Biomethane potential of pre-treated macroalgae and corn stover by trametes versicolor entrapped in Ca-alginate beads

Abstract

Microorganisms especially fungi are utilized in biological pre-treatment of lignocellulosic biomass. In this particular study, Trametes versicolor were entrapped in Ca-alginate beads in order to use them in the pre-treatment of macroalgae (Ulva sp.) and corn stover prior to anaerobic digestion process. After pre-treatment, anaerobic co-digestion of corn stover and macroalgae was carried out. According to results, laccase activities of samples were high enough to process pretreatment and activity of enzyme in sample containing corn stover only showed dramatic increase in the 2nd day of pre-treatment. The concentration of reducing sugars was increased after 24 hours for pre-treatment samples, and then tended to decrease following 6 days of pre-treatment. Methane yields of samples were increased by 26%, 24%, and 15% for macroalgae, corn, and co-digestion of both substrates, respectively. Soluble chemical oxygen demand and volatile fatty acid concentrations of digesters were obtained as strengthening the methane yield results. Nextgeneration sequencing analysis was conducted by using ION PGMTM in order to determine microbial communities in samples taken from the 20th day of anaerobic digestion process. Significant differences in microbial communities including bacteria and archaea were determined between non-treated and pre-treated digesters and pre-treatment of substrates increased microbial diversities inside of anaerobic digesters according to bioinformatics analysis. Overall, the results indicated that T. versicolor entrapped in Ca-alginate beads can be utilized in the pre-treatment of lignocellulosic biomass and macroalgae biomass in order to decrease the cost and time of the operation.