ISOLATION AND IDENTIFICATION OF LIGNIN-DEGRADING BACTERIAL STRAINS

Screening bacterial strains with lignin-degrading ability is very necessary for processing agricultural and forestry waste. In this experiment, we collected soil samples from the Qinling Mountains in China and isolated 99 bacterial strains. Further, 18 strains of bacteria were screened out using alkaline lignin solid medium and cultured at 30°C for 48 hours, and they were molecularly identified. After that, lignin liquid culture medium was used for shake flask culture, and a microplate reader was used to measure the absorbance changes of lignin at visible light at 280 nm before and after culture. A total of 12 strains of bacteria with lignin degradation ability were screened out, respectively. For QL-D3, QL-D5, QL-D6, QL -D7, QL-D8, QL-D9, QL-D11, QL-D13, QL-D14, QL-D16, QL-D17, QL -D18. Their lignin degradation rates after culturing in lignin 1,5 g/L liquid medium for 7 days were 13,01%, 16,76%, 10,48%, 23,3%, 6,88%, 12,48%, 22,07%, 11,84%, 18,62%, 17,88%, 13,95%, 16,28% respectively. Scanning electron microscopy was used to observe the morphology of the two bacterial strains QL-D7 and QL-D11 with the highest lignin degradation rate.