Biology subjects

Abendroth, C.

Publications and source records attributed to Abendroth, C..

8 recordsLinked to original sources

bioRxiv2025

Bioaugmentation in anaerobic digesters: A systematic review

Bioaugmentation, the intentional introduction of specific microorganisms into anaerobic digestion (AD) systems, has shown promise in enhancing methane production and in mitigating stressful conditions, particularly in systems operating below optimal performance. This review presents a systematic literature review (SLR) and meta-analysis to evaluate the efficacy of bioaugmentation strategies in AD. This review identified and analyzed studies meeting predefined eligibility criteria through a structured methodology involving research protocol, search, appraisal, synthesis, analysis, and reporting. A notable innovation of this review is its comprehensive critical comparison of different controls used in bioaugmentation studies, which has been inadequately addressed in previous literature. To facilitate the functional understanding, strains for bioaugmentation were grouped into the four phases of anaerobic digestion (hydrolysis, acidogenesis, acetogenesis and methanogenesis). A highly diverse set of microbes has been described for bioaugmentation, especially from the families Clostridiaceae, Pseudomonadaceae and Syntrophomonadaceae. Most works are related to hydrolysis. The few works that address acidogenesis are mostly related to dark fermentation. Several studies used methanogenic archaea as well as syntrophic acetate oxidising bacteria, despite the difficulties in culturing them. On the other hand, studies applying strains for acetogenesis were largely underrepresented. Especially works on syntrophic propionate and butyrate oxidation (SPO and SBO) were missing.

bioengineering↗

bioRxiv2025

Electro-composting: an emerging technology

The present study focuses on electrical stimulation for composting. Using the PSALSAR method, a systematic review resulted in 24 relevant articles. For each system, the review describes key materials, composter design, operating conditions, temperature evolution, compost maturity, microbial community, and outcome. The examined studies fall into four main systems: electric field-assisted aerobic composting (EAAC), electrolytic oxygen aerobic composting (EOAC), microbial fuel cells (MFC), and thermoelectric generators (TEG). Apart from the main systems highlighted above, there is a rare case, which remains hardly studied. This includes bioelectrochemically assisted anaerobic composting (AnCBE, III). EAAC and EOAC systems biologically balance microbial activity and organic matter decomposition, whereas MFC and TEG systems have dual functioning due to energy generated alongside waste degradation. These innovative systems significantly improve composting efficiency by speeding up organic matter breakdown, increasing oxygen supply, and facilitating energy recovery. Together, they overcome the drawbacks of conventional composting systems and promote more environmentally friendly waste management solutions. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/633320v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@108fa94org.highwire.dtl.DTLVardef@7b1b7dorg.highwire.dtl.DTLVardef@49d6dforg.highwire.dtl.DTLVardef@1b9fad5_HPS_FORMAT_FIGEXP M_FIG C_FIG Research HighlightsO_LIThe four most frequently investigated electro-composting systems are EAAC, EOAC, MFC, and TEG. C_LIO_LIMFCs make it easier to turn organic waste into electricity, which makes decomposition more environmentally friendly. C_LIO_LIThermal energy generated during decomposition is utilized by TEGs to produce electricity. C_LIO_LIThe research on AnCBE is highly limited. C_LI

bioengineering↗

bioRxiv2023

The quest for improved biohydrogen formation: are heat shocks the solution?

BackgroundThe integration of anaerobic digestion into bio-based industries can create synergies, which help to make anaerobic digestion self-sustaining. Two-stage digesters with separate acidification stages allow to produce green hydrogen and short-chain fatty acids, which are promising industrial products. Heat shocks can be used to foster the production of these products. However, the practical applicability is oft not addressed sufficiently. The here presented work aims to close this gap. MethodsBatch experiments were conducted in 5 litre double-walled tank reactors incubated at 37 {degrees}C. Short microwave heat shocks of 25 min duration and exposure times of 5 - 10 min at 80 {degrees}C were performed and compared to oven heat shocks. Pairwise experimental group differences for gas production and chemical parameters were determined using ANOVA and post-hoc tests. High-throughput 16S rRNA gene amplicon sequencing was performed to analyse taxonomic profiles. ResultsHeat shocking the entire seed sludge, the highest hydrogen productivity was observed at a substrate load of 50 g/l with 1.09 mol H2/mol hexose. With 1.01 mol H2/mol hexose, microwave assisted treatment was not significantly different from oven-based treatments. The study emphasised the better repeatability of heat shocks with microwave-assisted experiments, showing low variation coefficients averaging 29 %. Microwave pre-treatment indicates a high predictability and a stronger microbiome shift to Clostridia than the oven. The pre-treatment of heat shocks supported the formation of butyric acid up to 10.8 g/l in average and a peak of 24.01 g/l at a butyric/acetic acid ratio of 2.0. ConclusionResults show the suitability to heat shock the entire seed sludge rather than just a small inoculum, which makes the process more relevant for industrial application. A microwave-based treatment has proven to be a promising alternative to oven-based treatments, which ultimately might facilitate the implementation into industrial systems. The approach becomes economically sustainable with high-temperature heat pumps with a coefficient of performance (COP) of 4.3.

bioengineering↗

bioRxiv2023

Unveiling the ecology, taxonomy and metabolic capabilities of MBA03, a potential key player in anaerobic digestion

Biogas, a mix of CO2, CH4 and small proportions of other gases, is a biofuel obtained by anaerobic digestion (AD). Biogas production is often considered a black box process, as the role and dynamics of some of the microorganisms involved remain undisclosed. Previous metataxonomic studies in the frame of the MICRO4BIOGAS project (www.micro4biogas.eu) revealed that MBA03, an uncharacterised and uncultured bacterial taxon, was very prevalent and abundant in industrial full-scale AD plants. Surprisingly, no culturable specimen or genome of this taxon has ever been reported, so its role in AD has remained unclear. In the present work, thirty samples derived from anaerobic digesters were sequenced, allowing the reconstruction of 108 metagenome-assembled genomes (MAGs) potentially belonging to MBA03. According to phylogenetic analyses and genomic similarity indices, MBA03 constitutes a new bacterial order, proposed as Darwinibacteriales ord. nov., which includes Darwinibacter acetoxidans gen. nov., sp. nov. of the family Darwinibacteriaceae fam. nov., along with Wallacebacter cryptica gen. nov., sp. nov. of the Wallacebacteriaceae fam. nov. Ecotaxonomic studies determined that AD processes are the main ecological niche of Darwinibacteriales. Moreover, metabolic predictions identified Darwinibacteraceae members as putative syntrophic acetate oxidising bacteria (SAOB), as they encode for the reversed Wood-Ljungdahl (W-L) pathway coupled to the glycine cleavage system. This suggests that Darwinibacteraceae members work in collaboration with hydrogenotrophic archaea to produce methane in industrial biogas plants. Overall, our findings present Darwinibacteriales as a potential key player in anaerobic digestion and pave the way towards the complete characterisation of this newly described bacterial taxa.

ecology↗

bioRxiv2023

Multivariate comparison of taxonomic, chemical and technical data from 80 full-scale an-aerobic digester-related systems

This study represents one of the most comprehensive characterisations of the anaerobic digestion (AD) microbiome with 80 samples from 45 different large-scale reactors in three coun-tries. Technical, chemical and taxonomic data was thoroughly collected, analyzed and correlated to identify the main drivers of AD processes. Our results showed that MBA03, Proteiniphilum, a member of Dethiobacteraceae, and Caldicoprobacter were present in all the samples, while Meth-anosarcina was the most abundant and prevalent archaea. Two distinct bacterial clusters were iden-tified by correlating microbial abundances. One was correlated with hydrogenotrophic and the other with acetoclastic methanogenesis. Organic acids, ammonia, nitrogen, COD and the trace el-ements Fe, Mo, and the macro nutrient P had the greatest impact on AD microbiomes. Temperature, reactor type and substrate also influenced the formation of a specialized microbial community. Overall, this work sheds light on the microbial key players involved in AD and evaluates how they are affected by technical and chemical parameters. HighlightsO_LIGeneration of a holistic dataset of chemical, taxonomic and technical parameters of 80 large-scale anaerobic digestion systems. C_LIO_LIIdentification of a core microbiome comprising MBA03, Proteiniphilum, an uncultured or-ganism from the Dethiobacteraceae family, and the Caldicoprobacter family. C_LIO_LIIdentification of the main influencing parameters that determine the occurrence and non-occurrence of specific genera. C_LIO_LICorrelation of bacterial taxa with hydrogenotrophic and/or acetoclastic archaea. C_LI

microbiology↗

bioRxiv2019

Shedding light on biogas: a transparent reactor triggers the development of a biofilm dominated by Rhodopseudomonas faecalis that holds potential for improved biogas production

Conventional anaerobic digesters intended for the production of biogas usually operate in complete darkness. Therefore, little is known about the effect of light on microbial communities operating in anaerobic digesters. In the present work, we have studied through 16S rRNA gene amplicon Nanopore sequencing and shotgun metagenomic sequencing the taxonomic and functional structure of the microbial community forming a biofilm on the inner wall of a lab-scale transparent anaerobic biodigester illuminated with natural sunlight. The biofilm was composed of microorganisms involved in the four metabolic processes needed for biogas production. The biofilm proved surprisingly rich in Rhodopseudomonas faecalis, a versatile bacterium able to carry out a photoautotroph metabolism when grown under anaerobic conditions. Our results suggest that this bacterium, able to fix carbon dioxide, could be considered for its use in transparent biogas fermenters in order to contribute to the production of optimized biogas with a higher CH4:CO2 ratio than the biogas produced in regular, opaque digesters. To the best of our knowledge, this is the first study supporting illuminated bioreactors as a new bioprocess for the obtention of biogas enriched in methane.

microbiology↗

bioRxiv2018

Liquid co-substrates repower sewage microbiomes

A range of parameters are known to shape the methanogenic communities of biogas-producing digesters and to strongly influence the amount of biogas produced. In this work, liquid and solid fractions of grass biomass were used separately for semicontinuous batch methanation using sewage sludge as seed sludge. During 6 months of incubation, the amount of input COD was increased gradually, and the underlying methanogenic microbiome was assessed by means of microscopy-based automated cell counting and full-length 16S rRNA high-throughput sequencing. In this sense, we prove for the first time the suitability of the ONTMinION platform as a monitoring tool for anaerobic digestion systems. According to our results, solid-fed batches were highly unstable at higher COD input concentrations, and kept Methanosaeta spp. typically associated to sewage sludge-as the majoritary methanogenic archaea. In contrast, liquid-fed batches developed a more stable microbiome, proved enriched in Methanosarcina spp, and resulted in higher methanogenic yield. This work demonstrates the high repowering potential of microbiomes from sewage sludge digesters, and highlight the effectiveness of liquefied substrates for increasing biogas productivity in anaerobic digestions.

microbiology↗

bioRxiv2017

Warm and wet: robust lipase-producing bacteria from the indoor environment

Lipases are key biocatalysts with important biotechnological applications. With the aim of isolating robust lipolytic microbial strains, we have analyzed the bacterial communities inhabiting two domestic extreme environments: a thermophilic sauna and a dishwasher filter. Scanning electron microscopy revealed biofilm-forming and scattered microorganisms in the sauna and dishwasher sample, respectively. A culture-independent approach based on 16S rRNA analysis indicated a high abundance of Proteobacteria in the sauna sample; and, a large amount of Proteobacteria, Firmicutes, Cyanobacteria and Actinobacteria in the dishwasher filter. With a culture-dependent approach, we isolated 48 bacterial strains, screened their lipolytic activities on media with tributyrin as the main carbon source, and finally selected five isolates for further characterization. These strains, all of them identified as members of the genus Bacillus, displayed optimum lipolytic peaks at pH 6.5 and with 1-2% NaCl, and the activity proved very robust at a wide range of pH (up to 11.5) and added NaCl concentrations (up to 4%). The thermal, pH and salt robustness of the selected isolates is a valuable attribute for these strains, which are promising as highly tolerant biodetergents. To our knowledge, this is the first report regarding the isolation from an indoor environment of Bacillus strains with a high potential for industry.

microbiology↗