CIRIAF, Interuniversity Research Centre on Pollution and Environment "M.Felli", University of Perugia, Via G. Duranti 67, Perugia 06125, Italy.
University of Perugia, Piazza Università 1, Perugia 06123, Italy.
Enzyme Microb Technol. 2024 Dec;181:110516. doi: 10.1016/j.enzmictec.2024.110516. Epub 2024 Sep 17.
The extensive utilization of conventional plastics has resulted in a concerning surge in waste. A potential solution lies in biodegradable polymers mostly derived from renewable sources. Cupriavidus necator DSM 545 is a microorganism capable, under stress conditions, of intracellularly accumulating Poly(3-hydroxybutyrate) (PHB), a bio-polyester. This study aimed to identify optimal conditions to maximize the intracellular accumulation of PHB and its global production using natural media obtained by processing lignocellulosic residues of cardoon, a low-cost feedstock. An intracellular PHB accumulation was observed in all of the tested media, indicating a metabolic stress induced by the lack of macronutrients. Increasing C/N ratios led to a significant decrease in cellular biomass and PHB production. Furthermore C. necator DSM 545 was incapable of consuming more than 25 g/L of supplied monosaccharides. Surprisingly, in the samples supplied with 60 % of the pentose-rich liquid fraction, complete consumption of xylose was observed. This result was also confirmed by subsequent tests using Medium 1 growth media containing xylose as the sole carbon source. Using a diluted medium with a C/N ratio of 5, a PHB production of 5.84 g/L and intracellular PHB accumulation of 77 % w/w were respectively achieved. Finally, comparative shelf-life tests conducted against conventional pre-packaging materials in PP suggested that PHB films performed similarly in preserve ready-to-eat products.
传统塑料的广泛使用导致了废物的大量增加。一种潜在的解决方案是使用生物可降解聚合物，这些聚合物主要来自可再生资源。节杆菌（Cupriavidus necator）DSM 545 是一种微生物，在应激条件下能够在细胞内积累聚 3-羟基丁酸酯（PHB），这是一种生物聚酯。本研究旨在确定最佳条件，以最大限度地利用天然介质在细胞内积累 PHB 及其全球产量，这些天然介质是通过加工蓟的木质纤维素残渣获得的，蓟是一种低成本的原料。在所有测试的介质中都观察到了细胞内 PHB 的积累，这表明由于缺乏大量营养素而导致代谢应激。增加 C/N 比会导致细胞生物量和 PHB 产量的显著下降。此外，节杆菌（C. necator）DSM 545 无法消耗超过 25 g/L 的供应单糖。令人惊讶的是，在供应 60%戊糖丰富的液体部分的样品中，观察到木糖的完全消耗。这一结果也通过随后使用含有木糖作为唯一碳源的 Medium 1 生长培养基进行的测试得到了证实。使用 C/N 比为 5 的稀释培养基，分别实现了 5.84 g/L 的 PHB 产量和 77%w/w 的细胞内 PHB 积累。最后，与 PP 中的传统预包装材料进行的货架期比较测试表明，PHB 薄膜在保存即食产品方面表现相似。
