论文部分内容阅读
Ginseng is the rare herb in Araliaceae.Soil-borne disease is one of the main factors restricting the yield and quality of ginseng, and the yield loss in China caused by the disease is up to 20%-50% every year, which severely weakens the competitiveness of ginseng products in the international market.An antagonistic strain Bacillus subtilis X1 was screened from the rhizosphere soil of diseased ginseng in Tieli farm of Heilongjiang Province, which strongly inhibits pathogens such as Rhizoctonia solani, Fusarium oxysporum andFusarium solani.In order to investigate the colonization of Bacillus subtilis X1 in Ginseng rhizosphere,the strain was marked by using the method of antibiotic (rifampicin) resistance.The strain X1 could grow on NYDA plates containing 300ug/mLrifampicin normally after having been induced step by step, and its resistance kept on stablely.X1-Rif was cultured in 250-ml Erlenmeyer flasks containing 50 ml of NYD medium with 300ug/mLrifampicin in a rotary shaker at 150r/min at 30℃ for 48h.250ml ofX1-Rif angent (2×107 cfu/ml) was poured into the rhizosphere soil of each ginseng seedling, then the soil samples were collected regularly every 5d.The concentration(cfu/g) of X1-Rif was quantitated by serial dilution agar plate procedure, and the results showed that strain X1 colonized in the rhizosphere soil of ginseng seedling after watering root treatment in field.The X1 number of the soil samples reached 5.45 × 105, 1.10× 106, 1.05 × 105 and 2.65 × 105 cfu/g at 5d, 10d, 15d and 20d seperately.Bacillus subtilis X1 not only colonized in the soil, but also multiplied.The strong ability of Bacillus subtilis X l to colonize helped it to compete site and nutrients with pathogens and then to inhibit pathogens effectively.