Microbial growth control (Physical methods)

Why to control microbes?
To prevent transmission of disease.
To prevent the spoilage of food i.e preservation of food

1. microbial CONTROL PHYSICAL METHOD

2. What are microbes ? A microorganism or microbe is a microscopic organism, which may exist in its single-celled form, or in colony of cells.

3. history The possible existence of unseen microbial life was suspected from ancient times, such as in  Jain scriptures  from 6th century BC India, and the 1st century BC book  On Agriculture  by  Marcus Terentius Varro .  Microbiology , the scientific study of microorganisms, began with their observation under the  microscope  in the 1670s by  Antonie van Leeuwenhoek . In the 1850s,  Louis Pasteur  found that microorganisms caused  food spoilage , debunking the theory of  spontaneous generation . In the 1880s  Robert Koch  discovered that microorganisms caused the diseases  tuberculosis ,  cholera , and  anthrax .

4. A microbe, or “microscopic organism,” is a living thing that is too small to be seen with the naked eye. We need to use a microscope to see them . The term is very general. It is used to describe many different types of life forms, with dramatically different sizes and characteristics: Bacteria Archaea Fungi Protists Viruses Microscopic Animals

5. Why to control microbes? To prevent transmission of disease. To prevent the spoilage of food i.e preservation of food There are different ways to control growth Kill them Inhibit growth Remove them through filtration

6. Terms:- Sterilization – killing or removing all forms of microbial life in a material or object. Sepsis - comes from Greek for decay or putrid indicates bacterial contamination. Asepsis- absence of significant contamination. Aseptic techniques – they are used to prevent contamination of surgical instruments. Disinfection – reducing the no. of pathogenic microorganism to the point where they no longer causes diseases.

7. Physical methods of microbial control Microbial control KILLING MICROBES INHIBITING GROWTH OF MICROBES PREVENT FROM: transmission of disease, infection, contamination by growth of undesirable Microbes and undesirable spoilage.

8. Physical method used for control of microbes

9. TEMPERATURE Temperature above the maximum generally kill, while those below the minimum usually produce preservation. HIGH TEMPERATURE High temperature + high moisture  kills organisms Typically a pressure of 15 psi (pounds per square inch) is needed to create steam at a high temperature (121degree celcius ), microbes are killed in within 20 minutes. Low temperature Useful for preservation culture

10. Moist heat steam under pressure Pressurized steam heat has the advantages of rapid heating , penetration and moisture in abundance which facilitates the coagulation of protiens . Example- AUTOCLAVE

11. DRY HEAT HOT AIR STERILIZATION Used when undesirable to make a direct contact of the materials to be sterilized. E.g.- glasswares - petridishes, pipettes , oils, powder Example – Hot air oven 

12. DESICCATION It inhibits microbial growth because the evaporation of water inhibits metabolism It depends on several factors Kinds of microbes Material on which microbes are dried Physical conditions EXAMPLE - LYOPHILIZATION

13. filteration Filtration is the passage of air or a liquid through a material that traps and remove microbes. New type of filter has been developed called as membrane molecular filter. These membrane filter are composed of biologically inert cellulose esters and contain millions of microscopic pores of every uniform diameter. The development of HEPA filters had made possible to remove microbes from air. This type of air filteration together with a system of laminar air flow is now used to produce dust and bacteria free air.

14. Osmotic pressure High concentration of salt or sugar inhibit microbial growth by osmotic pressure. Hyperosmotic condition can preserve because they cause water to be drawn out of bacteria or fungi so that they cannot thrive. Eg - jam and pickle. Radiation Energy transmitted through space in variety of forms is generally called radiation. Most significant radiation is electromagnetic radiations. Gamma rays and X-rays sometimes called ionizing radiation.

15. Results of quantitative studies on the effect of ionizing radiations on the cell have resulted in the establishment of the “ target theory” of action which says that the radiant energy particles make a direct heat on some essential substances such as DNA within bacterial cell, causing ionization which results in death of cell .

16. CONCLUSION ANTIMICROBIAL ARE IMPORTANT TOOLS THAT ARE INTREGAL TO OUR COMPLEX FOOD SYSTEM .EG- ANTIBIOTICS IMPORTANCE – IN MEDICAL FIELD, PHARMACEUTICAL AND BIOTECHNOLOGY INDUSTRIES, ACADEMIC RESEARCH AND FOOD INDUSTRY.

17. THANK YOU!!