Mechanisms of adhesion of Paenibacillus polymyxa onto hematite, corundum and quartz

Adhesion of bacteria onto solid surfaces is a necessary event in nature for the utilization of inorganic and organic values and for the enhanced growt h of bacteria. Interactions between Paenibacillus polymyxa, with different minerals such as hematite, corundum and quartz are examined in this work in the light of Derjaguin, Landau, Verwey and Overbeek theory, popularly know n as DLVO theory and possible chemical interactions. The adhesion process i s normally controlled initially by physicochemical interactions between cel ls and mineral substrates and subsequently by the production of extra cellu lar polymers to make the attachment stronger, From this study, it is clear that maximum adsorption of cells on hematite and corundum occurs at a pH be low the isoelectric point, whereas in the case of quartz the adsorption of cells remained almost constant in the entire pH range studied. From adhesio n tests, it is also clear that the above bacteria adsorb preferentially on hematite and corundum than on quartz. It is obvious from the interaction en ergy calculations that the columbic forces play a major role in the interac tion of P. polymyxa with hematite, corundum and quartz. Although the columb ic forces do play such a role, it is evident from the Fourier Transform Inf rared Spectroscopy (FTIR) results that other forces such as chemical forces are also involved simultaneously. (C) 2001 Published by Elsevier Science B .V.