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 Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), 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. Cff colonies exhibit distinct pigmentation, suggesting their suitability for photoacoustic detection. We characterised the optical properties of Cff and developed an in vitro model to simulate conditions within Cff-infected bean seeds. The results demonstrate the efficiency of the photoacoustic technique in detecting Cff in a mimicked-bean seed and indicate the potential discrimination of different coloured Cff strains. This study paves the way for a novel, non-invasive approach to the early detection of Cff and other seed-borne pathogens, contributing to improve crop health and food security.