Biochemical Activities of Microorganisms
Objectives
1. To determine biochemical activities of microorganisms.
2. To observe the product of biochemical activities of microorganisms.
3. To learn the skills of inoculation agar tubes and agar plates.
Introduction
Microorganisms are able to carry out different biochemical activities with the ease of different enzymes. Each of these enzymes carries out one specific type of the chemical transformation. They convert substrates into product.
A) Carbohydrates Fermentation
Microorganisms utilize various carbohydrates as their source of energy. Different species of microorganisms breaking down different types of carbohydrates and produce various forms of products. This experiment is to test whether the microbes are fermentatively or oxidatively utilize the carbohydrates. OF agar is used as the nutrient medium and it will turns yellow when cultured with fermentative microbes and only top few mm will turns yellow when cultured with oxidative microbes.
B) Starch hydrolysis
Not every microbe can produce amylase to hydrolyze starch. This session is to test the ability of microbes for the activity of starch hydrolysis. The presence of blue color upon the adding of iodine indicates that starch is not hydrolyzed.
C) Gelatin Hydrolysis
Gelatin is the convenient substrate to test for proteolytic enzymes in microorganisms. This session will be testing the ability of different microbes to hydrolyze gelatin. The nutrient gelatin is in liquid form in room temperature but solidify in ice bath. When gelatin is hydrolyzed, the gelatin nutrient broth will remain as liquid in ice bath.
D) Utilization of amino acids
Amino acids may be utilized to yield energy for the cells, for examples. NH3, indole, and H2O.
- Indole Production
Trytophan degrades to form indole. Only certain bacteria form indole. Thus, the degradation is suitable as another differentiating reaction. The presence of indole is tested using the Kovacs method. The reddening of alcohol layer indicates the
1. To determine biochemical activities of microorganisms.
2. To observe the product of biochemical activities of microorganisms.
3. To learn the skills of inoculation agar tubes and agar plates.
Introduction
Microorganisms are able to carry out different biochemical activities with the ease of different enzymes. Each of these enzymes carries out one specific type of the chemical transformation. They convert substrates into product.
A) Carbohydrates Fermentation
Microorganisms utilize various carbohydrates as their source of energy. Different species of microorganisms breaking down different types of carbohydrates and produce various forms of products. This experiment is to test whether the microbes are fermentatively or oxidatively utilize the carbohydrates. OF agar is used as the nutrient medium and it will turns yellow when cultured with fermentative microbes and only top few mm will turns yellow when cultured with oxidative microbes.
B) Starch hydrolysis
Not every microbe can produce amylase to hydrolyze starch. This session is to test the ability of microbes for the activity of starch hydrolysis. The presence of blue color upon the adding of iodine indicates that starch is not hydrolyzed.
C) Gelatin Hydrolysis
Gelatin is the convenient substrate to test for proteolytic enzymes in microorganisms. This session will be testing the ability of different microbes to hydrolyze gelatin. The nutrient gelatin is in liquid form in room temperature but solidify in ice bath. When gelatin is hydrolyzed, the gelatin nutrient broth will remain as liquid in ice bath.
D) Utilization of amino acids
Amino acids may be utilized to yield energy for the cells, for examples. NH3, indole, and H2O.
- Indole Production
Trytophan degrades to form indole. Only certain bacteria form indole. Thus, the degradation is suitable as another differentiating reaction. The presence of indole is tested using the Kovacs method. The reddening of alcohol layer indicates the
References: 1. Clarke, P.H. (1955). Methods for Determining the Biochemical Activities of Microorganism as applied to Classification. Available from: < http://mic.sgmjournals.org/content/12/2/337.full.pdf >. [22th March 2013].