Acid sulphate soil (ASS) have a large distribution in the world (107-108 ha) and in Indonesia (6.71x 106 ha). ASS characterized by high concentration of Al3+ and Fe2+ ions and also high acidity resulted pyrite oxidation. The presence of these ions and lowering of pH causes some problem such as loss of agricultural productivity and environmental damage. To improve agriculture productivity, ASS requires remediation to minimize of Fe and Al activity and to increase soil pH. One of remediation

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... iques is microorganisms use (bioremediation). Bioremediation is a process that using living organisms to decrease toxic elements. Phosphate solubilizing microorganisms (PSM) remediate metal-contaminant in soil through decreasing metal toxicity by transforming metal species into immobile form. Some compounds which are excreted PSM and play a role in remediation are organic acid, exopoly saccharides and fosfatase enzyme. Organic acids and fosfatase enyme inactivate Al3+ and Fe2+ through the process of chelate and precipitate respectively. Absorption of H+ from solution by exopolysaccharides increase soil pH. Another mechanisms remediation by PSM is its accumulation of metal contaminated in cell surface. Decreasing of Al3+ and Fe2+ activity and acidity can increase agricultural productivity. This review is an effort to emphasize how PSM can be used to remediate acid sulphate soil dominated by Al, Fe and SO42-.