EXPRELA Group, Centro de Investigacións Científicas Avanzadas (CICA), Facultade de Ciencias, Universidade da Coruña, 15071, A Coruña, Spain.
Microb Cell Fact. 2018 Sep 3;17(1):137. doi: 10.1186/s12934-018-0988-6.
The recycling of agro-industrial wastes is at present limited by the availability of efficient and low-cost enzyme cocktails. The use of these materials as culture media to produce the enzymes can contribute to the profitability of the recycling process and to the circular economy. The aim of this work is the construction of a recombinant yeast strain efficient to grow in mixed whey (residue of cheese making) and beet molasses (residue of sugar manufacture) as culture medium, and to produce heterologous α-galactosidase, an enzyme with varied industrial applications and wide market.
The gene MEL1, encoding the α-galactosidase of Saccharomyces cerevisiae, was integrated (four copies) in the LAC4 locus of the Kluyveromyces lactis industrial strain GG799. The constructed recombinant strain produces high levels of extracellular α-galactosidase under the control of the LAC4 promoter, inducible by lactose and galactose, and the native MEL1 secretion signal peptide. K. lactis produces natively beta-galactosidase and invertase thus metabolizing the sugars of whey and molasses. A culture medium based on whey and molasses was statistically optimized, and then the cultures scaled-up at laboratory level, thus obtaining 19 U/mL of heterologous α-galactosidase with a productivity of 0.158 U/L h, which is the highest value reported hitherto from a cheap waste-based medium.
A K. lactis recombinant strain was constructed and a sustainable culture medium, based on a mixture of cheese whey and beet molasses, was optimized for high productivity of S. cerevisiae α-galactosidase, thus contributing to the circular economy by producing a heterologous enzyme from two agro-industrial wastes.
目前，农业工业废物的回收受到高效、低成本酶混合物的可用性的限制。将这些材料用作生产酶的培养基，可以提高回收过程的盈利能力和循环经济水平。本工作的目的是构建一种重组酵母菌株，该菌株能够在混合乳清（奶酪生产的残留物）和甜菜糖蜜（糖制造的残留物）作为培养基中生长，并生产具有多种工业应用和广泛市场的异源α-半乳糖苷酶。
将编码酿酒酵母α-半乳糖苷酶的基因 MEL1 整合（四个拷贝）到工业菌株 Kluyveromyces lactis GG799 的 LAC4 基因座中。构建的重组菌株在 LAC4 启动子的控制下，在乳糖和半乳糖的诱导下，产生高水平的细胞外α-半乳糖苷酶，并且使用天然的 MEL1 分泌信号肽。K. lactis 天然产生β-半乳糖苷酶和转化酶，从而代谢乳清和糖蜜中的糖。基于乳清和糖蜜的培养基进行了统计学优化，然后在实验室规模上进行培养，从而获得了 19 U/mL 的异源α-半乳糖苷酶，其生产力为 0.158 U/L·h，这是迄今为止从廉价废物基培养基中获得的最高值。
构建了一种 K. lactis 重组菌株，并优化了基于奶酪乳清和甜菜糖蜜混合物的可持续培养基，以获得酿酒酵母α-半乳糖苷酶的高产率，从而通过从两种农业工业废物生产异源酶为循环经济做出贡献。
