Abstract: In order to obtain cold-tolerant cellulolytic strains in the cushion structure of the Androsace tapete, the above-ground parts of the Androsace tapete from three regions with different survival states were used as materials, and the culturable microorganisms were isolated and purified by pure culture method. The cold-tolerant cellulolytic strains were screened by CMC solid medium and CMC-Congo Red solid culture at 4 ℃ and 15 ℃, respectively, and the strains were screened for molecular identification of 16S rRNA and ITS region sequences. The results showed that a total of 52 strains, 14 genera and 32 species of cold-tolerant cellulolytic strains were obtained, including 3 species of bacteria, 9 species of yeast and 20 species of filamentous fungi. The relative cellulase activities of the obtained cold-tolerant cellulolytic strains were high, and the representative strains were Didymella pomorum, Aureobasidium pullulans, Penicillium goetzii and Penicillium griseoroseum. The species composition of cold-tolerant cellulolytic strains differed significantly between individuals from different Androsace tapete and between Phyllospheric and endophytic cellulolytic strains, but there were no significant differences in relative cellulase activity.These cold-tolerant cellulolytic strains can effectively decompose litter in cushion structure, promote carbon cycling, and play an important role in the adaptation of Androsace tapete to extreme environments and perform ecosystem engineer functions, with the more active strains aiming to provide material for industrial applications of biodegradable cellulose in cold regions.

Key words: Qinghai-Tibetan Plateau, Androsace tapete, cold-tolerant strain, cellulolytic functional strain, extreme environment