Abstract

PAREDES-MENDOZA, Marianela  and  ESPINOSA-VICTORIA, David. Organic acids produced by phosphate solubilizing rhizobacteria: a critical review. Terra Latinoam [online]. 2010, vol.28, n.1, pp.61-70. ISSN 2395-8030.

The production of low molecular weight organic acids by the rhizobacteria is one of the most widely known mechanisms of soil phosphate solubilization, a process that makes phosphorus available for plant nutrition. The phosphate solubilizing capacity of organic acids, such as oxalic, citric, butyric, malonic, lactic, succinic, malic, gluconic, acetic, gliconic, fumaric, adipic, indoleacetic, and 2-ketogluconic acids, was reported during the period 1908-2008. Some bacterial genera that exhibit solubilizing phosphate activity through organic acid production are Pseudomonas, Rhizobium, Burkholderia, Achromobacter, Agrobacterium, Aereobacter, Flavobacterium, Yarowia, Streptosporangium, and Erwinia. Gluconic and 2-ketogluconic acids are the acids most frequently reported as phosphate solubilizing agents. The capacity of the organic acids to increase P availability not only results from the acidification of the plant rhizosphere, but also from their capacity to form stable complexes with some metals, such as Al and Fe. Organic acids also increase the availability of other soil micronutrients such as Mn, Al, and Zn when pH decreases in the rhizosphere or by chelation of micronutrients. At the same time, organic acids participate in other soil phenomena, such as microbial chemotaxis and metal detoxification. The objective of this paper is to analyze the role of the organic acids produced by rhizobacteria in the solubilization of mineral phosphate and its implications in the soil nutritional status.

Keywords : soluble P; solubilizing bacteria; rhizosphere; low molecular weight acids; 2-ketogluconic acid; aliphatic acids.

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