Effect of ambient environments on survival of selected bacterial populations in dairy waste solids

Survival of potentially pathogenic organisms, especially those causing mastitis, indigenous to dairy waste solids was measured over an exposure of 12 days. Selected genera of bacteria were Staphylococcus, Streptococcus, Pseudomonas, Salmonella, and Escherichia. Random samples were taken from four locations within each pile of dairy waste solids at 4-day intervals in four replicates. The number of streptococci and salmonella markedly decreased after the first 4 days. The pseudomonas and coliform populations decreased a small but significant amount as did the staphylococci. These results could be in part from various factors such as solar radiation, heavy metals in the solids, or the approximate 45 C increase in temperature within the piles.