It is always mentioned that microbiologists work under aseptic conditions or in fact, asepsis should be maintained while working with pure cultures. Now you might have guessed correctly that asepsis is a condition free of any form of microbial life, whether harmful or useful. Asepsis also stands for the sterile or germfree state of living or nonliving things. In terms of hospital or nosocomial environment, asepsis indicates conditions devoid of infectious agents. Aseptic conditions are mandatory in hospitals, operation theatres and equipments like incubators, all surgical instruments, clothing of doctors and nursing staff needs to be aseptic. Asepsis is always maintained by laboratories like microbiology, pharmaceutical, genetics and molecular biology, plant and animal tissue culture and vaccine production units. Industries like brewing, food processing and packaging, dairy, poultry, rubber and textile, oil recovery and biofertilizer production plants also maintain aseptic conditions during one or more operations. Naturally, all living things in their embryonic stage (egg or inside womb) including human embryo are sterile; they are devoid of normal flora organisms. As soon as after the birth, the babies first encounter with microorganisms present in the atmosphere and are no more sterile. Similarly, once egg is cracked, it cannot remain in germfree state. The practice of generating aseptic conditions employing various techniques was started in mid-19th century. In this regard, the most advanced work was done by English surgeon, Sir Joseph Lister. At that time, no means of asepsis was known; people were dying because of wound infections and septic formation. Lister, for the first time used dilute carbolic acid solution to soak surgical dressings which was found very effective for wound cleaning followed by rapid healing. He also discovered that carbolic acid effectively killed the bacteria. This was the first antiseptic used in medical practice and was the basis of present day aseptic techniques.
Now-a-days many aseptic techniques are available to kill or inhibit microbial growth. Several physical and chemical agents are practically applied to create and maintain aseptic conditions. Some of them are described here:
1. Physical sterilization - It includes complete removal and destruction of microorganisms by physical methods such as autoclaving, incineration, desiccation, high osmotic pressure, filtration, ionizing and nonionizing radiations.
2. Chemical sterilization - It involves killing of pathogens and contaminants by using chemical and antimicrobial agents. Various sterilization methods employ chemical like disinfectants, antiseptic creams, germicidal solutions, sanitizers and antibiotics. Active chemical groups like acids, alkalis, alcohols, phenol and derivatives, halogens like iodine, chlorine, heavy metals such as mercury, copper and silver, soaps and detergents, selective dyes acridine and crystal violet, gases like sulfur dioxide and vapors of formaldehyde or β-propiolactone are extensively used as effective microbicidal agents.
Germfree or gnotobiotic environment:
Gnotobiotic, germfree atmosphere can be created artificially. Growth chambers are supplied with sterile air, water and food. All operations including feeding, reproduction and cleaning are done under aseptic conditions. It's all started in 19th century, by raising chicken in sterile condition throughout successive generations. Many animals like rats, guinea pigs and rabbits were reared germfree in laboratory by scholars and researchers. Comparative study of animals reared germfree and nongermfree showed importance of microorganisms, bacteria especially required for normal growth of animals. It indicated that life is possible without microorganisms but it cannot be normal. Importance of normal flora particularly intestinal bacteria is outcome of germfree research. It showed that intestinal bacteria are essential in provision of vitamins and also enzymes required for digestion of cellulosic meals. Study also indicated that normal flora microbes are responsible for healthy functioning of immune system. Germfree animals usually exhibit underdeveloped immune system and hence susceptibility to numerous infections. They also require provision of high levels of vitamin K and B. Gnotobiotic conditions are used as model systems to compare normal animals with germfree and also to experiment the effect of various medicines on animals. Germfree research has great scope for studying biology, immunology and pharmacy of different animals.
What is so important about Asepsis?
To conclude, aseptic conditions are important to prevent transmission of diseases in humans, animals and plants. They are important to avoid decomposition and spoilage of foods and beverages. They are essential in pure culture studies to maintain pure culture characteristics and to inhibit interference from contaminating microorganisms.
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