Pseudomonas syringae is a plant pathogen that infects a wide range of crops, including tomatoes, wheat, beans, peas, beetroot, and apples, leading to significant agricultural losses. The global demand for food is projected to increase by 61% by 2050. Traditional plant protection methods, such as chemical and biological treatments, face limitations, including pathogen resistance and environmental concerns. Therefore, there is an urgent need for ecologically friendly and effective alternatives [1]. Antimicrobial photodynamic inactivation (API) is a promising approach that relies on a photosensitizer (PS), light, and molecular oxygen to generate reactive oxygen species (ROS), which induces oxidative damage and microbial inactivation [2]. The choice of PS plays a crucial role in determining API effectiveness, as different compounds vary in their absorption properties, ROS generation efficiency, and antimicrobial activity. Among natural PS, riboflavin (RF), a naturally occurring vitamin B\(_{2}\), has shown potential for API applications. Upon light activation, RF produces ROS capable of inactivating microbial cells [3].
This study investigates the potential of RF-based API (RF-API) as a novel approach for controlling P. syringae. To assess its effectiveness, P. syringae cultures were exposed to varying RF concentrations and different irradiation doses. Bacterial viability was evaluated using colony-forming unit (CFU) counting and spectrophotometric measurements of metabolic activity. Additionally, the study examined how the preincubation period, defined as the time bacterial cells were incubated at 28°C in the dark before irradiation, influences RF-API effectiveness.
This study aims to determine the optimal RF concentration and irradiation dose required for effective P. syringae inactivation. Moreover, the impact of preincubation conditions on API efficiency was investigated, providing insights into how pre-treatment conditions influence bacterial susceptibility. These are the first studies to examine the susceptibility of P. syringae to RF-API, contributing to the advancement of photodynamic antimicrobial strategies in plant pathogen control. The findings will provide insights into the feasibility of RF-API as a sustainable alternative for agricultural applications. The results and their implications will be presented in the poster session.
Keywords: Pseudomonas syringae, Antimicrobial Photodynamic Inactivation (API), riboflavin, plant pathogen