- تاریخ انتشار: 11 بهمن 1400
Soil autoclaving is a laboratory technique used to remove microorganisms from the soil and is often an important step in any agricultural research process.
How to sterilize soil with an autoclave
When sterilizing the soil in an autoclave, the most important factor to consider is the ability of the steam to penetrate completely into the soil and thus achieve proper sterilization. In other words, it is better to perform a vacuum cycle when sterilizing the soil.
A vacuum cycle consists of two vacuum phases before and after the cycle. Pre-cycle vacuum performance is the most important factor to consider when choosing an autoclave for soil processing. Air can be trapped in the soil, so a series of pre-cycle vacuum pulses ensure that steam penetrates the load properly.
The post-cycle vacuum phase is also recommended for sterilizing the soil, as the soil inevitably gets wet in concentrated steam during the cycle. The post-cycle vacuum (ie the drying phase) reduces the weight of the goods to be emptied from the autoclave.
When loading an autoclave with soil, proper loading and empty space are being sterilized. A layer of soil more than 4 inches deep or heavily packed in containers can retain air and prevent proper sterilization, even with a pre-cycle vacuum. Secondary restraint is also important if the trays in which the soil is to be sterilized have holes for drainage at the bottom, otherwise the soil may come out of the tray and block the autoclave drainage and / or into the internal piping of the sterilizer. To harm.
A typical autoclave cycle is for sterilizing soil for 30 to 60 minutes at 121 ° C or 20 to 30 minutes at 132 ° C.
Soil sterilization methods
Soil sterilization is an agricultural technique used to kill harmful microorganisms, pathogens, spores and plant pests from mineral soil without destroying the soil or drastically changing its chemical composition. Soil sterilization can help promote plant health. It can also increase product performance. Especially in fields that are replanted after a regular crop cycle.
Although there are many ways to sterilize soil, there are three main methods used in the laboratory:
- Chemical sterilization
- Gamma ray
- the heat
There are several disinfectants that you can use to chemically sterilize your soil. These include formaldehyde, phenols, cresylic acid, ethylene oxide, and methyl bromide, although the two most common are sodium azide and propylene oxide. Sodium azide, propylene oxide and other chemical treatments change the pH and soil chemistry without any guarantee of complete sterilization of the sample.
Sterile soil with gamma radiation
Gamma irradiation is another common method of sterilizing soil. Y-radiation at 10 kg is strong enough to kill actinomycetes, fungi and invertebrates in most soils, and most soil bacteria can be killed at 20 kg. Some contaminants – radio-resistant bacteria – require y-radiation at 70 kg.
Heat sterilization of soil
There are two ways to sterilize soil:
- Dry heat sterilization
- Steam sterilization
Dry heat sterilization of soil Although suitable for agricultural purposes, dry heat sterilization is not sufficient in laboratory activities. This is because although it significantly reduces the population of bacteria and other microbes in the soil, the dry heat approach does not completely eliminate them. Which confronts us with steam sterilization.
As the name implies, steam sterilization uses steam heat to sterilize soil samples. Steam temperature kills viruses, pathogens, bacteria, fungi, pests, etc.
For laboratory applications, where only a small volume of soil is sterilized at a given time. Autoclave is usually the method of choice for soil vaporization. Conceptually, this method works like sterilizing in the open ground or in a greenhouse. However, autoclaves can achieve higher temperatures and higher speeds, making this approach more efficient. Autoclaving is easier than other forms of soil sterilization, based on heat or otherwise. Because microbes in the soil can be extremely flexible.
Purchase of soil autoclave from Ferdows
With more than 15 years of experience in designing, manufacturing and installing autoclaves for research laboratories, universities, hospitals and more, Ferdows has made integrated sterilization systems a real science. No matter what you need to sterilize, Ferdows has the right autoclave to do the job. Best of all, we offer a wide range of customization options, so that your steam sterilizer meets your exact needs.