Biofilm formation by Xanthomonas campestris pv. viticola affected by abiotic surfaces and culture media

Abstract

Biofilms are dense surface-associated communities formed by microorganisms. Formation of these structures by the plant pathogenic bacterium Xanthomonas campestris pv. viticola (bacterial canker of grapevine) had not previously been studied. The ability of seven strains of this bacterium to adhere to abiotic surfaces and to form biofilms in vitro was evaluated under different conditions. The surfaces tested were polystyrene and glass using microtiter plates and tubes, respectively. Four liquid culture media were used, nutrient-dextrose-yeast extract (NYD), yeast extract-dextrose-calcium carbonate (YDC), Kado 523 (KADO) and Luria-Bertani (LB). The biofilm architecture was examined by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Seven strains adhered to polystyrene in the microtiter plates and formed biofilms in all culture media at weak, moderate, and strong levels. In glass tubes, only strains Xcv229 and Xcv158 formed biofilms. SEM of Xcv229 and Xcv158 revealed typical biofilm architectures. CLSM showed that only Xcv229 formed an initial matrix structure characteristic of biofilms. The X. campestris pv. viticola strains exhibited different levels of biofilm formation in different culture media, of which LB and KADO were the best. Therefore, bacterial growth in polystyrene microtiter plates using LB and KADO media is a good qualitative method for the detection of biofilms of this pathogen.