Energetics of Formate, Lactate, and Pyruvate Metabolism by an Obligate Anaerobic Sulfate-Reducing Bacterium, Desulfovibrio Vulgaris

Author

Edward L. Magee Jr.

Publication Date

9-29-1975

Abstract

The increase in growth of Desulfovibrio vulgaris NCIB 8303 in a basal medium containing either 0.1M lactate, 0.1M pyruvate or 0.1M formate was proportional to the energy derived by substrate oxidation. Parameters of growth included OD₅₈₀, counts of viable cells, mean generation time, maximum cell density and molar growth yield. Pyruvate stimulated the largest amount of growth by all parameters except the generation time which equalled that measured for growth on lactate. Lactate produced intermediate levels of growth and formate the least amount. Minimal growth occurred when the basal medium had no intermediate energy source. Growth on the isomers of lactate indicated utilization of both D and L stereoisomers. The generation time on the lithium salts of the isomers was twice that of the sodium salts of lactate. The presence of lithium ions were not found to inhibit growth, but possibly the insolubility of lithium lactate contributed to the lag in isomer generation time. The mixing of ¹⁴C-formate with whole cells indicated the formic dehydrogenase enzyme is inducible. No enzyme activity from lactate or pyruvate cells suggests formate is not an intermediate in the decarboxylation of pyruvate during substrate oxidation. The absence of labelled carbon in the cell pellets indicates formate is not readily incorporated into cellular material. The molar growth yields were divided by the anaerobic yield coefficient, (Y_ATP), to calculate the moles of ATP produced per mole substrate oxidized under laboratory conditions. The values obtained were 1.08 moles ATP produced per mole pyruvate metabolized, 0.58 mole ATP per mole lactate and 0.28 ATP per mole of formate. A comparison of these experimental energy yields was made with the substrate energetics from cell-free extracts of Desulfovibrio. The results indicate that at least one and as many as three oxidative phosphorylations occur during sulfate reduction when lactate, pyruvate or formate is oxidized.

Language

English

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Larry Barton

Second Committee Member

Paul Richard Kerkof

Third Committee Member

Tokio Kogoma

Recommended Citation

Magee, Edward L. Jr.. "Energetics of Formate, Lactate, and Pyruvate Metabolism by an Obligate Anaerobic Sulfate-Reducing Bacterium, Desulfovibrio Vulgaris." (1975). https://digitalrepository.unm.edu/biol_etds/495