A kinetic model for Xylella fastidiosa adhesion, biofilm formation, and virulence

Abstract

Xylella fastidiosa is the causal agent of citrus variegated chlorosis and Pierce's disease which are the major threat to the citrus and wine industries. The most accepted hypothesis for Xf diseases affirms that it is a vascular occlusion caused by bacterial biofilm, embedded in an extracellular translucent matrix that was deduced to be the exopolysaccharide fastidian. Fourier transform infrared spectroscopy analysis demonstrated that virulent cells which form biofilm on glass have low fastidian content similar to the weak virulent ones. This indicates that high amounts of fastidian are not necessary for adhesion. In this paper we propose a kinetic model for X. fastidiosa adhesion, biofilm formation, and virulence based on electrostatic attraction between bacterial surface proteins and xylem walls. Fastidian is involved in final biofilm formation and cation sequestration in dilute sap.

Disruption ofXylella fastidiosaCVCgumBandgumFgenes affects biofilm formation without a detectable influence on exopolysaccharide production

“…Partial evidence that X. fastidiosa produces low amounts of fastidian gum has recently been published (Osiro et al, 2004), supporting the contention that X. fastidiosa does not need high amounts of EPS for adhesion and biofilm formation (Leite et al, 2002) under low nutrient conditions, as was experienced by X. fastidiosa inside xylem vessels. These results indicate that the predicted 'fastidian gum' might be poorly expressed and might not be the major component of the matrix observed in X. fastidiosa cell clumps by SEM.…”

The role of conditioning film formation and surface chemical changes on Xylella fastidiosa adhesion and biofilm evolution

“…In the present study, the availability of magnesium and potassium in the PW broth could assist the formation of bonds between X. fastidiosa cells and the phosphate groups enriched at the substrate surface. In turn, Osiro et al [45] proposed a kinetic model where the adhesion process is dependent on the electrostatic attraction between positively charged surface proteins and negatively charged host surfaces. In this case, they considered that the number of positively charged amino acids (lysines, arginines, and histidines) exceeds the negative charges (glutamic and aspartic acids) in X. fastidiosa surface protein sequences.…”

Development of copper-charged polypropylene feedspacers for biofouling control

“…When analyzing the membrane that was fouled with the unmodified spacer, four additional peaks were present. These peaks appeared at wavenumbers of 970, 1053, 1380 and 1735 cm −1 and corresponded mainly with polysaccharides, but also to lipopolysaccharides, fatty acids and phospholipids [24,25,27,29]. A listing of these peaks, their band assignments and associated biomolecules can be seen in Table 1.…”

“…The spectrum of the membrane fouled with the Cu-charged spacer showed significant differences from the unfouled membrane, as it would be expected. The most prominent of these differences was the addition of the peak at a wavenumber of 1635 cm −1 , which is indicative of a protein carbonyl stretch, and is commonly referred to as the Amide I peak [24][25][26][27][28][29]. When analyzing the membrane that was fouled with the unmodified spacer, four additional peaks were present.…”