Department of Agronomy Food natural Resources Animals and Environment (DAFNAE), Università di Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro, PD, Italy.
Department of Agronomy Food natural Resources Animals and Environment (DAFNAE), Università di Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro, PD, Italy.
Bioresour Technol. 2018 Aug;261:176-181. doi: 10.1016/j.biortech.2018.04.021. Epub 2018 Apr 7.
Industrial manufacturing of polyhydroxyalkanoates (PHAs) requires purification of PHAs granules from high-cell-density cultures. Cells are broken by homogenization and PHAs granules are cleansed and treated to obtain PHAs latexes. However, cell lysis releases large amounts of DNA which results in an increasing viscosity of the medium, hampering the following downstream steps. Drop in viscosity is generally achieved by costly procedures such as heat treatment or the supplementation of hypochlorite and commercially available nucleases. Searching for a cost-effective solution to this issue, a nuclease gene from Staphylococcus aureus has been integrated into two efficient PHAs-producing bacteria: Cupriavidus necator DSM 545 and Delftia acidovorans DSM 39. Staphylococcal nuclease has been proficiently expressed in both microbial hosts without affecting PHAs production. Moreover, the viscosity of the lysates of recombinant C. necator cells was greatly reduced, indicating that the engineered strain is expected to yield large reduction cost in PHAs downstream processing.
工业制造聚羟基烷酸酯（PHAs）需要从高细胞密度培养物中纯化 PHA 颗粒。通过匀浆破碎细胞，然后对 PHA 颗粒进行清洗和处理，得到 PHA 乳胶。然而，细胞裂解会释放大量的 DNA，导致介质的粘度增加，从而阻碍后续的下游步骤。通常通过昂贵的处理方法，如热处理或补充次氯酸盐和市售的核酸酶来降低粘度。为了解决这个问题，人们从金黄色葡萄球菌中整合了一个核酸酶基因到两种高效生产 PHA 的细菌中：Cupriavidus necator DSM 545 和 Delftia acidovorans DSM 39。在这两种微生物宿主中，金黄色葡萄球菌核酸酶都得到了高效表达，而不影响 PHA 的生产。此外，重组 C. necator 细胞裂解物的粘度大大降低，表明工程菌株有望在 PHA 下游加工中降低大量成本。
