Toxin-producing Escherichia coli isolates from composting pig waste

Abstract

Freshly voided excreta of confined pigs were composted using the open heap technique for 40 weeks. At specific intervals, pH and temperature determination as well as isolation and identification of Escherichia coli were performed. All E. coli isolates recovered were tested for the presence of heat-labile and heat-stable toxins using standard techniques. The values for pH and temperature ranged between 5.8 -6.9 and 27 °C -37 °C respectively. A total of 10 (76.92%) out of 13 E. coli isolated produced heat-labile toxins while 6 (46.15%) produced heat-stable toxins. All isolates that produced heat-stable toxin also produced heat-labile toxins. Open heap technique should not be encouraged as a method of composting. However, techniques that will ensure temperature of ≥ 55 °C is advocated.