Abstract: Pythium aphanidermatum is known as an important plant pathogenic fungus that can cause various types of crops rot and damping off, as well as results in spoilage of fruits and vegetables, thus leading to great loss of agricultural production and food industry. In order to obtain spore-forming bacteria with anti-fungal activity for fruit and vegetable preservation and biological control, we have screened 204 strains of spore-forming bacteria isolated from 26 kinds of foods, such as lemon, grape, Chinese date, yogurt, fermented bean curd, Harbin sausage, bean paste and other food samples. Totally 62 strains of spore-forming bacteria were assessed by confrontation culture tests to reveal strong anti-fungal activity against P. aphanidermatum. The fermentation supernatants of 4 strains with stronger anti-fungal activity through Oxford cup plate assay method were tested for their anti-fungal activity, and L-NM62 revealed the strongest anti-fungal activity against P. aphanidermatum. The inhibition zone of cell free supernatant was (24.54 ± 0.13) mm in diameter. According to the characteristics of morphology, physiology and biochemistry tests, and the comparison of 16S rDNA sequence, strain L-NM62 was identified as Bacillus subtilis. Further study of L-NM62 on physiology characteristics showed that the optimal growth temperature, pH and inoculums were 37 ℃, 7.5 and 1.0%. Under these optimal conditions, L-NM62 had a wide anti-fungal and antibacterial activity and presented a potential prospect.

Key words: Bacillus subtilis, Pythium aphanidermatum, screening, anti-fungal activity, biological characteristics