A qPCR method to quantify bioavailable phosphorus using indigenous aquatic species

Bioavailable phosphorus (BAP) represents the sum of phosphorus that is readily available for algae growth and is useful to indicate the severity of eutrophication in aquatic environments.

Here, a quantitative real-time PCR (qPCR)-based bioassay was developed to quantify BAP using the indigenous cyanobacterium species Anabaena sp. of Lake Tai, a large and shallow eutrophic lake in the Yangtze Valley, China. Primers were designed to quantify the gene expression of alkaline phosphatase (phoA/phoA-like) and phosphate transporter (pst1) genes of Anabaena. The specificity and efficiency of the primer sets were evaluated by gel electrophoresis and real-time PCR. The results showed that the primers developed here could successfully be used to measure BAP in the water. The linear range of BAP measurements by the pst1 gene after 2 h incubation was 0.125-2.00 mg/L. Then, the qPCR-based bioassay was applied to analyze water samples from Tai Lake, which had BAP levels in the range of 0.239-0.459 mg/L.

The qPCR-based bioassay represents a promising biomonitoring tool that can quantify phosphorus bioavailability in aquatic environments.