We build parts for decolor-assistant proteins(ManA1, ArfB, XynB) to assemble decolor-assistant machines. Compared to existing decolor-assistant proteins, our proteins can work at high temperature and have synergistic effects, which may be useful in paper industry.

ManA1, ArfB, XynB are three genes each encoding an enzyme (three types of xylanase). With help of these proteins, the pulp(which then become paper) can be bleached by only little chemical reagent. Since using less chemical reagent(especially the chlorinated) can help protect the environment, nowadays enzyme-assisted bleaching method is getting popular in paper making industry.

In our project, we build parts for three decolor-assistant proteins(ManA1, ArfB, XynB) to assemble three decolor-assistant machines. Through experiments, we confirm their decolor-assistant function, and we observe their heat-resistant property and synergistic effect.

To better understand the bio-assistant trend in paper industry, we also talk to local paper factory (we asked for a visit, but they all refused us. Some said this is the secret, and other suggested they are under emission standard). At the same time, we tightly communicate with several iGEM teams to improve our idea and appreciate their work. This is our first time to join the iGEM competition, and we hope we can have fun and get inspired in the following months.

Paper Industry

Conventionally, the bleaching of digested pulp by chlorine has implied the generation of adsorbable organic halogen (AOX) which is problematic for biological wastewater treatment due to its high toxicity and low biodegradability.

Couples of years ago, people found Enzymes (xylanases) can be used as biotechnological alternative in the bleaching of pulp and lowers the cholorine comsumption. When the xylanases are mixed into the pulp kept in a holding tank for 1-3 hours, the pulp is bleached in the normal way.

Flow Chart Of Paper Bleaching R.C. Kuhad, Ajay Singh, Lignocellulose Biotechnology Future Prospects, 2007

But xylanase from different host requires different working conditions. Many people are seeking a kind of xylanase which can work in high temperature and under alkaline conditions.

Availability of the enzyme that is cellulase-free, working at temperature above 80°C and pH >8.0 would be very beneficial. In this respect, the thermostable and alkalistable xylanases have high potential in pulp bleaching process in paper industry.

R.C. Kuhad, Ajay Singh, Lignocellulose Biotechnology Future Prospects, 2007 Sierra et al, 1994

And this is what our enzyme can do. In our experiment, the enzyme can work high temperature, even in 94.7°C! Due to time limit, other properties (Such as synergistic effect and alkalistability) of our enzyme are still under validation.

Future Resouce

Besides useful in paper industry, our enzyme may be useful in the field of future resources. Recently some people think lignocellulosic biomass is very promising to be a clean resource of fuel. The conversion is based on pretreatment of lignin, and this is exactly what our enzyme can do.

Therefore, the challenges involved in the production of lignocellulosic biomass derived fuels and chemicals must be addressed. The search for economic pretreatment methods has been recognized as one of the main hurdles for the processing of biomass to biofuels and chemicals. The conversion of all biomass components, lignin in particular, would greatly contribute to the economic viability of biomass based processes for 2nd generation biofuels and chemicals.

Lignocellulose processing: a current challenge in ROYAL SOCIETY OF CHEMISTRY

In fact, Someone had already used xylanase (the enzyme is the same as ours, but different in natural host) to assemble a pretreatment machine.

Recently, Morais et al. have integrated six dockerin-bearing cellulases and xylanases from the highly cellulolytic bacterium, Thermobifida fusca, into a chimeric scaffolding, engineered to bear a cellulose-binding module and the appropriate matching cohesin modules. The resultant hexavalent designer cellulosome was fully functional and achieved enhanced levels (up to 1.6-fold) of untreated wheat straw degradation compared to those of the wild-type free enzymes.

Lignocellulose processing: a current challenge in ROYAL SOCIETY OF CHEMISTRY S. Morais, E. Morag and E. A. Bayer, mBio, 2012, 3(6), e00508–00512.

Therefore, to the best of our knowledge, our project may be beneficial to industrial paper bleaching and future resource development.