Tales from the Lab #4: More About Mold

I had intended to post a blog yesterday, but my plans got a bit derailed by a little thing called fungus. In other words, work was very busy and by the time I got home, I was too drained to do much more than order a pizza. The realization that it was Thursday, and that I was due to post a blog, never occurred to me.

I had a plan for my March issue of Tales from the Lab, describing an incident with an anaerobic box and an unwary manager that walked into the lab and wasn’t prepared for the odor, but I wasn’t too keen on it. Instead, I’d like to share a fungus story because it seems more interesting than my original plan.

I had a large set of environmental plates to look at one day (196 if anyone is counting). In a batch of that size, I typically see 2-3 unique colonies of mold. These particular plates are usually fairly clean, and about a third have no growth on them. Part of my job is to count colonies on these plates and report to management what I find; colonies include both bacteria and fungi (yeast or mold). With that number of plates, it takes a few hours to go through everything, plus some extra time to perform preliminary identifications.

Most of the molds I encounter aren’t very exciting. They are usually brown or gray, sometimes white, but usually not colorful. When I encounter something colorful or unique, I tend to get excited. Figuring out what that colony is becomes a puzzle that I need to solve. This is the part of microbiology that I fell in love with.

I suppose one can say it’s a similar process to identify bacteria, but it is not the same. Many bacterial colonies are similar, and identification always begins with a gram stain. This allows me to determine basic cellular structure. For the purpose of my current job, our bacterial identification ends there. The equipment involved in getting a full genus and species identification is costly, but gram stains are fast and inexpensive. It gives enough information about the bacteria to be useful in terms of cleaning procedures or human contamination. I once worked in a lab that did have the equipment to run full identifications on bacteria, and while it was interesting to learn what some of the cultures were, the process is very automated and leaves little to the imagination. (In a regulated industry, that’s usually a good thing, it’s just boring).

Molds, on the other hand, can be identified to genus using a microscope, as long as the sample contains spores. In my first Tales from the Lab post, I explained the process a little bit. For me, that more hands-on method of identifying an organism is far more fascinating. Sure, it probably takes a bit more time, and it does require more background knowledge about the organism to obtain a proper identification, but there are tools and resources in abundance to assist with that. Furthermore, this type of work feels much more like an investigative process than running a sample through a machine does, and I find that much more enjoyable. (Not all microbiologists would agree, but everyone has their own likes/dislikes).

Here is a plate showing not one, but two, very colorful molds that I encountered recently. The gray/brown one with the almost-teal border was not something I’d seen previously, and it was too pretty to pass up a photo opportunity. The photo doesn’t do enough justice to the true colors that were on that plate, but it was the best I could do. The teal seemed much more vibrant in the lab than it does in the photo. The smaller colony was likewise more yellow in the center than the photo makes it seem.

At the time of writing this post, I do not know what either of the mold colonies are. In order to get a true identification, the colonies must be isolated first, and it takes time for them to regrow on new plates. The faster-growing varieties can be identified within a few days, but others might take a few weeks. Not all fungi grow equally, even when given optimal conditions.

Anyway, enough about mold. Thank you as always for reading my post, and I hope you have a great weekend.