Abstract Organic acids produced by microorganisms have been proposed as a biotechnological tool to release phosphorus (P) from sparingly soluble rock phosphates (RPs). In this work, organic acids commonly associated with microbial P solubilization (citric, gluconic, itaconic, malic, and oxalic) were applied at increasing doses to solubilize RPs with distinct reactivity grades. P solubilization by organic acids was compared to sulfuric acid, the traditional reagent applied in RP solubilization for fertilizer production. The acid type and its concentration had more influence on solubilized P than RP reactivity. In general, the efficiency of organic acids was oxalic > citric ≥ malic > itaconic > gluconic. Oxalic and sulfuric acids solubilized 100% of the P contained in all RPs composed by apatite [Ca5(PO4)3(OH,F,Cl)]. However, oxalic acid was superior to sulfuric acid, releasing more P per mmol of acid applied. In average, each mmol of oxalic acid released 21 mg P, while sulfuric acid solubilized 14 mg P mmol−1. Thus, microorganisms producing oxalic acid appear as a promising alternative to process RP via a biotechnological route.

中文翻译：

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草酸对磷矿增溶作用比硫酸更有效

摘要 微生物产生的有机酸已被提议作为一种生物技术工具，用于从微溶磷酸盐 (RP) 中释放磷 (P)。在这项工作中，通常与微生物 P 增溶相关的有机酸（柠檬酸、葡萄糖酸、衣康酸、苹果酸和草酸）以增加的剂量应用，以溶解具有不同反应性等级的 RP。有机酸对磷的增溶与硫酸相比，硫酸是用于肥料生产的 RP 增溶的传统试剂。酸类型及其浓度对溶解的 P 的影响比对 RP 反应性的影响更大。一般来说，有机酸的效率为草酸>柠檬酸≥苹果酸>衣康酸>葡萄糖酸。草酸和硫酸使磷灰石 [Ca5(PO4)3(OH,F,Cl)] 组成的所有 RP 中 P 的 100% 溶解。然而，草酸优于硫酸，每 mmol 酸释放更多 P。平均而言，每 mmol 草酸释放 21 mg P，而硫酸溶解 14 mg P mmol-1。因此，产生草酸的微生物似乎是通过生物技术途径处理 RP 的有希望的替代品。