Test Overview
Duration: Variable
Bacterial plating tests are used to detect specific seedborne bacterial pathogens. Seed extracts are cultured on selective growth media designed to encourage growth of the target bacteria while limiting the growth of other microorganisms.
Testing procedures, sample size, and duration vary depending on the crop and target pathogen.
Test Details
Seeds are soaked in an extraction buffer to release bacteria that may be present on or in the seed. Depending on the seed type and target pathogen, seeds may also be ground during the extraction process.
Dilutions of the seed extract are plated onto selective agar media and incubated under conditions appropriate for the target organism. Plates are then examined for bacterial colonies with characteristics consistent with the target pathogen.
Additional testing, such as PCR or pathogenicity testing, may be used when necessary to confirm the identity of suspect bacterial colonies.
Sample Requirements
Sample requirements vary by crop, pathogen, and testing protocol. Typical sample sizes range from 1,000–5,000 seeds for larger-seeded crops, such as corn and cucurbits, to 10,000–30,000 seeds for smaller-seeded crops, such as pepper, tomato, and lettuce.
Additional seed may be required when multiple tests are requested on the same sample.