WITHDRAWN: Biomethane production from lignocellulosic biomass enhanced by bioaugmentation with anaerobic rumen fungi

Abstract

Abstract The aim of this study was to reveal the effect of bioaugmentation with anaerobic rumen fungi on biogas production from lignocellulosic biomass, such as manure and macroalgae. Anaerobic rumen fungi Orpinomyces sp. , Piromyces sp. , Anaeromyces sp. and Neocallimastix frontalis, which received groups of genes that originated in bacteria by way of horizontal gene transfer, were used in the study to enhance biomethane yield. Rumen fungi at a concentration of 15% achieved greater production of biogas (3500 mL/d) and methane (+54.7%) in the digesters fed with the macroalgae Ulva lactuca and manure. Microbial community dynamics and quantification of rumen fungi in anaerobic digesters were also detected by next-generation sequencing and real-time quantitative PCR to control the effect of fungal augmentation. Diversity of bacterial and archaeal communities and quantities of anaerobic rumen fungi showed the increased performance of anaerobic digesters fed with Ulva lactuca thanks to the addition of anaerobic rumen fungi. The results also indicated that concentrations of rumen fungi and anaerobic microorganisms should be balanced for sufficient biomethane yield. Because of their nonspecific extracellular enzyme systems, anaerobic rumen fungi may be a promising alternative to improve biogas production from different types of algae and lignocellulosic compounds.