17 research outputs found
Effects of co-composting of faecal sludge and agricultural wastes on tomato transplant and growth
Mechanisms determining aerobic or anaerobic growth in the facultative anaerobe Salmonella typhimurium.
Analysis of Proteins Induced by the Salmonella typhimurium Phage P221, a Hybrid between Serologically and Morphologically Unrelated Phages P22 and Fels 1
Isolation of Thermophilic Mutants of Bacillus subtilis and Bacillus pumilus and Transformation of the Thermophilic Trait to Mesophilic Strains
Demonstration of cel operon expression of Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa at elevated temperatures refractory to their growth
High Frequency Transduction by Phage Hybrids Between Coliphage o80 and Salmonella Phage P22
Determining Thermal Inactivation of Escherichia coli O157:H7 in Fresh Compost by Simulating Early Phases of the Composting Process â–¿
A three-strain mixture of Escherichia coli O157:H7 was inoculated into fresh dairy compost (ca. 107 CFU/g) with 40 or 50% moisture and was placed in an environmental chamber (ca. 70% humidity) that was programmed to ramp from room temperature to selected composting temperatures in 2 and 5 days to simulate the early composting phase. The surviving E. coli O157:H7 population was analyzed by direct plating and enrichment. Optimal and suboptimal compost mixes, with carbon/nitrogen (C/N) ratios of 25:1 and 16:1, respectively, were compared in this study. In the optimal compost mix, E. coli O157:H7 survived for 72, 48, and 24 h in compost with 40% moisture and for 72, 24, and 24 h with 50% moisture at 50, 55, and 60°C, respectively, following 2 days of come-up time (rate of heating up). However, in the suboptimal compost mix, the pathogen survived for 288, 72, and 48 h in compost with 40% moisture and for 240, 72, 24 h in compost with 50% moisture at the same temperatures, respectively. Pathogen survival was longer, with 5 days of come-up time compared with 2 days of come-up. Overall, E. coli O157:H7 was inactivated faster in the compost with 50% moisture than in the compost with 40% at 55 and 60°C. Both moisture and come-up time were significant factors affecting Weibull model parameters. Our results suggest that slow come-up time at the beginning of composting can extend pathogen survival during composting. Additionally, both the C/N ratio and the initial moisture level in the compost mix affect the rate of pathogen inactivation as well