Identification of unknown filamentous fungi from willow wood and sorghum chips

Molecular biological methods are generally applied in the identification processes of microorganisms. We aimed to isolate numerous cellulolytic filamentous fungi strains from willow wood and sorghum chips, and attempted to identify them with polymerase chain reaction (PCR). Modified Czapek-Dox medium was used with the addition of microcrystalline cellulose and carboxymethyl cellulose (CMC) as a source of carbon, in order to isolate cellulolytic filamentous fungi strains. Through sequence-based identification, representatives of the genera Trichoderma, Aspergillus and Fusarium were identified

Happy marriage across the evolution: co-operation of methanogenic archaea and anaerobic fungi

Four anaerobic fungi (AF) strains, isolated from faeces of anoa, giraffe, bison and moose, were assessed for their ability to degrade lignocellulosic biomass. The effects on biogas production of anaerobic fungi from these animal species were determined in two step batch experiments. The hydrolysis process during the AF incubation led to an initial increase of biogas production, an accelerated degradation of dry matter and an increased concentration of volatile fatty acids. Thus, a separate hydrolytic pre-treatment phase with anaerobic fungi, represents a feasible strategy to improve biogas production from lignocellulosic substrates

Improving methane production from lignocellulosic biomass pre-treated with anaerobic fungi

Two anaerobic fungi (AF) strains, isolated from faeces of an elephant and of a sheep, were assessed for their ability to degrade lignocellulosic biomass. The effects on biogas production of anaerobic fungi from both animal species were determined in two step batch experiments. The hydrolysis process during the AF incubation led to an initial increase of biogas production, an accelerated degradation of dry matter and an increased concentration of volatile fatty acids. Thus, a separate hydrolytic pre-treatment phase with anaerobic fungi, represents a feasible strategy to improve biogas production from lignocellulosic substrates

The Planktonic Core Microbiome and Core Functions in the Cattle Rumen by Next Generation Sequencing

The cow rumen harbors a great variety of diverse microbes, which form a complex, organized community. Understanding the behavior of this multifarious network is crucial in improving ruminant nutrient use efficiency. The aim of this study was to expand our knowledge by examining 10 Holstein dairy cow rumen fluid fraction whole metagenome and transcriptome datasets. DNA and mRNA sequence data, generated by Ion Torrent, was subjected to quality control and filtering before analysis for core elements. The taxonomic core microbiome consisted of 48 genera belonging to Bacteria (47) and Archaea (1). The genus Prevotella predominated the planktonic core community. Core functional groups were identified using co-occurrence analysis and resulted in 587 genes, from which 62 could be assigned to metabolic functions. Although this was a minimal functional core, it revealed key enzymes participating in various metabolic processes. A diverse and rich collection of enzymes involved in carbohydrate metabolism and other functions were identified. Transcripts coding for enzymes active in methanogenesis made up 1% of the core functions. The genera associated with the core enzyme functions were also identified. Linking genera to functions showed that the main metabolic pathways are primarily provided by Bacteria and several genera may serve as a “back-up” team for the central functions. The key actors in most essential metabolic routes belong to the genus Prevotella. Confirming earlier studies, the genus Methanobrevibacter carries out the overwhelming majority of rumen methanogenesis and therefore methane emission mitigation seems conceivable via targeting the hydrogenotrophic methanogenesis

Biogas production from agroindustrial waste pre-treated with lignolytic fungi

Renewable energy was never more important than in a century when energy consumption is unprecedented. Biogas is considered to be one of the most important natural energy sources. We aim to enhance biogas production through the pre-treatment of substrates, that are normally hard to digest because of their high content of cellulose, hemi- and lignocellulose. As part of fungal pre-treatment we used Aspergillus nidulans and Trichoderma reesei. Both of these filamentous fungi are well known for their ability to synthetise various enzymes – including cellulases. During our experiments A. nidulans and T. reesei filamentous fungi’s endoglucanase activities were measured by spectrophotometer and methane-producing was monitorized by gas chromatography

Enhancing Biogas Production from Agroindustrial Waste Pre-Treated with Filamentous fungi

Biogas is the product of anaerobic digestion (AD) of organic waste and is considered to be one of the most valuable natural renewable energy carriers. Plant biomass represents the most abundant eco-friendly energy reservoir on Earth. However, the tenacious and heterogeneous structure of the lignocellulose-rich elements makes it difcult for the involved microbes to digest the recalcitrant substrates. Both the degradation process and the biogas production yield can be enhanced by appropriate pre-treatment of lignocellulosic materials. Filamentous fungi have been known as profcient colonizers of lignocellulosic plant tissues and have been recognized as producers of exceptionally rich and diverse hydrolytic enzymes. We tested Aspergillus nidulans, Trichoderma reesei, Rhizomucor miehei and Gilbertella persicaria flamentous fungal strains for pre-treatment of various agricultural lignocellulosic wastes. During the pre-treatment phase, the β-glucosidase and endoglucanase activity was measured spectrophotometrically. In the AD step, methane production was monitored by gas chromatography. The preliminary results showed that all the applied strains (Aspergillus nidulans, Trichoderma reesei, Rhizomucor miehei and Gilbertella persicaria) were highly effective in producing both β-glucosidase and endo-(1,4)-β-D-glucanase enzymes, which might explain the greatly improved AD results. Pre-treatment with the above-mentioned flamentous fungi positively affected the biogas production, although the effect strongly depended on the selection of the fungal partner for any given biomass substrate. Depending on the used substrate and the pre-treatment strain, overall methane yields were elevated two-fold relative to the controls

Analyses of the Large Subunit Histidine-Rich Motif Expose an Alternative Proton Transfer Pathway in [NiFe] Hydrogenases

A highly conserved histidine-rich region with unknown function was recognized in the large subunit of [NiFe] hydrogenases. The HxHxxHxxHxH sequence occurs in most membrane-bound hydrogenases, but only two of these histidines are present in the cytoplasmic ones. Site-directed mutagenesis of the His-rich region of the T. roseopersicina membrane-attached Hyn hydrogenase disclosed that the enzyme activity was significantly affected only by the replacement of the His104 residue. Computational analysis of the hydrogen bond network in the large subunits indicated that the second histidine of this motif might be a component of a proton transfer pathway including Arg487, Asp103, His104 and Glu436. Substitutions of the conserved amino acids of the presumed transfer route impaired the activity of the Hyn hydrogenase. Western hybridization was applied to demonstrate that the cellular level of the mutant hydrogenases was similar to that of the wild type. Mostly based on theoretical modeling, few proton transfer pathways have already been suggested for [NiFe] hydrogenases. Our results propose an alternative route for proton transfer between the [NiFe] active center and the surface of the protein. A novel feature of this model is that this proton pathway is located on the opposite side of the large subunit relative to the position of the small subunit. This is the first study presenting a systematic analysis of an in silico predicted proton translocation pathway in [NiFe] hydrogenases by site-directed mutagenesis