fumarates and ethylene

Dehalococcoides mccartyi strains conserve energy from reductive dechlorination reactions catalyzed by corrinoid-dependent reductive dehalogenase enzyme systems. Dehalococcoides lacks the ability for de novo corrinoid synthesis, and pure cultures require the addition of cyanocobalamin (vitamin B(12)) for growth. In contrast, Geobacter lovleyi, which dechlorinates tetrachloroethene to cis-1,2-dichloroethene (cis-DCE), and the nondechlorinating species Geobacter sulfurreducens have complete sets of cobamide biosynthesis genes and produced 12.9 ± 2.4 and 24.2 ± 5.8 ng of extracellular cobamide per liter of culture suspension, respectively, during growth with acetate and fumarate in a completely synthetic medium. G. lovleyi-D. mccartyi strain BAV1 or strain FL2 cocultures provided evidence for interspecies corrinoid transfer, and cis-DCE was dechlorinated to vinyl chloride and ethene concomitant with Dehalococcoides growth. In contrast, negligible increase in Dehalococcoides 16S rRNA gene copies and insignificant dechlorination occurred in G. sulfurreducens-D. mccartyi strain BAV1 or strain FL2 cocultures. Apparently, G. lovleyi produces a cobamide that complements Dehalococcoides' nutritional requirements, whereas G. sulfurreducens does not. Interestingly, Dehalococcoides dechlorination activity and growth could be restored in G. sulfurreducens-Dehalococcoides cocultures by adding 10 μM 5',6'-dimethylbenzimidazole. Observations made with the G. sulfurreducens-Dehalococcoides cocultures suggest that the exchange of the lower ligand generated a cobalamin, which supported Dehalococcoides activity. These findings have implications for in situ bioremediation and suggest that the corrinoid metabolism of Dehalococcoides must be understood to faithfully predict, and possibly enhance, reductive dechlorination activities.

Topics: Acetates; Bacterial Load; Chloroflexi; Cobamides; Coculture Techniques; Culture Media; Ethylenes; Fumarates; Geobacter; Vinyl Chloride

Synthesis of ethylene in static cultures as well as the effect of endogenous and exogenous ethylene on the synthesis of polygalacturonase by Aspergillus niger were determined. This strain produced maximum ethylene amounts when cultured at 30 degrees C for 3 d. The effect of adding ethylene precursors (citrate-cycle intermediates) on ethylene production was investigated. Best intracellular and extracellular polygalacturonase production was obtained with 2-oxoglutaric, pyruvic and fumaric acids, and with glutamic acid too. Addition of ethylene to the culture medium also increased the synthesis of polygalacturonase, although to a lower degree than when glutamic acid was added.

Topics: Aspergillus niger; Biomass; Citric Acid Cycle; Culture Media; Ethylenes; Fumarates; Glutamic Acid; Ketoglutaric Acids; Kinetics; Polygalacturonase; Pyruvic Acid

Topics: Animals; Cataract; Cattle; Ethylenes; Free Radicals; Fumarates; Glutathione; In Vitro Techniques; Light; Oxidation-Reduction; Oxygen; Potassium Iodide; Riboflavin