Microbial adhesion to hydrocarbons (MATH), a widely used test for measuring cell surface hydrophobicity in LAB was utilised to observe the hydrophobicity of L. plantarum, A17 and B21.
The results are shown qualitatively in Fig. 2.
According to Ofek, Hasty, and Doyle (2003), hydrophobicity of bacterial cells is the tendency of a microorganism to adhere to a nonpolar material in preference to water.
In the current study, the hydrophobicity of the cell surface was measured by careful and thorough mixing of live cells with hexadecane (a non-polar solvent).
Aqueous suspensions of both L. plantarum A17 and B21 were layered with the hydrocarbon phase as shown in Fig. 2a. After mixing vigorously for 2 min, it was observed that droplets of hexadecane were dispersed into the aqueous phase and the hydrophobic cells were associated with the nonpolar material.
When allowed to stand for 15 min, the hydrocarbon phase, being less dense than water, rose to the surface taking with it the cells as indicated by a creamy layer (Fig. 2b)