Influence of prior mode of growth on physiological properties of Campylobacter cells

Campylobacter is an important foodborne pathogen of worldwide concern. Planktonic (broth) or sessile (agar) modes of growth have been suggested to affect cell physiology and virulence of pathogenic bacteria. This work aimed to investigate the influence of prior mode of growth (planktonic and sessile culture) on selected physiological properties of cells of two Campylobacter strains (one Campylobacter jejuni strain and one C. coli strain). Specifically, cell surface hydrophobicity, surface charge, capsular polysaccharide (CPS) and lipooligosaccharide (LOS) expression and quantification, autoagglutination and adhesiveness were examined. Cell surface hydrophobicity, surface charge and autoagglutination were determined by water contact angle, zeta potential and optical density measurements, respectively. Expression of CPS and LOS were determined using SDS-PAGE with Alcian blue staining and quantified using an acid hydrolysis method. The adhesiveness of Campylobacter was evaluated based on the numbers of cells attaching to stainless steel and glass. There was no significant (P>0.05) difference between planktonic and sessile cells with regards to zeta potential values, indicating prior mode of growth may not affect cell surface charge of Campylobacter. Cells grown under both culture conditions demonstrated similar CPS and LOS profiles and produced comparable (P>0.05) amounts of CPS and LOS, suggesting growing Campylobacter in either planktonic or sessile mode may not influence CPS and LOS expression and quantification. However, cells exhibited a significantly (P<0.05) higher degree of hydrophobicity, autoagglutination activity and attachment to stainless steel and glass when grown in planktonic culture than in sessile culture. These findings suggest prior mode of growth strongly affects the physiology of Campylobacter.