Abstract:

In this study，rhizosphere soil of the healthy plants of Lycium barbarum‘Ningqi 5’was collected for bacteria isolation and screening using dilution coating method based on the colony morphological characteristics，and the purified rhizosphere bacteria were classified based on biochemical and molecular identification. The preliminary and secondary screenings were conducted based on plate confrontation experiments and the growth inhibition of pathogenic mycelium using fermentation broth，respectively. Results indicated that a total of 18 strains of bacteria with different colony morphology characteristics were isolated and screened from the rhizosphere soil of the healthy‘Ningqi 5’，and were identified subsequently，belonging to Bacillus spp. and Staphylococcus sp. There were 11 strains exhibiting notable inhibitory effects on both Fusarium oxysporum and Rhizoctonia solani，with the bacteriostatic rate of more than 50%. All the 11 strains were identified to be Bacillus spp. The culture broth of Bacillus sp. JK-B-01 was found to possess the best inhibitory effect on four pathogens，R. solani，F. oxysporum，F. redolens，and F. solani. There might be high-temperature resistant antibacterial substances present in the extracellular metabolites of Bacillus sp. JK-B-01. In pot experiment，the occurrence of root rot was prevented after inoculation of Bacillus sp. JK-B-01 via root irrigation，suggesting that it had a certain preventive effect on root rot disease of L. barbarum caused by F. oxysporum. In general，an indigenous bacterium Bacillus sp. JK-B-01 was obtained from the rhizosphere of‘Ningqi 5’，and its potential as a candidate strain of BCAs against root rot disease of L. barbarum was proved via in vitro bacteriostatic activity determination and in vivo pot experiment. This study expanded the strain resources for the research and development of efficient BCAs against the root rot disease of L. barbarum in Ningxia.

Key words: Lycium barbarum, root rot, biological control, antagonistic bacteria, Bacillus