Functionalized microchannels as xylem-mimicking environment: Quantifying X. fastidiosa cell adhesion.

Area of Science:

• Plant Pathology
• Microfluidics
• Biomaterials Science

Background:

• Xylem vessels are crucial for plant water transport but also serve as habitats for phytopathogens like Xylella fastidiosa.
• Understanding phytopathogen colonization within xylem requires controlled experimental systems that mimic the native environment.

Purpose of the Study:

• To investigate surface functionalization strategies for microchannels to simulate xylem vessels.
• To study the colonization of Xylella fastidiosa subsp. pauca within functionalized microfluidic devices.

Main Methods:

• Fabrication and surface functionalization of polydimethylsiloxane and glass microchannels.
• Immobilization of carboxymethylcellulose (CMC) and XadA1 protein on microchannel surfaces.
• Quantitative evaluation of bacterial adhesion, growth, and motility under controlled flow conditions using mathematical modeling.

Main Results:

• XadA1 protein functionalization significantly increased Xylella fastidiosa bacterial density compared to CMC.
• Bacterial cells exhibited approximately 82% better adhesion rates on XadA1-functionalized surfaces versus pristine channels.
• Adhesion forces against shear stress doubled in XadA1-functionalized microchannels, indicating enhanced bacterial attachment.

Conclusions:

• Functionalized microchannels effectively mimic xylem vessels for studying phytopathogen colonization.
• The XadA1 adhesin plays a critical role in early-stage Xylella fastidiosa biofilm formation and modulates bacterial adhesivity.