Abstract: The type of soil microbial population plays an important role in soil quality and growth of crops. Studying the impact characteristics of different oligosaccharides on soil microbial population will help to use oligosaccharides correctly, efficiently and safely. In this study, the soils were placed in an artificial climate chamber, 50mg·L−1 Chitosan oligosaccharide (CSOS) and Cello-oligosaccharide (COS) solution were applied into the soils, treated with clean water (CK) as the control, cultured for 6 days, sampled, and analyzed the structure composition and diversity distribution characteristics of soil microbial community by high-throughput sequencing technology. The CSOS and COS treatments significantly changed the community structure of bacteria and fungi, increased the observed number of bacterial species. Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes and Bacteroidetes were the dominant bacteria. Ascomycota, Basidiomycota and Mortierllomycota were the dominant fungi. Through the comparative analysis of community composition among groups, it could be seen that the treatments both reduced the relative abundance of Acidobacteria in different degrees, and increased Proteobacteria, Actinobacteria, Gemmatimonadetes, Chytridiomycota and beneficial bacteria, Lysobacter, Nitrospira, Haliangium, Blastococcus and Streptomyces. However, compared with the COS, the CSOS treatment had a greater change in microbial community composition. In addition, the CSOS and COS treatments had some differences in regulating soil microbial community structure. The relative abundance of beneficial bacteria Talaromyces treated with the CSOS increased by 195%, and the relative abundance of beneficial bacteria Pseudomonas treated with the COS increased by 215%. In conclusion, chitosan oligosaccharide and cello-oligosaccharide both could optimize the structure and composition of soil microbial community. The difference between the CSOS and COS helped to realize the regulating mechanism, and promote their application and popularization.

Key words: Chitosan oligosaccharides, Cello-oligosaccharide, High-throughput sequencing, Bacterial community structure, Fungal community structure