METHOD OF DETERMINING DECARBOXYLASE ACTIVITY OF LACTIC ACID BACTERIA

摘要

FIELD: biotechnologies.;SUBSTANCE: microorganisms are subcultured daily into the liquid culture fluid MRS containing 0.1% of the corresponding amino acid (tyrosine, histidine monohydrochlorid, ornithine, lysine), 0.005% of pyridoxal-5-phosphate for the activation of the decarboxylase enzyme, during 7 days. From the resulting biomass, the lactic acid that was formed is removed. For that purpose, the biomass, after the last subculture, is centrifuged in Eppendorf tubes at 12000 rpm during 5 minutes and mixed thoroughly in 1ml of physiological saline solution. The biomass in the physiological saline solution is introduced into cyanide broth dispensed into tubes in 5 ml portions, and sterilised by autoclaving at 1.1atm (121°C) during 10 minutes. The final pH of the broth at 25°C should be 6.0±0.2. For the following 48 hours, the broth colour change is recorded, from yellow to red/violet due to alkalisation with biogenic amines being formed.;EFFECT: allows to increase accuracy of determination of decarboxylase activity of lactic acid bacteria, prevents from error resulting from incorrect method implementation.;1 tbl, 9 ex