Team:HUST-China/Description
Discription
Shewanella
In the part of Shewanella, we employ Shewanella oneidensis MR-1 as our chassis and pyydt as the plasmid. Shewanella could utilize the lactate as its carbon source and produce electricity with the help of a multiprotein porin-cytochrome complex on its outer membrane called MtrABC. MtrABC could transfer the electron from Shewanella’s inner membrane to the surrounding. pYYDT is a shuttle plasmid between E.Coli and Shewanella. We constructed this plasmid in E.Coli and transferred it into Shewanella by conjugating these two kinds of bacteria.
Our design of constructing Shewanella is devided into two parts: improvement of utilization of lactate and increment of the amount of NADH in Shewanella.
(1). Improvement of utilization of lactate: To make the use of lactate more efficiently, we overexpress four genes: dld-Ⅱ, lldE, lldF, lldG.
①. dld-Ⅱ: dld-Ⅱ refers to FAD-dependent D-lactate dehydrogenase which could catalyze D-lactate’s transformation into pyruvate.
②. lldE/lldF/lldG: They could encode a L-lactate dehydrogenase complex which could catalyze D-lactate’s transformation into pyruvate.
We constructed them separately in pYYDT and found out if there was any improvement at the amount of electricty produced by our Shewanella.
Then we put these four genes in one circuit to level up the production of electricity.
(2). Increment of the amount of NADH in Shewanella
To achieve this goal, we overexpress these four genes: gapA2, mdh, pflB, fdh*. We chose them according to our reference.
①. gapA2: It encodes glyceraldehyde-3-phosphate dehydrogenase which could transform 3- phosphoglyceraldehyde into 1,3- diphosphoglycerate
②. mdh: It encodes NAD dependent malate dehydrogenase which transforms malate into pyruvate
③. pflB: It encodes pyruvate formate-lyase to transform pyruvate into Acetyl-CoA
④. pflB: It encodes pyruvate formate-lyase to transform pyruvate into Acetyl-CoA
According to our model, we divided these four genes into two groups: gapA2/mdh and pflB/fdh*.
Finally, we put all these genes into one circuit and found out if the amount of electricity could reach the maximum.
