http://hdl.handle.net/10854/6545 2026-04-17T10:27:10Z http://hdl.handle.net/10854/6606 Integrated solid-state enzymatic hydrolysis and solid-state fermentation for producing sustainable polyhydroxyalkanoates from low-cost agro-industrial residues Martínez-Avila, Oscar; Llimós Turet, Jordi; Ponsá Salas, Sergio Polyhydroxyalkanoates (PHA) are biodegradable bioplastics of interest as potential substitutes of petroleum-derived plastics that can be produced starting from lignocellulosic-derived residues. This study presents the combined solid-state enzymatic hydrolysis (SSEH) and solid-state fermentation (SSF) as a sustainable approach for obtaining PHA using the leftovers brewer's spent grain (BSG), grape pomace (GP) and olive-mill solid waste (OSW) as substrates. SSEH performance was influenced by the intrinsic characteristics of each residue, the temperature, and the type of enzymatic extract used. Thus, the maximum sugars release (0.16 g g-1 of dry residue (gTS)) was obtained with GP. Furthermore, coupling SSEH and SSF promoted PHA yield increases of up to 54%, 41% and 31% for BSG, GP and OSW respectively, compared to SSF alone. The maximum PHA yield was achieved using hydrolyzed BSG with 12.5 mg g-1TS (0.33 g kg-1 h-1). Results show the potential of this approach as an attractive alternative to obtain bioproducts such as PHA sustainably in residue-based systems. 2021-01-01T00:00:00Z http://hdl.handle.net/10854/6605 Brewer’s spent grain as a no-cost substrate for polyhydroxyalkanoates production: assessment of pretreatment strategies and different bacterial strains Corchado-Lopo, Carlos; Martínez-Avila, Oscar; Marti Serrano, Elisabet; Llimós Turet, Jordi; Busquets Monsó, Anna M.; Kucera, Dan; Obruca, Stanislav; Llenas, Laia; Ponsá Salas, Sergio Polyhydroxyalkanoates (PHAs) are polyesters of significant interest due to their biodegradability and properties similar to petroleum-derived plastics, as well as the fact that they can be produced from renewable sources such as by-product streams. In this study, brewer’s spent grain (BSG), the main by-product of the brewing industry, was subjected to a set of physicochemical pretreatments and their effect on the release of reducing sugars (RS) was evaluated. The RS obtained were used as a substrate for further PHA production in Burkholderia cepacia, Bacillus cereus, and Cupriavidus necator in liquid cultures. Although some pretreatments proved efficient in releasing RS (acidthermal pretreatment up to 42.1 gRS L-1 and 0.77 gRS g-1 dried BSG), the generation of inhibitors in such scenarios likely affected PHA production compared with the process run without pretreatment (direct enzymatic hydrolysis of BSG). Thus, the maximum PHA accumulation from BSG hydrolysates was found in the reference case with 0.31 ± 0.02 g PHA per g cell dried weight, corresponding to 1.13 ± 0.06 g L-1 and a PHA yield of 23 ± 1 mg g-1 BSG. It was also found that C. necator presented the highest PHA accumulation of the tested strains followed closely by B. cepacia, reaching their maxima at 48 h. Although BSG has been used as a source for other bioproducts, these results show the potential of this by-product as a no-cost raw material for producing PHAs in a waste valorization and circular economy scheme. 2021-01-01T00:00:00Z http://hdl.handle.net/10854/6547 Brewer’s spent grain biotransformation to produce lignocellulolytic enzymes and polyhydroxyalkanoates in a two-stage valorization scheme Llimós Turet, Jordi; Martínez-Avila, Oscar; Marti Serrano, Elisabet; Corchado-Lopo, Carlos; Llenas, Laia; Ponsá Salas, Sergio; Gea Leiva, Teresa Lignocellulolytic enzymes from low-cost sources are gaining attention as a tool to reduce production costs. Such enzymes can be obtained sustainably by diverse fungal strains via solid-state fermentation (SSF) of lignocellulosic-derived residues as substrates. Besides, these enzymes allow hydrolyzing the same residue, releasing fermentable sugars that can be transformed into value-added products. This study shows a two-stage valorization approach for the lignocellulosic leftover brewer’s spent grain (BSG): first, by producing lignocellulolytic enzymes through the SSF of BSG using three fungal strains and, second, by using the self-produced enzymes to hydrolyze the same BSG and obtaining sugar-rich hydrolysates that serve as an alternative carbon source for polyhydroxyalkanoates (PHA) production. From the evaluated set, Aspergillus niger and Thermoascus aurantiacus produced the highest xylanase activities compared with Trichoderma reesei (268 ± 24, 241 ± 10, and 150 ± 24 U per gram of dry BSG, respectively). Also, A. niger extracts resulted in the most effective for releasing sugars from BSG, obtaining up to 0.56 g per gram of dry BSG after 24 h without any pretreatment needed. Thus, the sugar-rich hydrolysate obtained with A. niger was used as a source for producing PHA by using two bacterial strains, namely, Burkholderia cepacia and Cupriavidus necator. Maximum PHA yield was achieved by using C. necator after 48 h with 9.0 ± 0.44 mg PHA·g−1 dry BSG. These results show the significant potential of BSG as raw material for obtaining value-added bioproducts and the importance of multiple valorization schemes to improve the feasibility of similar residue-based systems. Llimos, J., Martinez-Avila, O., Marti, E., Corchado-Lopo, C., Llenas, L., Gea, T., Ponsa S. (2020). Brewer's spent grain biotransformation to produce lignocellulolytic enzymes and polyhydroxyalkanoates in a two-stage valorization scheme . Biomass Conversion and Biorefinery , ( ), 0-0. doi: 10.1007/s13399-020-00918-4. 2020-01-01T00:00:00Z http://hdl.handle.net/10854/6546 Evaluation of Pre-treatments of Brewery’s Spent Grain for Growing Bacteria in the Production of Polyhydroxyalkanoates Mendez, Daniel A.; Marti Serrano, Elisabet; Puyuelo Sánchez, Belén; Colón Jordà, Joan; Ponsá Salas, Sergio A suitable solution to solve the problems related to the conventional plastics is their replacement by biodegradable materials with similar properties such as polyhydroxyalkanoates (PHAs). PHAs can be produced by microorganisms using abundant low-cost substrates such as brewery’s spent grain (BSG). In this work, different pre-treatments were tested on BSG to improve the growth and production of biomass using three different strains highly recognized for their ability to produce PHA. A solid-state fermentation (SSF) was carried out to evaluate PHA production. An evaluation of biomass growth kinetics of the three selected bacteria was made after different hydrolytic pre-treatments of BSG. Results showed that bacteria did not grow in control BSG and the pre-treatments were necessary to release the principal substrate metabolised by bacteria. The best result was obtained with alkali pre-treatment although microwave pre-treatment showed good results too. The strains P. putida and C. necator showed productions of 1.95 and 1.45 mg biomass/g BSG and viable cell counts of 1.5 E+16 and 1.3 E+08 CFU/g BSG after 72 hours of SSF, respectively. On the other hand, Bacillus cereus was not able to grow in the pre-treated substrates. BSG is a promising substrate for bacterial growth and PHA production for its nutrient content. 2018-01-01T00:00:00Z