ABSTRACTIn this study, we designed and evaluated a microalgal pretreatment method using cellulolytic bacteria that naturally degrades microalgae in their native habitat. Bacterial strains were isolated from each of two mollusk species in a medium containing 1% carboxymethyl cellulose agar. We selected nine bacterial strains that had endoglucanase activity: five strains fromMytilus chilensis, a Chilean mussel, and four strains fromMesodesma donacium, a clam found in the Southern Pacific. These strains were identified phylogenetically as belonging to the generaAeromonas,Pseudomonas,Chryseobacterium, andRaoultella. The cellulase-producing capacities of these strains were characterized, and the degradation of cell walls inBotryococcus brauniiandNannochloropsis gaditanawas tested with “whole-cell” cellulolytic experiments.Aeromonas bivalviumMA2,Raoultella ornithinolyticaMA5, andAeromonas salmonicidaMC25 degradedB. braunii, andR. ornithinolyticaMC3 and MA5 degradedN. gaditana. In addition,N. gaditanawas pretreated withR. ornithinolyticastrains MC3 and MA5 and was then subjected to an anaerobic digestion process, which increased the yield of methane by 140.32% and 158.68%, respectively, over that from nonpretreated microalgae. Therefore, a “whole-cell” cellulolytic pretreatment can increase the performance and efficiency of biogas production.
Enzymatic pretreatment of steam-exploded birch wood for increased biogas production and lignin degradation
