Biofilm Formation in Arcobacter butzleri and Arcobacter cryaerophilus: Phenotypic and Genotypic Characterization of Food and Environmental Isolates

<i>Arcobacter butzleri</i> and <i>Arcobacter cryaerophilus</i> are emerging foodborne and waterborne pathogens associated with enteritis and extraintestinal infections in humans. Their persistence in the environment and resistance to antimicrobial treatment are closely related to their ability to form biofilms, which provide protection against adverse conditions and support survival on food contact surfaces. This study evaluated both the genotypic and phenotypic aspects of biofilm formation among <i>A</i>. <i>butzleri</i> and <i>A</i>. <i>cryaerophilus</i> isolates from food and environmental sources. Six biofilm-associated genes (<i>flaA</i>, <i>flaB</i>, <i>fliS</i>, <i>luxS</i>, <i>pta</i>, and <i>spoT</i>) were detected by multiplex PCR, and biofilm production was assessed using the Christensen microtiter plate assay and Congo Red Agar (CRA) test. All <i>A</i>. <i>cryaerophilus</i> isolates carried the same gene set as <i>A</i>. <i>butzleri</i>, suggesting conserved genetic determinants of motility and <i>Quorum sensing</i>. However, phenotypic assays revealed interspecific variability: while most <i>A</i>. <i>butzleri</i> isolates formed strong biofilms, 70% of <i>A</i>. <i>cryaerophilus</i> strains showed moderate to strong formation despite all being CRA-negative. No direct correlation between gene presence and biofilm intensity was observed, indicating complex regulation of biofilm development. This study provides a comparative overview of biofilm formation in <i>A</i>. <i>butzleri</i> and <i>A</i>. <i>cryaerophilus</i> and highlights their adaptive potential and persistence in food-related environments.