Microbial diversity and microcystin levels in pond water sources of Knox County

Microcystin production by cyanobacterial blooms represent a hazard to public health through the contamination of drinking water. The role of microbial diversity in toxin production is poorly understood, especially in small water sources such as ponds. We undertook a study of microcystin levels and microbial diversity in ponds of Knox County, a rural county with agricultural activity. Water samples were collected from twenty-six unique ponds, wetlands, and lakes on both public and private properties. On site tests were conducted to determine environmental factors including pH and DO (dissolved oxygen). In lab tests were performed on nutrient levels. DNA was isolated and purified from 21 samples filtered wit 0.u pore size. The samples were sent for qPCR (targeting PC-IGS gene) sequencing and 16S barcoding to determine what the composition of the microbial community was for the selected samples. In most ponds, Planktothrix and Planktophila were the most abundant prokaryotes, whereas Microcystis (producer of microcystin) was relatively low, even in a pond that showed high microcystin levels. The grazing ciliate Oligohymenophorea showed a surprising correlation with microcystin levels, which may reflect some environmental factor that influences toxin production by Microcystis. Principal component analysis (PCA) revealed a strong correlation between intensity of human land use and the presence of selected bacterial genera. The eukaryotic PCA showed a weaker correlation between human land use intensity and selected eukaryotic genera.