Ammonium sulphate enhances adherence of Escherichia coli J-5 to hydrocarbon and polystyrene

Bacterial adherence to hydrocarbons (BATH) is a convenient method for the study of relatively pronounced cell surface hydrophobicity exhibited by various microbial cells, but has proven relatively ineffective in the study of less pronounced examples of bacterial hydrophobicity. It is well known that hydrophobic interactions can be enhanced by addition of salting-out agents, such as ammonium sulphate. In the present manuscript, the effect of ammonium sulphate on adherence to hexadecane of Escherichia coli strains K-12 and J-5 was studied. In the absence of ammonium sulphate, neither strain adhered to hexadecane. However, adherence of rough strain J-5 was enhanced dramatically in the presence of rising ammonium sulphate concentrations. Ammonium sulphate similarly enhanced adherence to other test hydrocarbons, and to the solid hydrophobic surface, polystyrene. The results show that the presence of ammonium sulphate can promote bacterial adherence to hydrocarbon and thus extend the use of this technique to include a wider array of microorganisms.