Features Of Growth Promoting Bacteria From Surface And Endogenous Of Root Tubers

As one of the essential nutritions, nitrogenis is mainly obtained from three sources:nitrogen-fixing plant, rain water and manure. As the biggest provider with 75% of fixed nitrogen for all the plants on the global, Biological nitrogen fixation (BNF) plays an important role not only in the nature nitrogen circulation but also the agricultural production and potential application value, so many countries regard it as one of the most significative projects and do a large number of researches on it. In this study,219 nitrogen-fixation bacteria were isolated and identified from 14 tuber or root crops such as Yam, carrot, potato, sweet potato, lotus root, taro, ginger, purple carrots, white radish and cabbage. All these 219 nitrogen-fixation bacteria belongs to 24 genera and 79 biological species. Through the 16S rDNA gene sequences phylogenetic analysis, we found that the genera Bacillus (38% of the total) and Pseudomonas (15% of the total) were the abundant groups. As the research object to 79 biological species,43 isolates (54.43% of the total) were found to be able to solubilize organic phosphate and 4 isolates (5.06% of the total) were found to be able to solubilize inorganic phosphate; 7 bacteria (9.72% of the total) were found the ACC-deaminase activities and Enterobacter sp.654gz02 was found the highest ACC-deaminase (13.76±0.99 μmol mg protein-1 h-1); 51 isolates (64.56% of the total) were found to be able to produce indole acetic acid (IAA) and Pantoea sp.657gz07 was found the highest IAA production (28.99±1.03μg ml-1); 5 strains were effective against all of the three phytopathogenic fungi MLS-OF (Fusarium oxysporum),37402 (Fungi Imperficti) and 37438 (Fusdrzum oxysporum) and antagonistic activity ranged from 46% to 63%. These 5 strains belonged to the genera Bacillus (4) and Brevibacillus (1). Besides, a strain belonged to Bacillus can also against Fusarium oxysporum MLS-OF effectively.