Centre of Biological Engineering of the University of Minho

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Publications

Single-Cell Oil Production by Engineered Ashbya gossypii from Non-Detoxified Lignocellulosic Biomass Hydrolysate

Publication . Francisco, Miguel; Aguiar, Tatiana Q.; Abreu, Gabriel; Marques, Susana; Gírio, Francisco; Domingues, Lucília

ABSTRACT: In this work, microbial lipid production from non-detoxified Eucalyptus bark hydrolysate (EBH) with oleaginous xylose-utilizing Ashbya gossypii strains was explored. The best producing strain from a set of engineered strains was identified in synthetic media mimicking the composition of the non-detoxified EBH (SM), the lipid profile was characterized, and yeast extract and corn steep liquor (CSL) were pinpointed as supplements enabling a good balance between lipid accumulation, biomass production, and autolysis by A. gossypii. The potential of the engineered A. gossypii A877 strain to produce lipids was further validated and optimized with minimally processed inhibitor-containing hydrolysate and high sugar concentration, and scaled up in a 2 L bioreactor. Lipid production from non-detoxified EBH supplemented with CSL reached a lipid titer of 1.42 g/L, paving the way for sustainable single-cell oil production within the concept of circular economy and placing lipids as an alternative by-product within microbial biorefineries.

2023-09Journal article

Open access

Biomass and microbial lipids production by Yarrowia lipolytica W29 from eucalyptus bark hydrolysate

Publication . Dias, Bruna; Lopes, Marlene; Fernandes, Helena; Marques, Susana; Gírio, Francisco; Belo, Isabel

ABSTRACT: Using lignocellulosic biomass hydrolysate as a renewable and abundant feedstock for microbial lipids production is a sustainable and economic high-potential approach. This study investigated the potential of the oleaginous yeast Yarrowia lipolytica to produce lipids-rich biomass from eucalyptus bark hydrolysate (EBH) obtained by enzymatic hydrolysis of the biomass pretreated by steam explosion. The effect of EBH concentration (undiluted and 1:3 v/v diluted) and medium supplementation (CSL and KH2PO4) was evaluated in Erlenmeyer flasks and lab-scale stirred tank bioreactor, respectively. Additionally, the effect of volumetric oxygen transfer coefficient (kLa) and mode of operation (batch and two-stage repeated batch) was also assessed in the bioreactor. Under the best experimental conditions (undiluted EBH, 2 g center dot L-1 CSL, 1.8 g center dot L-1 (NH4)2SO4, and kLa of 66 h-1), Y. lipolytica W29 grown in batch cultures accumulated 26 % (w/w) of intracellular lipids, corresponding to 5.6 g center dot L-1 of concentration. Lipids of Y. lipolytica were highly unsaturated and mainly composed of oleic acid (48 %), followed by palmitoleic (20 %), linoleic (17 %) and palmitic acids (14 %). This composition of Y. lipolytica lipids suggests their potential use as feedstock for biodiesel (a renewable biofuel). This work demonstrated the robust features of Y. lipolytica W29 as a potential lipids production platform to implement lignocellulose-based biorefineries.

2024-04Journal article

Open access

Optimizing bacterial nanocellulose production from eucalyptus bark: A circular approach to wastewater management and resource recovery

Publication . Rodrigues, Ana Cristina; Martins, Daniela; Duarte, Maria Salomé; Marques, Susana; Gama, Miguel; Dourado, Fernando; Carvalho, Ricardo; Cavaleiro, Ana

ABSTRACT: The production cost of bacterial nanocellulose (BNC) is a major limitation to its widespread use. However, this limitation can be addressed by using alternative low-cost substrates and high-yield strains. Agro-industrial wastederived substrates offer a cost-effective and sustainable solution, but their high organic load often requires additional downstream wastewater treatments. Here, we optimized static BNC production using eucalyptus bark hydrolysate (EBH) as a low-cost carbon source and proposed a circular approach for wastewater management. Optimization was performed using response surface methodology - central composite design. The optimized EBH medium yielded a 39.7-fold increase compared to standard medium, with a maximum BNC production of 8.29 f 0.21 g/L. Fermentation wastewater only (WaF) and combined with BNC washing streams (WaW) revealed high levels of organic matter, namely chemical oxygen demand (COD) of 159.0 f 2.0 and 41.1 f 0.3 g/L, and volatile solids (VS) of 99.5 f 0.9 and 26.3 f 0.2 g/L, respectively, requiring treatment before disposal. A sequential anaerobic-aerobic digestion was investigated for wastewater treatment and valorisation. Anaerobic digestion proved to be effective in treating the wastewater: methanization percentages over 87 % were achieved, and methane productions of 486 f 2 and 544 f 30 L/kg VS were obtained from WaF and WaW, respectively. Subsequent aerobic treatment was unsuccessful in further reducing COD levels (approximately 1.5 g/L). Notably, treated wastewater was recycled into the production process up to 45 % without affecting the BNC yield. This study provides valuable insights into the optimization of BNC production from lignocellulosic biomass and the management of wastewater streams, contributing to the development of a more sustainable and economically viable process.

2025-01Journal article

Open access