Study on agricultural function and activity of marine bacterium N-LY-1 and its species identification

【Objective】To clarify the bacteriostasis,growth promoting effect and life promoting mechanism of marine bacterium N-LY-1,and determine its taxonomic status,so as to provide reference for the further development of this strain and agricultural microbial preparation.【Method】Marine bacterial strain N-LY-1 isolated from the intestines of perch in Lianyungang sea area of Jiangsu Province was used as materials. The bacteriostatic effect of strain N-LY-1 on 12 plant pathogenic fungi and strain N-LY-1 growth promoting and disease controlling effect on cucumber were determined by plate confrontation method,Oxford cup method and indoor pot experiment. The growth promoting mechanism of strain N-LY-1 was explored by measuring its phosphorus,potassium and nitrogen fixation,indoleacetic acid(IAA)production and siderophores capacity. The strains were identified by morphological observation,physiological and biochemical test and 16S rDNA gene sequence analysis.【Result】N-LY-1 strain and sterile fermentation broth had obvious bacteriostatic effect on 12 plant pathogenic fungi,with the width of inhibitory zone greater than 5.00 mm. The fermentation broth had strong inhibitory effect on apple ring rot,wheat scab,strawberry gray mold,apple rot,tomato early blight and Cucumber Fusarium wilt,with the antibacterial band width more than 16.00 mm. The N-LY-1 fermentation broth could promote the growth of cucumber seedlings,and the control effect on Cucumber Fusarium wilt was up to 81.5% in the range of tested concentration. The strain had the function of nitrogen fixation,organic phosphorus reconciliation and IAA and siderophoresproduction.N-LY-1 strain was identified as Sphingomonas echinoides. Based on the colony morphological observation, physiological and biochemical characteristics and molecular biological identification.【Conclusion】N-LY-1 strain,a Sphingomonas of sea urchin,has functions of bacteriostasis,disease prevention,plant growth promotion. Nitrogen fixation, organophosphorus decomposition and IAA and siderophores production form the growth promoting mechanisms of the strain. N-LY-1 strain has the potential to be further developed into agricultural microbial agents.