Production of citric acid from sugars present in wood hemicellulose usingAspergillus niger andSaccharomycopsis lipolytica

Summary One strain each of the fungus,Aspergillus niger, and the yeast,Saccharomycopsis lipolytica, were investigated for their ability to produce citric acid from the sugars present in hemicellulose hydrolysates.S. lipolytica produced citric acid as efficiently from mannose as from glucose, but failed to assimilate xylose, arabinose or galactose.A. niger readily assimilated mannose, xylose and arabinose, and produced citric acid from these sugars although the yields were lower than from glucose. A possible inhibitory effect of arabinose on citric acid production from other sugars was observed usingA. niger.     

Nitrilase-catalyzed production ofp-aminobenzoic acid fromp-aminobenzonitrile withRhodococcus rhodochrous J1

Summary The reaction conditions for the enzymatic production ofp-aminobenzoic acid were optimized, using a nitrilase in cells ofRhodococcus rhodochrous J1. The highest accumulation, 110 gp-aminobenzoic acid/liter of reaction mixture, was attained fromp-aminobenzonitrile, with a conversion yield of 100%.     

D-malic acid production from maleic acid using microorganism: Screening of microorganism

Summary Some bacteria belonging to Arthrobacter, Brevibacterium, Corynebacterium, Pseudomonas, Bacillus, and Acinetobacter produced D-malic acid from maleic acid when the cells grown in a medium containing citraconic acid were reacted aerobically with maleic acid in the pH 7.0 phosphate buffer containing 0.1% sodium chloride.     

Pyridoxamine-alpha-keto acid transamination activity of aspartate apoaminotransferases

Pyridoxamine-α-keto acid transamination activities of homogeneous aspartate apoaminotransferases from various organisms were determined. Aspartate apoaminotransferases from pig heart cytosol and bakers' yeast utilized both oxalacetate and α-keto-glutarate as amino acceptors, while those from pig heart mitochondria and bacteria (Escherichiacoli B and Pseudomonas striata) showed reactivity only toward oxalacetate. Specific activities of bacterial aspartate apoaminotransferases were very high compared to those of the yeast and animal apoenzymes. Phosphate and various anions, including sulfate, raised the pyridoxamine-α-keto acid transamination activity of all the aspartate apoaminotransferases examined. However, a high concentration of phosphate inhibited the reaction.     

Production of acetic acid in packed bed fermenters

Summary Production of acetic acid from ethanol byAcetobacter aceti attached to a variety of support materials has been examined in fixed-film packed bed fermenters. Overall batch acid productivities with triangular ceramic particles and nylon mesh were respectively 56% and 30% greater than that for woodshavings, with comparable high acid yields. The highest batch acid productivity attained was 0.75 g/l h with the ceramic support. Continuous operation with the same material resulted in an acid productivity of 4.0 to 4.5 g/l h at a yield of 80%. This was increased to 10.7 g/l h by feeding oxygen-enriched air to the fermenter.Stability of theAcetobacter populations, judged by reproducibility in batch operation and attainment, reproducibility and maintenance of steady operating conditions in continuous operation, was very high.     

Metabolism of valproic acid by hepatic microsomal cytochrome P-450

Incubation of valproic acid with rat liver microsomes led to the formation of 3-, 4- and 5-hydroxy-valproic acid. The latter two metabolites, which have been characterized previously from in vivo studies, may be regarded as products of fatty acid ω-1 and ω hydroxylation, respectively. 3-Hydroxy-valproic acid, however, had been thought to derive from the β-oxidation pathway in mitochondria. Conversion of valproic acid to all three metabolites in microsomes required NADPH (NADH was less effective), utilized molecular oxygen, was suppressed by inhibitors of cytochrome P-450 and was stimulated (notably at C-3 and C-4) by phenobarbital pretreatment of the rats. It is concluded that rat liver microsomal cytochrome P-450 catalyzes ω-2 hydroxylation of valproic acid, a reaction not detected previously with fatty acids in mammalian systems, and that the product, 3-hydroxyvalproic acid, should not be used to assess in vivo metabolism of valproate via the β-oxidation pathway.     

Production of chrysanthemic acid and pyrethrins by tissue cultures ofChrysanthemum cinerariaefolium

Tissue cultures ofChrysanthemum cinerariaefolium were established, and then used to study the production of pyrethrin insecticides, and their precursor chrysanthemic acid. Callus cultures and root-differentiated cultures did not contain pyrethrins whereas shoot differentiated callus was found to produce the pyrethrins. Chrysanthemic acid was isolated by extraction from callus cultures, and feeding¹⁴C-labelled chrysanthemic acid to a cell suspension ofC. cinerariaefolium established that the acid accumulates largely as a glucoside ester.Abbreviations MS Murashige and Skoog (1962) medium - 2,4-D 2,4-dichlorophenoxyacetic acid - 1AA Indoleacetic acid - BAP 6-Benzylaminopurine - GC-MS Gas chromatography - mass spectrometry     

Production of xylonic acid byPseudomonas fragi

Summary Eleven microbial strains were tested for their ability to produce xylonic acid from xylose. The production of xylonic acid by one of the strains,Pseudomonas fragi ATCC 4973, was further studied in laboratory fermenter scale. The yield of xylonic acid was 92 % of original sugar. Xylonic acid production seemed to be growth associated and it was found to be very sensitive to the decrease of pH.     

D-malic acid production from DL-malic acid by enantiospecific assimilation with Acinetobacter lwofii

Summary Acinetobacter lwofii ATCC 9036 assimilated L-malic acid eantiospecifically and left D-malic acid when grown in a medium containing DL-malic acid. The optical purity of the D-malic acid isolated from the culture filtrate was 100%. When the organism was incubated at 26°C, 220 r.p.m. in a Erlenmeyer flask containing 100g/l of disodium maleate, L-malic acid was completely consumed during 7 days incubation and D-malic acid remained at the concentration of 35g/l.     

Grape pomace: A novel substrate for microbial production of citric acid

Summary Grape pomace was used as substrate for microbial production of citric acid. Of the five cultures examined,Aspergillus niger NRRL 567 was found to produce the greatest amount of citric acid from grape pomace in the presence of methanol at a concentration of 3% (vol/wt). The yield was 60% based on the amount of fermentable sugar consumed.     

Enantioselective oxidation of mandelic acid using a phenylmalonate metabolizing pathway of a soil bacteriumAlcaligenes bronchisepticus KU 1201

Summary The metabolic pathway of phenylmalonic acid byAlcaligenes bronchisepticus KU1201, which catalyzes the asymmetric decarboxylation of -aryl--methylmalonic acids to -arylpropionic acids, is demonstrated. Enantioselective oxidation of mandelic acid was investigated using the metabolizing pathway in this strain. Incubation of (±)-mandelic acid withA. bronchisepticus afforded optically pure (R)-one accompanied by benzoylformic acid and benzoic acid. This enzymatic oxidation is also applicable to various substituted mandelic acids.     

Effect of substrate moisture content on fungal production of citric acid in a solid state fermentation system

Summary Under solid state fermentation conditions, the production of citric acid byAspergillus niger varied considerably with the initial moisture content of apple pomace. The stimulating effect of methanol on fungal production of citric acid decreased markedly as the substrate moisture decreased.     

Heterogeneity of lipoteichoic acid detected by anion exchange chromatography

A complex polydispersity became apparent when the poly(glycerophosphate) lipoteichoic acid of Enterococcus faecalis was chromatographed on DEAE-sephadex. The chain length varied between 13 and 33 glycerophosphate residues per lipid anchor. In parallel, the extent of chain glycosylation increased from 0.2 to 0.4 diglucosyl residues per glycerophosphate unit. Substitution with D-alanine ester showed a reverse distribution dropping with increasing chain length from 0.53 to 0.23 mol D-alanine per mol phosphorus. Variations in the fatty acid composition were also observed. The results extent and modify the current picture of lipoteichoic acid biosynthesis. They further suggest that during infection the mammalian organism may be confronted particularly with long-chain less hydrophobic molecular species.     

p-Toluenesulfonic acid/methanol: Mild reagent for the preparation of bile acid methyl esters

An improved method for the preparation of bile acid methyl esters is described. This is achieved by the addition of catalytic amounts of p-toluenesulfonic acid in a solution of bile acid in methanol. Advantages of this procedure over conventional methods include (1) use of a mild solid acid catalyst which prevents the formation of undesirable byproducts, (2) isolation of a solid product of high purity and (3) utilization of a relatively safe reagent in comparison to other methods involving diazomethane, hydrochloric acid or sulfuric acid.     

Apple pomace: A potential substrate for citric acid production by Aspergillus niger

Summary Apple pomace was used as a fsubstrate for citric acid production by five strains of Aspergillus niger. A. niger NRRL 567 produced the greatest amount of citric acid from apple pomace in the presence of 4% methanol. The yield was 88% based on the amount of sugar consumed.     

Lactic acid bacteria active during the fermentation of wheat silage in small scale silos

Summary Wheat was ensiled and periodically analyzed for lactic acid bacteria present. Initially Lactobacillus plantarum, Leuconostoc mesenteroides, Lactobacillus cellobiosus and Streptococcus lactis predominated. After two to four days enterococci including S. faecium and S. bovis were present in high populations as well as Lactobacillus plantarum. It was concluded that mixed populations of enterococci and L. plantarum are active in the successful fermentation of wheat silage.     

Production of acetone - butanol from acid whey

Summary Clostridium acetobutylicum ATCC 824 was used to produce butanol and acetone by fermenting acid whey. Results showed that both autoclaving and agitation played roles in solvent production. Maximum production was obtained in 120 h using autoclaved, pH adjusted (6.0) acid whey at 37 °C in a fermentor that was not agitated.     

Production of extracellular 5-aminolevulinic acid byClostridium thermoaceticum grown in minimal medium

Summary A growth associated formation of extracellular 5-aminolevulinic acid (ALA) was found in the homoacetogenesis of glucose byClostridium thermoaceticum grown in minimal defined medium. The growth and ALA production was enhanced by L-cysteine HCl both in complex medium (UM) and minimal defined medium (MDM). The amount of ALA produced extracellularly in MDM wasca. 15 mg/L after 90-h anaerobic cultivation (cell-mass: 1.5 g/l; glucose consumed: 20 g/l).     

Cryopreservation of immature spring wheat zygotic embryos using an abscisic acid pretreatment

Spring wheat (Triticum aestivum L.) zygotic embryos were successfully cryopreserved, without the addition of exogenous cryoprotectants, using only an abscisic acid (ABA) pretreatment. Optimum survival was obtained when embryos were cultured in vitro for 10 days on semisolid Murashige and Skoog (MS) nutrient medium supplemented with 0.5 mg/L (±) ABA prior to cryopreservation. The embryos resumed growth within three days when returned to MS medium devoid of ABA but containing 2mg/L 2,4-dichlorophenoxyacetic acid. The embryogenic calli produced from these embryos exhibited normal plant regeneration on auxin-free media. Changes in dw/fw ratio, as well as the esterified fatty acid and sucrose concentrations correlated positively with the development of tolerance to cryopreservation.NRCC Publication No. 33519     

Biotechniques for improving acid aluminum tolerance in alfalfa

Alfalfa (Medicago sativa L.), cultivars ARC, Regen Y and Saranac were selected in vitro in a recently developed acid/aluminum toxic media. The new media produced higher initiation rates and higher fresh callus weights than those obtainable with the media described by Meredith and Connor for the selection of aluminum resistant variants in Nicotiana plumbaginofolia. Both rescue and direct initiation yielded adequate amounts of healthy callus for the initiation of embryogenesis. The toxic effect of the acid/aluminum media is expressed in both the percent of explants initiating callus and in the fresh-weights obtained during initiation and two subsequent subcultures.