Survey of bacterial community dynamics in corn and on growth and development of Maize
|Keywords||Maize endophytic bacteria growth-promoting bacteria fermentationoptimization|
Numerous, diverse and widespread, endophytic bacteria have coevolved with theirhost plants through long processes and gradually occupied ecological niches with greatadvantages inside their host plants. Making good use of these beneficial endophyticbacteria can reduce the impact of using chemicals on environment and crop. Therefore,the exploration and application of endophytic bacteria as a kind of biological fertilizerresource will be an inevitable trend. In our research, we used maize from Heilongjiangas our experimental materials. Endophytic bacteria were isolated from these maize,these bacteria’s community dynamics were investigated. Among them the endophyticbacteria that can promote the growth of maize were selected. Combined with the growthactivity test, fermentation of these bacteria was optimized and finally achieved theoptimal effect of promoting their growth.The morphological and physiological-biochemical methods were used to identifythe endophytic bacteria isolated from the tested maize. The results indicated that thesebacteria belong to six different generas including Bacillus sp., Micrococcus sp.,Sphingomonas sp., Corynebacterium sp., Enterobacter sp. and Pseudomonas sp..Among them, Bacillus sp. were the most predominant genera, and were classified asseven different species, they were B. subtilis, B. megaterium, B. cereus, B. mycoides, B.Licheniformis, B. pumilus and B. circulans.A strain of enophytic bacteria SYL4that can promote the growth of maize wasselected, and16S rDNA gene sequence analysis was done. As a result, it and manyother B. subtilis strains showed the similarities of16S rDNA gene sequence99%.Together with the result of morphological and physiological-biochemical identification,SYL4was preliminarily identified as B. subtilis, and Rif resistance marker method was also used to complete SYL4endogenous test.Fermentation of SYL4optimizaiton was conducted. The optimal component ratioof culture medium were as follows: glucose0.5%, peptone1.5%, CaCO30.25%. Theoptimal culture conditions were250ml Erlenmeyer flask containing50ml medium,medium pH7.0,5%amount of inoculation,31℃incubating temperature and200r/minculture for48h. Then the growth-promoting effect of fermentation broth that had beenoptimized on maize was verified, the results showed that the length and weight of leavesand roots of maize seedlings treated with optimized fermentation broth were better thanthose untreated, and the differences were significant. Moreover, POD activity of maizeseedlings promoted a lot also. This result successfully proved that the endophyticbactera achieved a great fermentation and growth-promoting effect.