Purpose: The purpose of this study was to control the growth of Aspergillus niger on strawberries by applying recombinant tobacco osmotin (rOSM) for extending the shelf life.
Methods: Recombinant tobacco osmotin was expressed in Escherichia coli and purified on cobalt-agarose affinity column. The inhibition on spore germination and mycelia growth of Aspergillus niger was tested. Strawberries were disinfected in 70% ethanol and rinsed in sterile water, and spot-inoculated with Aspergillus niger spores. Inoculated strawberries were dipped into rOSM solutions (350 to 1,400 µg/ml) for 1 min. After being air dried, strawberries were then stored at 4 and 25 °C for testing the anti-fungal activities. Results were compared using ANOVA.
Results: The inhibition of Aspergillus niger spore germination was 50% at 700 µg/ml concentration, and the mycelia growth was significantly inhibited. After 7 days stored at 25 °C, the reductions of strawberries infection in treated at 350, 700 and 1,400 µg/ml rOSM were 5, 10 and 20%, respectively compared to the control group (no rOSM treated). Strawberries in all treatments didn’t show significant fungal growth at 4 °C after two weeks of storage.
Significance: This results showed promise for rOSM in controlling fungal growth. The rOSM has the potential to extend the shelf life of strawberries in the market.