MICROBIOLOGICAL LABORATORY EQUIPMENT
In this blog contains spesifications for microbiological laboratory equipment.
Incubators must maintain a uniform and constant temperature at all times in all areas, that is, they must not vary more than + 0,5°C in the areas used. Obtain such accuracy by using a water-jacketed or anhydric-type incubator with thermostatically controlled low-temperature electric heating units properly insulated and located or adjacent to the walls or floor of the chamber and preferably equipped with mechanical means of circulating air.
Incubator equipped with high-temperature heating units are unsatisfactory, because such sources of heat, when inproperly placed, frequenyly cause localized overheating and excessive drying of media, with consequent inhibition of bacterial growth.
2. Hot-Air Sterilizing oven
Used hot air sterilizing oven of sufficient size to prevent internal crowding ; constructed to give uniform and adequate sterilizing temperature of 170 + 10°C ; and equipped with suitable thermometers. Optionally use a temperature-recording instrument.
Use autoclaves of sufficient size to prevent internal crowding ; constructed to provide uniform temperature within the chamber (up to and including the sterilizing temperature of 121°C):equipped with an accurate thermometer the bulb of which is locatedproperly of the exhaust line so as to register minimum temperature within the sterilizing chambers(temperature-recording instruments is optional) ; equipped with pressure gauge and properly adjusted safety valves connected directly with saturated steam supply line equipped or appropriate filters to remove particulates and iol droplets or directly to a suitable special steam generator (do not use steam from boiler treated with animes for corrosion control) ; and capable of reaching desired temperature within 30 minute.
Comfirm, by chemical or toxicity tests, that the steam supply has not been treated with amines or other corrosion-control chemicals that will impart toxicity.
Use balances providing a sensitvity of at least 0,1 g at a load of 150 g, with appropriate weights. Use an analitycal balance having a sensitivity of 1 mg under a load of 10 g for weighing small quantities (less than 2 g) of materials. Single-pan rapid-weigh balances are most convenient.
5. Media Preperation Utensils.
Use borosilicate glass or other suitable noncorrosive equipment such as stainless steel. Use glassware that is clean and free of residues, dried agar or other foreign materials that may contamined media.
6. Pipet and Graduated Cylinders.
Use pipets of any convinent size, provided that they deliver that required volume accurately and quickly. The error of calibration for a given manufacturer’s lot must not exceed 2,5%.
Use pipets having graduations distinctly marked and with unbroken tips. Bacteriological transfer pipets or pipet conforming to APHA standards may be used. Do not pipet by mouth ; use pipets aid.
Use graduated cylinders meeting ASTM Standard (D-86 and D-216) and with accuracy limits established by NIST where appropriate.
7. Pipet Container
Use of boxes alumunium or stainless steel, end measurement 5 to 7,5 cm, cylindrical or rectangular, and length about 40 cm. When these are not available,, paper warppings for individual pipet may be subsituted. To avoid excessive charring during sterilization, use best-quality sulfate pulp (kraft) paper. Do not use copper or copper alloy cans or boxes as pipet containers.
Use a refrigerator maintaining a temperature of 1 to 4.4 °C to store sample, media, reagent, etc. Do not store volatile solvents, food, or beverages in a refrigerator with media. Frost-free refrigerators may cause excessive media dehydration on storage longer than 1 week.
9. Petri Dishes
For the plate count, use glass or plstic petri dishes about 100x15mm. Use dishes the bottoms of which are free from bubbles and scratches and flat so that the medium will be of uniform thickness throughout the plate. For the membran filter technique use loose-lid glass or plastic dishes, 60x15 mm or tight-lid 50x12 mm. Sterilize petri dishes and store in metal cans (alumunium or stainless steel but not copper) or wrap in paper-preferably best-quality sulfate pulp (kraft)-before sterilizing. Presterilized petri dishes are commercially available.
10. Membrane Filtration Equipment
Use filter funnel and membrane holder made of seamless stainless steel, glass, or autoclavable plastic that does not leak and is not subject to corrosion. Field laboratory kits are acceptable but standard laboratory filtration equipment and procedures are required.
11. Fermentation Tube and Vial
Use fermentation tubes of any type, if their design permits conforming to medium and volume requirements for concentration of nutritive ingredients as discribed subsequently. Where tubes used for a test of gas production, enlose a shell vial, inverted.
Use tubes and vial of such size that the vial will be filled completely with medium, at least partly submerged in the tube, and large enough to make glass bubbles easily visible.
12. Sample Bottles
For bacteriological samples, use sterilizable bottle of glass or plastic of any suitable size and shape. Use bottle capable of holding a sufficient volume of sample for all required test and an adequite air space, premitting proper washing and maintaining sample uncontaminated until examinations are complete. Ground-glass-stoppered bottles, preferably wide-mounthed and of resostant glass, are recommanded. Plastic bottles of suitable size, wide-mouthed, and made of nontoxic materials such as polyprpylene than can be sterilized repeatedly are satisfactory as sample container.
Before sterilization, cover tops and necks of sample bottles having glass closures with alumunium foil or heavy kraft paper.