Microbiology Assignment Help

Microbiology is a broad term which includes virology, mycology, parasitology, bacteriology and other branches

What is basic techniques in Microbiology laboratory?

Microbiology laboratory is a field of biology which deals with microorganisms(which cannot be seen with naked eyes) and their effect on other living beings specially human beings.

Introduction to microbiology laboratory

The primary or basic working place of a microbiologists is microbiology laboratory. In these laboratories all types of microbiology experiments related to microbiology are done. For example staining, culturing, identification and lots of other research work. These experiments are also related to biochemistry, biotechnology and some other branches of modern biology.

There are several rules followed in any microbiology laboratory like any other science laboratory. One of the most important rule followed in microbiology laboratory is to maintain extremely clean, sterile(free of any living organism) condition inside the microbiology laboratory. In simple words, microbiology laboratory must be free of any unwanted living being.

There are a wide variety of equipment in a microbiology laboratory used . But the most common and most important tool used in microbiology laboratory is microscope. Microbiology laboratory is totally incomplete without microscope as it is the most frequently used instrument in any microbiology laboratory. There are many more equipment used in microbiology lab equipment homework assignment help .

Basic Rules and Fundamental Equipments in Microbiology Laboratory

Following are the main rules followed in any general microbiology laboratory:

  1. Sterile condition must be maintained inside the laboratory. All the microbiology tools and equipments used in the lab should be sterilized prior to the use for any experiment.

  2. Microbiologist also have to strictly maintain sterile condition. Before entering into the lab microbiologists have to take bath, change clothes and pass through a sterile chamber. Prior to any experiment must clean hands with soap and then sterilize with alcohol(wipe hands with cotton soaked in alcohol).

  3. Flame resistant or retardant lab coat or apron is must inside the lab for everyone.

  4. It is suggested not to work with open wound or cut inside the lab as it may result in infection.

  5. Books or other items must not kept in working place.

  6. Place provided for the experiment must be cleaned with provided disinfectant prior to the experiment.

  7. Contaminated cultures must be discarded and burnt. And contaminated equipments must be properly sterilized for further use.

  8. Eating or smoking is not allowed inside the lab.

  9. Talking during performing an experiment must be prohibited.

10. Shoes worn inside the lab must not be used outside the lab.                                                                                                                

11. Aseptic condition must be always maintained while dealing with microbial cultures.

Essential microbiology lab equipments in microbiology laboratory include centrifuge, laminar air flow, autoclave, incubator, hot air oven, colony counter,Spectrophotometer, pH meter, balances, stirrers, shakers, glass equipments.

Primary functions of these microbiology laboratory equipments:

1. Centrifuge- mainly used to disrupt cells to release cellular constituents.

2. Laminar air flow- release sterile air and in this chamber experiments are performed.

3. Autoclave- all the heat resistant equipments are sterilized under high pressure steam for 15 to 20minutes.

4. Incubator- cultures are incubated for growth of microorganisms.

5. Hot air oven- is an electrical device which use dry heat for sterilization.

6. Colony counter is used to count number of colonies grown on any culture media.

7. Spectrophotometer- mainly use light intensity to measure microbial growth, assays and many other purposes.

8. pH meter is used to measure pH of different liquids used in microbiology lab.

9. Balances are used to weigh different substances used for experiments. For example constituents for preparing a medium.

10. Shakers and stirrers are also used for various purposes like oxygen supply.

11. Glass equipments- lots and lots of glass equipments are used in microbiology laboratory for a wide range of purposes. For example petriplates are used to transfer bacterial culture to freshly prepared medium for bacterial growth.

Basic microbiology lab techniques : Microbiology Laboratory

The basic microbiology experiments and lab techniques done in microbiology laboratory include following:

1. Sterilization-most repeatedly used technique in microbiology lab to obtain lab materials free from any living organism.

2. Staining- is done to increase contrast to highlight any living cell in the microscopic image.

3.Observation under microscope- microscopy is used to observe unicellular organisms or cell clusters for their identification, characterization and to know their various properties.

4. Incubation- is done to maintain microbial culture specially bacterial culture at a particular temperature for a specific  time length to obtain growth.

5. Centrifugation- is used in microbial lab mainly to disperse cells and also to obtain a specific substance(for example- plasmid, specific protein etc).

6. Preparation of microbiological culture- main purpose of preparing microbial cultures include their study for various reasons like determining the type of microorganism, abundance of a particular organism, identification of pathogen etc.

7. Biochemical tests- are done mainly for identification of a microorganism and to know about it's characteristic features.

8. Quantitative and qualitative analysis- this technique is generally used to determine amount of various biochemical constituents in a specific sample. For example number of rhizobium cells present in a specific soil sample.

There are many more basic microbiology lab techniques done in microbiology laboratory during various experiments. These techniques include electrophoresis, blotting, hybridization, fermentation etc.


The  metabolism  of carbohydrates meets with different fates as it  is subjected to different enzyme systems, different  locales of reaction and most importantly, the presence or absence of oxygen.  

The  carbohydrates like glucose, fructose etc  breakdown into two molecules of pyruvate. In the presence of oxygen, the pyruvate  is oxidised via the TCA cycle  into CO2  and water with liberatin of energy.

But in the absence  of oxygen, that is anaerobically, they are  converted into lactic acid by the process of  lactic acid fermentation  as seen in humans and other mammals.

Lactic acid fermentation occur  in anaerobes like bacteria and in cerain cells like muscle cells and also in  facultative anaerobes.

Process of Lactic acid  formation:
The process   of lactic acid fermentation can be divided into two types
Homofermentive fermentation----
   one molecule of glucose produces 2 molecules of lactic acid  in lactic acid fermentation

                                     C6H12O6 → 2 CH3CHOHCOOH
                                   (Glucose)         (Lactic acid)

B) Heterofermentative fermentation----
      One molecule of  glucose  produces lactic acid, ethanol and  CO
2     by the phosphoketolase pathway  in the lactic acid fermentation                                                                                                                                                     
6 H12  O6 ----> CH3CHOHCOOH     +    C2 H5OH   + CO 2                                                     
                                                                                        (ethyl alcohol)

  • Initially, glucose is converted into pyruvic acid by  glycolysis 
  • The pyruvate produced, in presence of O2  moves into cellular respiration but in absence of O2  undergoes fermentation to produce ATP.


is required for the process of glycolysis to continue         
   In the same proces, NAD
+ is oxidised to NADH  which must be reconverted to NAD+  for the continuation of the process of glycolysis.
     NADH donates the electrons to pyruvate and gets converted to NAD
+    .Pyruvate is converted to lactic acid  by the process.
   The lactic acid thus produces undergoes fermentation to produce  lactate  (measurable form of lactic acid)   or lactic acid
.                 img         

 Homofermentive    lactic acid fermentation                      


 Heterofermentative lactic acid fermentation      

Energy Produced:

Only 2 ATP molecules are produced  by lactic acid fermentation.

In the muscles glycogenolysis or breakdown of glycogen provides the energy   But in intense muscular activity the muscles suffer a loss of oxygen and under anaerobic conditions, energy is channeled through the  anaerobic system   pyruvic acid is converted to lactate by lactate dehydrogenase.

The fermentation oxidises the NADH to NAD+ which is supplied back for glycogenolysis, and lactate is converted to pyruvate for Krebs cycle..

Fate of Lactate:Cori cycle

The lactate formed in the muscle is not stored in it but removed by the bloodstream to enter the Cori cycle  in the liver.Here gluconeogenesis occurs where glucose is again reproduced .Thus the muscle is  relieved of the lactic acid load
 By the Cori'd cycle the the lactic acid is reconverted to glucose  via pyruvate.     
         img                        img
                                                                 CORI CYCLE

Use of Cori Cycle:   Cori cycle prevents lactic acidosis

Microbiology of Lactic Acid Fermentation:


The process of lactic acid fermentation  is also performed by microbes like fungi and bacteria, of whom the most important  bacteria is Lactobacillus  sp.  Others  include  Pediococcus cerevisiae,  Streptococcus lactis   , Bifidobacterium bifidus  etc.

Lactic acid fermentation is used to prepare food throughout the world like  yogurt,( Lactobacillus bulgaricus and Streptococcus thermophilus),   sourdough breads, sauerkraut, cucumber pickles,  kefir, ( bacteria as well as yeasts.)  laban rayab and laban zeer ,  pickled vegetables,  magou ,(Lactobacillus delbreuckii )  ,   balao balao  etc in different parts of the world.
 It is also used industrially.


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