Journal of New Discovery in Microbiology

The increasing use of animal wastes as organic soil amendments necessitates appropriate treatment to improve their physicochemical quality and reduce microbiological risks associated with agricultural application. This study evaluated the physicochemical characteristics of untreated, composted, and incinerated animal wastes and assessed faecal indicator organisms in manure-amended soils and Talinum triangulare (waterleaf) cultivated in Calabar, Nigeria. Fresh cow dung, poultry droppings, pig slurry, and their combinations were subjected to untreated, aerobic composting, and incineration treatments. Physicochemical parameters assessed included moisture content, organic matter, organic carbon, total nitrogen, pH, total solids, volatile solids, and dry matter. Faecal coliforms were enumerated in wastes, amended soils, and harvested waterleaf, while bacterial isolates were identified using standard microbiological methods. Selected representative Escherichia coli and Salmonella spp. isolates were characterised by PCR targeting the uidA, invA, and hns genes, respectively. Untreated wastes recorded higher moisture, organic matter, organic carbon, and nitrogen contents than treated wastes. Composting reduced moisture and faecal coliform loads while retaining more organic matter and nitrogen than incineration. Untreated manure-amended soils recorded the highest faecal coliform counts (5.30 × 10⁵–2.10 × 10⁶ CFU/g), compared with 1.50 × 10³–4.23 × 10³ CFU/g in composted treatments and 1.20 × 10¹–2.00 × 10¹ CFU/g in incinerated treatments. Similar reductions occurred in waterleaf cultivated with treated wastes. E. coli, Klebsiella spp., Enterobacter spp., Citrobacter spp., Proteus spp., and Salmonella spp. were recovered, particularly from untreated treatments. PCR confirmed selected representative isolates, with expected uidA (147 bp), invA (284 bp), and hns (152–156 bp) products. Overall, composting substantially reduced faecal contamination while retaining more physicochemical properties than incineration, indicating its potential as a safer treatment option for agricultural use of animal wastes.