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.

低成本来源的木质纤维素分解酶作为降低生产成本的工具正受到关注。此类酶可以通过木质纤维素衍生的残基作为底物的固态发酵（SSF）由各种真菌菌株持续获得。此外，这些酶还可以水解相同的残基，释放出可发酵的糖，这些糖可以转化为增值产品。这项研究显示了木质纤维素剩余啤酒酿造商的废粮（BSG）的两阶段增值方法：首先，通过使用三种真菌菌株通过BSG的SSF生产木质纤维素分解酶，其次，使用自产的酶水解相同的BSG并获得富含糖的水解产物，该产物可作为聚羟基链烷酸酯（PHA）生产的替代碳源。从评估集中与里氏木霉（Trichoderma reesei）相比，黑曲霉和金黄色嗜热菌产生最高的木聚糖酶活性（分别为每克干BSG 268±24、241±10和150±24 U）。同样，黑曲霉提取物导致最有效的从BSG中释放糖分，在24小时后无需任何预处理即可获得每克干BSG高达0.56 g的糖。因此，利用黑曲霉获得的富含糖的水解产物被用作通过使用两种细菌菌株即洋葱伯克霍尔德氏菌和硝化铜菌而产生PHA的来源。通过使用C. necator获得最大的PHA产量48小时后，用9.0±0.44mg PHA·g ^-1干BSG。这些结果表明，BSG作为获得增值生物产品的原材料具有巨大的潜力，并且有多种增值方案对于提高类似基于残渣的系统的可行性的重要性。