Insightover0 lactobacillus plantarum 299v physicohemical characteristics of aggregation kinetics under starvation and different pH conditions estudio sobre las caracterÍsticas

Abstract

Bacterialaggregationisruledbyspecificandnonspecificadhesionmechanisms.FortheprobioticstrainLactobacillusplantarum 299v (Lp299v) the biochemistry of adhesion has been previously studied and S-layer proteins have been identified. However, physicochemical mechanisms which ruled the aggregation and adhesion phenomena able to change through the time under different pH conditions have not been completely elucidated. In this study we have described the non-specific adhesion mechanisms (hydrophobicity, zeta potential and morphology) of Lp299v auto-aggregates over time (24 h) at different pH levels (from 5.0 to 9.0) under starvation conditions. Auto-aggregation was time-dependent increasing up to 60% after 22 h at pH 5. On the other hand, the acidophilic nature of the Lp299v cell surface was confirmed showing higher affinity with chloroform than with n-hexadecane, while zeta potential was negative in all cases. Size and shape parameters were found to be time and pH dependent.AstrongPearsoncorrelation(0.991)wasobservedbetweencircularityandauto-aggregation.Inconclusion,Lp299v’s nonspecific adhesion mechanism was found to be more related to time than to pH levels, indicating that van der Waals and hydrophobic forces have the potential to dominate the auto-aggregation of Lp299v. Finally, the results showed that lower pH may promote auto-aggregation possibly easing the colonization at the upper level of the digestive system.