“挂壁”法筛选常温稻秆腐解菌及其降解能力研究

采用"挂壁"法对稻秆高效腐解菌群进行富集,并以稻秆粉为唯一碳源筛选到生长能力强的腐解菌12株,进一步复筛从中获得腐解能力较强的细菌2株和真菌2株,通过16S rDNA、ITS序列分析及菌株形态学观察,初步鉴定菌株GS2-3、ZJA-6分别为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)和类芽孢杆菌(Paenibacillus pabuli),菌株ZJB-5、ZJC-1分别为哈茨木霉(Trichoderma harzianum)和拟康宁木霉(Trichoderma koningiopsis).细菌GS2-3、ZJA-6和真菌ZJB-5、ZJC-1均具有较高的纤维素酶和半纤维素酶活性,纤维素酶活力分别达到21.85、13.20、106.48、187.13 U·mL^-1,半纤维素酶活力分别达到960.70、1 879.67、100.64、6 727.30 U·mL^-1;液体培养7 d后,菌株GS2-3、ZJA-6、ZJB-5和ZJC-1对稻秆的相对降解率分别为22.78%、34.25%、33.32%和27.99%,显著高于其他降解菌;土培降解试验表明,4株腐解菌均有较强的腐解稻秆能力,处理28 d后菌株ZJC-1、GS2-3、ZJA-6、ZJB-5的腐解率分别达到23.2%、19.2%、17.8%、14.7%.这表明采用"挂壁"法进行优势菌群的富集,为针对性地获得稻秆还田腐解菌提供了新的思路.

Degradation of Rice Straw by Degrading Strains Isolated by a"Hanging-Enrichment"Method

In this study, a "Hanging-enrichment" method was developed to isolate and screen high-performance straw-degrading strains. By utilizing rice straw powder as sole carbon source, twelve strains with abilities to degrade straw were obtained. Then two bacterial (GS2-3 and ZJA-6) and two fungal(JB-5 and ZJC-1) strains with better degradation performance were selected for further studies. The strains GS2-3, ZJA-6, JB-5 and ZJC-1 were preliminarily identified as Bacillus amyloliquefaciens, Paenibacillus pabuli, Trichoderma harzianum, and T. koningiopsis, respectively, based on the morphological observation and 16S rDNA and ITS sequencing. Cellulase activity was 21.85, 13.20, 106.48, and 187.13 U·mL^-1, and hemicellulase activity was 960.70, 1 879.67, 100.64, and 6 727.30 U· mL^-1, for the strains GS2-3, ZJA-6, JB-5, and ZJC-1, respectively. The relative degradation rates of rice straw by strains GS2-3, ZJA-6, ZJB-5, and ZJC-1 were 22.78%, 34.25%, 33.32%, and 27.99%, respectively, all significantly higher than those of other strains after 7 day incubation in liquid medium. The rice straw degradation experiment in soil showed that these strains had stronger ability to degrade rice straw. Under soil conditions, the degradation rate was 20%, 18%, 15.2%, and 24% for the strains GS2-3, ZJA-6, ZJB-5, and ZJC-1 after 28 d, respectively. In conclusion, "Hanging-enrichment" method could be a potential approach to obtaining rice straw degrading microorganisms.