Exploiting Bacterial Pigmentation for Non-Destructive Detection of Seed-Borne Pathogens by Using Photoacoustic Techniques

Seed-borne pathogens pose a significant threat to global food security. This study focuses on <i>Curtobacterium flaccumfaciens</i> pv. <i>flaccumfaciens</i> (<i>Cff</i>), a quarantine plant pathogen causing bacterial wilt of common beans. Despite its global spread and economic impact, effective control measures are limited. Existing diagnostic methods, such as PCR, are time-consuming, destructive, and challenging for large-scale screening. This study explores the potential of photoacoustic techniques as a non-destructive, rapid, and high-throughput alternative. These techniques leverage the photoacoustic effect to measure optical absorption, offering high sensitivity and accuracy. <i>Cff</i> colonies exhibit distinct pigmentation, suggesting their suitability for photoacoustic detection. We characterised the optical properties of <i>Cff</i> and developed an in vitro model to simulate conditions within <i>Cff</i>-infected bean seeds. The results demonstrate the efficiency of the photoacoustic technique in detecting <i>Cff</i> in a mimicked-bean seed and indicate the potential discrimination of different coloured <i>Cff</i> strains. This study paves the way for a novel, non-invasive approach to the early detection of <i>Cff</i> and other seed-borne pathogens, contributing to improve crop health and food security.