柑橘黄龙病兼性厌氧型伴生细菌的分离及优势菌群分析

Isolation of facultative anaerobic and entophytic bacteria companioned Huanglongbing pathogen-infected citrus tissues and determination of dominant bacterial populations

柑橘黄龙病是世界柑橘生产上最具毁灭性的病害,主要由难人工培养的韧皮杆菌所引起（Candidatus Liberibacter asiaticus）[1]。近年的研究结果表明黄龙病发病组织内除了韧皮杆菌外,

To analyze the diversity of entophytic bacteria and find the companion microbe in Huanglongbing pathogen-infected and healthy citrus plant tissues,various parts of citrus tissues were collected from different locations of citrus planting areas.The facultative anaerobic and entophytic bacteria were isolated and identified based on bacterial morphology,physiology,biochemistry characteristics and PCR-DGGE analysis（denaturing gradient gel electrophoresis,analysis of the sequence of 16S rRNA V6-V8 fragment）.By the directional isolation of the facultative anaerobic and entophytic bacteria and 16S rDNA amplification methods,total 12 genera of bacteria were identified from 19 cultivable bacterial populations.The dominant bacterial population were Bacillus sp.（IF： 21.03%）,Planococcus sp.（IF：20.69%） and Pseudomonas sp.（IF：17.44%） in healthy citrus tissues,while Curtobacterium sp.（IF： 29.07%）,Bacillus sp.（IF： 23.12%）,Microbacterium sp.（IF： 21.09%）in infected citrus plants.Based on the results of DGGE,9 genera of cultured bacteria were identified.The dominant bacteria population was Serratia sp.（IF： 28%）,and Pantoea sp.（IF： 14%）was second only to it.＇Candidatus Liberibacter asiaticus＇ was found only in tangerine pith of deformed orange fruit,which suggested that the contents（1%）of Huanglongbing were more in diseased fruits.The density and species of entophytic bacteria were also observed in remarkable difference between infected and healthy citrus plants according to the DGGE profiles.