Talk:Polylactic acid/Research Development
Pearce and Poli emails
Hi Joshua, I am still very interested in attempting to produce a polylactic acid bioplastic in your lab next summer. I have been doing research to fully sketch out the process. Over the last month I have done more research on lactic acid production and its purification.
A bioreactor/fermentor would be the most efficient route to produce PLA on a (semi)-continuous basis and make for more interesting experiments. A lactic acid bacteria Bacillus coagulans could be an optimal organism due to producing only the L+ LA, and having a high optimal growth temperature of 55C, which prevents contamination and removes the need for an initial feedstock sterilization step. This organism's LA production capability has been characterized and requires some nutrient supplementation but I haven't found any reports of polymerization of the product. Purification of LA seems to start with filtration of cells and debris and then use conventional and water splitting electrodialysis followed by polishing steps, usually ion-exchange of with a strong cation membrane and weak anion membrane. The purification equipment would best be borrowed from another lab and would require purchasing semipermeable membranes.
I have been exchanging emails with Kerem Bora a post doc at Sabanci University in Istanbul who works on coculture fermentation and is working on an open source bioreactor and arduino program. His project is to monitor pH and temperature, include temperature control, and pass the data through a networked arduino to an internet connected server. He is interested in the project and hopes to have the source code distributed in a few months. At the start of Sept I am rotating with a lab that designs photobioreactors and should pick up some knowledge on bioreactor design.
To move forward I will try to contact more faculty here at MSU with PLA expertise, make a bioreactor parts list, make a parts list for the chemical reactor, and outline the purification steps. What are your thoughts on moving forward and the feasibility of conducting a meaningful project next summer over a two month period? There are a number of directions the project could take but what would you like to focus on?
Hi Eric This looks like a pretty good plan. I have been making friends with MTU faculty in chemical engineering - so I dont think we will have much trouble getting the necessary equipment. Can you send me a full list with as much detail on the specifications as possible and I will get some solid confirmations.
In addition - a list of consumeables and supplies with sources and price estimates/quotes. We have an Arduino expert here we can call upon for getting Kerem's program up and running here.
As my experience is in materials - I would think the project would be to get the system up and running and then focus on materials characterization and quality. We have a number of projects on the go now that this will feed into - including mechanical testing and other properties of the 3D printing filaments.
We have started on other side projects that will also fit in - such as an environmental chamber for the 3d printer to help cut down on variables....that would arise with testing a new flavor of PLA....along with the extruders necessary to turn raw material into filament.
Hi Joshua, It's good to hear that this could fit nicely into some of your current projects. Creating a polymer that is useful for 3D printing would be the ultimate goal of the project. I've been working on a proposal for external fellowships this month but the proposal is in final draft so I can get back into this project. I sent out a couple emails to MSU faculty specifically about LA purification, and hopefully can get some good input. I'll work on getting a materials list together for each step.
Hello Joshua, Hope all is going well. Attached is an outline of the materials and protocol as I have worked it out so far. Its still a pretty rough draft but I think I have an idea of what's involved in each step, my thoughts are at the end on questions I am still thinking about. Recently I have been researching the best route for purification and have decided on membrane filtration. Using size selective membranes, bacterial cells (by microfiltration) and unused sugar (by nanofiltration) can be separated from the lactic acid and recycled back to the reactor. These membranes should be configured for crossflow filtration to prevent fouling. Reportedly high yields are achievable but further concentration and purification is probably still necessary. I am focusing on electrodialysis but solvent extraction also has merit. Membranes and purification seem to be the major cost in production.
Kerem will send me his plans and program when he releases it, hopefully sometime next month. I emailed Dr Shanmugam at University of Florida who produced the genome of Bacillus coagulans (through Michigan State actually) about getting ahold of the strain. I am working on the exact feedstock and growth protocol for the bacteria now. My goal is to have a full literature review and plan for all steps done by the end of January.
File:Materials and protocol rough draft.doc
Hi Eric Thanks this is really nice work -laid out well. I am going to start shopping this project around my chemistry prof colleagues here -- my only main concern now is that my lab does not have any of the equipment you need - I am going to see if I can sell someone who does on he idea.
Hi Joshua, I think the project is doable - going from raw feedstock to polymerized material - but it will take bringing together basically a laboratory scale chemical synthesis plant. If you are able to locate most of the hardware I will also need some technical assistance from the owner for proper and optimal use. Let me know what necessary hardware you are able to locate and I will be working out some finer details for the protocol. I'll keep you updated with progress.