Antagonistic Bacteria In The Lettuce Rhizosphere Screening And Identification

Lettuce is a kind of herbaceous plants which is called green angel in vegetables and rich in nutritional value and therapeutic efficacy.Lettuce's leaves and stem are edible parts, however , fertilizer residues, pesticide residues caused by excessive using of traditional chemical fertilizers and pesticides to control pests and diseases were not only harm to human healthy,but also posed a great threat to the environment . An effective way to solve this problem is to development of environment-friendly pesticides, development and application of bio-pesticides, use of biological control, it should be more conducive to the development of eco-agriculture, green agriculture,and organic agriculture.In this experiment,the sample was collected from experimental plot of Jiezhuang of Jining.The organisms of lettuce rhizosphere soil were isolated . The two antagonistic organisms agaist Fusarium oxysporm were screened and identified.According to the observation of the morphological characteristic ,physiology and biochemistry test ,the two strains are similar to the Bacillus.subtilis.After extract the genome DNA,amplify and sequence the 16S rDNA,the two strains were identified as Bacillus.subtilis.The Genebank accession number of two strain are EU521704 and EU521705 respectively. Bacteria can inhibit a variety of pathogenic fungi by studying the strain WSZ1 antibacterial spectrum. To apply to actual production, studying of the fermentation conditions of strain WSZ1 showed that the strain can achieve maximum biomass when culture time 48h,temperature 30℃,initial pH7.0,amount of innoculation 4%,amount of load 30ml(in 250ml flask).This paper provided an effective antagonistic strains for the biological control lettuce disease , and laid the foundation for the antagonistic substances extraction.