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- Food waste biorefinery : stability of an acidogenic fermentation system with carbon dioxide sequestration and electricity generationPublication . Ortigueira, Joana; Pacheco, Marta; Trancoso, Maria Ascensão; Farrancha, Pedro; Correia, Jorge; Silva, Carla M.; Moura, PatríciaABSTRACT: The present study focused on the integration of the non-sterile conversion of food waste (FW) into hydrogen (H2) through dark fermentation with the subsequent electricity generation in a proton-exchange membrane fuel cell (PEMFC), and the assessment of the global warming potential (GWP) of the process. The acidogenic conversion of FW performed in continuous operation for 16 days produced 45.6 ± 0.1 L H2 at an average H2 productivity of 6.1 ± 1.3 L L−1 d−1. Butyric and acetic acid were simultaneously produced at average concentrations of 3.6 ± 0.5 and 1.6 ± 0.3 g L −1, respectively. The carbon dioxide (CO2) from biogas product was sequestered by reaction with sodium hydroxide and the resulting H2-rich stream was fed to a PEMFC, producing 1.7 Wh L−1 H2. The process scale-up was simulated based on the bench-scale conversion yields and was used to assess the GWP. Two of the developed scenarios, which considered the reuse of the fermentation sludge as nitrogen source in the acidogenic fermentation, diminished the GWP emissions by 63.8% and 64.3% when compared to the default condition. In the best-case scenario, an annual average of 0.18 t of CO2 per t of FW separately collected was generated.
- Biocatalytic performance of Butyribacterium methylotrophicum in the long-term conversion of synthesis gas produced from low-grade lignin gasification by Butyribacterium methylotrophicum [Resumo]Publication . Pacheco, Marta; Pinto, Filomena; Andre, Rui N.; Marques, Paula; Gírio, Francisco; Moura, PatríciaABSTRACT: Second-generation biorefineries produce large streams of low-grade lignin. Its thermochemical conversion, through gasification, enables the carbon recovery from an otherwise recalcitrant by-product. The main product of gasification is producer synthesis gas (PS), which is mainly composed by carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2), methane (CH4) and minor impurities. Carboxydotrophic acetogenic bacteria can utilize CO and CO2 as carbon and energy source, and convert them into biomass, biofuels and biochemicals through the Wood-Ljungdahl pathway.
- Lignin syngas bioconversion by Butyribacterium methylotrophicum: advancing towards an integrated biorefineryPublication . Pacheco, Marta; Pinto, Filomena; Ortigueira, Joana; Silva, Carla; Gírio, FranciscoABSTRACT: Hybrid bio-thermochemical based technologies have the potential to ensure greater feedstock flexibility for the production of bioenergy and bioproducts. This study focused on the bioconversion of syngas produced from low grade technical lignin to C-2-/C-4-carboxylic acids by Butyribacterium methylotrophicum. The effects of pH, medium supplementation and the use of crude syngas were analyzed. At pH 6.0, B. methylotrophicum consumed CO, CO2 and H-2 simultaneously up to 87 mol% of carbon fixation, and the supplementation of the medium with acetate increased the production of butyrate by 6.3 times. In long-term bioreactor experiments, B. methylotrophicum produced 38.3 and 51.1 mM acetic acid and 0.7 and 2.0 mM butyric acid from synthetic and lignin syngas, respectively. Carbon fixation reached 83 and 88 mol%, respectively. The lignin syngas conversion rate decreased from 13.3 to 0.9 NmL/h throughout the assay. The appearance of a grayish pellet and cell aggregates after approximately 220 h was indicative of tar deposition. Nevertheless, the stressed cells remained metabolically active and maintained acetate and butyrate production from lignin syngas. The challenge that impurities represent in the bioconversion of crude syngas has a direct impact on syngas cleaning requirements and operation costs, supporting the pursuit for more robust and versatile acetogens.
- Infraestrutura de investigação para a biomassa e a bioenergia: BBRI - Biomass and Bioenergy Research InfrastructurePublication . Reis, Alberto; Abreu, Mariana; Pacheco, Marta; Bernardo, Joana; Silva, R.; Domingues, Lucília; Teixeira, J.A.; Gírio, FranciscoRESUMO: A BBRI é a única Infraestrutura Nacional de Investigação em Biomassa e Bioenergia, que integra o Roteiro Nacional de Infraestruturas de Investigação de Interesse Estratégico em Portugal desde 2014, sendo distribuída por dois nós. O nó de Lisboa tem por base as infraestruturas laboratoriais e piloto existentes na Unidade de Bioenergia e Biorrefinarias (UBB) do Laboratório Nacional de Energia e Geologia (LNEG) e o nó de Braga, as infraestruturas laboratoriais e tecnológicas do Centro de Engenharia Biológica (CEB) da Universidade do Minho (UM). As atividades científicas da BBRI estão focadas nas tecnologias de conversão de biomassa para obtenção de biocombustíveis avançados, produtos não-energéticos de base biológica e outros biomateriais, inseridas em seis sub-plataformas de investigação (sub-RIs). O trabalho da BBRI nestas 6 sub-RIs encontra-se complementarmente organizado em atividades de formação, serviços e atividades de disseminação, visando a capacitação de novos profissionais em bioenergia sustentável e contribuindo para a excelência da investigação em Portugal no domínio da Bioenergia e Bioeconomia.
- On the road to cost-effective fossil fuel desulfurization by Gordonia alkanivorans strain 1BPublication . Pacheco, Marta; Paixão, Susana M.; Silva, Tiago; Alves, LuísABSTRACT: Biodesulfurization (BDS) is an ecofriendly process that uses microorganisms to efficiently remove sulfur from fossil fuels. To make the BDS process economically competitive with the deep hydrodesulfurization process, which is currently used in the oil industry, it is necessary to improve several factors. One crucial limitation to be overcome, common within many other biotechnological processes, is the cost of the culture medium. Therefore, an important line of work to make BDS scale-up less costly is the optimization of the culture medium composition aiming to reduce operating expenses and maximize biocatalyst production. In this context, the main goal of this study was on the minimization of inorganic key components of sulfur-free mineral (SFM) medium in order to get the maximal production of efficient desulfurizing biocatalysts. Hence, a set of assays was carried out to develop an optimal culture medium containing minimal amounts of nitrogen (N) and magnesium (Mg) sources and trace elements solution (TES). These assays allowed the design of a SFMM (SFM minimum) medium containing 85% N-source, 25% Mg-source and 25% TES. Further validation consisted of testing this minimized medium using two carbon sources: the commercial C-source (glucose + fructose) versus Jerusalem artichoke juice (JAJ) as a cheaper alternative. SFMM medium allowed microbial cells to almost duplicate their specific desulfurization rate (q(2-HBP)) for both tested C-sources, namely from 2.15 to 3.39 mu moL g(-1) (DCW) h(-1) for Fru + Glu and from 1.91 to 3.58 mu moL g(-1) (DCW) h(-1) for JAJ, achieving a similar net 2-hydroxybiphenyl produced per g of consumed sugar (similar to 17 mu moL g(-1)). These results point out the great advantage of using cheaper culture medium that in addition enhances the bioprocess effectiveness, paving the way to a sustainable scale-up for fossil fuel BDS.
- Effects of Lignin Gasification Impurities on the Growth and Product Distribution of Butyribacterium methylotrophicum during Syngas FermentationPublication . Pacheco, Marta; Pinto, Filomena; Brunsvik, Anders; Andre, Rui N.; Marques, Paula; Mata, Ricardo; Ortigueira, Joana; Gírio, Francisco; Moura, PatríciaABSTRACT: This work evaluated the effects of condensable syngas impurities on the cell viability and product distribution of Butyribacterium methylotrophicum in syngas fermentation. The condensates were collected during the gasification of two technical lignins derived from wheat straw (WST) and softwood (SW) at different temperatures and in the presence or absence of catalysts. The cleanest syngas with 169 and 3020 ppmv of H2S and NH3, respectively, was obtained at 800 degrees C using dolomite as catalyst. Pyridines were the prevalent compounds in most condensates and the highest variety of aromatics with cyanide substituents were originated during WST lignin gasification at 800 degrees C without catalyst. In contrast with SW lignin-based condensates, the fermentation media supplemented with WST lignin-derived condensates at 1:100 vol. only supported residual growth of B. methylotrophicum. By decreasing the condensate concentration in the medium, growth inhibition ceased and a trend toward butyrate production over acetate was observed. The highest butyrate-to-acetate ratio of 1.3 was obtained by supplementing the fermentation media at 1:1000 vol. with the condensate derived from the WST lignin, which was gasified at 800 degrees C in the presence of olivine. B. methylotrophicum was able to adapt and resist the impurities of the crude syngas and altered its metabolism to produce additional butyrate.
- A Systematic Review of Syngas Bioconversion to Value-Added Products from 2012 to 2022Publication . Pacheco, Marta; Moura, Patrícia; Silva, CarlaABSTRACT: Synthesis gas (syngas) fermentation is a biological carbon fixation process through which carboxydotrophic acetogenic bacteria convert CO, CO2, and H-2 into platform chemicals. To obtain an accurate overview of the syngas fermentation research and innovation from 2012 to 2022, a systematic search was performed on Web of Science and The Lens, focusing on academic publications and patents that were published or granted during this period. Overall, the research focus was centered on process optimization, the genetic manipulation of microorganisms, and bioreactor design, in order to increase the plethora of fermentation products and expand their possible applications. Most of the published research was initially funded and developed in the United States of America. However, over the years, European countries have become the major contributors to syngas fermentation research, followed by China. Syngas fermentation seems to be developing at "two-speeds", with a small number of companies controlling the technology that is needed for large-scale applications, while academia still focuses on low technology readiness level (TRL) research. This systematic review also showed that the fermentation of raw syngas, the effects of syngas impurities on acetogen viability and product distribution, and the process integration of gasification and fermentation are currently underdeveloped research topics, in which an investment is needed to achieve technological breakthroughs.
- Fixação biológica de CO, CO2 e H2: fermentação de gás de síntese com produção de ácidos orgânicos de cadeia curtaPublication . Pacheco, Marta; Ortigueira, Joana; Gírio, Francisco; Moura, PatríciaRESUMO: Os perfis de assimilação de monóxido de carbono (CO), dióxido de carbono (CO2) e hidrogénio (H2) de gás de síntese (singás) por Butyribacterium methylotrophicum foram caracterizados e foram determinadas as percentagens de fixação de carbono. Testaram-se duas formulações diferentes de singás, duas condições de pH para a cultura do microrganismo e o efeito da suplementação do meio com acetato de sódio (NaAc). Foi observada uma assimilação mais rápida do CO por B. methylotrophicum acompanhada por crescimento celular. A assimilação de CO2 foi limitada pela disponibilidade de H2. O microrganismo produziu maioritariamente ácido acético, mas a razão butirato/acetato aumentou significativamente após suplementação do meio de cultura com NaAc. O valor mais elevado de fixação de carbono do singás por B. methylotrophicum foi de 87 %(mol/mol). Este trabalho veio demonstrar o potencial da fermentação de singás para a fixação biológica de carbono na forma de ácidos orgânicos como possíveis precursores de combustíveis avançados, por ex. ácido butírico para esterificação a butil-butirato.