Lactate dehydrogenase activity in cell-free extracts of sulfate-reducing bacteria Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9
University of Veterinary and Pharmaceutical Sciences Brno
1/3, Palackeho, CZ-61242 Brno, Czech Republic
Lactate dehydrogenase activity in cell-free extracts of the sulfate-reducing bacteria Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9 isolated from human intestine was studied. The optimal temperature (+35ºC) and pH 8.0 for lactate dehydrogenase reaction in the extracts of both bacterial strains were defined. Analysis of the kinetic properties of the bacterial lactate dehydrogenase was carried out. The lactate dehydrogenase activity, initial (instantaneous) reaction rate (V0) and maximum rate of the lactate dehydrogenase reaction (Vmax) was significantly higher in the D. piger Vib-7 cells than in the Desulfomicrobium sp. Rod-9. The kinetic parameters of lactate dehydrogenase activity depended on the substrate concentration. According to the obtained results, lactate increase in concentrations range from 1.0 to 9.0 mM causes a increase in enzymatic activity of the studied enzyme and after that activity was maintained on an unchanged (plateau) level. Michaelis constants (Km) of the studied enzyme reaction (0.83±0.07 mM for D. piger Vib-7 and 1.54±0.14 mM for Desulfomicrobium sp. Rod-9) were calculated.
Keywords: sulfate-reducing bacteria, lactate dehydrogenase, intestinal microbiocenosis, inflammatory bowel diseases