关键词: 秸秆还田, 筛选, 鉴定, 纤维素酶, 傅里叶变换红外光谱

Abstract: In order to screen highly efficient cellulose-decomposing strains for corn straw, the soil samples which corn straw was returned in were collected for enrichment culture at 20℃. The initial screening was carried out by solid isolation medium using corn straw cellulose as the sole carbon source and Congo red staining method, and then the culture supernatants of the screened strains through liquid fermentation were collected and used for determination of enzyme activity. At last, fungus SY-403 with strong production of cellulase was obtained. The strain SY-403 was identified as Talaromyces stollii by morphological characterization and the results of molecular biology identification. The study of its cellulase characterization showed that, the optimum reaction pH was 6.0 and the optimum reaction temperature was 20℃. Under the simulated outdoor conditions (15℃), when corn straw was treated with SY-403 for 40 d, the weight loss rate of corn straw and the decomposition rate of cellulose were 42.67% and 55.26%, respectively. Changes of functional groups during the corn straw degradation process were determined by Fourier transform infrared spectroscopy. And the results showed that the peak area of cellulose (1 052~1 054 cm-1) decreased, while the peak area of hydroxyl (1 328~1 330 cm-1) increased, which indicated that cellulose had been broken down into available short chain structures. The results proved that the strain SY-403 could be used to degrade corn straw.

Key words: straw returning, screening, identification, cellulase, Fourier transform infrared spectroscopy