Question

Although macroscopic observations of microbial growth can provide much valuable information, microbiologists often follow such observations with microscopic analysis. What information might one learn by using a microscope? What are some additional factors to test in trying to identify an unknown microbe obtained from the environment?

Answer 1

INFORMATION LEARN BY USING MICROSCOPE:-

• Microscope is absolutely essential for the microbiological lab, most micro-organisms cannot be seen with naked eye so it is important to use microscope to differentiate the bacteria, viruses and other pathogenic organisms that cannot be seen with naked eyes.
• Microscope is helpful in labortaries to diagnose disease such as in case of urinary tract infections urine slide is made and viewed under microscope to interpret the cause of infection and to check the number of puss cells or if any RBC's present or not.
• It also help the physicians to diagnose the malarial parasites by viewing blood smear slide under microscope and also sometimes the number of TLC's and DLC's,
• It is also helpful in the detection of organism stained with different fluoroscent dyes and other markers has proved to be successful in detection of such specific species of bacteria and viruses.

IDENTIFICATION OF UNKNOWN MICROBE OBTAINED FROM ENVIRONMENT:-

The following techniques are used to identify the unknown microbe;

• Staining
• culture media

STAINING:- It includes

1. Simple staining:- Basic dyes such as methylene blue or basic fuchsin is used.
2. Negative staining:- Microbe is mixed with dyes such as India ink or nigrosin. The background gets stain and unstained microbe stand out in contrast.
3. Differential stains:- They impart different color to different microbes or with different structures. It further includes Gram stain and Acid-Fast stain.

• Gram-Positive:- resist decolorisation and retain the color of primary stain, i.e. violet.
• Gram-Negative:- decolorised by acetone/alcohol and therefore, take counter stain and appear red.

CULTURE MEDIA:- Various types of culture medias are used to identify the unknown microbe which is as follows:

1. SIMPLE MEDIA:- Nutrient broth is used in this media. It contains peptone water and meat extract 1%, when glucose(0.5%) is added it is called glucose broth.
2. COMPLEX MEDIA:- It have added ingredients for bringing out certain properties or providing special nutrients.
3. SPECIAL MEDIA:- It includes the following:-

• Enriched media:- Media is added with nutrients such as blood, serum or egg.
• Enrichment media:- Media is used to grow thw wanted microbes related to other microbes. Tetrathionate is added in this which inhibit coliforms while allowing typhoid bacilli to grow.
• Selective media:- These media is used to isolate the particular microbe from the specimens where mixed flora is expected. Deoxycholate citrate agar is used
• Differential media:- It contains substances that help to distinguish between different types of microbes and their characteristics.
• Indicator media:- It contains the indicator which change the color of the microbe present in it.
• Transport media:- Used in case of delicate organisms that leads to transport to other place for testing.
• Dehydrated media:- It is used in other media making. It contains distilled water that can be sterilised before use.

TYPES OF CULTURE METHODS:-

• Streak culture:- Loop full of specimen is poured near the peripheral area of plate then spread into whole plate by making streaks to obtain isolated colonies. Culture plate is incubated at 37^. C for overnight.
• Lawn culture:- It is obtained by flooding the surface of plate with microbe suspension or culture. The plate is kept for minute and then excess material is poured off. Plate is incubated at 37^. C overnight to obtain colonies.
• Anaerobic culture media:- In this microbe is grown in the absence of oxygen, usually methylene blue is used as indicator of anaerobosis in the jar. It reamins colorless in anaerobic conditions and become blue on exposure of oxygen.

Thus by all the above discussed methods we can identify the unknown microbe found in the environment.