Ectoine, a cyclic amino acid derivative of aspartate, is a natural stabiliser of proteins, nucleic acids and the cell membrane found in a wide range of bacteria. It helps organisms survive salt, drought, high or freezing temperatures, and other environmental stresses. These days, ectoine is exploited as a bioactive ingredient in cosmetics to protect the skin from UV irradiation and dryness. It is also an active component in some healthcare products. However, challenges around scaling up its industrial production are proving a big obstacle for companies keen to benefit from its many properties.
Commercial ectoine is traditionally produced via ‘bacterial milking’ of the halophilic bacterium Halomonas elongate. This involves repeatedly exposing it to high salinity and low salinity culture mediums. In contrast, biotechnologically engineering the typical industrial strains, such as Escherichia coli (E. coli) or Corynebacterium glutamicum, to produce ectoine under mild cultivation, avoids the application of high salinity and simplifies the production procedure.
A study published in the KeAi journal Green Chemical Engineering, has reported the biotechnological construction of an efficient ectoine cell factory based on E. coli BL21(DE3). Using metabolic engineering, researchers synthesised the ectoine with the E. coli, using glucose as the sole carbon source. By reconstructing the ectoine synthetic pathway, and enhancing the biosynthesis of ectoine precursor in E. coli, a high level of 60.7 g/L of ectoine was produced using a fed-batch fermentation approach.
Co-corresponding author Zhen Kang, from Jiangnan University in China, explains: “E. coli is one of the most widely-used industrial bacteria. Its genetic background and metabolic pathways are well studied. There are also sophisticated and easy-to-operate cultivation procedures. Using E. coli in this process increases the efficiency of the ectoine production process. In addition, the recombinant strain displays better growth and higher productivity compared with other ectoine-producing strains. Importantly, it also doesn’t knock out genomic genes and is therefore more genetically stable.”