Effect of culture media onLactobacillus hydrophobicity and electrophoretic mobility

The hydrophobicity of six strains representing three species ofLactobacillus was measured using dextran-polyethylene glycol contact angle measurements. These ranged from 123.6° forLactobacillus casei douche to 26.2° forL. casei RC-17 under identical growth conditions. The results indicated that the nutritional environment affected bacterial hydrophobicity. Electrophoretic mobilities of the lactobacilli were also determined and found to be negative for all specimens, and to vary with growth media, especially when sugars were added to urine. The electrophoretic mobility histograms showed one main peak for all strains, exceptLactobacillus acidophilus T-13 which had two peaks, suggesting two morphological sizes or types within its population. In addition, strain T-13 was more positively charged than the other five strains after growth in agar, urine, and supplemented urine. The use of contact angle and electrophoretic mobility techniques allows examination of cell surface properties of lactobacilli that may have importance in the colonization of mucosal epithelia.