Science Buddies: "Ask an Expert"

Hello my name is Dan and I am trying to find a good idea. I want to do something more advanced than normal and I just don't know what to do.

I have been thinking about developing a bioplastic capable of being biodegraded in the ocean. Where can i start with this idea? First of how would i develop a bioplastic to begin with and what can I do ? I found this online:

A recipe for PLA bioplastics

Take some corn kernels (lots of them).
Process and mill them to extract the dextrose (a type of sugar) from their starch.
Use fermenting vats to turn the dextrose into lactic acid.
In a chemical plant, convert the lactic acid into lactide.
Polymerize the lactide to make long-chain molecules of polylactide acid (PLA).
https://www.explainthatstuff.com/bioplastics.html

How can I do this with the limited resources at my school or home or is it even possible. What i want to do is modify this and make some other bioplastic using some other main material which is not corn. Then do something to them which makes it easier for bacteria in the ocean to decompose. I suppose i would have to find out what bacteria is present in the ocean and in which parts of the ocean which are present.

Crucial characteristics responsible for plastics’ resistance to biodegradation include a long-chain polymer structure, a high molecular weight (MW), lack of a favorable functional group, hydrophobicity, and crystallinity (Wilkes and Aristilde 2017). A high MW is a crucial obstacle, because large compounds cannot be transported across the cellular membrane of microorganisms. Thus, long-chain polymers have to be first depolymerized to smaller monomers before they can cross the cell membrane (Shah et al., 2008). Next, monomers can pass through the cell membrane, followed by assimilation by intracellular metabolism (Kolvenbach et al. 2014).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6132502/

The other question I have is can you explain this passage in more simpler terms so i can understand I am really sorry that I don't understand but I feel like this information can help my idea.

In general I know i sound random and lost but the main driving idea is to making a bioplastic which can be decomposed in the ocean or at least a certain part of it. Just about any ideas, links, information and anything else would be helpful. if none of my ideas seem reasonable what direction can i go with this, i don't want to do a simple project but I haven't exactly learned a lot about the things I am researching at school so that is a barrier for me.

Finally sorry for the lengthy post I really hope you can help me.
Thank you Very much for volunteering your time to help people like me

Dan
P.S. I am thinking of finishing this science fair project in about 7-8 months

You have some great ideas, Dan, and thanks for taking the time to post them in detail. What you have outlined is a great project and perfectly clear to me. Every day we hear another report about plastic building up in the oceans as well as in our landfills, and now the existence of plastic nanoparticles is in the news to add to the hazard.

What you propose is way beyond a high school project but that does not mean you can't attempt it. The description you included of making poly-lactide is useful as an example of how to go from a natural material--corn in that case--to a biodegradable plastic. You could possibly do this, but there may be other easier ways.

As you point out, there are specific organisms in the ocean that might or might not be capable of digesting bioplastics [that's my term]. Considering the amount of plastic that has accumulated in parts of the ocean, these bacteria are not capable of breaking it down very quickly.

There are two ways to approach this problem and from my reading, more companies seem to be researching the microbial angle than the synthesis of bioplastics. There are bacteria and fungi capable of degrading the plastics that are being used now, but the problem seems to be that they are not easy to grow and maintain, for example, in a landfill. I have no idea what kinds of bacteria could grow in the ocean AND digest plastic. If you could find such a creature it would be in great demand.

You asked about translating that technical passage, so I will try to help.

Crucial characteristics responsible for plastics’ resistance to biodegradation [being eaten by bacteria or fungi] include a long-chain polymer [a long molecule made up of repeating units (monomers) chemically attached end-to-end] structure, a high molecular weight (MW) [the mass of a molecule calculated by adding up all the masses of the individual atoms], lack of a favorable functional group [a part of the molecule that bacteria can eat], hydrophobicity [this means 'water-shunning' and refers to molecules like oils and waxes that are not soluble in water], and crystallinity [I don't know how this refers to biodegradabilty; plastics are not crystals; crystals have regular rempeating structures held in place by positive and negative charges] (Wilkes and Aristilde 2017). A high MW is a crucial obstacle, because large compounds cannot be transported across the cellular membrane of microorganisms [this just means that a bacterium cannot eat the plastic if it cannot get inside the cell]. Thus, long-chain polymers have to be first depolymerized to smaller monomers before they can cross the cell membrane (Shah et al., 2008). Next, monomers can pass through the cell membrane, followed by assimilation by intracellular metabolism [once the partially degraded plastic is inside the bacterial cell, it can be attacked by bacterial enzymes that will break it up into harmless bits than can be reused or spit out] (Kolvenbach et al. 2014).

I hope that helps! It would be a lot easier if we could be speaking together but this is the best we can do for now. Post again with more questions and I'll try to steer you along into a doable project that is still interesting and important.

Sybee

You have some great ideas, Dan, and thanks for taking the time to post them in detail. What you have outlined is a great project and perfectly clear to me. Every day we hear another report about plastic building up in the oceans as well as in our landfills, and now the existence of plastic nanoparticles is in the news to add to the hazard.

What you propose is way beyond a high school project but that does not mean you can't attempt it. The description you included of making poly-lactide is useful as an example of how to go from a natural material--corn in that case--to a biodegradable plastic. You could possibly do this, but there may be other easier ways.

As you point out, there are specific organisms in the ocean that might or might not be capable of digesting bioplastics [that's my term]. Considering the amount of plastic that has accumulated in parts of the ocean, these bacteria are not capable of breaking it down very quickly.

There are two ways to approach this problem and from my reading, more companies seem to be researching the microbial angle than the synthesis of bioplastics. There are bacteria and fungi capable of degrading the plastics that are being used now, but the problem seems to be that they are not easy to grow and maintain, for example, in a landfill. I have no idea what kinds of bacteria could grow in the ocean AND digest plastic. If you could find such a creature it would be in great demand.

You asked about translating that technical passage, so I will try to help.

Crucial characteristics responsible for plastics’ resistance to biodegradation [being eaten by bacteria or fungi] include a long-chain polymer [a long molecule made up of repeating units (monomers) chemically attached end-to-end] structure, a high molecular weight (MW) [the mass of a molecule calculated by adding up all the masses of the individual atoms], lack of a favorable functional group [a part of the molecule that bacteria can eat], hydrophobicity [this means 'water-shunning' and refers to molecules like oils and waxes that are not soluble in water], and crystallinity [I don't know how this refers to biodegradabilty; plastics are not crystals; crystals have regular rempeating structures held in place by positive and negative charges] (Wilkes and Aristilde 2017). A high MW is a crucial obstacle, because large compounds cannot be transported across the cellular membrane of microorganisms [this just means that a bacterium cannot eat the plastic if it cannot get inside the cell]. Thus, long-chain polymers have to be first depolymerized to smaller monomers before they can cross the cell membrane (Shah et al., 2008). Next, monomers can pass through the cell membrane, followed by assimilation by intracellular metabolism [once the partially degraded plastic is inside the bacterial cell, it can be attacked by bacterial enzymes that will break it up into harmless bits than can be reused or spit out] (Kolvenbach et al. 2014).

I hope that helps! It would be a lot easier if we could be speaking together but this is the best we can do for now. Post again with more questions and I'll try to steer you along into a doable project that is still interesting and important.

Sybee