Fate of manure-borne pathogen surrogates in static composting piles of chicken litter and peanut hulls

The fate of manure-borne pathogen surrogates (gfp-labeled Escherichia coli O157:H7 and Listeria innocua and avirulent Salmonella Typhimurium) in the field was monitored at both sub-surface (30cm from surface) and surface sites of static composting piles (3.5-m base diameter) composed of chicken litter and peanut hulls. Despite exposure to elevated temperatures, Salmonella was detected by enrichment culture in sub-surface samples following 14days of composting. In surface samples, pathogen surrogates were detected in the summer after 4days of composting by enrichment culture only, whereas E. coli O157:H7 and L. innocua remained detectable by direct plating (>2log10cfu/g) up to 28days in piles composted during the fall and winter. All three types of bacteria remained detectable by enrichment culture in surface samples composted for 56days during the winter.