Giacobbe Simona, Piscitelli Alessandra, Raganati Francesca, Lettera Vincenzo, Sannia Giovanni, Marzocchella Antonio, Pezzella Cinzia
Biopox srl, Via Salita Arenella 9, Naples, Italy.
2Dipartimento di Scienze chimiche, Università degli Studi di Napoli"Federico II", Via Cintia 4, 80126 Naples, Italy.
Biotechnol Biofuels. 2019 Mar 5;12:47. doi: 10.1186/s13068-019-1383-1. eCollection 2019.
Beer is the most popular alcoholic beverage worldwide. In the manufacture of beer, various by-products and residues are generated, and the most abundant (85% of total by-products) are spent grains. Thanks to its high (hemi)cellulose content (about 50% w/w dry weight), this secondary raw material is attractive for the production of second-generation biofuels as butanol through fermentation processes.
This study reports the ability of two laccase preparations from to delignify and detoxify milled brewer's spent grains (BSG). Up to 94% of phenols reduction was achieved. Moreover, thanks to the mild conditions of enzymatic pretreatment, the formation of other inhibitory compounds was avoided allowing to apply the sequential enzymatic pretreatment and hydrolysis process (no filtration and washing steps between the two phases). As expected, the high detoxification and delignification yields achieved by laccase pretreatment resulted in great saccharification. As a fact, no loss of carbohydrates was observed thanks to the novel sequential strategy, and thus the totality of polysaccharides was hydrolysed into fermentable sugars. The enzymatic hydrolysate was fermented to acetone-butanol-ethanol (ABE) by obtaining about 12.6 g/L ABE and 7.83 g/L butanol within 190 h.
The applied sequential pretreatment and hydrolysis process resulted to be very effective for the milled BSG, allowing reduction of inhibitory compounds and lignin content with a consequent efficient saccharification. was able to ferment the BSG hydrolysate with ABE yields similar to those obtained by using synthetic media. The proposed strategy reduces the amount of wastewater and the cost of the overall process. Based on the reported results, the potential production of butanol from the fermentation of BSG hydrolysate can be envisaged.
啤酒是全球最受欢迎的酒精饮料。在啤酒生产过程中，会产生各种副产品和残渣，其中最丰富的（占副产品总量的85%）是谷皮。由于其高（半）纤维素含量（约占干重的50% w/w），这种二次原料对于通过发酵过程生产第二代生物燃料如丁醇具有吸引力。
本研究报道了两种漆酶制剂对研磨后的啤酒糟（BSG）进行脱木质素和解毒的能力。酚类物质减少了高达94%。此外，由于酶预处理条件温和，避免了其他抑制性化合物的形成，从而可以应用顺序酶预处理和水解过程（两阶段之间无需过滤和洗涤步骤）。正如预期的那样，漆酶预处理实现的高解毒和脱木质素产率导致了高效的糖化。事实上，由于采用了新颖的顺序策略，未观察到碳水化合物的损失，因此所有多糖都被水解成了可发酵糖。酶水解产物通过发酵生成丙酮-丁醇-乙醇（ABE），在190小时内获得了约12.6 g/L的ABE和7.83 g/L的丁醇。
所应用的顺序预处理和水解过程对研磨后的BSG非常有效，能够减少抑制性化合物和木质素含量，从而实现高效糖化。能够发酵BSG水解产物，其ABE产率与使用合成培养基获得的产率相似。所提出的策略减少了废水量和整个过程的成本。基于报道的结果，可以设想从BSG水解产物的发酵中潜在生产丁醇。
