| Popis: |
We aimed to test if anthropogenic P input into ecosystems reduces microbial resource allocation to acquire N (and alleviate N shortage if any) because microbes no longer produce N-rich phosphatase for P acquisition. Literatures reporting the effect of P fertilization on C-acquiring (β-1,4-glucosidase, BG) and N-acquiring (β-1,4-N-acetylglucosaminidase, NAG, which also acquires C) enzymes were collected and synthesized. We predicted that P addition elevates BG:NAG especially in P-poor ecosystems because P addition alleviates N shortage and reduces the microbial resource allocation to acquire N relative to C. The synthesized data demonstrated that P fertilization occasionally reduced BG:NAG, which is inconsistent with the prediction. However, this might not mean that the initial hypothesis was rejected. Stimulated microbial activity and turnover by P fertilization could have caused microbes depend the C sources more on chitin (and peptidoglycan) compared with on cellulose because chitin (and peptidoglycan) is a main component of microbial body and re-provided through microbial turnover. The changes in C resources accompanied by the altered P availability may have largely influenced BG:NAG, masking the role of BG:NAG for indicating microbial resource allocation to C and N acquisitions. |
