Transmission Electronic Microscopy of Vibrio cholerae Biofilms on Chitin-Containing Substrates

Abstract

Introduction. The evolutionary association of Vibrio cholerae with chitin provided resistance to stress and protection from predators. The most important mechanism that provided V. cholerae with the effectiveness of association with chitin is biofilm formation. The ability to form a biofilm in V. cholerae depends on the presence of a factor, toxin-corrected adhesion pili (TCP), which are synthesized by the tcp A-F genes. One of the key methods for studying biofilms is microscopy. It allows one to visualize the structural elements and study various parameters of biofilms and the effects of various factors on them. Aim. To determine the epidemiological significance of the biofilm-forming ability of toxigenic strains by their morphological characteristics on chitin-containing substrates. Study of structural differences in biofilms of Vibrio cholerae tcpA+– and tcpA– strains on chitin-containing substrates. Results. It has been shown that Vibrio cholerae tcpA+– and tcpA– strains are able to form biofilms on the surface of chitin-containing substrates. The intensity of biofilm formation is more pronounced in tcpA+ strains, because V. cholerae ctxA+ tcpA+ cells in the biofilm are predominantly singly located and the surface of the chitinous exoskeleton with which they are in contact is intact, V. cholerae ctxA– tcpA– cells form chains in the biofilm, which indicates division processes, and scattered chitin of the endocuticle indicates activity of metabolic processes. Conclusion. The strains of V. cholerae used in the work, regardless of the presence or absence of the ctx and tcp genes, form bioplecs on a chitin substrate. The indicator of biofilm formation in terms of the thickness of the biofilm matrix is higher in V. cholerae ctxA+ tcpA+ , in terms of the degree of degradation of the chitin substrate it is higher in V. cholerae ctxA– tcpA– .