Aerobic Microbial Cellulase Systems

摘要: tons pr oduc ed by plants eac h year (1). M ost terrestrialcellulose isdeg raded celluloly tic micr oo rganisms, imar ily fung iand bact eria,althoug hsome cellulose isrecy cled Þr e and phot odeg radation (2). A erobic oorganisms arerespo nsible for m u ch ofthe deg rada tion in soils,bu tther also are ma ny species ofcelluloly anaer obic soil eria suc as C lostridiu therm ocellu ,C. cellulovor ans ,andA cetivibrio cellulosolvens(3Ð5). Termit es some other insects very impor tant cellu-lose radation, especially tropical regions, most rading containsymbiotic oorganisms, even thoug man y termit pro-duc cellulases (6, 7). Some utiliz aerobic symbiotic ticfung i to breakdo w n plant mat erial their nests then eat the residual plantmat (8). R uminants, cows, sheep , deer de-grading organisms but all of that tilize is d eg sym biotic rumenmicr eria.The rumen an extremely en vironment andthis area has been review recently (9, 10), so these illnot be discussedfu rth er ere.M icroorganisms catalyz radat ion p roducing enzy mes called cellulases,whic hyd rolyze ! -1-4 linkages esent cellulose. Almost allcelluly oorganismssecr ete outside cellwall, iare unable transpor tinsoluble erials, like cellulose, inside cell.T he soluble sugars cellulasedigestion ted th cell etabolized . N ative cellu lose isvery resistant hydr olysis because itis insoluble contains crystalline regions hic hthe adjac ent molecules ha ve strong interactions, ogen bonds andhydr ophobic stacking .T us, speciÞc activities indi vidual uc low ertha tho se ofmo st mes. H ow ever,in term s ofca talytic enha nc ement, veryactive mes, half-life wat at neut ral estimat edto about 100 million years. It tak conc rated sulfur ic acid 125uC olyz enati a reasonable rate.W hen assa yed on molecular eightsoluble subst rates, sho or mal ich aelis-M kinetics hig speciÞcactivities, ing basically similar ever,when cellulasesare assayed solu ble su bstrates, ey ave ifferen t rop erties, assays