Fungi open new possibilities for anaerobic fermentation of organic residues

Abstract

Background: Large amounts of fibre-rich organic waste material from public green and private gardens have to be treated environmentally friendly; however, this fibre-rich biomass has low biogas yields. This study investigated the presence of fungi in full-scale biogas plants as well as in laboratory reactors and elucidated the importance of fungi for the biogas process. Methods: The dominating members of the eukaryotic community were identified by analyzing 18S rRNA gene and internal transcribed spacer 1 (ITS1) region fragments of clone libraries. These identifications were accompanied by diverse microscopic techniques such as fluorescence microscopy and conventional scanning electron microscopy. Results: Cells of presumably fungal origin were characterized by intensive fluorescence and were about 1 order of magnitude larger than prokaryotic cells. Molecular techniques enabled to identify fungi from the subphyla Agaricomycotina, Mucoromycotina, Pezizomycotina, Pucciniomycotina and Saccharomycotina and from the class Neocallimastigomycetes. Members of these groups can be important for microbial degradation of complex compounds, due to the ability to penetrate cell walls, and thus open the cells for the influx of bacteria, further enhancing degradation.

Different response of bacteria, archaea and fungi to process parameters in nine full‐scale anaerobic digesters

“…There are only few reports about fungi in anaerobic reactors (Ritari et al ., ; Bengelsdorf et al ., ; Kazda et al ., ; Dollhofer et al ., ; Young et al ., ). Fungal ribosomal rRNA from an astonishing variety of taxa ( Ascomycota and Basidiomycota ) was found in the present study.…”

“…Lignocellulosic biomass has a high potential as feedstock for production of renewable energy, since it is the most common renewable resource on earth (Millati et al ., ). Under anaerobic conditions, lignocellulosic biomass is persistent and only poorly degraded (Kazda et al ., ). Hemicellulose and cellulose fractions are embedded in lignin (Lynd et al ., ) which makes hemicellulose and cellulose not easily accessible for bacterial degradation.…”

“…Hemicellulose and cellulose fractions are embedded in lignin (Lynd et al ., ) which makes hemicellulose and cellulose not easily accessible for bacterial degradation. Fungi could open new possibilities for anaerobic digestion of lignocellulosic biomass (Kazda et al ., ). A wide range of fungi has a high fibrolytic potential.…”

“…() did not consider facultative anaerobic fungi. The presence of facultative anaerobic fungi in anaerobic digesters has been mainly investigated by means of DNA sequencing (Ritari et al ., ; Bengelsdorf et al ., ; Kazda et al ., ). Young et al .…”

Microbiology and Molecular Biology Tools for Biogas Process Analysis, Diagnosis and Control

“…When compared to aerobic degradation of lignocellulose, considerably less is known on the corresponding anaerobic process and the organisms involved. Besides bacteria, other organisms such as anaerobic fungi may be involved in efficient initial LCB attack and degradation [13]. Chapter 2 in this book is dedicated to anaerobic fungi and recent perceptions of their role in anaerobic LCB digestion.…”