Identification and purification of an antibiotic protein produced by Pseudomonas fluorescens strain CZ with inhibitory effect to tobacco mosaic virus

Tobacco mosaic virus (TMV) is a broad host range virus that inhibits the growth of a wide range of plant species, with devastating effects on crop production. In this study, the inhibitory effect of Pseudomonas fluorescens strain CZ against TMV was analyzed. Inoculation of a necrotic spot host, Nicotiana tabacum cv. Samsum NN, showed that strain CZ was most effective (99.5% suppression in vitro) when applied simultaneously with TMV, and was slightly less effective following preventive application (95.8%). Post-infection control was shown to confer the lowest inhibitory effect (69.7%) against TMV. The crude extracellular protein at concentrations of 5.0724 μg/ml and 0.9867 μg/ml conferred the suppression in vitro of 100% and 80.24%, respectively. Crude protein was extracted by salting out using ammonium sulfate from the CZ culture and purified by anion exchange chromatography, sephadex G-75 gel chromatography and SDS-polyacrylamide gel electrophoresis. The molecular weight of the protein was 39.4 kDa and it conferred 74.81% inhibition against TMV.

► We investigated the inhibition to TMV by Pseudomonas fluorescens CZ.
► CZ culture showed most effective of suppression in vitro to TMV.
► The suppression in vitro to TMV by CZ crude protein was tested.
► The extracellular protein of CZ was purified.