桐花树内生细菌动态及拮抗植物病原菌菌株筛选鉴定

The Spatiotemporal Dynamic of Endophytic Bacteria in Aegiceras corniculatum and Screening and Identification of Antagonistic Bacteria Against Plant Pathogens

以荧光显微计数法和平板分离法分别对桐花树根茎叶内生细菌总量和可培养细菌数量进行周年动态初步测定．并对拮抗植物病原菌的可培养细菌菌株进行筛选鉴定。结果表明：桐花树根茎叶内均含有大量的内生细菌，其中根部内生细菌总量为0．88×10^7-49．67×10^7 ind．/gFW，7月份最大，叶部细菌总量为1．07×10^7-65．07×10^7 ind．/gFW，也以7月份最大，茎部细菌总量为1．1×10^7-19．73×10^7ind．／gFW，以5月份最大；而根茎叶可培养细菌含量分别为1．02×10^3～13．18×10^3、0．13×10^3-11．24×10^3、0．31×10^3-10．36×10^3CFU／gFW，均以3月份数量最大，周年不同月份之间细菌总量和可培养细菌数量均差异显著。用平板对峙生长法．从86株可培养内生细菌中筛选获得1株对香蕉叶鞘腐败病菌、香蕉枯萎病菌、马拉巴栗茎腐病等植物病原菌均有较强拈抗作用的Aec23菌株，经形态、生理生化测试及16SrDNA序列比较分析，Aec23菌株初步鉴定为解淀粉芽孢杆菌（Bacillusamyloliquefaciens）。

Annual dynamic of total amount of endogenous bacteria and cuhurable endophytic bacteria in different organs of the Aegiceras corniculatum were investigated by acridine orange fluorescence microscopy and tablet separation, respectively. The culturable endophytic bacteria were determined antagonism against Pantoea agglomerans, Fusarium oxysporum f.sp. cubense, Colletotrichum gloeosporioides and Phytophthora palmivora by dual culture method, then screened and identified. The results showed as follows： a large number of endophytic bacteria were distributed in different tissues of A. corniculatum, in which the fluctuating range of endophytic bacteria of root, stem and leaf were 0.88×107-49.67×107, 1.07×107-65.07×107, 1.1×107-19.73×107 ind./g FW and the maximum of root and leaf were both appeared in July, but stem in May. In culturable bacteria aspects, the content of bacteria in different parts were all pinnacled full year and maximal in March, and the fluctuating ranges of root, stem and leaf were corresponding to 1.02 ×103-13.18×103, 0.13 ×103-11.24 ×103. 0.31 ×103-10.36 ×103 CFU/g FW, respectively. Both amount of total endogenous bacteria and cuhurable endophytic bacteria were significant difference between different months in a year. The strain Ace23 was obtained from 86 culturable endophytic bacterial strains of A. corniculatum, which owned the best antimicrobial activity against tested pathogens. It was preliminarily identified as Bacillus amyloliquefaciens based on morphology, physiological and biochemical property together with 16S rDNA sequence analysis.