Determination of the cellulase activity distribution in Clostridium thermocellum and Caldicellulosiruptor obsidiansis cultures using a fluorescent substrate  

作　　者：Jennifer L.Morrell-Falvey James G.Elkins Zhi-Wu Wang 

机构地区：[1]Bio Energy Science Center, Biosciences Division, Oak Ridge National Laboratory [2]The Ohio State University ATI

出　　处：《Journal of Environmental Sciences》2015年第8期212-218,共7页环境科学学报（英文版）

基　　金：supported by the Bio Energy Science Center (BESC), which is a US Department of Energy Bioenergy Research Center supported by the Office of Biological and Environmental Research in the DOE Office of Science.Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the US Department of Energy under contract DE-AC05-00OR22725

摘　　要：This study took advantage of resorufin cellobioside as a fluorescent substrate to determine the distribution of cellulase activity in cellulosic biomass fermentation systems. Cellulolytic biofilms were found to express nearly four orders greater cellulase activity compared to planktonic cultures of Clostridium thermocellum and Caldicellulosiruptor obsidiansis, which can be primarily attributed to the high cell concentration and surface attachment. The formation of biofilms results in cellulases being secreted close to their substrates, which appears to be an energetically favorable stategy for insoluble substrate utilization. For the same reason,cellulases should be closely associated with the surfaces of suspended cell in soluble substrate-fed culture, which has been verified with cellobiose-fed cultures of C. thermocellum and C. obsidiansis. This study addressed the importance of cellulase activity distribution in cellulosic biomass fermentation, and provided theoretical foundation for the leading role of biofilm in cellulose degradation. System optimization and reactor designs that promote biofilm formation in cellulosic biomass hydrolysis may promise an improved cellulosic biofuel process.This study took advantage of resorufin cellobioside as a fluorescent substrate to determine the distribution of cellulase activity in cellulosic biomass fermentation systems. Cellulolytic biofilms were found to express nearly four orders greater cellulase activity compared to planktonic cultures of Clostridium thermocellum and Caldicellulosiruptor obsidiansis, which can be primarily attributed to the high cell concentration and surface attachment. The formation of biofilms results in cellulases being secreted close to their substrates, which appears to be an energetically favorable stategy for insoluble substrate utilization. For the same reason,cellulases should be closely associated with the surfaces of suspended cell in soluble substrate-fed culture, which has been verified with cellobiose-fed cultures of C. thermocellum and C. obsidiansis. This study addressed the importance of cellulase activity distribution in cellulosic biomass fermentation, and provided theoretical foundation for the leading role of biofilm in cellulose degradation. System optimization and reactor designs that promote biofilm formation in cellulosic biomass hydrolysis may promise an improved cellulosic biofuel process.

关 键 词：Thermophilic Biofilm Cellulose Cellulase Biofuel 

分 类 号：X172[环境科学与工程—环境科学]