Musatti Alida, Ficara Elena, Mapelli Chiara, Sambusiti Cecilia, Rollini Manuela
Università degli Studi di Milano, DEFENS, Section of Food Microbiology and Bioprocessing, Via G. Celoria 2, 20133, Milano, Italy.
Politecnico di Milano, DICA, Environmental Section, Piazza L. da Vinci, 32, 20133, Milano, Italy.
J Environ Manage. 2017 Sep 1;199:1-6. doi: 10.1016/j.jenvman.2017.05.022. Epub 2017 May 15.
Studies were performed on the use of the solid fraction of digestate (D) for the production of lignocellulolytic enzymes (endo- and exo-glucanase, xylanase, β-glucosidase and laccase) by fungi, in comparison with wheat straw (benchmark) (W). To date, this is the first report on the use of such an inexpensive substrate in a liquid environment. Submerged instead of solid state fermentation was applied to overcome pH inhibition and increase surface accessibility. A total of 21 fungal strains were tested: the most performing ones were Irpex lacteus DSM1183 for both β-glucosidase (52 IU/g with D, + 400% compared to W) and endo-glucanase (236 IU/g with D, + 470% compared to W), Schizophyllum commune CBS30132 for xylanase (715 IU/g with W, + 145% compared to D) and Pleurotus ostreatus ATCC96997 for laccase (124 IU/g with D, +230% compared to D). Cultures from S. commune and P. ostreatus were analyzed at the beginning and at the end of the growth test to determine soluble COD, total (TS) and volatile (VS) solids. COD was always lower at the end of the test suggesting a faster uptake than hydrolysis. P. ostreatus evidenced a higher VS reduction (-11% rather than -32%), suggesting a more effective growth of this strain on D. Results may open up new avenues for the utilization of solid digestate, an inexpensive agricultural by-product, for the production of value-added products as well as to increase biodegradation of lignocellulosic materials.
开展了相关研究，以比较真菌利用沼渣固体部分（D）和小麦秸秆（对照物）（W）生产木质纤维素酶（内切葡聚糖酶、外切葡聚糖酶、木聚糖酶、β-葡萄糖苷酶和漆酶）的情况。迄今为止，这是关于在液体环境中使用这种廉价底物的首份报告。采用液体深层发酵而非固态发酵，以克服pH抑制并提高表面可及性。共测试了21种真菌菌株：表现最佳的是产黄纤孔菌DSM1183，其β-葡萄糖苷酶产量（以D为底物时为52 IU/g，相比W提高了400%）和内切葡聚糖酶产量（以D为底物时为236 IU/g，相比W提高了470%）均最高；裂褶菌CBS30132的木聚糖酶产量最高（以W为底物时为715 IU/g，相比D提高了145%）；糙皮侧耳ATCC96997的漆酶产量最高（以D为底物时为124 IU/g，相比D提高了230%）。在生长试验开始和结束时，对裂褶菌和平菇的培养物进行了分析，以测定可溶性化学需氧量、总固体（TS）和挥发性固体（VS）。试验结束时，化学需氧量始终较低，表明吸收速度快于水解速度。平菇的挥发性固体减少量更高（-11%，而非-32%），表明该菌株在D上的生长更有效。这些结果可能为利用固体沼渣（一种廉价的农业副产品）生产高附加值产品以及增强木质纤维素材料的生物降解开辟新途径。
