Isolation of novel cellulosic biomass-utilizing microorganisms and improvement of cellulose degradation efficiency using biosurfactant produced by pseudomonas aeruginosa

Abstract

An efficient cellulose-degrading microbial consortium obtained from Suncheon bay was analyzed to degrade cellulosic materials. In order to determine the properties of its cellulose degradation efficiency, the metabolic products, and its microbial composition, the capabilities of our microbial consortium were compared to two other cellulase systems after enrichment processes. Filter paper was more efficiently degraded by the cellulases (I; 57.1 % and II; 55.7 %) than the microbial community (20 %). However, the pretreated rice straw was decomposed nearly 56 % by the microbial community. The cellulases degraded the pretreated rice straw to 69 % and 49 %, respectively. The metabolic concentrations of the glucose and the acetate in the culture medium of the microbial system were higher than the cellulases in both filter paper and the pretreated rice straw degradations. 16s rDNA sequence analysis of the cellulolytic isolates showed that the microorganisms in our microbial consortium were one bacterium (Bacillus cereus strain 5YW5, 99 %) and three fungi (unidentified; Penicillium sp. KH00319, 99 %; Aspergillus sydowii strain QLF51, 100 %). Furthermore, three more cellulolytic bacteria were isolated from the mixed-culture of some Suncheon bay samples (namely Pseudomonas aeruginosa strain 1248, Alcaligenes sp. A72, and Ochrobactrum sp. c261). It was also performed that the comparison between the pure strain and of the mixed-culture in filter paper degradation processes. Cellulose-degrading efficiency of the single cellulolytic isolate, P. aeruginosa, was remarkably lower than that of the mixed-culture in terms of the concentrations of metabolic products. Pseudomonas aeruginosa strain 1248 isolated through this work can produce a unique biosurfactant called rhamnolipid. It has the ability to enhance the cellulose degradation efficiency. Extracted biosurfactant was added to enzymatic hydrolysis of filter paper and cellulase activity was more effectively stimulated in coo...