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Research Project
Biomass and Bioenergy Research Infrastructure
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Impact of brewery wastewater inhibitors in pure and mixed cultures of the yeast Rhodosporidium toruloides NCYC 921 and the microalga Tetradesmus obliquus ACOI 204/07
Publication . Dias, Carla; Santos, J. A. L.; Reis, Alberto; Silva, Teresa Lopes da
ABSTRACT: Brewery wastewater (BWW) is an appealing low-cost substrate for the production of single cell oils by oleaginous microorganisms. However, it may contain inhibitor compounds that may affect the microbial metabolism. This work investigated, for the first time, the presence of potential inhibitor compounds in primary brewery wastewater (PBWW) and secondary brewery wastewater (SBWW) for the pure and mixed cultivation of the yeast Rhodosporidium toruloides NCYC 921 and the microalga Tetradesmus obliquus ACOI 204/07. Three organic acids (OrgAc) were identified in the brewery effluents (acetic, propionic and butyric acids). Yeast and microalga pure and mixed cultivations were performed in PBWW and SBWW in order to understand the behaviour of the microorganisms, individually and together. Flow cytometry (FC) was used to monitor each microbial population during the mixed cultivations, and to study the yeast and microalga cell viability throughout all cultivations. The yeast cells in pure cultures grown in both effluents were severely affected by the OrgAc presence confirmed by the cell stress results obtained by FC. However, in the mixed cultures, the yeast cells were able to develop, and the levels of stress conditions were considerably lower. Only in microalga pure and mixed cultures efficient OrgAc removal was observed.
The Role of Mild Alkaline Pretreatment in the Biorefinery Upgrade of Spent Coffee Grounds
Publication . Ribeiro, Gabriel Mota; Martins, Pedro L.; Oliveira, Ana Cristina; Carvalheiro, Florbela; Fragoso, Rita; Duarte, Luís C.
ABSTRACT: This work proposes a valorization route for spent coffee grounds (SCG), a widespread lignocellulosic residue, encompassing the production of: biomethane, lignin, and oligosaccharides as value-added products obtained simultaneously during a mild alkaline (NaOH) pretreatment. The studied operational variables were the reaction time (60-240 min), temperature (25-75 degrees C), and the NaOH concentration (0-2.5 M). The severity factor suitably describes the global process kinetics, with higher severities (log Mo = 5.5) yielding high product yields, 18.02% and 13.25% (on dry SCG basis) for lignin and oligosaccharides (XGMOS), respectively. Solid yield is negatively impacted by all studied variables (at the 95% confidence level). Conversely, XGMOS yield is positively influenced both by time and catalyst concentration, whereas lignin yield is only (positively) influenced by catalyst concentration. Optimal balance between product formation and potential operational costs is putatively achieved when using 0.625 M NaOH, at 50 degrees C for 60 min. The mild alkaline pretreated biomass (MAP-SCG) was compared to untreated SCG for biomethane production by anaerobic co-digestion with pig slurry (PS), using a ratio of biomass/PS = 1/3 (volatile solids (VS) basis). The proposed valorization route enabled the sequential production of 6.25 kg lignin, 6.36 kg oligosaccharides, and 138.05 kg biomethane per 100 kg of non-extracted SCG (and 287.60 kg pig slurry), in an integrated process that is technically feasible and promotes the circular bioeconomy.
Production of Mannosylerythritol Lipids Using Oils from Oleaginous Microalgae: Two Sequential Microorganism Culture Approach
Publication . Nascimento, Miguel Figueiredo; Coelho, Tiago; Reis, Alberto; Gouveia, Luisa; Faria, Nuno Torres; Ferreira, Frederico Castelo
ABSTRACT: Mannosylerythritol lipids (MELs) are biosurfactants with excellent biochemical properties and a wide range of potential applications. However, most of the studies focusing on MELs high titre production have been relying in the use of vegetable oils with impact on the sustainability and process economy. Herein, we report for the first time MELs production using oils produced from microalgae. The bio-oil was extracted from Neochloris oleoabundans and evaluated for their use as sole carbon source or in a co-substrate strategy, using as an additional carbon source D-glucose, on Moesziomyces spp. cultures to support cell growth and induce the production of MELs. Both Moesziomyces antarcticus and M. aphidis were able to grow and produce MELs using algae-derived bio-oils as a carbon source. Using a medium containing as carbon sources 40 g/L of D-glucose and 20 g/L of bio-oils, Moesziomyces antarcticus and M. aphidis produced 12.47 +/- 0.28 and 5.72 +/- 2.32 g/L of MELs, respectively. Interestingly, there are no significant differences in productivity when using oils from microalgae or vegetable oils as carbon sources. The MELs productivities achieved were 1.78 +/- 0.04 and 1.99 +/- 0.12 g/L/h, respectively, for M. antarcticus fed with algae-derived or vegetable oils. These results open new perspectives for the production of MELs in systems combining different microorganisms.
Development of an innovative macroalgae biorefinery: Oligosaccharides as pivotal compounds
Publication . Andrade, Cristiana; Martins, Pedro L.; Duarte, Luís C.; Oliveira, Ana Cristina; Carvalheiro, Florbela
ABSTRACT: Macroalgae have significant advantages over land-living biomass resources and are promising pivotal feedstocks for the onset of the blue bioeconomy. Among these, Ulva lactuca has demonstrated a high potential due to its wide distribution and high productivity. In this work, a detailed chemical characterization of U. lactuca enabled the identification of polysaccharides as the main macromolecular component of the organic fraction. They present a high diversity of sugar constituents and hence can be a relevant source of added-value oligosaccharides for the food/feed industries. Four processes, with increasing operational temperatures, were compared for the selective production of oligosaccharides: Conventional Soxhlet Extraction, Accelerated Solvent Extraction, Hydrothermal treatment (HT) and Dilute Acid Hydrolysis (DAH). All processes presented high oligosaccharide/monosaccharide ratios, with HT and DAH exhibiting the highest oligosaccharides yields (10.6 and 16.6 g/100 g initial biomass, respectively). These oligosaccharides were obtained under milder, more economic conditions than the reported for lignocellulosic (land) plants and can represent an important added-value income of the algae biorefineries and thus contribute to their economic sustainability.
Supercritical CO2 extract from microalga Tetradesmus obliquus: the effect of high-pressure pre-treatment
Publication . Vladic, Jelena; Jerkovic, Igor; Radman, Sanja; Jazic, Jelena Molnar; Ferreira, Alice; Maletic, Snezana; Gouveia, Luisa
ABSTRACT: High-pressure pre-treatment followed by supercritical carbon dioxide (ScCO2) extraction (300 bar, 40 degrees C) was applied for the attainment of the lipophilic fraction of microalga Tetradesmus obliquus. The chemical profile of supercritical extracts of T. obliquus was analyzed by ultra-highperformance liquid chromatography-high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). Moreover, the impact of ScCO(2 )on the microbiological and metal profile of the biomass was monitored. The application of the pre-treatment increased the extraction yield approximately three-fold compared to the control. In the obtained extracts (control and pre-treated extracts), the identified components belonged to triacylglyceroles, fatty acid derivatives, diacylglycerophosphocholines and diacylglycerophosphoserines, pigments, terpenes, and steroids. Triacylglycerols (65%) were the most dominant group of compounds in the control extract. The pre-treatment decreased the percentage of triacylglycerols to 2%, while the abundance of fatty acid derivatives was significantly increased (82%). In addition, the pre-treatment led to an increase in the percentages of carotenoids, terpenoids, and steroids. Furthermore, it was determined that ScCO2 extraction reduced the number of microorganisms in the biomass. Considering its microbiological and metal profiles, the biomass after ScCO2 can potentially be used as a safe and important source of organic compounds.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
9444 - RNIIIE
Funding Award Number
PINFRA/22059/2016