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对安徽省淮北市小麦植株根、茎、叶中内生细菌的数量进行了调查和筛选,并测定了其抑菌活性。小麦根、茎和叶中的内生细菌的数量分别为7.01×105、4.26×105和0.94×105CFU·g-1鲜重。从健康小麦植株体内分离到131株内生细菌,通过对峙实验,筛选到6株对禾谷镰刀菌有拮抗作用的菌株,占所分离内生细菌总数的4.58%。来自根系组织中的菌株HB022的抑菌效果最佳,抑菌半径为17.0mm。根据形态特征、生理生化特性和16SrDNA序列分析,将菌株HB022初步鉴定为多粘类芽孢杆菌(Paenibacilluspolymyxa)。抑菌试验结果表明,100倍稀释的菌株HB022无菌发酵滤液对禾谷镰刀菌菌丝生长具有明显抑制作用,5倍稀释的无菌发酵滤液可完全抑制禾谷镰刀菌分生孢子萌发。可见,内生细菌HB022具有潜在生防应用前景。
The number of endophytic bacteria in the roots, stems and leaves of wheat plants in Huaibei City of Anhui Province was investigated and screened, and its antibacterial activity was measured. The numbers of endophytic bacteria in wheat roots, stems and leaves were 7.01 × 105, 4.26 × 105 and 0.94 × 105CFU · g-1 fresh weight, respectively. Totally 131 endophytic bacteria were isolated from healthy wheat plants. Six antagonistic strains of Fusarium graminearum were screened through confrontation experiments, accounting for 4.58% of the total number of endophytic bacteria isolated. The strain HB022 from the root system showed the best antibacterial activity with an antibacterial radius of 17.0mm. According to morphological, physiological and biochemical characteristics and 16S rDNA sequence analysis, strain HB022 was initially identified as Paenibacillus polymyxa. Bacteriostasis test results showed that 100 times diluted strain HB022 aseptic fermentation filtrate on Fusarium graminearum mycelial growth was significantly inhibited, 5-fold diluted sterile fermentation filtrate can completely inhibit Fusarium graminearum spore germination. Visible, endophytic bacteria HB022 has the potential of biocontrol applications.