Microbiological assessment of dry oat (Avena sativa L.) seeds before and after maceration

The aim of this study was to differentiate surface-associated microflora and microorganisms resistant to washing in dry oat (Avena sativa L.) seeds and to evaluate the effect of 24 h maceration in sterile distilled water on microbial release. Commercial seed samples were processed aseptically in the microbiology laboratory. Two experimental phases were applied: (i) pre-maceration, where seeds were briefly rinsed in sterile distilled water and the suspension was analyzed for surface-associated microorganisms, and (ii) post-maceration, where seeds were soaked for 24 h, allowing the release of microorganisms resistant to washing and associated with protected seed-coat niches. Suspensions were filtered through 0.45 μm membranes and cultured on selective and differential media: nutrient agar for heterotrophs, m-Endo agar for total coliforms, m-FC agar for fecal coliforms, Salmonella–Shigella agar for enteric pathogens, and potato dextrose agar (PDA) for yeasts and molds. Results showed that before maceration, the highest microbial load was fecal coliforms (244 CFU/100 mL), followed by heterotrophs and total coliforms (39 CFU/100 mL), while no yeasts or molds were detected. After maceration, microbial counts decreased by 41% for fecal coliforms, 90% for Salmonella/Shigella, and more than 90% for heterotrophs. These findings indicate that dry oat seeds may harbor potentially harmful microorganisms not only on the surface but also tightly associated with protected structures of the seed coat. The internal presence of microorganisms has important implications for agriculture, as it may adversely affect seed germination and early plant de- velopment in the field, thereby reducing growth quality and productivity. Maceration combined with membrane filtration represents a simple and effective approach to detect these risks, with direct relevance for seed quality control and food safety.