extract required for the maximal production of l-glutamic acid was 0.005% under the conditions used. As the yeast extract concentration was increased, growth increased proportionally; but the l-glutamic acid production did not exceed the control’s to which glucose and ammonium chloride had been added. l-Glutamic acid produced by both growing cultures and resting cells was derived from glucose and ammonium salt of dl-PCA. Isotope experiments suggested that the l-glutamic acid produced was partially derived from ammonium salt of dl-PCA in the growing culture which had been supplemented with d-glucose-U-¹⁴C or dl-PCA-1-¹⁴C and that ammonium salt of dl-PCA was consumed as the source of nitrogen and carbon for l-glutamic acid.     

Renierol from marine sponge Haliclona.SP.: A natural inhibitor of xanthine oxidase with hypouricemic effects

The purpose of this study was to evaluate the inhibitory effect of renierol, extracted from marine sponge Halicdona.SP., on xanthine oxidase (XO) and its hypouricemic effect in vivo. Renierol and a positive control, allopurinol, were tested for their effects on XO activity by measuring the formation of uric acid and superoxide radical from xanthine. Renierol inhibited XO in a concentration-dependent and competitive manner. IC₅₀ value was 1.85 μg·ml^{? 1} through the measuring of uric acid and was 1.36 μg.ml^{? 1} through the measuring of superoxide radical. Renierol was found to have an in vivo hypouricemic activity against potassium oxonate-induced hyperuricaemia in mice. After oral administration of renierol at doses of 10, 20 and 30 mg.kg^{? 1}, there was a significant decrease in the serum urate level (4.08 ± 0.09 mg.dl^{? 1}, P < 0.01), (3.47 ± 0.11 mg.dl^{? 1}, P < 0.01) and (3.12 ± 0.08 mg.dl^{? 1}, P < 0.01), when compared to the hyperuricaemic control (6.74 ± 0.23 mg.dl^{? 1}). Renierol was a potent XO inhibitor with hypouricemic activity in mice.     

Total Synthesis of dl-Deguelin

Starting with resorcinol, the total synthesis of dl-deguelin (VI) was accomplished. In the course of this investigation, dihydrodeguelic acid (II), dihydroisodeguelic acid (X), dihydro-dehydrodeguelin (III), dehydrodeguelin (IV), dl-deguelol (V) and dihydro-β-rotenonone (XI) were prepared. But the reduction of dihydrodehydrodeguelin (III) to dihydrodeguelin (XII) resulted in failure. The preparation of dihydrodeguelol (XIIIa), its acetate (XIIIb) and dihydro-desoxy-Δ¹¹-dehydrodeguelin (XIV) was also described.     

Racemic Resolution of some <Emphasis Type="SmallCaps">dl</Emphasis>-Amino Acids using <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis><Emphasis Type="SmallCaps">l</Emphasis>-Amino Acid Oxidase

The ability of Aspergillus fumigatus l-amino acid oxidase (l-aao) to cause the resolution of racemic mixtures of dl-amino acids was investigated with dl-alanine, dl-phenylalanine, dl-tyrosine, and dl-aspartic acid. A chiral column, Crownpak CR+ was used for the analysis of the amino acids. The enzyme was able to cause the resolution of the three dl-amino acids resulting in the production of optically pure d-alanine (100% resolution), d-phenylalanine (80.2%), and d-tyrosine (84.1%), respectively. The optically pure d-amino acids have many uses and thus can be exploited industrially. This is the first report of the use of A. fumigatus l-amino acid oxidase for racemic resolution of dl-amino acids.     

Differential effects of amino acid analogs on growth and heterocyst differentiation in two nitrogen-fixing blue-green algae

Effects of a few amino acid analogs on growth and heterocyst differentiation have been studied in two nitrogen-fixing species ofAnabaena. All the analogs except α-methyl-dl-aspartic acid inhibited growth. Exposure ofAnabaena doliolum, todl-5-fluorotryptophan anddl-p-fluorophenylalanine caused pronounced fragmentation of filaments into single cells. At low concentrations (0.01 mM), α-methyl-dl-aspartic acid stimulated growth of the strain ofA. doliolum as well as the strain of the second (unidentified)Anabaena species. Ethionine,dl-p-fluorophenylalanine,dl-5-fluorotryptophan, and canavanine blocked heterocyst differentiation, whereas α-methyl-dl-aspartic acid, α-methyl-dl-methionine,N-o-nitrophenylsulfenyl-l-tryptophan, norleucine, andS-2-aminoethyl-l-cysteine did not show any significant effect. Treatment with 7-azatryptophan,dl-β-hydroxynorvaline,l-methionine-dl-sulfoximine,l-methionine sulfone, and β-2-thienyl-dl-alanine led to a twofold increase in heterocyst frequency. Possible modes of action of the analogs in growth inhibition and changes in heterocyst frequency are discussed.     

Identification and characterization of the zosA gene involved in copper uptake in Bacillus subtilis 168

dl-Penicillamine, a copper-specific metal chelator, remarkably suppressed the growth of Bacillus subtilis 168 when added to a synthetic medium under Cu²⁺ limitation. DNA microarray and screening of 2,602 knockout mutants showed that the zosA gene was de-repressed in the presence of 0.1% dl-penicillamine, and that the zosA mutant was sensitive to dl-penicillamine medium. The zosA mutant delayed the growth under Cu-limitation even without the chelator, and the sensitivity to dl-penicillamine was reversed by induction using 0.3 mM IPTG and the Pspac promoter inserted directly upstream of the zosA gene. Furthermore, the zosA mutant showed elevated tolerance of excessive Cu²⁺ but not of excessive Zn²⁺ added to LB and synthetic media. Homology modeling of the ZosA protein suggested that the protein can fold itself into essential domains for constituting a metal transporting ATPase. Our study suggests that zosA is a candidate gene involved in copper uptake.     

Studies on Metabolism of Pyrrolidone Carboxylic Acid in Bacteria

l-Glutamic acid was formed from d-, l-, and dl-PCA with cell-free extract of Pseudomonas alcaligenes ATCC-12815 grown in the medium containing dl-PCA as a sole source of carbon and nitrogen. The enzyme(s) involved in this conversion reaction was distributed in the soluble fraction within the cell and in 0.5 saturated fraction at the fractionation procedure with the saturation of ammonium sulfate. Optimum pH of this enzyme(s) lied at pH 8.5 and optimum temperature was 30°C. Cu (5 × 10^?3 m) inhibited the reaction considerably while Ca or Fe accelerated it. PALP (1×10^?3 m) also gave an enhanced activity to some extent. The enzyme preparation converted dextro-rotatory enan-thiomorph of PCA to its laevo-rotatory one which in turn was not converted to the opposite rotation direction by this enzyme. Furthermore, the preparation did not, if any, show d-glutamic acid racemase activity. Isotopic experiments with using dl-PCA-1-¹⁴C revealed that l-glutamic acid-1-¹⁴C was formed by the cleavage of –CO–NH– bond of pyrrolidone ring of PCA. It was concluded that dl-PCA when assimilated by the present bacterium is at first transformed to l-PCA by the optically isomerizing enzyme and subsequently is cleaved to l-glutamic acid probably by the PCA hydrolysing enzyme.     

The aerobic growth and product formation of Lactobacillus,Leuconostoc, Brochothrix,and Carnobacterium in batch cultures

Summary The aerobic growth and metabolism of eleven homofermentative and three heterofermentative Lactobacillus strains, three Leuconostoc strains, two Brochothrix thermosphacta strains and two Carnobacterium strains were studied in batch cultures at pH 6.0 and 25°C on a complex substrate containing 10.0 g glucose per litre. All strains, except Carnobacterium divergens 69, grew well aerobically. An oxygen consumption was registered for 18 of the strains—the exceptions being Lactobacillus alimentarius DSM 20249^T, Lactobacillus farciminis DSM 20284^T and Lactobacillus sharpeae DSM 20505^T. The homofermentative lactobacilli showed a maximal oxygen consumption during the stationary growth phase and this was coupled with a low final viable count. Leuconostoc strains, heterofermentative lactobacilli, Brochothrix thermosphacta and Carnobacterium strains showed a maximal oxygen consumption during the exponential growth phase together with a high final viable count. The maximum specific growth rate varied from 0.19 to 0.54 h^-1 while the growth yield varied from 19 to 86 g dry weight per mol glucose consumed. In general, homofermentative lactobacilli produced dl-lactic acid, acetic acid and acetoin. The three heterofermentative lactobacilli produced dl-lactic acid and acetic acid, two strains also produced ethanol Leuconostoc spp. formed d-lactic acid, acetic acid, and ethanol. B. thermosphacta produced acetoin, acetic acid, formic acid, isobutyric acid and isovaleric acid but no lactic acid. Carnobacterium produced l-lactic acid, acetic acid and acetoin. All strains accumulated hydrogen peroxide except L. alimentarius DSM 20249^T, Carnobacterium piscicola 3 and B. thermosphacta.née Blickstad     

Lipoic acid metabolism in the rat

dl-[1,6-¹⁴C]Lipoic acid was administered by intraperitoneal injection to rats at the level of 0.5 mg/100 g body weight. Approximately 56% of the radioactivity was recovered in the urine. When acidified and extracted with benzene, 92% of the radioactivity remained in the aqueous phase. Gel-filtration and paper chromatography were used to identify three of the compounds in the benzene extract as lipoic, bisnorlipoic and tetranorlipoic acids. In addition, a keto compound appears to be present. The aqueous phase contained several radioactive components separable by ion-exchange and paper chromatographies. Two of these compounds were identified as lipoate and β-hydroxybisnorlipoate. No evidence for oxidation of the dithiolane ring of lipoic acid was observed. dl-[7,8-¹⁴C]Lipoic acid was administered to rats under the same conditions. The urine contained 81% of the radioactivity, 72% of which remained in the aqueous phase and 28% was extracted into benzene. In contrast to over 30% of the label from dl-(1,6-¹⁴C] lipoate being expired as ¹⁴CO₂, a negligible amount of ¹⁴CO₂ was produced by rats injected with dl-[7,8-¹⁴C]lipoate. The catabolites identified were the same as those found using the 1,6-labeled lipoate. Another dithiolane-intact compound was also isolated. It appears that the rat, similar to Pseudomonas putida LP, metabolizes lipoate mainly via β-oxidation of the valeric acid side chain.     

The Synthesis of Dimethyl Esters of dl-O,O′-Dimethylfukiic Acid and dl-O,O′-Dimethylepifukiic Acid

The synthesis of dimethyl esters of dl-O,O′-dimethylfukiic acid (11) and dl-O,O′-dimethylepifukiic acid (12) are described.     

Cloning, expression, characterization and application of atcA, atcB and atcC from Pseudomonas sp. for the production of L-cysteine

An isolate of a Pseudomonas sp. uses the l-NCC (N-carbamoyl-l-cysteine) pathway to convert dl-2-amino-Δ²-thiazoline-4-carboxylic acid (dl-ATC) to l-cysteine. Genes encoding ATC racemase (AtcA), l-ATC hydrolase (AtcB) and l-NCC amidohydrolase (AtcC), involved in this pathway, were cloned from the Pseudomonas sp. and expressed in Escherichia coli BL21 via pET-28a(+). The resulting enzymes were purified, their functions identified, and their biochemical properties are described. In vitro catalysis experiments, using these enzymes, revealed that the bioconversion rate of l-cysteine from dl-ATC in the presence of AtcA was more efficient than in the absence of AtcA. This is the first report describing simultaneous cloning and expression of atcA, atcB and atcC and characterization of their enzymes for l-cysteine production from dl-ATC via the l-NCC pathway, enabling the complete l-NCC pathway to be elucidated.     

Phytochemical Studies on the Tobacco Alkaloids

Duplicate feeding experiments of dl-ornithine-2-¹⁴C to the excised tobacco root culture were made, and the radioactive nornicotine was isolated. Approximately two thirds of the radioactivity was located in the 2-position of the pyrrolidine of the nornicotine in these experiments. This fact indicates that there are two modes in nornicotine biosynthesis: exclusive incorporation to the C-2 and equal incorporation to C-2 and C-5 from C-2 of ornithine.

On the basis of this finding, biosynthetic route was discussed.

dl-Ornithine-2-¹⁴C, dl-methionine-¹⁴CH₃ and partially racemized l-nornicotine-2,5-¹⁴C were administered to aseptically grown excised roots (N. rustica var. Brasilia). Incorporation of their radioactivity to nicotine was compared. The extent of their radioactive incorporation to nicotine was high in the order of ornithine, methionine and nornicotine; incorporation of radioactivity of nornicotine to nicotine was extraordinarily low. ¹⁵N-Labeled nornicotine was also fed to the same materials and ¹⁵N distribution was examined. Most of ¹⁵N still remained in the nornicotine reisolated. Marked amounts of ¹⁵N were located in the ethanol-insoluble fraction, the amino acid fraction and the substances having chromatographic R_F value close to that of nicotine. Only small amount of ¹⁵N was incorporated to the isolated nicotine.

Nornicotine is generally accepted to be a direct precursor of nicotine in tobacco plants. From these findings, however, it can be said that the biosynthesis of nicotine can occur through other routes without going through nornicotine.     

Hematology and plasma chemistry of wild shortnose sturgeon Acipenser brevirostrum from Delaware River,USA

The effects of gender, maturity, intersex condition and annual and seasonal variability were studied on hematology and plasma chemistry of wild shortnose sturgeon Acipenser brevirostrum from the Delaware River. A total of 68 fish were captured by gill net and examined in May‐June, and 61 additional fish were captured and examined in November during 2006–2011. Total leukocyte counts (WBC), leukogram, PCV and the plasmatic concentrations of 13 biochemical analytes were measured from these fish using standard clinical methods. Season and gender had no effect on hematologic indices, but PCV was inversely related to maturity of fish (robust intervals: 27–40% in immature fish, 21–36% in mature fish). Significant annual variation was detected in eosinophil (annual range in robust interval: 0–1176 lower limit, 670–7882 upper limit) and monocyte (0–210 lower limit, 560–1980 upper limit) counts (cells μl^?1). The lower limit of the robust interval varied annually by as much as 6% for sodium and 12% for chloride, while the upper limit of the robust interval varied annually by as much as 8% for sodium and 15% for chloride. Seasonal differences in mean sodium and chloride (6–7% higher in autumn) and proteins (5–13% higher in autumn) may reflect environmentally induced changes in osmoregulation, while aspartate aminotransferase was 38–55% higher in the spring. In females, calcium and total protein were highest in mature fish (robust intervals: 10.5–22.1 mg dl^?1 Ca²⁺, 4.1–6.9 g dl^?1 TP) compared to immature (7.3–16.9 mg dl^?1 Ca²⁺, 2.8–5.2 g dl^?1 TP) and developing fish (7.8–18.9 mg dl^?1 Ca²⁺, 3.2–5.6 g dl^?1 TP), indicating changes associated with vitellogenesis. Glucose was significantly higher in females (robust interval: 23–167 mg dl^?1) than males (35–138 mg dl^?1), possibly indicating gender‐based differences in energetic requirements. Intersex condition was associated with lowered glucose, potassium and creatinine phosphokinase. Reference intervals reported here are useful for evaluating the health and physiological condition of shortnose sturgeon.     

On the Mechanism for the Formation of Indole Alkaloids in Penicillium concavo-rugulosum

Experiments on the biosynthesis and microbiological conversion of indole alkaloids in Pénicillium concavo-rugulosum were carried out with the growing and resting mycelia, respectively, of a selected strain of the same mold. The former experiments were performed by the use of dl-tryptophan-3-¹⁴C or dl-mevalonic acid-2-¹⁴C-lactone as a precursor, while the latter experiments by the use of rugulovasine A–³H, dihydrorugulovasine A–³H, 4-[γ, γ-dimethylallyl]-tryptophan-³H, chanoclavine-[I]–³H or the other tritilated ergoline alkaloids. The results of these experiments suggested that in the Penicillium mold employed there exist the following biosynthetic route: tryptophan + mevalonic acid→4-[γ, γ-dimethylallyl]-tryptophan→rugulovasine A→dihydrorugulovasine A→dihydrorugulovasine A-lactam.     

The Biosynthesis of Some Isothiocyanates and Oxazolidinethiones in Rape (Brassica campestris L.)

The incorporation of the radioactivity from acetate-1-¹⁴C, acetate-2-¹⁴C, dl-methionine-1-¹⁴C, dl-methionine-2-¹⁴C, dl-methionine-3,4-¹⁴C, dl-homomethionine-2-¹⁴C, dl-allyl-glycine-2-¹⁴C, and dl-2-amino-5-hydroxyvalerate-2-¹⁴C into the aglycones of progoitrin, gluconapin, and glucobrassicanapin of maturing rape plants (Brassica campestris L.) was investigated. Radioactivity from dl-methionine-2-¹⁴C, dl-methionine-3,4-¹⁴C, dl-homomethionine-2-¹⁴C, and acetate-2-¹⁴C were incorporated into the 3 major thioglucosides. The other organic compounds were poorly incorporated except for dl-allylglycine-2-¹⁴C into glucobrassicanapin. The results obtained suggest that the rape plant can synthesize amino acids by the condensation of acetate (as acetyl CoA) to α-keto acids to yield a homologue of the original amino acid. These newly formed amino acids are then employed to synthesize the 3 major thioglucosides.     

In vivo nuclear-magnetic-resonance analysis of polyamine and alkaloid metabolism in transformed root cultures of Datura stramonium L.: evidence for the involvement of putrescine in phytohormone-induced de-differentiation

The utilisation and accumulation of ¹⁵N-labeled metabolites by a ¹⁵N-labeled transformed root culture of Daturastramonium L. was investigated by in vivo ¹⁵N-nuclear-magnetic-resonance (NMR) spectroscopy. After resuspension in spent growth medium, the pools of [¹⁵N]glutamate and [¹⁵N]glutamine were rapidly depleted and there was an increase in the ¹⁵N-NMR signals from conjugated putrescines and hyoscyamine. The signal from the conjugated putrescines passed through a maximum 2 d after the roots were resuspended, and it was concluded that putrescine could be stored as putrescine conjugates prior to its utilisation in other pathways. The transient accumulation of ¹⁵N-label in the hydroxy-cinnamoylputrescines was reduced when the de-differentiation of the root cultures into a suspension culture was initiated by exposure to a medium containing α-napthaleneacetic acid and kinetin. This led to the hypothesis that phytohormone-induced de-differentiation of the root cultures required the presence of free polyamines, and this was tested using two potent inhibitors of putrescine biosynthesis, dl-α-difluoromethylarginine and dl-α-difluoromethylornithine. In-vivo ¹⁵N-NMR spectra of roots grown in ¹⁵N-enriched medium supplemented with these inhibitors showed that the ¹⁵N-labelling of the conjugated polyamines and hyoscyamine was markedly reduced. dl-α-difluoromethylarginine also prevented the phytohormone induced de-differentiation of the root cultures, and this effect could be reversed by the supply of exogenous putrescine. Thus the supply of putrescine appears to play a crucial role in mediating the phytohormone induced de-differentiation of the root culture. Received: 13 September 1997 / Accepted: 12 November 1997     

Studies on dl-Alanine Formation by Thermophilic Bacteria

During the course of the screening of thermophilic microorganisms, several strains were found to accumulate amino-acids. Of those strains that were isolated from feces source with Bennett medium, one strain was found to produce a large amount of an amino acid. This amino acid was isolated in crystalline form and identified as dl-alanine by IR absorption spectrum, specific rotatory power and elementary analysis. The taxonomic studies were carried out and this strain was identified as Bacillus coagulans. The strain B. coagulans B₉-17 produced dl-alanine as much as 1000 mg/l after 24 hours at 50°C in shake culture.

The yield of dl-alanine was increased up to 16.5 g/l with some improvements.     

Degradation of 3-chloro-2-methylpropionic acid by Xanthobacter sp. CIMW 99

Summary Both stereoisomers of 3-chloro-2-methylpropionic acid (CMPA) and its methyl esters (MeCMPA) serve as growth substrates for a bacterial isolate (Xanthobacter sp. CIMW 99) when supplied as sole source of carbon and energy. Biodegradation of dl-CMPA and dl-MeCMPA was shown to be via a common pathway; an initial, constitutive, esterase converted the methyl ester to the corresponding carboxylic acid. Further metabolism required the activation of CMPA involving a CoA-, ATP-, Mg²⁺-dependent chloroacyl-CoA synthetase. Most noteworthy, it was the product of this reaction (3-chloro-2-methylpropionyl-CoA) that underwent hydrolytic dehalogenation to give 3-hydroxy-2-methylpropionyl-CoA (3-hydroxyisobutyryl-CoA). Further biodegradation proceeded by the action of a dehydrogenase on the CoA derivative to give methylmalonate-CoA-semialdahyde. Cells of CIMW 99 also contained a stable, constitutive, highly active 3-hydroxyisobutyrate dehydrogenase that was specific for the l(+) isomer. However, evidence is presented suggesting that this enzyme was not involved in the catabolism of the chlorinated substrates. Offprint requests to: M. R. Smith     

<Emphasis Type="Italic">Pseudomonas stutzeri</Emphasis> as a novel biocatalyst for pyruvate production from<Emphasis Type="SmallCaps"> DL</Emphasis>-lactate

Pseudomonas stutzeri SDM oxidized dl-lactic acid (25.5 g l^-1) into pyruvic acid (22.6 g l^-1) over 24 h. Both NAD⁺-independent d-lactate dehydrogenase and NAD⁺-independent l-lactate dehydrogenase were found for the first time in the bioconversion of lactate to pyruvate based on the enzyme activity assay and proteomic analysis. Jianrong Hao and Cuiqing Ma contributed equally to this work     

Effect of amino acids on growth ofSphaerotilus discophorus

The effect of casein hydrolysate, of mixtures of amino acids and of individual amino acids on the growth of 4 strains ofSphaerotilus discophorus was determined. Growth was virtually completely inhibited by 1.0% Bacto Casamino Acids, 0.54% simulated casein hydrolysate and 0.2% of a uniform mixture of 18 amino acids. The latter were prepared withl amino acids except thatdl-serine,dl-valine anddl-threonine were present in the uniform amino acid mixture.Experiments designed to test the toxicity of the 18 individual amino acids at 0.018 – 0.36% concentration indicated that arginine, glutamic acid, leucine, lysine and proline were non-toxic. However, aspartic acid and methionine were moderately toxic; growth was greatly repressed at a concentration of 0.36%. The remaining 11 amino acids which included alanine, cystine, glycine, tyrosine, histidine, isoleucine, phenylalanine, serine, threonine, tryptophane and valine were the most toxic of the group. They prevented growth partially or completely, at a concentration of 0.18% or 0.36%.dl-Serine anddl-valine were especially toxic and prevented growth at a concentration of 0.018%. The toxicity of the individuall-amino acids can account for the toxicity of Casamino Acids and simulated casein hydrolysate. l-Methionine or cyanocobalamin (vitamin B₁₂) is required for the growth ofS. discophorus. Alsod- anddl-methionine can replace cyanocobalamin although they completely repress growth when used at the relatively high concentration of 200 µg per ml of medium.