ena-STUDY-BOGAZICI UNIVERSITY-13-06-2018-11:15:33:963-607
Biological pretreatment with Trametes versicolor to enhance methane production from lignocellulosic biomass: a metagenomic approach
The presence of poorly biodegradable components in lignocellulosic biomass limits the methane recovery in anaerobic digesters. The main reason to go for aerobic pretreatment before anaerobic digestion is to enable enzymatic cleavage of the aromatic rings in lignin by oxygen since it cannot be degraded anaerobically. In this study, we took the advantage of highly-cellulolytic white-rot fungus T. versicolor by aerobic pretreatment prior to anaerobic co-digestion of cow manure and selected cereal crop materials (wheat, rye, barley, triticale) harvested at different stages. The highest methane yield was obtained during the anaerobic co-digestion of cow manure and early-harvested barley in both non-treated and pretreated trials. Fungal pretreatment boosted the methane yield by 10-18% and cellulose removal up to 80%. A higher VFA speciation was also found in the anaerobic digesters upon fungal pretreatment.16S rRNA gene amplicon sequencing revealed that microbial communities were clustered in terms of similarity with respect to the application of pretreatment and crop material (whole crop vs. crop resides). Porphyromonadaceae (phylum: Bacteroidetes), Caldicoprobacteraceae (phylum: Firmicutes) and Clostridiaceae (phylum: Firmicutes) were the most abundant bacterial families in anaerobic digesters; meanwhile Anaerobaculaceae (phylum: Synergistetes) was only detected in pretreated digesters at a high abundance. Methanomicrobiaceae and Methanosarcinaceae were the predominant methanogenic archaeal communities in pretreated anaerobic digesters; however, non-treated control digesters were only dominated by Methanosarcinaceae. Overall, aerobic pretreatment of lignocellulosic agricultural feedstock with T. versicolor contributed a higher cellulose degradation and a more diverse microbiome in anaerobic digesters which in return ensured higher methane yield.
The presence of poorly biodegradable components in lignocellulosic biomass limits the methane recovery in anaerobic digesters. The main reason to go for aerobic pretreatment before anaerobic digestion is to enable enzymatic cleavage of the aromatic rings in lignin by oxygen since it cannot be degraded anaerobically. In this study, we took the advantage of highly-cellulolytic white-rot fungus T. versicolor by aerobic pretreatment prior to anaerobic co-digestion of cow manure and selected cereal crop materials (wheat, rye, barley, triticale) harvested at different stages. The highest methane yield was obtained during the anaerobic co-digestion of cow manure and early-harvested barley in both non-treated and pretreated trials. Fungal pretreatment boosted the methane yield by 10-18% and cellulose removal up to 80%. A higher VFA speciation was also found in the anaerobic digesters upon fungal pretreatment.16S rRNA gene amplicon sequencing revealed that microbial communities were clustered in terms of similarity with respect to the application of pretreatment and crop material (whole crop vs. crop resides). Porphyromonadaceae (phylum: Bacteroidetes), Caldicoprobacteraceae (phylum: Firmicutes) and Clostridiaceae (phylum: Firmicutes) were the most abundant bacterial families in anaerobic digesters; meanwhile Anaerobaculaceae (phylum: Synergistetes) was only detected in pretreated digesters at a high abundance. Methanomicrobiaceae and Methanosarcinaceae were the predominant methanogenic archaeal communities in pretreated anaerobic digesters; however, non-treated control digesters were only dominated by Methanosarcinaceae. Overall, aerobic pretreatment of lignocellulosic agricultural feedstock with T. versicolor contributed a higher cellulose degradation and a more diverse microbiome in anaerobic digesters which in return ensured higher methane yield.