Takeda M, Knight J D
Department of Soil Science, University of Saskatchewan, Saskatoon, SK, Canada.
Can J Microbiol. 2006 Nov;52(11):1121-9. doi: 10.1139/w06-074.
Little is known about how pH-buffering capacity affects phosphorus (P) solubilization by Penicillium bilaiae. This study compared solubilization of rock phosphate (RP) by P. bilaiae in nonbuffered (pH 5.0) and buffered (pH 7.0) media. Fungal growth reached the stationary phase around day 12 and was slightly enhanced in the buffered medium. The fungus reduced solution pH from 5.0 to 4.1 in the nonbuffered medium and from 7.0 to 4.9 in the buffered medium by day 12. Phosphorus concentrations increased after day 9 more in the buffered than in the nonbuffered media (53 and 5 mg P x L(-1), respectively, on day 12). On day 12, higher concentrations of citric and oxalic acids were detected in the buffered (2.0 and 1.2 g x L(-1), respectively) than nonbuffered media (0.5 and 0.04 g x L(-1), respectively). Solubilization of RP was simulated without P. bilaiae in solutions equivalent to the nonbuffered and buffered cultures of P. bilaiae grown with RP. After a 24 h incubation, the P concentrations were of similar magnitudes to those observed in the P. bilaiae culture (18 and 47 mg P x L(-1), respectively, in the nonbuffered and buffered media). Under increased pH-buffering conditions, the enhanced production of citric and oxalic acids led to significant RP solubilization.
关于pH缓冲能力如何影响双孢青霉对磷（P）的溶解作用，目前所知甚少。本研究比较了双孢青霉在非缓冲（pH 5.0）和缓冲（pH 7.0）培养基中对磷矿粉（RP）的溶解情况。真菌生长在第12天左右达到稳定期，且在缓冲培养基中略有增强。到第12天，真菌在非缓冲培养基中将溶液pH从5.0降至4.1，在缓冲培养基中将溶液pH从7.0降至4.9。第9天后，缓冲培养基中磷浓度的增加幅度大于非缓冲培养基（第12天分别为53和5 mg P·L⁻¹）。在第12天，缓冲培养基中检测到的柠檬酸和草酸浓度更高（分别为2.0和1.2 g·L⁻¹），而非缓冲培养基中分别为0.5和0.04 g·L⁻¹。在相当于用RP培养双孢青霉的非缓冲和缓冲培养物的溶液中，模拟了没有双孢青霉时RP的溶解情况。孵育24小时后，磷浓度与在双孢青霉培养物中观察到的浓度相似（非缓冲和缓冲培养基中分别为18和47 mg P·L⁻¹）。在增加的pH缓冲条件下，柠檬酸和草酸产量的增加导致了显著的RP溶解。
