Influence of biotic and abiotic factors on human pathogens in a finished compost

The role of indigenous micro\ufb02ora of a \ufb01nished compost, de\ufb01ned NK12, on the growth suppression of pathogens under different moisture and temperature storages was investigated. Total count of mesophilic and thermophilic bacteria was evaluated by the most probable number method and growth of seeded Salmonella arizonae 3924 serogroup B and enteropathogenic Escherichia coli 84M in NK12 at different moisture temperature conditions was monitored. Results on sterile and non-sterile NK12 were compared. In all tested experimental conditions, the NK12 indigenous micro\ufb02ora was stable and biologically active. S. arizonae 3924 and E. coli 84M grew rapidly in sterilized NK12 at different moistures and storage temperatures, and their growth was suppressed in non-sterilized NK12. Pathogens inactivation was lower when compost was stored at 40% and 80% humidity and at 37C. Our results show that the major role in the pathogens suppression was played by the indigenous micro\ufb02ora of the \ufb01nished compost, although physical factors too in\ufb02uenced the growth phenomenon