关键词: 土壤作物系统, 有毒污染物, 食物安全, 土壤环境标准, 模型

Abstract: In this paper, the population density of endophytic bacteria in the wheat plants collected from Huaibei City of Anhui Province was investigated, and the endophytic bacteria were screened, with their fungistatic activity determined. The population density of endophytic bacteria in wheat root, stem, and leaf was 7.01×10⁵, 4.26×10⁵, and 0.94×10⁵ CFU·g^-1 fresh weight, respectively, and a total of 131 endophytic bacterial strains were isolated from the health wheat plants. By using dual culture technique, 6 strains with antagonistic effect on Fusarium graminearum were screened, accounting for 4.58% of the isolated endophytic bacteria. The strain HB022 from wheat root had the best fungistatic effect, with an inhibition zone of radius 17.0 mm. Based on the morphological, physiological, and biochemical characteristics as well as the sequencing of 16S rDNA, the strain HB022 was preliminary identified as Paenibacillus polymyxa. Fungistatic assay showed that the 100-times diluted culture filtrate of strain HB022 was effective in inhibiting the mycelium growth of F. graminearum, and the 5-times diluted culture filtrate completely inhibited spore germination, suggesting that the endophytic P. polymyxa strain HB022 had the potential in biological control of F. graminearum.

Key words: Soil crop system, Potentially toxic pollutants, Food security, Soil protection guidelines, Modeling