Biocontrol Effect And The Antibiotics Of Endophyte Pseudomonas Aeruginosa PY11T-3-1 Isolated From Pinellia Ternata

Pinellia ternata(Thunb.)Breit. has been used as a traditional Chinese herb over thousands of years, which is susceptible to a soft rot disease caused by Pecctobacterium carotovorum subsp.carotovorum. Biocontrol is an emerging trend aimed at reducing chemical input while increasing plant fitness, productivity and resistance to diseases in sustainable agriculture especially for Chinese herb. The objective of this study was to investigate the biocontrol effect and analysis the antibiotics of P. aeruginosa pY11T-3-1.Firstly, antagonistic assays, growth-promoting and toxicity test were carried out in greenhouse and (or) field. P. aeruginosa pY11T-3-1 greatly inhibited the soft rot of P. ternata, cabbage and tomato, with at least 84.4% inhibition. It promoted the germination of the seeds of the three plants, and obviously increased fresh weight, daily increase, and height of the plants. In the toxicity test P. aeruginosa pY11T-3-1 with high concentration inhibited the growth of plants, yet growth-promoting was observed in the treatment with lower fermertation.Secondly, the culture condition was optimized to produce antibiotics. The optimized was as follows: 140ml fermentation broth in 250ml triangular flask, pH 7.0, 10% inoculum, cultured at 30℃for 24-48h. The fermentation was operated in 6L-fermentor using above conditions, and the growth was prolonged and the inhibition activity of the fermentation was lower. The antibiotics produced by P. aeruginosa pY11T-3-1 could be tolerant in high temperature and alkaline. Drying using freeze and vacuum had no effect on the activity of the antibiotics, thus can be used in crude extraction.Lastly, the antibiotics were separated, purified and identified. PW4040F ultrafiltration membrane was found to have higher separation efficiency. The solution was effectively concentrated using DK4040F nanofiltration membrane. The antibiotics could also be extracted using acetic ether. Two methods above could be used for primary extraction. The antibiotics were successfully purified using TLC and Silica Gel Column, and 3-5 bands and 10 active portion ware obtained respectively. Among which, ASW20 showed the highest inhibition activity. It was further purified using HPLC with mobile phase of CH3OH: H2O =78:12, and two peaks were obtained with peaks area 42.2%, 36.71%. Accordingly, two peaks of ASN206 and ASN207 were identified, and the relative molecular weight were 259 and 271, respectively. They are pridicted to be pyoluteorin and pyrronitrin. Extra nine elements were obtained, which need further identification.In summary, endophyte P. aeruginosa pY11T-3-1 could be savely applicable in planting since it had good inhibtion against soft rot and growth-promoting. The constructed methods of extract and purification and the identified antibiocs were helpful for further research.