ANALYSIS OF AIR

Aim:

To study the air flora of any environment by gravity sedimentation method

Principle:

Microbial flora of air is transient and variable. Organisms usually adhere onto particulate material such as dust, carbon, saliva etc. The conditions of air prevent growth of organisms vegetative cells like Staphylococci, Streptococci and Mycobacteria resist drying and are carried over long distances

Theory:

Air sampling is done by impinging air onto a solid surface during a brief exposure. The agar surface subsequently is incubated till visible colonies appear. The sampling method rests on sedimentation of particulate matter under the influence of gravity.

Materials Required:

LB Agar plates

Potato dextrose Agar plates

Procedure:

Expose the LB agar and Potato Dextrose Agar plates to air for 10 min/1hr and then incubate them at RT and 37oC for 48 hrs.

Observations:

Location LB Agar PDA

28oC 37oC 28oCCar Park 140 125 25M. Sc Part I Lab 90 115 20Laminar 15 12 3

Calculations:

The rate of micro-organisms (biological aerosols) falling on to a critical surface can be calculated by the following formula:

Øc= Vc X Pc,

where Øc is the contamination flow, i.e., the count of settling cfu per unit surface and per unit time; Pc is the contamination density, i.e., the count of cfu per unit volume; Vc is the contamination velocity, i.e., the settling velocity of cfu.

Result:

Conclusion: The qualitative and quantitative analysis of air was done the resulting colonies were observed and studied.

ANALYSIS OF SOIL

Aim:

To carry microbial analysis of the given soil sample

Principle/Theory:

The microbial analysis of soil is carried out to find out the different types of microbes present in the soil and their effect on the soil. Microbes in the soil are important because they affect the structure and fertility of the soil. Soil microbes can be classified as bacteria actinomycetes fungi algae and protozoa.

Material Required:

Glassware:

Sterile Petriplates

Sterile 1 ml and 10 ml pipettes

Sterile test tubes

Sterile beaker

Spreaders

Media:

Luria Bertani Agar (LB agar)

Potato Dextrose Agar (PDA)

Physiological saline (0.85%)

Sample:

Soil from university compound

Procedure

1. Weigh 1 gm of the soil sample and resuspend in 10 ml of sterile distilled water.2. Prepare serial dilutions of the sample.3. Plate out 100 µl of 10-6, 10-7 and 10-8 on LB agar plates (two each) and the lowest one on

PDA.4. For pour plate, add 100 µl of the above dilutions to 25 ml of the molten medium

(maintained at 50oC).5. Incubate one plate of each dilution at 37oC and the other plate at 28oC for 48 hours.

Incubate PDA at 28oC for 48 hours.6. Check for colonies.7. Quantify using cfu/ml

Observation:

Dilution LB Agar PDA28oC 37oC 28oC

10-6 700 670 NA10-7 75 65 1010-8 8 10 2

Figure 1: Soil sample on PDA plates

Calculation:

Result:

Conclusion: The soil sample was analyzed and various organism found were Isolated and studied.

ANALYSIS OF WATER

Aim:

To determine the microbial load in the given sample of water

Principle/Theory:

There are different organisms present in water some are pathogenic some are not. The pathogenic bacteria are generally gram negative short rods called coliforms which are found in water depending if the water was stagnant or polluted a number of other organisms such as algae n different microbes can be found in it. By performing the water analysis we can find out the different organisms present and can also isolate a possible threat of contamination.

Material Required:

Glassware:

Sterile Petriplates

Sterile 1 ml and 10 ml pipettes

Sterile test tubes

Sterile beaker

Spreaders

Media:

Luria Bertani Agar (LB agar)

Potato Dextrose Agar (PDA)

MacConkeys’s Agar

Physiological saline (0.85%)

Sample:

Soil from university compound

Procedure

1. Collect water sample from pond and water cooler.2. Perform serial dilutions of both the samples.3. Plate out 100 µl of 10-6, 10-7 and 10-8 dilutions of pond water sample on LB agar plates

(two each).4. For pour plate, add 100 µl of the above dilutions to 25 ml of the molten medium

(maintained at 50oC).5. Plate out 100 µl of 10-2, 10-4 and 10-6 dilutions of cooler water sample on LB agar plates. 6. Incubate one plate of each dilution at 37oC and the other plate at 28oC for 48 hours.7. For MacConkey’s and PDA plates, plate out 100 µl of 10-2, 10-4 dilution of cooler water

and 100 µl of 10-4, 10-6 dilution of pond water.8. Incubate MacConkey’s plates at 37oC and PDA at 28oC.9. Check for colonies.10. Quantify using cfu/ml

Observation:

Pond water count

Dilution LB Agar PDA MacConkey’s Agar

28oC 37oC 28oC 37oC10-6 700 670 10 7810-7 75 65 1 810-8 8 10 NA NA

Cooler water count

Dilution LB Agar PDA MacConkey’s Agar

28oC 37oC 28oC 37oC10-2 133 120 5 7010-4 20 11 - 8

10-6 4 1 NA NA

Figure 2: Cooler water Sample on LB Agar plate

Calculation:

Result:

Conclusion:The analysis of water was carried out and the colonies of different microbes were observed