| By soil culture collection, silane derivatization separation,the main components of potato root exudates were identified by gas chromatography\|mass spectrometry (GC-MS) at seedling stage, squaring stage and anthesis stage. Semisolid plate, capillary\|like test and crystal violet staining method were used to compare the effects of root exudates and different amino acids on chemotaxis and biofilm formation of Bacillus atrophaeus QHZ3 at different growth stages of potatoto, in order to reveal the colonization mechanism of Bacillus atrophaeus QHZ3 in potato rhizosphere. Five amino acids were identified in potato root exudates: proline, glycine, aspartic acid, phenylalanine and tyrosine. Qualitative tests showed that root exudates from different growth stages of potato and other four amino acids except proline had significant positive chemotactic effects on strain QHZ3, and glycine had the strongest effect, and its chemotactic circle diameter (6.40cm) was 1.84 times that of the control (3.48 cm). The results of quantitative test showed that root exudates (120 μg·mL-1 and 240 μg·mL-1), glycine (10~50 μmol·L-1), aspartic acid (50~75 μmol·L-1) and phenylalanine (25~50 μmol·L-1) all had significant positive chemotactic effects on strain QHZ3, especially with 25 μmol·L-1 glycine, the chemotaxis index was the highest, and the number of bacteria in the capillary (5.13×105 CFU·mL-1) was 3.3 times higher than that in the control group (1.53×105 CFU·mL-1). Crystal violet staining showed that root exudates, glycine (25~100 μmol·L-1), proline (75~100 μmol·L-1) and phenylalanine (25~100 μmol·L-1) significantly promoted the formation of biofilm in strain QHZ3. Both root exudates and amino acids promoted the chemotaxis and film formation of strain QHZ3 in the potato rhizosphere, but the effects of the five amino acids were different. Among them, aspartic acid and tyrosine had significant effects on the chemotaxis of strain QHZ3, and proline significantly affected the biofilm formation of the strain, while glycine and phenylalanine had significant effects on the chemotaxis and biofilm formation. |