Introduction:-
There are different types of equipment and materials used in microbiology laboratories. These equipments are used for various purposes such as for sterilization, for transformation of micro-organisms and other materials for cultivation of micro-organisms and for the maintenance and supply of cultures and other materials. Therefore it is essential to be familiar with the principles procedures involved in handling these equipment.
Some of the common equipments used in microbiology laboratory are as follow:
i) Wine Loops and needles
ii) Pipette
iii) Bunsen Burner
iv) Water Bath
v) Hot air oven
vi) Autoclave
vii) Incubator
viii) Biological Safety cabinet (laminar flow)
ix) Refrigerator
i) Water Bath: It is an insulating metal box fitted with an electric heating mechanism and a thermostat. which maintains temperature at desired level. The bath is filled with water until it rises almost to the top of the racks. The shaking water bath is used for cultivation of micro-organism in a broth medium. It is better than an incubator because it provides a rapid and uniform transfer of heat to the culture vessel.
ii) Hot air Oven: It is an instrument used for the sterilization process by dry-heat method. Heating by exposure to hot air is an accepted method for sterilizing load that cannot be really penetrated by steam and can tolerate the high temperature (160°C – 180°C) required. Hot air oven is fitted with a fan to provide forced air circulation throughout the oven chamber, a temperature indicator, control thermostat and timer and adequate wall insulation. According to medical research council the commonly used time-temperature relation of hot air oven are given below:
| Temperature (0C ) | Time (minutes) |
| 1400C | 120 minutes |
| 1600C | 60 minutes |
| 1700C | 40 minutes |
| 1800C | 28 minutes |
It is particularly for laboratory glass waves such as test-tube, Petri-dishes, flasks, pipettes, syringes and for metal instruments such as forceps, etc. Besides these, it is also used for oils, powders and similar substances.
iii)) Autoclave: The laboratory apparatus designed to use steam under pressure for sterilizing heat stable material is called Auto-clave, Autoclave provides moist heat at temperatures higher than 100°c. It does so by exposure of the steam under increased pressure.This steam is biocidal. Time and temperature for sterilization by steam under pressure in the autoclave are given below in the table :
| Temperature | Pressure above atm(ic) pressure (lb/in2) | sterilization holding time (min) |
| (115-118)0C | 10 lb/in2 | 30 min |
| (121-124)0C | 15 lb/in2 | 15 min |
| (134-138)0C | 30 lb/in2 | 3 min |
The autoclave is used to sterilize anything that is not injured by steam and high temperature like solid and liquid media solution, rubber, tubing, stoppers, discarded, cultures and contaminated media prior to washing etc.
iv) Incubator: An incubator is a controlled chamber where the required degree of temperature can be achieved to facilitate microbial growth. Incubator may also contain atmospheric gasses such as O2 and CO₂, that may be required for growth of certain microbes.For routine culture in microbiology laboratory, small capacity incubator fitted with thermostat is generally used. It is supplied with shelves and has an inner glass door which closes on to reduce heat loss. A thermometer has been fitted at the upper inner part of the incubator and air is circulated in it by natural convection for psychrophilic organisms, Optimum temperature is 15-20°C: for mesophilic organisms, optimum temperature is 37°c. For thermophilic organisms. Optimum temperature is 45°c or above.
v) Biological Safety: Cabinet (Laminar flow): A biological safety cabinet is a device that encloses a workspace in such a way as to prevent workers from exposure to infectious agents i.e. using a safety cabinet, germfree environment (air) is created at working area. Air that has passed over, infectious material is sterilized, either by heat uv light or most commonly by passage through a high efficiency particulate air (HEPA) filter that removes most particles larger than 0.34 Um in diameter. These cabinets have three kinds of safety cabinets class I, II & III. Most hospital clinical laboratory techniques used class cabinets.
vi) Refrigerator: A refrigerator is used for a wide variety of purposes such as maintenance and storage of stock cultures between subculture period & stravage of sterile media to prevent dehydration.
Procedure:
1. All the instruments used in the microbiology Laboratory were viewed and were carefully studied.
2. The working mechanism was also learned from teachers.
Conclusion:
Hence, different instruments used in the laboratory were studied.
Precautions:
1. Pipetting by mouth is not allowed, it is to be performed with the aid of mechanical devices.
2. All glasses should be sterilized and dried before placing in the oven.
3. Incubator should always be positioned on a level surface.
4. Incubator should be cleaned regularly.
5. Glass doors should be opened for a long time.
References:
Shah PK, Dahal PR, Amatya J; ‘2009’ “ practical microbiology” Detta offset press page 7-12.