Phosphatase Activities of Root-Nodule Bacteria and Nutritional Factors Affecting Production of Phosphatases by Representative Bacteria From Three Different Genera

Fifty six strains of root-nodule bacteria isolated from 3 medicinal legumes including Indigofera
tinctoria L., Derris elliptica Benth. and Pueraria mirifica Airy Shaw & Suvat. were measured for
their acid-, neutral- and alkaline phosphatase activities. All strains produced extracellular
phosphatases, while almost no cell-bound phosphatase activities were observed. The unidentified
strain DASA 68062 and Bradyrhizobium sp. DASA 64011 produced the highest activity of acid
phosphatase, the unidentified strain DASA 68032 and Bradyrhizobium sp. DASA 68056 produced
the highest activity of neutral phosphatase and the strain DASA 68056 also produced the highest
activity of alkaline phosphatase which differed significantly from other strains. Effects of 14
nutritional factors on production of phosphatases by the strain DASA 57020 in
Ralstonia/Cupriavidus group, Bradyrhizobium sp. DASA 68056 and Rhizobium sp. DASA 68066
were determined. The stimulation of extracellular acid-, neutral- and alkaline phosphatase
activities of the strain DASA 57020 occurred when the strain utilized D-fructose, D-xylose and Dmannitol
as sole carbon sources and urea as a sole nitrogen source. The significant increase of
extracellular acid-, neutral- and alkaline phosphatase activities of the strain DASA 68056 was
detected in the presence of D-fructose and D-xylose. The factors including D-fructose, sucrose and
KNO3 could increase extracellular acid-, neutral- and alkaline phosphatase activities of the strain
DASA 68066. The carbon source, D-fructose, was the only factor that induced production of acid-,
neutral- and alkaline phosphatases by all strains tested.
Keywords: acid phosphatase, alkaline phosphatase, neutral phosphatase, root-nodule bacteria

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E-mail: neelawan@su.ac.th