Reduction of Escherichia coli O157:H7 and Salmonella enterica Serovar Enteritidis in Chicken Manure by Larvae of the Black Soldier Fly

Abstract

Green fluorescent protein-labeled Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis were inoculated at 10(7) 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 degrees 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 degrees C than at 23 degrees 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.

High waste-to-biomass conversion and efficient Salmonella spp. reduction using black soldier fly for waste recycling

“…No identification of the specific coliform species was performed; however, it is likely that a large part of the coliforms included in the analyses were not E. coli. Erickson et al (2004) demonstrated a greater reduction in E. coli O157:H7 at 27-31°C in fly larvae-treated chicken manure compared to the reduction found in cattle manure. The reduction was increased with increasing temperature and similar reduction as observed in this study was observed in chicken manure at 23°C.…”

“…Chicken manure is considerably higher in ammonia than cattle manure (Paul and Beauchamp 1989); uncharged ammonia is well known to be toxic to microorganisms and as the concentration of uncharged ammonia increases with temperature (Nordin et al 2009). The reduction of E. coli observed by Erickson et al (2004) in chicken manure and the increased reduction observed at elevated temperatures could therefore have been caused by increased concentration of uncharged ammonia and be unrelated to larval activity. The mechanism behind the reduction of salmonella observed in this study is not known.…”

“…In a previous study, it was shown that the content of the zoonotic bacteria such as salmonella was reduced in the material to such a degree that it was not detectable in the harvested prepupae (Lalander et al 2013). Other zoonotic bacteria were not tested, but in other studies a, similar reduction of another Gram-positive bacteria, E. coli O157, has been observed (Erickson et al 2004). Due to the reduction of zoonotic bacteria, the risk of disease transmission -when feeding animals other than the ones providing the feed to the larvae -is a low-risk management system.…”

“…In several studies, black solider fly larvae waste treatment systems have been shown to remove bacteria in the Enterobacteriaceae family: the concentration of Salmonella spp. was reduced by 7 log 10 in 8 days in a small batchoperated fly larvae system treating fecal sludge (Lalander et al 2013); Erickson et al (2004) observed the reduction of Salmonella enterica Serovar Enteritidis and Escherichia coli O157:H7 in cattle manure, while Liu et al (2008) have reported on the reduction of E. coli in poultry manure. However, a l t h o u g h a h i g h r e d u c t i o n i n b a c t e r i a o f t h e Enterobacteriaceae family occur, reduction of other organisms has not been observed.…”

The environmental sustainability of insects as food and feed. A review

“…2). It utilizes this waste and can simultaneously kill pathogenic bacteria such as Escherichia coli or Salmonella enterica present in, for instance, chicken or cattle manure (Erickson et al 2004;Liu et al 2008). It has even been proposed as a sanitation method for getting rid of human feces (Lalander et al 2013;Banks et al 2014).…”