ProGreS 3rd Workshop (IProPBio Workshop Series): From biomass characterization to process synthesis
ProGreS 3rd Workshop (IProPBio Workshop Series): From biomass characterization to process synthesis. Universidad de Salamanca, 3-4 noviembre, Salamanca (España).
Hijosa-Valsero, María; Paniagua-García, Ana I.; Díez-Antolínez, Rebeca. Winery by-products as feedstocks for bioprocesses.
The Spanish winery industry produced 3.701 ML wine and 745 ML grape must in 2021, with a total vineyard surface of 930.889 ha (MAPA, 2021). Alone in the region of Castile and Leon, it is estimated that winery activities generated 165.699 t vine shoots, 67.846 t grape marc, 13.569 t grape stalks and 5.088 t wine lees in the campaign of 2019-2020 (BIOVINO, 2021). This biomass is frequently underused or discarded. In addition, wine surplus or grape must surplus can suppose a commercial problem due to market imbalances (Hijosa-Valsero et al., 2021a).
The aim of the project BIOVINO is to valorise winery by-products by developing new models of multiproduct biorefinery. These feedstocks could be an interesting substrate for microbially-mediated bioprocesses, since they contain carbohydrates and nitrogen, which are essential for microbial growth. Therefore, the suitability of winery by-products was assessed for the production of alcohols (butanol), polyols (erythritol and mannitol) and organic acids (lactic acid and succinic acid) by various bacteria and fungi.
It should be noted that every type of winery by-product has its particular chemical composition. Lignocellulosic biomass, such as vine shoots, grape marc or grape stalks, contain important amounts of carbohydrates in the form of cellulose and hemicellulose, which cannot be directly metabolised by most fermentative microorganisms. In order to release simple sugars from cellulose and hemicellulose fibres, pretreatments involving physicochemical actions and/or enzymatic hydrolysis must be applied, thus complicating the general process. Contrarily, other feedstocks, such as surplus grape must, contain available simple sugars that are readily transformable by microorganisms. Furthermore, wine lees possess important amounts of organic nitrogen and could be employed as nutritional supplement in microbial processes.
Consequently, after a physicochemical pretreatment and an enzymatic hydrolysis, vine shoots were fermented by different microorganisms, yielding 8 g/L butanol with Clostridium beijerinckii (Garita-Cambronero et al., 2021a), 29 g/L lactic acid with Bacillus coagulans (Garita-Cambronero et al., 2021b) and 21 g/L succinic acid with Actinobacillus succinogenes (Hijosa-Valsero et al., 2022). In the case of lactic acid production, wine lees were efficiently employed as the only nitrogen source during the fermentation. On the other hand, surplus grape musts, which are directly fermentable, were successfully used to obtain 96 g/L erythritol with Moniliella pollinis (Hijosa-Valsero et al., 2021a), 80 g/L mannitol with Lactobacillus intermedius (Hijosa-Valsero et al., 2021b) and 89 g/L succinic acid with A. succinogenes (Hijosa-Valsero et al., 2022). The addition of wine lees as nitrogen source for mannitol production allowed a correct fermentation, although production yields decreased.
Accordingly, these results pave a promising way for the future founding of biorefineries based on winery by-products, in the framework of a circular economy perspective.
Acknowledgements: This study was funded by the European Regional Development Fund (ERDF) within the programme Interreg V-A España-Portugal (POCTEP) 2014-2020 through the project BIOVINO (0688_BIOVINO_6_E).
References
- BIOVINO, 2021, Prospección de residuos y subproductos del sector vitivinícola en Castilla y León. Potencial para su valorización mediante procesos de biorrefinería. https://biovino.es/informe-sobre-los-residuos-vitivinicolas-en-castilla-y-leon-espana/.
- J. Garita-Cambronero et al., 2021a, Biobutanol production from pruned vine shoots, Renewable Energy, 177, 124-133. https://doi.org/10.1016/j.renene.2021.05.093.
- J. Garita-Cambronero et al., 2021b, Revisiting the production of L( +)-lactic acid from vine shoots: bioconversion improvements by employing thermotolerant bacteria, Applied Microbiology and Biotechnology, 105, 9385–9402. https://doi.org/10.1007/s00253-021-11693-1.
- M. Hijosa-Valsero et al., 2021a, By-products of sugar factories and wineries as feedstocks for erythritol generation, Food and Bioproducts Processing, 126, 345-355. https://doi.org/10.1016/j.fbp.2021.02.001.
- M. Hijosa-Valsero et al., 2021b, Mannitol bioproduction from surplus grape musts and wine lees, LWT, 151, 112083. https://doi.org/10.1016/j.lwt.2021.112083.
- M. Hijosa-Valsero et al., 2022, Assessment of vine shoots and surplus grape must for succinic acid bioproduction, Applied Microbiology and Biotechnology. https://doi.org/10.1007/s00253-022-12063-1.
- MAPA, 2021, Superficies y producciones anuales de cultivos, Avance de datos de viñedo 2021, https://www.mapa.gob.es/es/estadistica/temas/estadisticas-agrarias/agricultura/superficies-producciones-anuales-cultivos/ .
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