Abstract: Bacillus amyloliquefaciens SZ-60 has great potential in the prevention and control of ginseng diseases and the microbial remediation of soil after ginseng planting, but there are problems such as less viable bacteria and unstable control effect when applied directly. Taken biocarbon as the basic carrier, the modification conditions of carbon-based carriers suitable for the colonization of B. amyloliquefaciens was screened and optimized, and the relationship between the property changes of carriers before and after modification and the changes of colonization capacity was analyze, which will lay a foundation for improving the control effect of SZ-60, and development and utilization of this kind of bacteria. The results showed that the most suitable modification method for immobilized microorganisms on biochar was ultrasonic coupling acetic acid modification. The optimum modification process is as follows, acetic acid concentration 0.2 mol/L, immersion time 30 min, material liquid ratio 1:3, and ultrasonic time 10 min. The number of biocontrol bacteria colonization on the modified carbon-based carrier was 2.88 times of that on the original carbon. A total of 16 indicators of carbon-based carrier changed significantly before and after modification, with the most significant change in nutrient element content, ranging from 33.71% to 91.87%. The content of iron and zinc, the proportion of fixed carbon and the proportion of volatile matter are the key indicators affecting the colonization effect. The results showed that ultrasonic coupling acetic acid modification could significantly affect the nutrient properties of biochar carrier, thereby increasing the number of viable bacteria colonized by B. amyloliquefaciens. The construction of the carrier has laid a good foundation for further soil microbial remediation experiments and the development of microbial agents based on relevant biochar.

Key words: modification, microbial immobilization technology, biocontrol bacteria, Panax ginseng