A method of screening for highly inhibitory lactic acid bacteria

KOCIUBINSKI G.; PEREZ, P.; AÑÓN MC; DE ANTONI G

JOURNAL OF FOOD PROTECTION

INT ASSOC FOOD PROTECTION

Año: 1996 vol. 59 p. 739 - 745

0362-028X

A rapid method of screening for lactic acid bacteria with highinhibitory power was developed. The methodology employed wasthe agar-diffusion assay, which was standardized for the indicatorstrain, medium composition, and incubation conditions. The assaywas performed in nutrient agar at 30°C with 108 spores of Bacillussubtilis per plate as indicator strain. The inhibition produced bysupernatants of lactic acid bacteria cultures harvested at stationaryphase was determined. The inhibitory powers of different strainswere compared with a standard curve obtained with racemic lacticacid. Results obtained with lactic acid and supernatants of bacterialcultures demonstrate that the diameter of the inhibition zone (d)was related to the pH by the exponential relation d = a exp (- bpH). Results obtained with strains that produced inhibitory substancesother than lactic acid could not be fitted into the standardlinear curves obtained in the plot of In d versus pH of lactic acid.