Agar plates are sterile dishes containing a nutrient-rich gel that serves as a solid surface for growing and studying microorganisms like bacteria and fungi. They are a foundational tool for home science projects, student experiments, and mycology hobbies, allowing users to observe the invisible world of microbes. Locating a reliable supplier is the first step for anyone looking to begin culturing samples from their environment. This guide details where to purchase these plates and how to handle them for successful and safe experimentation.
Primary Sources for Purchasing
The easiest places for the general public to acquire agar plates fall into three main categories, each offering a different balance of convenience and selection. Educational and hobby science suppliers are the most reliable source, specializing in providing pre-poured plates and kits designed for non-professional use. Companies like Flinn Scientific or Carolina Biological Supply offer products with clear instructions and guaranteed sterility, though they may be slightly more expensive.
Large online marketplaces, such as Amazon or Etsy, also sell a wide variety of agar plates, often from smaller, specialized vendors. These platforms offer convenience and competitive pricing but require careful vetting of the seller to ensure quality and sterility. Quality control can vary significantly, so look for vendors with high ratings and specific product details. Specialized mycological or biological supply stores cater to users with more advanced needs, offering media for growing specific types of fungi or bacteria beyond general-purpose plates. These suppliers are excellent for advanced hobbyists needing particular nutrient blends, such as Malt Extract Agar (MEA) for mushroom cultivation.
Ready-Made Plates Versus DIY Kits
A decision when purchasing is choosing between ready-made, pre-poured plates and do-it-yourself (DIY) kits. Ready-made plates are the most convenient option, arriving fully sterilized and ready for immediate use, which reduces the risk of contamination for beginners. However, this convenience comes at a higher cost per plate, and they have a shorter shelf life, often only a few months, even when refrigerated.
DIY kits consist of dehydrated media powder and empty sterile petri dishes, making them significantly more cost-effective in the long run, as the media powder has a much longer shelf life. Preparing plates requires dissolving the media in water and then sterilizing it, usually in a pressure cooker to kill all contaminants. This method requires a higher level of aseptic technique and sterilization equipment, increasing the chance of contamination if not performed carefully. For users needing a large volume of plates or planning to customize their media, the initial investment in time and equipment for the DIY method quickly pays off.
Choosing the Right Media and Supplies
Selecting the appropriate growth medium is important, as different microbes have distinct nutritional requirements. For general home science experiments aiming to grow various environmental bacteria, Tryptic Soy Agar (TSA) or Nutrient Agar (NA) are the standard choices, supporting a wide range of non-fastidious organisms. If the goal is to culture fungi or mold, Potato Dextrose Agar (PDA) or Malt Extract Agar (MEA) are better suited, providing the sugars and nutrients preferred by these organisms.
Plates come in a standard size of 100 x 15 mm, which provides sufficient surface area for most experiments. Consider the quantity needed, as plates are often sold in sleeves of 10, and having extras is advisable to account for accidental contamination. Beyond the plates, accessory supplies are needed, such as sterile cotton swabs for collecting samples or sterile inoculation loops for transferring cultures. Other useful items include sealing tape, like parafilm, to secure the lids after inoculation and a permanent marker for labeling the plate bottoms.
Storage and Safe Disposal
Proper handling after purchase is necessary to maintain the integrity of the sterile plates. Pre-poured agar plates should be stored inverted in their original sealed packaging inside a refrigerator, ideally at around 4°C, to minimize condensation and slow drying. When stored correctly, general-purpose plates remain viable for three to six months, though it is best to use them as close to the purchase date as possible.
Once the experiment is finished, used agar plates must be sterilized before disposal to prevent the release of cultured microbes into the environment. This is important since the general public handles unknown microorganisms. A common method involves adding a 10% bleach solution directly onto the agar surface and allowing it to sit for at least an hour to kill the microbial growth. After sterilization, the plates and their contents can be double-bagged and disposed of with regular household trash.