Stem Bromelain has always been a very important protease in industrial production. We obtained a more active variant of bromelain by site-directed mutagenesis, which enhanced the reactivity of bromelain with substrate. This enzyme can also be used for the subsequent research and development of bromelain and the exploration of more properties of bromelain by other IGEM teams later. You can see further details and experiment data in the page of Proof of Concept page.

Since bromelain has been widely used in processed feed, we have produced a variant that is more convenient in processing feed and has a greater ability to break down protein, making it easier for livestock to absorb the nutrients in the fodder.

At present, there are three methods to produce bromelain in the Chinese market (kaolin adsorption process, tannin precipitation process and ultrafiltration concentrated organic solvent extraction process). They all have some common shortcomings:

1. They all choose pineapple as raw material, resulting in the yield of bromelain is greatly dependent on the yield of pineapple, this source itself is unstable; At the same time, the use of agricultural products to produce such high value-added products is a kind of occupation and waste of land resources.
2. The current three methods of bromelain production will more or less pollute the environment and do not meet the needs of current sustainable development.

So We have developed a biological way to produce bromelain, which is quick and easy to do without causing pollution.

We first transformed the plasmid with sqr gene and T7 promoter to E.coli BL21(DE3). After appropriate induction by IPTG, SDS-PAGE experiment and Coomassie brilliant blue staining showed that the expression of each target protein could be realized in E.coli BL21(DE3).

SDS-PAGE bands of sqr regulated by T7 promoter with and without IPTG.

As Tongji_China 2021 did last year, we also configured a series of sodium sulfide solutions with concentration gradient and tested them with detection reagents according to certain methods. The standard curve obtained is ideal.

We put the engineered bacteria and wild-type bacteria into a certain concentration of sodium sulfide solution, take out the bacterial solution every 30 min to detect the residual sulfide concentration. It can be concluded from the curve that our engineered bacteria can oxidize sulfide better. (Ps: The bacteria have a certain adsorption effect on sulfide, thus the initial sulfur ion concentration of the two groups of added bacterial solution is lower than blank).