Separation And Identification Of Chitosan Degrading Fungus And The Biocontrol To Banana Fusarium Wilt

Chitosan is the most abundant high molecular raw carbohydrates.which is used in all parts of industry and agriculture and medicine and environment protection.But its insolubility has become the restriction factors which would be widely used in production. Chito-oligosaccharides,the degradation products of chitosan by chitoanase have better solubility,unique biological activity and physiological function,and also has won the attention of many researchers.This paper mainly study on several aspects as follows.We collected 142 soil samples from Guangdong and Hainan province,screened fungi with the culture medium using chitosan as the only carbon source and nitrogen source,and isolated 363 fungi strains totally.We gained a better effect fungus by the antibacterial effect determination, to which is numbered 080409-13.The inhibition rate is 60.74% by using confront culture test of fungi 080409-13 and fusarium oxysporum f sp cubense.The determination results indicated that the inhibition effect increased with increasing the concentration,the inhibition rate was 62.00% with with treatment of fermentation filtrate at terminal concentration of 5% and the subsequent effect was significant.The pot experiment indicated that the protection effect was the best, when treated with 50×dilutes of 107/mL original spore solution,and reached 83.34%.Based on the Internal transcribed spacer sequece results and the morphological observation, the microorganism 080409-13 was identified as Paecilomyces lilacinus.The results of biological characteristics indicated that the suitable temperature spans was 5-40℃.the optimum growth temperature was 29℃.080409-13 strains had better pH tolerance,and could grow at the range of 4-10.