Biological Action Of Marine Bacteria AiL3Against Banana Fusarium Wilt And Effects On Microorganism In The Rhizosphere

The endophytic bacteria from mangroves and the isolate among them antagonisticagainst Fusarium oxysporum f.sp.cubense and Colletotrichum gloeosporioiles were studiedin this paper. Especially, the colonization in banana and rhizosphere soil, growth promotion,biological control of the banana fusarium wilt and impacting rhizosphere microorganismcommunity with the bacterium AiL3isolated from the inside of the leaf of Acanthusilicifolius were tested.Tagged by the resistance to Rif.(300μg/ml) and F. oxysporum f.sp. cubense, thecolonization of the strain AiL3was tested by root watering. The result showed that thisstrain could colonize in banana, and the colonization duration in the root, the leaf and thestem is more than30d. In addition, it was more easily to colonize in the stem and the rootthan in the leaf and rhizosphere soil.The effects of the strain AiL3on the plants growth and biological control of thebanana fusarium wilt showed that: In pots tests, when treated with the bacterial suspensionof strain AiL3by different methods and solid bacterium agent, the plant grown well.Especially, the disease was reduced by100%by root dipping, leaf daubing and rootwatering, compared to the control. And the plant height, the leaf number, the stem diameter,the fresh weight and the dry weight of all treatments observably increased, compared to thecontrol. The bacterial suspension and its agent mixed with the bacterial suspension canconspicuously promote growth.In field tests, the disease were reduced by95.83%and53.12%(8months), and theleaf number, the stem diameter and chlorophyll concentration markedly increased, by thebacterial suspension and its agent mixed with the bacterial suspension, respectively,compared to the control. In short, there was a budding in advance by the use of the strainAiL3in field.Effect of strain AiL3on microorganism community in the rhizosphere in field byculture method showed that the population of culture bacteria, fungus of budding andactinomycetes from the soil rhizosphere of banana increased, and the amount of fungus ofpregnant budding reduced, but the population of endophytic culture microorganism of roothad no changes. PCR－DGGE indicated that the population and type of unculturedmicroorganism had no changes, however, species diversity and the type of unculturedbacteria reduced.