The use of Isopropyl β-D-1-thiogalactopyranoside (IPTG) has been the primary method to induce recombinant protein synthesis in systems operating with the lac repressor. However, IPTG has limitations due to its toxicity to cells as well as its cost. This poster aims to present that milk permeate (MP), a waste product of the dairy industry that is produced when milk is filtered to remove most of its fat, is a viable alternative to IPTG.
As the biotechnology industry continues to grow, competition raises the bar to find cheaper and more sustainable alternatives to currently used practices. The most popular inducer of recombinant protein synthesis, namely IPTG, has an astonishing cost of around 100$ per gram. On the other hand, the price of MP is as low as 10$ per 25 kg. Thus, using MP alleviates the cost issues arising from the use of IPTG while adhering to circular economy principles.
It has been shown that IPTG not only itself is toxic, but also exacerbates the toxicity of substrates, causing additional stress to host cells, whereas using the natural inducer of P lac drastically alleviates the stress without compromising the efficiency of induction [1]. Milk permeate, primarily composed of lactose, is thought to have similar stress alleviation to that of lactose when compared to IPTG, thus MP appears to be a better alternative to IPTG especially for longer induction times.
In this study, experiments using MP as an inducer for recombinant protein synthesis were carried out. First, optimal conditions for recombinant synthesis were found, followed by experiments which revealed that MP indeed produces recombinant proteins, using two control inducers: lactose and IPTG. Synthesis induction of a variety of recombinant proteins was performed, their length varied from 23 kDa to 99 kDa. As the synthesized recombinant proteins were enzymes, it was additionally shown that the proteins resulting from the induction with MP were active, using Zymography methods.