Team:BUAP Mexico/Description
Motivation
Recently the Puebla’s government approved a law to ban the use of plastics package as part of several action to decrease the negative impact caused by this material. On the other hand, Mexico city (cdmx) registered the highest air pollution levels in the last ten years, leading an environmental crisis which affects states around cdmx like Puebla, guerrero, tlaxcala and morelos. At first sight, this phenomena had a negative impact just in people living in this cities, however, based on this situation we decided to look for more information about the indirect effects on the environment and living organisms. Then, we noticed that we just saw the tip of the iceberg and this phenomenon has so many negative impacts but we had special interest in the ocean acidification which is one of the most unstudied and perhaps will be the most dangerous for the marine environment in the future. Then, as students of the faculty of Biological Sciences of the BUAP we decided to try to solve this problem and we looked for different projects that would be related and we found a lot of interesting ideas, but the most remarkable were the project from NCKU Tainan and UESTC-China, they motivated us to try to solve this potentially dangerous problem at the same that we would be able to produce a beneficial material from this process. In our case we decided to produce polyhydroxybutyrate (PHB) from the molecule causing the ocean acidification, the CO2. PHB might be used like a substitute of the plastic polymer, and it has the benefit to be biodegradable and ecofriendly, supporting in this way the government's efforts to avoid the use of plastic.
Abstract
Nowadays the excessive production of CO₂ is causing a phenomenon called ocean acidification (OA) which combined with tons of plastics in the ocean are both main problems in the marine environment. Through genetically transformation, E. coli BL-21 bacterium will combine the capability of plants to get CO₂ from the marine environment (decreasing the OA) and the skill from some bacterium to degradate of vegetable waste in order to have sugar source. Both processes are vital in order to produce great pyruvate quantities to get polyhydroxybutyrate, which is used to produce bioplastics that could replace the prevailing polymer . For maintaining the Pyruvate production and photorespiration in the highest and lowest level, respectively we will design a system which works under anaerobic conditions and repress the aerobic metabolism using arcA protein and for measuring the pyruvate production we design a biosensor.
Development
To solve this problem we think of modifying a strain of E. coli to carry out the production of bioplastic from the CO₂ that is found in the marine environment; a high quality and low cost material can be a viable option to replace plastic polymers that generate negative impacts on the environment. This will be carried out in 3 modules: degradation, fixation and polymerization. In the degradation module carbohydrates like xylose and glucose will be obtained from low-cost sources, such as the organic residues of sugarcane, this in order to provide sufficient raw material to the path of the pentose phosphate and to glycolysis. Both routes of vital importance since the first one provides ribulose 5-fostato and the second one 3PG (3-phosphoglycerate).
The fixation module will take the ribulose 5-phosphate molecule to produce ribulose 1,5-bisphosphate that will be used by rubisco to fix the CO₂ that acidifies the marine environment and thus obtain more 3PG molecules.
The molecules of 3PG will be metabolized in the glycolysis for the final obtaining of pyruvate, which, in the polymerization module will be used to produce PHB's, molecules that can replace the plastic, being these low-cost and biodegradable.
References
Baudel, Zaror C & C., D. A. (2005) Improving the value of sugarcane bagasse wastes via integrated chemical production systems: an environmentally friendly approach. Ind Crops Prod. 309-315.
Antonovsky et al., (2016). Sugar Synthesis from CO2 in Escherichia coli. (Cell 166, pp. 115–125)
Mackey, K.R.M., J.J. Morris, F.M.M. Morel, and S.A. Kranz. 2015. Response of photosynthesis to ocean acidification. Oceanography 28(2):74–91, http://dx.doi.org/10.5670/oceanog.2015.33.