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

Makimi Sugawa¹Kozue Sawada²Hitoshi Moro¹Kazunari Nagaoka³Shigeto Otsuka⁴Hirotaka Sumi⁵Takashi Kunito^6*

• ¹Shinshu Daigaku, Matsumoto, Japan
• ²Nagoya Daigaku, Nagoya, Japan
• ³Nogyo Shokuhin Sangyo Gijutsu Sogo Kenkyu Kiko Chuo Nogyo Sogo Kenkyu Center, Tsukuba, Japan
• ⁴Tokyo Daigaku, Bunkyo, Japan
• ⁵Chubu Daigaku, Kasugai, Japan
• ⁶Shinshu University, Matsumoto, Japan

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 Aall three phosphatases were primarily produced by bacteria in both 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 besuggest that fungi are 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.These findings also imply that production of the three phosphatase types tends to be synchronized, with either bacteria or fungi serving as the predominant producers of all phosphatases. Finally, the dominant producer (bacteria vs. fungi) might be influenced by soil pH.