College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
Department of Earth & Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada.
Environ Sci Pollut Res Int. 2021 Dec;28(48):69393-69400. doi: 10.1007/s11356-021-15551-5. Epub 2021 Jul 23.
Fluorapatite (FAp) is the largest phosphorous (P) reservoir on Earth. However, due to its low solubility, dissolved P is severely deficient in the pedosphere. Fungi play a significant role in P dissolution via excretion of organic acids, and in this regard, it is important to understand their impact on P cycling. The object of this study was to elucidate the balance between P release and F toxicity during FAp dissolution. The bioweathering of FAp was assisted by a typical phosphate-solubilizing fungus, Aspergillus niger. The release of elements and microbial activities were monitored during 5-day incubation. We found that the release of fluorine (F) was activated after day 1 (~90 mg/L), which significantly lowered the phosphate-solubilizing process by day 2. Despite P release from FAp being enhanced over the following 3 days, decreases in both the amount of biomass (52% decline) and the respiration rate (81% decline) suggest the strong inhibitory effect of F on the fungus. We thus concluded that F toxicity outweighs P supply, which in turn inhibits fungi growth and prevents further dissolution of FAp. This mechanism might reflect an underappreciated cause for P deficiency in soils.
氟磷灰石（FAp）是地球上最大的磷（P）储存库。然而，由于其溶解度低，土壤中溶解态 P 严重缺乏。真菌通过分泌有机酸在 P 溶解中起着重要作用，因此了解它们对 P 循环的影响很重要。本研究的目的是阐明 FAp 溶解过程中 P 释放和 F 毒性之间的平衡。通过典型的解磷真菌黑曲霉辅助 FAp 的生物风化。在 5 天的孵育过程中监测元素的释放和微生物活性。我们发现，F 的释放在第 1 天（约 90 mg/L）后被激活，这显著降低了第 2 天的磷酸盐溶解过程。尽管 FAp 释放的 P 在接下来的 3 天内增加，但生物量（下降 52%）和呼吸速率（下降 81%）的减少表明 F 对真菌有很强的抑制作用。因此，我们得出结论，F 毒性超过了 P 的供应，这反过来又抑制了真菌的生长，阻止了 FAp 的进一步溶解。这种机制可能反映了土壤中 P 缺乏的一个被低估的原因。
