Enhanced biogas yield from energy crops with rumen anaerobic fungi

Abstract

Anaerobic fungi (AF) are able to degrade crop substrates with higher efficiency than commonly used anaerobic bacteria. The aim of this study was to investigate ways of use of rumen AF to improve biogas production from energy crops under laboratory conditions. In this study, strains of AF isolated from feces or rumen fluid of cows and deer were tested for their ability to integrate into the anaerobic bacterial ecosystem used for biogas production, in order to improve degradation of substrate polysaccharides and consequently the biogas yield. Batch culture, fed batch culture, and semicontinuous experiments have been performed using anaerobic sludge from pig slurry fermentation and different kinds of substrates (celluloses, maize, and grass silage) inoculated by different genera of AF. All experiments showed a positive effect of AF on the biogas yield and quality. AF improved the biogas production by 4–22%, depending on the substrate and AF species used. However, all the cultivation experiments indicated that rumen fungi do not show long‐term survival in fermenters with digestate from pig slurry. The best results were achieved during fed batch experiment with fungal culture Anaeromyces (KF8), in which biogas production was enhanced during the whole experimental period of 140 days. This result has not been achieved in semicontinuous experiment, where increment in biogas production in fungal enriched reactor was only 4% after 42 days.

Anaerobic fungi (phylumNeocallimastigomycota): advances in understanding their taxonomy, life cycle, ecology, role and biotechnological potential

“…In contrast, the direct incorporation of anaerobic fungi into these bioreactors would eliminate the requirement of an aerobic predigestion. Incorporation of anaerobic fungi in bioreactors improved biogas yield for up to 10 days postinoculation, enhancing yield by 4–22% depending on the substrate and fungal species used (Fliegerova et al ., ; Procházka et al ., ). Unfortunately, the inability of anaerobic fungi to survive long term in fermenters, however, makes the application of anaerobic fungi in commercial full‐scale biogas production systems unfeasible using current technologies (Procházka et al ., ).…”

“…A promising source of renewable, environmentally friendly energy is the production of biogas from the anaerobic digestion of organic waste. Currently used bioreactors display somewhat low degradation of organic material (40–60%) (Procházka et al ., ) thus, technologies that can improve this efficiency are needed. The biological pretreatment of crop residues with white and brown rot fungi has been shown to be effective at improving biogas production (Ghosh & Bhattacharyya, ).…”

Quantitative microbial indices in biogas and raw cattle slurries

“…In contrast, Procházka et al. observed that rumen cultivable fungi do not exhibit long‐term survival in biogas fermenters.…”

“…The current results are consistent with the view of McGranaghan et al [43] that many fungi remain viable in the anaerobic environment of cattle feces, slurries, and manures for long periods. In contrast, Procházka et al [22] observed that rumen cultivable fungi do not exhibit long-term survival in biogas fermenters.…”

Quantitation of the Inhibition Effect of Model Compounds Representing Plant Biomass Degradation Products on Methane Production

“…These natural polymers interact closely together and create a complex matrix that is rather resistant to biotic and abiotic degradation, especially under anaerobic conditions (Adney et al 1991;Prochazka et al 2012). Cellulose constitutes a major component of plant biomass, consisting of β(1→4) glycosidic bonds connected D-glucose units.…”