Journal of Pure and Applied MicrobiologyVol. 3 No. 2

Influence of Abiotic Factors on Multigeneric Coaggregation Among Diazotrophic Bacteria

K. Kannan¹ and C. Sekar²

¹Department of Biotechnology, T. John College, Bangalore - 560 083, India. ²Department of Microbiology, Faculty of Agriculture, Annamalai University.

Received on 18 February 2009 and accepted on 21 April 2009



The effect of different abiotic factors viz., growth temperature, pH, divalent cations and chelating agents, on the development of ‘Multigeneric diazotrophic coaggregates”, consisting of triple efficient diazotrophic isolates viz., Azospirillum (AZS-3), Azotobacter (AZT-3) and Rhizobium (RZB-3), was studied with a view to optimize the abiotic factors for the mass scale production of the novel formulation of bioinoculant. In the present study, it was observed that the diazotrophic cells of the triple genera grown at 35°C temperature exhibited more coaggregation followed by 40, 45, 30 and 25 degrees of temperature. pH at a level of 7.5 exhibited more coaggregation than other pH levels. Addition of divalent cation viz., Ca2+ at 0.1 mM concentration augmented more coaggregation followed by Mg2+ and Ba2+. Interestingly, addition of chelating agent viz., EDTA drastically reduced the coaggregation percentage of diazotrophic cells to a higher level than EGTA. It was concluded that maximization of “Multigeneric diazotrophic coaggregates” could be possible at 35°C growth temperature of diazotrophic cells at a pH level of 7.5 in the presence of Ca2+ cation.

Keywords : Multigeneric diazotrophic coaggregates, growth temperature, pH, cation, coaggregation percentage.