Propionate Oxidation by and Methanol Inhibition of Anaerobic Ammonium-Oxidizing Bacteria

ABSTRACT Anaerobic ammonium oxidation (anammox) is a recently discovered microbial pathway and a cost-effective way to remove ammonium from wastewater. Anammox bacteria have been described as obligate chemolithoautotrophs. However, many chemolithoautotrophs (i.e., nitrifiers) can use organic compounds as a supplementary carbon source. In this study, the effect of organic compounds on anammox bacteria was investigated. It was shown that alcohols inhibited anammox bacteria, while organic acids were converted by them. Methanol was the most potent inhibitor, leading to complete and irreversible loss of activity at concentrations as low as 0.5 mM. Of the organic acids acetate and propionate, propionate was consumed at a higher rate (0.8 nmol min−1 mg of protein−1) by Percoll-purified anammox cells. Glucose, formate, and alanine had no effect on the anammox process. It was shown that propionate was oxidized mainly to CO2, with nitrate and/or nitrite as the electron acceptor. The anammox bacteria carried out propionate oxidation simultaneously with anaerobic ammonium oxidation. In an anammox enrichment culture fed with propionate for 150 days, the relative amounts of anammox cells and denitrifiers did not change significantly over time, indicating that anammox bacteria could compete successfully with heterotrophic denitrifiers for propionate. In conclusion, this study shows that anammox bacteria have a more versatile metabolism than previously assumed.

Megakaryocyte maturation indicated by methanol inhibition of an acid phosphatase shared by magakaryocytes and platelets

Optimal conditions necessary for the cytochemical demonstration of megakaryocyte (Mk) and platelet acid phosphatase (AP) were determined. Methanol, a constituent of fixatives commonly used in AP cytochemistry, was found to inhibit MkAP, and the degree of inhibition varied with Mk maturity. Immature Mk contained predominantly methanol-resistant AP, and mature Mk, predominantly methanol-sensitive AP. Platelets contained methanol-sensitive AP similar to mature Mk, suggesting that this enzyme provides an index of platelet formation by Mk. Soluble platelet AP showed three bands on polyacrylamide gel electrophoresis, visualized by the same reactions applied cytochemically. Two bands, accounting for 98% of the platelet AP activity, were slow moving and methanol sensitive; and one fast moving band accounting for 2% of activity was methanol resistant. Measurement of Mk and platelet AP isoenzymes may prove to have applications in evaluating Mk function.

Megakaryocyte maturation indicated by methanol inhibition of an acid phosphatase shared by magakaryocytes and platelets

Optimal conditions necessary for the cytochemical demonstration of megakaryocyte (Mk) and platelet acid phosphatase (AP) were determined. Methanol, a constituent of fixatives commonly used in AP cytochemistry, was found to inhibit MkAP, and the degree of inhibition varied with Mk maturity. Immature Mk contained predominantly methanol-resistant AP, and mature Mk, predominantly methanol-sensitive AP. Platelets contained methanol-sensitive AP similar to mature Mk, suggesting that this enzyme provides an index of platelet formation by Mk. Soluble platelet AP showed three bands on polyacrylamide gel electrophoresis, visualized by the same reactions applied cytochemically. Two bands, accounting for 98% of the platelet AP activity, were slow moving and methanol sensitive; and one fast moving band accounting for 2% of activity was methanol resistant. Measurement of Mk and platelet AP isoenzymes may prove to have applications in evaluating Mk function.