Growth of Salmonella on sprouting alfalfa seeds as affected by the inoculum size, native microbial load and Pseudomonas fluorescens 2-79

Abstract

Aims: To investigate the growth of salmonellae on sprouting alfalfa seeds as affected by the inoculum size, microbial load and Pseudomonas fluorescens 2–79. Methods and Results: Alfalfa seeds pre-inoculated with ≤10¹–10³ CFU g⁻¹ of salmonellae and with or without Ps. fluorescens 2–79 were sprouted in glass jars and the population of salmonellae were determined daily for up to 6 days. The population of salmonellae on germinating seeds reached the maximum 2–3 days after sprouting when total bacterial count reached the maximum (10⁹ CFU g⁻¹). The population of salmonellae on sprouting seeds not treated with Ps. fluorescens 2–79 showed a net increase of 3–4 log units. However, the population of salmonellae on alfalfa seeds treated with Ps. fluorescens 2–79 showed a net increase of only 1–2 log units. Disinfection of seeds with calcium hypochlorite enhanced the growth of salmonellae. Conclusions: Treatment of seeds with Ps. fluorescens 2–79 reduced the growth of salmonellae by 2–3 log units. Significance and Impact of the Study: The potential of Ps. fluorescens 2–79 as a biological agent for use in control of salmonellae on sprouting seeds was demonstrated and warrants further investigation.