Please accept this Petri dish usage guide~
A petri dish is a glass or plastic round vessel used to hold liquid culture medium or solid agar medium for cell culture. The petri dish consists of a bottom and a lid, and is a chemical device used for culturing bacteria. The main material is glass or plastic.
Petri dishes are fragile and fragile, so they should be handled with care and care when cleaning and handling. It is best to clean the used petri dish in time and store it in a safe and fixed place to prevent damage and breakage.
Classification of petri dishes
According to the different uses of the petri dish, it can be divided into cell culture dish and bacterial culture dish;
According to the different manufacturing materials, it is divided into plastic petri dishes and glass petri dishes, but most of the imported petri dishes and disposable petri dishes are plastic materials;
According to the different sizes, it can usually be divided into 35mm, 60mm, 90mm, 150mm petri dishes;
According to the difference of separation, it can be divided into 2-separated petri dishes, 3-separated petri dishes, etc.;
The materials of petri dishes are basically divided into two categories, mainly plastic and glass, and glass can be used for plant material, microbial culture and animal cell adhesion. The plastic ones may be polyethylene materials, which are disposable and multiple-use, suitable for laboratory inoculation, streaking, and bacterial isolation operations, and can be used for the cultivation of plant materials.
Difference Between Petri Dish and Evaporating Dish
The petri dish consists of a bottom and a lid and is generally used for culture experiments. Usually made of glass or plastic. The upper cover has the function of keeping warm and moisturizing. The evaporating dish has no cover and is used to evaporate concentrated solutions or burn solids. The bottom of the mouth is shallow, and there are two types of round bottom and flat bottom with handle. The most commonly used is a porcelain evaporating dish, but also made of glass, quartz, platinum, etc. Different materials have different corrosion resistance, and should be appropriately selected according to the properties of the solution and solid.
Purpose of petri dishes
It is suitable for epidemic prevention stations, hospitals, biological products, food industry, pharmaceutical industry and other units for bacterial isolation and culture, antibiotic titer testing and qualitative testing and analysis. In agricultural, aquatic and other scientific research, it is used for artificial cultivation and incubation of seeds, plants, insects, and fish. The electronics industry or other industries are used as utensils.
Petri Dish Instructions
Petri dishes are usually plated with solid medium (hence the name plate). The preparation of plate medium is to dissolve the packed sterile agar medium with warm water (sterile), remove the cotton plug of the test tube, pass the mouth of the tube on the flame of the alcohol lamp, and then slightly open the sterilized petri dish cover to make the plate medium. It is advisable that the mouth of the test tube can be deep, and after pouring the medium, it can be sealed tightly, and then gently shake the poured medium to make it evenly distributed on the bottom of the dish to condense, that is, the plate medium.
Because the reproduction, development and growth of bacteria are directly related to the medium (nutrient) supplied, especially for quantitative inspection and analysis, it is of decisive significance for the amount of nutrients provided. It is extremely important to know how much and whether the nutrients are evenly provided during bacterial culture, and whether the bottom of the petri dish is flat. If the bottom of the petri dish is uneven, the medium distribution of the agar will be thick or thin depending on whether the bottom of the petri dish is flat, and the nutrient supply of the thin part will be insufficient, which is closely related to quantitative analysis. However, for general characterization (testing bacteria, colony growth, reproduction, etc.), ordinary petri dishes can be used.
In the isolation and culture of bacteria, several kinds of bacteria are often mixed in the general specimen at the same time, such as oral and throat bacteria and ear secretions, sputum, urine, stool, etc. All bacteria to be studied must first be cultured by separation and culture to make them into a pure breed. By culturing the bacteria with pure breeds, use a solid medium of gravy plus 2% agar, filter them with absorbent cotton through an insulating funnel, and inject them into a test tube. After two days, check that there is no new bacteria, then put it into a petri dish, make a plate first, and inoculate it under aseptic conditions. The droplets are dropped into the bottom of the dish, which affects the growth of the colony), and the morphology and color of the bacteria are further observed through cultivation to study the pathogenic bacteria and the effect of chemical control.
Precautions for the use of petri dishes
1. After cleaning and disinfection before use, whether the petri dish is clean or not has a great influence on the work, which can affect the pH of the medium. If there are certain chemicals, it will inhibit the growth of bacteria.
2. The newly purchased petri dish should be rinsed with hot water first, then soaked in a hydrochloric acid solution with a mass fraction of 1% or 2% for several hours to remove free alkaline substances, and then rinsed twice with distilled water.
3. To cultivate bacteria, use high-pressure steam (usually 6.8*10 Pa high-pressure steam), sterilize at 120°C for 30 minutes, and dry at room temperature; or use dry heat to sterilize the petri dish. Placed in an oven, the temperature is controlled at about 120 ℃ for 2 hours, and the cytars of bacteria can be killed.
4. Disinfected petri dishes can be used for inoculation and culture;
5. Why turn the petri dish upside down during plate culture:
Reason: more water vapor will be generated in the petri dish during cultivation, and the water vapor will condense on the lid of the dish to produce water droplets. If the petri dish is placed upright, the droplets will wash away the colony, so that a large colony may be dispersed into a Many small colonies cause great trouble for bacterial culture and enumeration. If it is inverted, the medium is on the top and the lid is on the bottom, and the water droplets will not drip on the colonies.
Cleaning of petri dishes
soak
New or used glassware should first be soaked in water to soften and dissolve attachments. Before using new glassware, simply brush it with tap water, and then soak it in 5% hydrochloric acid overnight; used glassware often has a lot of protein and oil attached, which is not easy to wash off after drying, so it should be immersed in clean water immediately after use for brushing. .
scrub
Put the soaked glassware in the detergent water and brush repeatedly with a soft brush. Do not leave dead corners and prevent damage to the surface finish of the utensils. Wash and dry the cleaned glassware for pickling.
Pickling
Pickling is to soak the above-mentioned utensils in a cleaning solution, also known as acid solution, to remove possible residual substances on the surface of the utensils through the strong oxidation of the acid solution. Pickling should not be less than six hours, usually overnight or longer. Be careful when handling utensils.
rinse
The utensils after brushing and pickling must be fully rinsed with water. Whether the utensils are cleaned after pickling directly affects the success or failure of cell culture. When washing the pickled utensils by hand, each utensil should be refilled with water at least 15 times and emptied for more than 15 times. Finally, it should be immersed in re-distilled water for 2-3 times, and then dried or dried before packing for later use.
