![]() (Identifying viruses on agar plates is a different story and rely on methods such as differences in viral plaque phenotype.) What color are the colonies? Do they look slimy? Or wrinkly? As microbiologists combined different formulations of nutrients with agar to grow a diverse set of microorganisms, they created another tool for microbial identification: selective and differential media that help microbiologists identify bacteria and yeast species. When scientists began cultivating microbes on agar media in the 1880s (thanks to the contributions of Angelina Hesse), they could more easily study the macroscopic characteristics of microbial populations. Source: How Agar Media Helps Us Identify Microbes The Gram stain differentiates organisms by the way the react with colored stains: Gram-negative rods (L) stain pink/red Gram-positive rods (R) stain blue/purple. Other types of staining can tell microbiologists whether certain features are present: spores ( Schaeffer-Fulton staining), capsules ( India ink or nigrosin) and mycolic acids ( acid-fast staining). Gram created this technique to make bacteria more visible in stained lung tissue sections, and not for classifying microbes, as it is commonly applied today. To better visualize the microscopic amongst us, Hans Christian Gram developed the Gram stain technique in 1884. He documented the findings, describing what he saw as “animalcules,” derived from the Latin “animalculum” or "tiny animal." These microbes came from decaying bodies, animals, vegetables, and water. Antoni van Leeuwenhoek first saw microbes through a microscope in the 1670s. The earliest microbial identifications relied on observations of the microbe’s physical characteristics: shape, size, and the types of dyes it absorbed. Early Microbial Identification Studies By Microscopy From identifying microbes by physical and functional characteristics to the adaptation of more modern techniques, microbiologists (and future microbiologists) are continually building a vast toolkit to uncover the identities of previously unknown microscopic life. This student project has many parallels to what microbiologists have been doing for centuries. Not all microbes grow on the same type of nutrients, or at the same temperature.) I later learned that despite the absence of microbes on my plate, there might still be microbes present on my bathroom mirror. ![]() (To my disappointment, not much grew on my bathroom mirror plate. Once the microbes revealed themselves on the agar plates, it was time to identify them. After swabbing and spreading the invisible contents onto the agar plate, we placed our agar plates in the incubator and awaited the microbial surprises the following class period. Many students choose to sample the places they consider dirtiest: toilet handles, doorknobs, or the floors in the school hallway (when I took my first microbiology lab course, I sampled the dorm bathroom mirror). Armed with cotton swabs and Petri dishes full of nutient agar, students head out of the lab to see what lives on surfaces they encounter everyday. This fact is revealed to microbiology students who are tasked with a classic project: to identify bacteria and fungi from their environment. We may not see them, but microbes are all around.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |