| Exploiting and utilizing of renewable energy substance has been becoming the main way to solve these crises in the wake of global energy crise and environmental pollution have been being increasingly serious. Nowadays, cellulose-degrading microbial is the foundation of utilizing cellulose; isolation and cultivation of efficiently degrading-microbial is its main measure. Single substrate was used to isolate cellulose-degrading microbial in previous study, strain obtained have some defects such as lower enzyme activity and weaker adaptability generally. The isolation and cultivation based on multiple substrates and the climate of region and constructing degrading consortia using high enzyme activity strains may get some strains and consortia which have high degrading efficiency and adapt region climate.According to features of lower temperature in the northeast of Inner Mongolia and the seasons having lower temperature last longer, this study isolated and screened room-and low temperature cellulose-degrading bacteria from Hulunbeier forest soil respectively using three different carbons(Avicel, CMC and D-salicin) measured enzyme activity of strains. Then construct consortia of 25℃ and 4℃ separately using strains have high activity at corresponding temperature and measure their ability of degrading filter paper. The results and concludes of this study are as follows:(1)Cellulose-degrading strains at 25℃ (cultivate temperature):258 strains were obtained at 25℃. On the class lever, bacteria could utilize avicel were classified 5 classes, the proportion of γ-Proteobacteria in Proteobacteria phylum was 38%, was the dominant class, followed by were α-Proteobacteria(26%) and Micrococcales(17%), on the genus lever, Pseudomonas(23%) was the dominant genus, followed by were Rhizobium(12%), Lelliottia(12%), Oerskovia(12%) and Bacillus(12%); On the class lever, bacteria could degrade CMC were classified 6classes, γ-Proteobacteria(34%) was the dominant class, followed by were α-Proteobacteria(21%) and Micrococcales(19%), on the genus lever, Pseudomonas(23%) was the dominant genus; On the class lever, bacteria could utilize D-salcilin were classified 6 classes, γ-Proteobacteria(38%) was the dominant class, followed by were α-Proteobacteria(23%) and Micrococcales(20%), on the genus lever, Pseudomonas(26%) was the dominant genus, followed by was Oerskovia(20%).(2)Cellulose-degrading strains at 4℃ (cultivate temperature):172 strains were obtained at 25℃. Bacteria could degrade avicel and CMC were classified same 4 classes, γ-Proteobacteria(54% and 48%) was the dominant class, followed by was α-Proteobacteria(28% and 26%), on the genus lever, Pseudomonas(35%) was the dominant genus in bacteria degrading aviel, followed by was Rhizobium(15%), Pseudomonas(26%) was the dominant genus in bacteria degrading CMC, followed by were Rhizobium(12%) and Oerskovia(12%), on the class lever, bacteria could utilize D-salcilin were classified 6 classes, γ-Proteobacteria(55%) was the dominant class, followed by was α-Proteobacteria(34%), on the genus lever, Pseudomonas(26%) was the dominant genus, followed by were Lelliottia(19%) and Rhizobium(16%).It followed that whatever from temperature condition or the perspective of carbon utilizing, γ-Proteobacteria takes the predominant position in the cellulose-degrading bacteria community and α-Proteobacteria was the second predominant community, which indicated that Proteobacteria take the absolute numerical advantage among the cellulose-degrading bacteria; secondly, Actinobacteria also had a certain proportion in it.(3)Degrading consortia at 25℃ (cultivate temperature):choose 3 strains bacteria having the highest activity in each carbon of three carbons (strains degrading avicel were DCXA52、DCXA22 and DCXA58, strains utilizing CMC were DCXC50, DCXC10 and DCXC16, strains hydrolysis D-salicin were DCXD27, DCXD7-1 and DCXD68),27 degrading consortia were constructed. The highest filter paper activity of these degrading consortia was 208.79U/mL, which are approximately 8.0 folds,9.8 fold and 9.2 folds of which of its members DCXA58, DCXC50 and DCXD27, and its rate of filter paper degradation at 7day is 32.4%.(4)Degrading consortia at 4℃ (cultivate temperature):choose 3 strains bacteria having the highest activity in each carbon of three carbons (strains degrading avicel were 4DXA13,4DXA23 and 4DXA41, strains utilizing CMC were 4DXC19,4DXC32 and 4DXC64, strains may degrade D-salicin were 4DXD98,4DXD101 and 4DXD114),27 degrading consortia were constructed. The highest filter paper activity of consortia 7(D131) and 8(D132)was 158.02U/mL, the former’s filter paper activity was approximate 9 folds,5 fold and 9 folds of which of its member strains 4CXA13,4CXC64 and 4CXD98, the later’s was about 9 folds,5 fold and 10 folds of which of its member strains 4CXA13, 4CXC64 and 4CXD101. Their rates of filter paper degradation at 7day were 16.8% and 18.8% respectively.430 strains cellulose-degrading bacteria were obtained in this study, which were classified 5 phyla,6 classes and 21 genera, in which the highest cellulase activity at 25℃ and 4℃ were 82.97U/mL and 19.1U/mL respectively, the highest filter paper activity of constructed cellulose-degrading consortia at 25℃ and 4℃ were 208.79 U/mL and 158.02U/mL respectively. These results revealed that cellulose-degrading bacteria have high species diversity and high degrading ability and have high potential for application. This study provides based foundation for understanding of and utilizing the diversity of cellulose-degrading microbe in Hulunbeier forest soil. |
PDF Full Text Request