Affiliation:
1. 1Center for Food Safety and Department of Food Science and Technology, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223
2. 2Department of Entomology, Coastal Plain Experiment Station, University of Georgia, Tifton, Georgia 31793, USA
Abstract
Green fluorescent protein–labeled Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis were inoculated at 107 CFU/g into cow, hog, or chicken manure. Ten- or 11-day-old soldier fly larvae ( Hermetia illucens L.) (7 to 10 g) were added to the manure and held at 23, 27, or 32°C for 3 to 6 days. Soldier fly larvae accelerated inactivation of E. coli O157: H7 in chicken manure but had no effect in cow manure and enhanced survival in hog manure. The initial pH values of the hog and chicken manure were 6.0 to 6.2 and 7.4 to 8.2, respectively, and it is surmised that these conditions affected the stability of the larval antimicrobial system. Reductions of E. coli O157:H7 populations in chicken manure by larvae were affected by storage temperature, with greater reductions in samples held for 3 days at 27 or 32°C than at 23°C. Pathogen inactivation in chicken manure by larvae was not affected by the indigenous microflora of chicken manure, because Salmonella Enteritidis populations in larvae-treated samples were approximately 2.5 log lower than control samples without larvae when either autoclaved or nonautoclaved chicken manure was used as the contaminated medium during 3 days of storage. Extending the storage time to 6 days, larvae again accelerated the reduction in Salmonella Enteritidis populations in chicken manure during the first 4 days of storage; however, larvae became contaminated with the pathogen. After 2 days of feeding on contaminated manure, Salmonella Enteritidis populations in larvae averaged 3.3 log CFU/g. Populations decreased to 1.9 log CFU/g after 6 days of exposure to contaminated chicken manure; however, the absence of feeding activity by the maggots in later stages of storage may be responsible for the continued presence of Salmonella Enteritidis in larvae. Transfer of contaminated larvae to fresh chicken manure restored feeding activity but led to cross-contamination of the fresh manure.
Publisher
International Association for Food Protection
Subject
Microbiology,Food Science
Cited by
269 articles.
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