Cofactor F tail length distribution in different environmental samples.

Cofactor F is an electron carrier playing a crucial role in a variety of microorganisms during redox reactions of the primary and secondary metabolism due to its low redox potential and thus arouses increasing interest. In this study, cofactor F glutamyl tail length spectra in various habitats like manure, compost, soil, and digester sludge samples and their respective microbial communities were investigated using high performance liquid chromatography and an amplicon sequencing approach A previous study was used to identify F producing microorganisms. The highest concentration of cofactor F could be achieved in the horse manure, digester sludge, and mixed manure samples, which was approximately 100-fold higher than in all the other samples.

Pre-treatment with Trichoderma viride: Towards a better understanding of its consequences for anaerobic digestion.

Understanding and optimising biological pre-treatment strategies for enhanced bio-methane production is a central aspect in second-generation biofuel research. In this regard, the application of fungi for pre-treatment seems highly promising; however, understanding the mode of action is crucial. Here, we show how aerobic pre-treatment of crystalline cellulose with the cellulolytic Trichoderma viride affects substrate degradability during mesophilic, anaerobic digestion.

Gasification chars and activated carbon: Systematic physico-chemical characterization and effect on biogas production.

Gasification residues/chars (GR) and activated carbon (AC) are added to wastewater treatment processes mainly as a fourth purification stage, e.g., to adsorb heavy metals or pharmaceutical residues.

Meso- and thermophilic posttreatment of press water coming from a thermophilic municipal solid waste digester.

An efficient biogas production out of organic (waste) materials is important to contribute to a carbon-neutral future. In this study, thermophilic press water (PW) coming from an organic fraction of the municipal solid waste digester was further digested in a thermo- and mesophilic posttreatment approach using two semicontinuous 14 L digesters. The results showed that the PW can still have considerable high biogas potential-at least during the touristic high season in central Europe.

Effects of phenyl acids on different degradation phases during thermophilic anaerobic digestion.

Aromatic compounds like phenyl acids (PA) can accumulate during anaerobic digestion (AD) of organic wastes due to an increased entry of lignocellulose, secondary plant metabolites or proteins, and thermodynamic challenges in degrading the benzene ring. The effects of aromatic compounds can be various - from being highly toxic to be stimulating for methanogenesis - depending on many parameters like inoculum or molecular characteristics of the aromatic compound. To contribute to a better understanding of the consequences of PA exposure during AD, the aim was to evaluate the effects of 10 mM PA on microbial communities degrading different, degradation phase-specific substrates in thermophilic batch reactors within 28  days: Microcrystalline cellulose (MCC, promoting hydrolytic to methanogenic microorganisms), butyrate or propionate (promoting syntrophic volatile fatty acid (VFA) oxidisers to methanogens), or acetate (promoting syntrophic acetate oxidisers to methanogens).

Extraction of Cofactor F420 for Analysis of Polyglutamate Tail Length from Methanogenic Pure Cultures and Environmental Samples.

The cofactor F420 plays a central role as a hydride carrier in the primary and secondary metabolism of many bacterial and archaeal taxa. The cofactor is best known for its role in methanogenesis, where it facilitates thermodynamically difficult reactions. As the polyglutamate tail varies in length between different organisms, length profile analyses might be a powerful tool for distinguishing and characterizing different groups and pathways in various habitats.

Lignin intermediates lead to phenyl acid formation and microbial community shifts in meso- and thermophilic batch reactors.

Background: Lignin intermediates resulting from lignocellulose degradation have been suspected to hinder anaerobic mineralisation of organic materials to biogas. Phenyl acids like phenylacetate (PAA) are early detectable intermediates during anaerobic digestion (AD) of aromatic compounds. Studying the phenyl acid formation dynamics and concomitant microbial community shifts can help to understand the microbial interdependencies during AD of aromatic compounds and may be beneficial to counteract disturbances.

Microbial community dynamics in mesophilic and thermophilic batch reactors under methanogenic, phenyl acid-forming conditions.

Background: Proteinaceous wastes exhibit high theoretical methane yields and their residues are considered valuable fertilisers. The routine anaerobic degradation of proteins often raises problems like high aromatic compound concentrations caused by the entry of aromatic amino acids into the system. A profound investigation of the consequences of aromatic compound exposure on various microorganisms, which cascade-like and interdependently degrade complex molecules to biogas, is still pending.

Microbial and Phenyl Acid Dynamics during the Start-up Phase of Anaerobic Straw Degradation in Meso- and Thermophilic Batch Reactors.

Aromatic compounds like phenyl acids derived from lignocellulose degradation have been suspected to negatively influence biogas production processes. However, results on this topic are still inconclusive. To study phenyl acid formation in batch reactors during the start-up phase of anaerobic degradation, different amounts of straw from grain were mixed with mesophilic and thermophilic sludge, respectively.

Biological Pretreatment Strategies for Second-Generation Lignocellulosic Resources to Enhance Biogas Production.

With regard to social and environmental sustainability, second-generation biofuel and biogas production from lignocellulosic material provides considerable potential, since lignocellulose represents an inexhaustible, ubiquitous natural resource, and is therefore one important step towards independence from fossil fuel combustion. However, the highly heterogeneous structure and recalcitrant nature of lignocellulose restricts its commercial utilization in biogas plants. Improvements therefore rely on effective pretreatment methods to overcome structural impediments, thus facilitating the accessibility and digestibility of (ligno)cellulosic substrates during anaerobic digestion.

Formation of phenylacetic acid and phenylpropionic acid under different overload conditions during mesophilic and thermophilic anaerobic digestion.

Background: Substrate spectra for anaerobic digestion have been broadened in the past decade, inter alia, due to the application of different pretreatment strategies and now include materials rich in lignocellulose, protein, and/or fat. The application of these substrates, however, also entails risks regarding the formation of undesired by-products, among which phenolic compounds are known to accumulate under unfavorable digestion conditions.

Methods: Different states of overload were simulated in batch experiments while reviewing the generation of phenyl acids out of different lab-use substrates in order to evaluate the impact on biogas and methane production as well as some additional process performance parameters under defined laboratory conditions.