The Identification Of Two Antagonistic Bacteria And Preliminary Study On Their Acting Mechanisms

Forest fruits and trunk's disease is a kind of important biological disaster and damage is very serious. Research on the control of forest fruit and branches disease in china mainly uses cultivation measures and chemical control measures at present, despite it had got a certain effect, but the chemical control of branch diseases had polluted the environment and had some other deficiencies, the chemical control was extremely limited. so seeking new disease control methods have become the key point on the forest fruit and branches disease.The biological control method is an effective disease control measures. The new biological source medicament discovery, exploitation and the creation had become hot spot and focus for biological control method. At present, biological medicament discovery, exploitation and the creation in tree and forest fruit branch diseases were rarely reported in china. This paper mainly research on the two antagonistic bacteria from pomegranate fruit (antagonistic bacteria A) and the bark of Sophora japonica L(antagonistic bacteria B), research on the culture characteristics, the morphological features, physiological and biochemical characteristics and 16S rDNA molecular characteristics and clarify the taxonomic status,at the same time, the author use the six pathogen of important branches and fruit diseases for the tests, studied on the two antagonism of the antibacterial activity, finally,the author also preliminy study on the resisting mechanism for two antagonistics bacteria. The major results and the conclusions are as follows:1.The cultivated, morphological and physiological and biochemical characteristics of the two antagonistic bacteria results indicated that the two antagonistic bacteria single colony are round,smooth in surface,ridgy in center,easy in emulsification on the PDA culture medium,when obserbed in the refraction and transmission,they have breastical lights, opacity bacteria groups like butter and full brim; the measure of morphological characteristics indicated that these two antagonistic bacteria are rod shape, the antagonistic strain A is 1.03×0.44μm on average, but the antagonistics strain B is 1.0×0.37μm on average, litter smaller than the antagonistics strain A, the result of physiological and biochemical characteristics are showed that the Gram's of two antagonistic bacteria are all masculine,they can use dextrose and diacid salt,can make nitrate deoxidized and process contactical enzyme reactivity.these two antagonistic bacterias all like oxygen,they are able to endure salt and liquid glutin in the same time, and also can create H₂S, but the two bacteria plants can't use citric acid, the V-P and M.R tests also indicated lunar reactivity. 16S rDNA 's molecule size of the two bacteria are 1530bp and 1531bp and only three bases are different, these DNA sequences had 99.8% identity; the results of construction phylogenetic tree and others indicated that two antagonistic bacterias belong to different strains which one species of Bacillus sublitis.2. The measures of antibacterial action and antibacterial mechanism indicated that two bacteria could inhibit the pathogen of the branches and fruit pathogen to some extents, the effect on the pathogen to canker disease of forest fruit's trunk and branches disease of pomegranate scab are obvious, meanwhile the inhibitory effect had some to other pathogens. Two antagonistic bacteria can lead the mostly top cells of mycelium of the bacteria which caused by Botryosphaeria dothidea on forest branches and fruits to enlarge and thickene cell wall and stop grow as well, but they can not cause the cells of mycelium die, as far as the pahtogen caused by poplar rotten disease,two antagonistic bacteria can cause the top cells of mycelium die, meanwhile there is no phenomenon that enlargement of top cells of mycelium and cell wall thickening.