Phosphate-solubilizing fungi in riparian sediment of Xiangxi Bay (China) and implications of phosphorus pollution control

Abstract

Abstract The implementation of the Three Gorges Project (Yangtze River, China) has caused severe eutrophication in Xiangxi Bay (XXB). Although several studies have investigated the mechanism of eutrophication in physical and chemical fields, biological factors were neglected. Discarded food, phosphate rock mining, and transportation result in the nutrient input to XXB. To better understand the aquatic eutrophication in XXB, we screened phosphate-solubilizing fungi (PSF) from XXB riparian sediments and studied the factors influencing PSF activities. It was observed that (1) PSF was present in all seven sampling sites, (2) strains of Penicillium sp. XXR-A and Aspergillus sp. XXR-B1 exhibited higher phosphorus release than Talaromyces sp. XXR-F and Talaromyces sp. XXR-D, and (3) Aspergillus. sp. XXR-B1 could solubilize phosphate rock efficiently, and some substances derived from discarded food could influence its phosphorus-release activity. Based on this study, we suggest the following: a) covering the phosphate rock piles on wharves could reduce the inflow of phosphate rock powder into XXB with rainwater, which is a simple and emerging strategy; b) prevention of the discharge of food waste into XXB can abate the nutrient supply for PSF and c) decrease of nitrogen content (especially NO3–-N) can influence on the behavior of PSF. Moreover, PSF may be an active participant during XXB eutrophication. Furthermore, nutrient conditions play an important role in regulating the phosphorus-release activity of PSF.