Bacterial and fungal contributions to the production of phosphatases in arable and forest soils

Phosphatases play a key role in the mineralization of organic phosphorus in soils; however, the relative contributions of bacteria and fungi to phosphatase activities remain unclear. Sources of activities of two phosphomonoesterases (acid phosphatase and alkaline phosphatase) and phosphodiesterase in two arable Andisols and two forested Inceptisols were evaluated using selective inhibition with antibiotics. The results showed that all three phosphatases were primarily produced by bacteria in the two arable soils and one forest soil, whereas all three phosphatases were primarily produced by fungi in the forest soil with the lowest pH. These results indicated that fungi can be the primary contributors to alkaline phosphatase production in some soils, challenging the common assumption that bacteria are the main source of alkaline phosphatase activity. Moreover, within a given soil, either bacteria or fungi tend to be the dominant producers of all three phosphatase types, and the identity of the dominant producer appears to be influenced by soil pH. These results highlight the importance of considering the dominant microbial producers when interpreting soil phosphatase activities and organic phosphorus mineralization.