Differential enumeration of silage inoculants based on utilization of enzymatic activity and antibiotic sensitivity of bacteria

The differences in the composition of culture media inoculated with strains of Leuconostoc oenos were more quantitative than qualitative. Both temperature of incubation and pH significantly affected bacterial growth, the rates of substrate consumption and consequently the amount of metabolites produced. All strains degraded 5 g 1^-1 malate, except one at pH 3.5 and 25°C. Malate was metabolized before glucose except at higher pH (4.0 and 4.5) and temperature (32°C). Citrate was completely metabolized and its consumption rate was pH- and temperature-dependent. Neither acids contributed energy for growth as the Y_glu remained constant in the presence or absence of acids. There was a significant increase in fructose consumed at higher temperature. Also, the final concentration of mannitol was higher but not significantly different. The addition of acids, particularly citrate, significantly repressed mannitol formation.