Abstract: 【Objective】The objective of this study is to screen a bacteria strain with significant anti-virus activity against TMV (Tobacco mosaic virus) and PVY (Potato virus Y). 【Method】The strain was isolated from the soil around the roots of healthy tobacco plants of Zhongyan100 (Nicotiana tabacum var. Zhongyan 100) grown in the high incidence of virus disease in many regions plantation of Shandong Province. The anti-TMV strain was tested by half-leaf method on hypersensitive plants (N. tabacum var. Samsun), and identified by the physiological and biochemical and molecular methods. Real-time quantitative PCR was used to test the inhibition of TMV and PVY for further verifying the anti-viral activity. Field trials were conducted with three treatments. The mixture was inoculated to tobacco NC89 (N. tabacum var. NC89) after the virus juice mixed with fermentation for 2 h (I). The fermentation was firstly sprayed on the tobacco plant, then inoculated the virus to NC89 2 h later (II). The virus was inoculated to the tobacco plant, then the fermentation was inoculated to the tobacco plant 2 h later (III). 8% of ningnanmycin and soapy water mixed with virus respectively were chosen as the positive control, and LB culture was mixed with virus as the blank control. The text result was verified through the inactivation of fermentation to the virus on the scissors.【Result】The anti-virus capacity of the strain named as 4A1 was up to 98%. Sequence analysis results showed that the nucleotide sequence of the 16S rDNA of the strain had 99% identity with that of Pseudomonas monteiliis. The strain 4A1 was gram-negative. Enzyme, starch hydrolysis reaction such as VP and indole were negative, gelatin, liquefaction, glucose response were positive and could move. 4A1 was identified as P. monteilii based on the above physiological, biochemical and molecular test results. Real-time quantitative PCR was used to test the inhibition of TMV and PVY for further verifying the anti-viral activity. And the results showed the fermentation of 4A1 had significant inhibitory activity. The field test results showed that treatment I TMV and PVY incidence rates were 5.3% and 7.7%, and disease indexes were 0.8 and 2.9. Treatment II incidence rates were 33.3% and 36.7%, and disease indexes were 4.2 and 6.0, and treatment III tobacco incidence rates were 95.0% and 92.0% with disease indexes 24.5 and 20.1. TMV and PVY incidence rates were 99.3% and 95.4%, and the disease indexes were 38.6 and 45.1 in CK. The anti-virus effect was up to more than 95% in the treatment of fermentation spraying to the leaf-cutting tools. The effect was significantly higher than that of other treatments. 【Conclusion】The selected strain could be used as biological disinfectants and antiviral agents for planting tools in tobacco production.

Key words: tobacco virus disease, biocontrol bacteria, Pseudomonas monteilii, antiviral activity