In this video, we're going to talk about yet another chemical gas used for controlling microbial growth, and that is formaldehyde gas. And so formaldehyde gas is a colorless, strong-smelling aldehyde in a gas form that is made by oxidizing a chemical called methanol, whose chemical formula is CH2O. Now formaldehyde gas can actually be used as a disinfectant at a 3% dilution, or it could be used as a sterilant at a higher concentrated form of a 37% solution. Although formaldehyde is available in a gas form, it's also commonly available in a 37% aqueous solution or a liquid form that is called formalin. And so formalin is really just the liquid version of formaldehyde. Now, whether you're using formaldehyde gas or this liquid form of formaldehyde, formalin, it is going to kill microbes by causing protein DNA cross-linking, basically covalently linking proteins to DNA. And this cross-linking will eventually damage the DNA and denature proteins. And of course, damaging the DNA and denaturing proteins can lead to the destruction of the microbe, allowing formaldehyde gas and formalin to be used to control microbial growth.
And so if we take a look at this image down below, we're focusing in on formaldehyde as a gas. And over here we're showing you the chemical formula and the chemical structure of formaldehyde. And over here what we have is a little bottle that can contain the liquid version of formaldehyde, the formalin aqueous solution. And so the use of formaldehyde gas or this liquid formalin form of formaldehyde will lead to the same result. And so the formaldehyde is able to diffuse across a cell's plasma membrane here, and it's able to interact with proteins that are found inside the cell. It's also able to interact with the DNA that's found inside the cell as well. And so it can cause these DNA-protein cross-links, basically covalently linking the protein to the DNA, and that can again, damage the DNA and denature proteins, leading to the destruction of the microbe.
This here concludes our brief lesson on the use of formaldehyde gas as a means for controlling microbial growth. And we'll be able to get some practice applying these concepts and then learn about ozone in our next lesson video. So I'll see you all in that video.
