Abstract

--- - "Introduction: Polymicrobial biofilms have a significant impact on pathogenesis of infectious microorgan-isms. Many human diseases are affected by colonization of multi-species communities affecting nega-tively the treatments and increase the risks for the health. In particular, in the epithelium of the stomach co-existence between C. albicans and H. pylori has been described, which has been associated to a synergistic effect on ulcer pathogenesis. Objective: The objective of this work was to advance in the understanding of surface interaction between H. pylori and C. albicans for the formation of polymicrobial biofilms." - "Methods: Studies of microbial surfaces both bacterium, yeast and co-cultures of them were carried out by infrared spectroscopy, deconvolution analysis, transmission and scanning electron microscopies, and optic microscopy. Additional methods were used to contrast the results as dynamic light scattering, con-tact angle, agarose gel electrophoresis and gene amplification." - "Results: Several surface interaction mechanisms promote the anchoring of H. pylori on C. albicans, cell co-aggregation, and polymicrobial biofilm formation, main identified interactions were: (i) hydrophobic interactions between non-polar peptide chains and lipid structures, characterized by theta(w) among 84.9 +/- 1.6 (gamma = 22.78 mJ/m(2) with 95.3 of dispersive contribution) and 76.6 +/- 3.8 (gamma = 17.34 mJ/m2, 40.2 of dispersive contribution) for C. albicans and H. pylori, respectively, (ii) hydrogen bonds between surface components of yeast and bacterium (e.g., -S-H center dot center dot center dot NH2- or -S-H center dot center dot center dot O=CO-) and (iii) thiol-mediated surface interactions identified by displacements to lower wavenumbers (Delta v = 5 cm(-1)). Evidence of internalization and electrostatic interactions were not evidenced. All observations were congruent with the biofilm formation, including the identification of small-size biostructures (i.e., 122-459 nm) associated with extracellular proteins, extracellular DNA, or outer membrane vesicles were observed characteristic of biofilm formation." - "Conclusion: It is concluded that biofilm is formed by co-aggregation after anchoring of H. pylori on C. albicans. Several surface interactions were associated with the prevalence of H. pylori, the possibility to find C. albicans in the stomach epithelium infected by H. pylori, but also, strength interactions could be interfering in experimental observations associated with bacterial-DNA detection in culture mixtures. (C) 2021 The Authors. Published by Elsevier B.V. on behalf of Cairo University."