Epsilon Archive for Student Projects

Abstract

High nutrient content of chicken litter has made it one of the best organic fertilizers for agricultural land. However, reusing poultry litter in agriculture can be associated with food-borne pathogens such as E.coli, Salmonella and Campylobacter. To inactivate pathogens and minimize the environmental risks, manure could be treated before spreading on the field. Composting is an effective method to reduce pathogenic bacteria counts. Stacking the manure in containers is a minimally managed method to prevent the manure particles and effluents from entering the surrounding environment and decontaminate the manure before land application. However, more knowledge about bacterial decontamination is needed to ensure complete decontamination and reduce storage time and space.
This study was conducted to estimate microbial growth or inactivation as a function of environmental and physico-chemical factors during six months of storage in containers. First, the fluctuations in the number of Enterobacteriaceae bacteria were investigated in two big containers with or without adding wheat straw regarding alterations in temperature, dry matter (DM), pH, and oxygen levels. Second, the survival of bacteria belonging to Enterobacteriaceae, Salmonella typhimurium and Campylobacter jejuni were examined in a bucket filled with the same manure. This allows for the anticipation of pathogenic bacterial elimination in the containers concerning the Enterobacteriaceae population.
According to bacterial analyses, the number of Enterobacteriaceae went below detection limit after nine weeks for the containers and four weeks for the bucket. Salmonella was detected after enrichment during the whole experiment period in the samples from the surface of the bucket, while it was not detected from sixth week in the middle of the bucket, except for week 12. Campylobacter could not be detected by enrichment one week after inoculation. According to our results, direct cultivation on selective agar media following dilution for Enterobacteriaceae is not a reliable indicator for complete Salmonella inactivation in a sample. This thesis further emphasizes the significant impact of different physico-chemical parameters on manure composting. Low pH, desiccation, and heat were some of the parameters that contributed to the bacterial inactivation. A closely monitored process with proper amounts of required elements results in faster organic decomposition and bacterial decontamination.