Abstract:
Phosphate solubilising bacteria possess the ability to solubilise insoluble phosphate to soluble
forms enhancing the nutrient status of the soil. This process not only compensates increasing cost of
phosphatic fertilisers but also minimises the negative environmental impacts associated with the
application of inorganic fertilisers. Phosphate solubilising bacteria (PSB) were screened based on the
size of a halo/ clear zone around the colony (NBRIP agar plate assay) and by measuring solubilise
phosphorous content (colorimetric method). The aim of this work was to assess the comparative
reliability of quantitative and qualitative methods of isolation of phosphate solubilising bacteria.
Bacterial strains which showed very poor performance in qualitative method were proven to be good
phosphates solubilisers in quantitative method and vice versa. Therefore no positive relationship
among the values obtained from qualitative and quantitative methods could be observed. Furthermore
qualitative method did not reflect the real ability of the phosphate solubilising bacteria to solubilise
insoluble phosphates. From the results of the present study, it can be concluded that isolation of
efficient phosphate solubilising bacteria through quantitative method could give better results than
that of qualitative method.
