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Inhibitory effects of B. velezensis strain on plant pathogens of the genus Xanthomonas
Švecová, Magdaléna ; Palyzová, Andrea (advisor) ; Jelínková, Markéta (referee)
Biological control is a method of applied ecology that uses one organism, or its product, to inhibit another pathogenic organism. This method in plant protection should be more environmentally friendly than commonly used pesticides. The rhizobacterium Bacillus velezensis FZB42, which can suppress the growth of other microorganisms, can be used as a biological control agent. Xanthomonas campestris pv. campestris is a phytopathogen that causes significant losses in agricultural production. This diploma thesis proved an antagonistic effect of the bacterial strain B. velezensis FZB42 on the phytopathogenic bacteria Xanthomonas campestris pv. campestris SU in mixed culture. The study confirmed that the antibiotic effect of B. velezensis strain FZB42 against X. campestris pv. campestris SU in mixed culture depends on the inoculation ratios of both strains. The interaction of the two bacterial strains was characterized by metabolomics analysis, it was confirmed that B. velezensis FZB42 produces four dominant secondary metabolites: lipopeptides surfactin, fengycin, and bacillomycin and siderophore bacillibactin, which show antifungal and antibiotic activity. The inhibitory activity of B. velezensis strain FZB42 was further monitored by SEM analysis, which showed damage to X. campesris pv. campestris SU...
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Functional membrane microdomains in the bacterial cytoplasmic membrane
Švecová, Magdaléna ; Mikušová, Gabriela (advisor) ; Koukalová, Alena (referee)
Functional membrane microdomains are structural heterogeneities in bacterial cytoplasmic membrane with up to few tens of nanometers in size. Same as in the case of eukaryotic lipid rafts the lipid and protein composition and fluidity of bacterial membrane microdomains differ from the rest of the membrane. Membrane microdomains contain the structural analogues of eukaryotic flotilin as well as hopanoids and carotenoids as functional analogues of cholesterol in eukaryotic lipid rafts. In functional membrane microdomains there are located proteins associated with membrane trafficking, signaling, secretion, biofilm formation, and sporulation. Functional membrane microdomains are specific sites for the entry of certain antibiotics into cells. What is more, disassembly of functional membrane microdomains might be regarded as a possible novel mechanism of bacterial infections suppression that is caused by antibiotic resistant bacterial pathogens. In the absence of membrane domains proteins which require for their functions the membrane domain localization lose their activity. This may result in inhibition of bacterial cell growth. Key words: Functional membrane microdomains, bacterial cytoplasmic membrane, cardiolipin, hopanoids, flotilins, antibiotic resistance
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