Physiological and Biochemical Methods
Physiological and biochemical based strain identification techniques have been widely used, and many of these tests have become critical for the identification of certain strains.
Creative Enzymes' strain identification platform has developed a series of biochemical tests to help our clients obtain more accurate and clear information about their strains.
Biochemical Test-Based Strain Identification
The biochemical tests are based on the fact that each strain has a different enzyme system and therefore a different ability to break down nutrients. Biochemical tests can be used to accurately reveal important information needed to identify strains of various genera in a sample. By their nature, bacteria produce a large number of enzymes that can be identified by biochemical methods. The species of bacteria can be classified according to the type of enzymes they produce.
Fig. 1 Example of biochemical tests for the preliminary identification of Salmonella spp. (Samad, 2019)
The Basis for Using Biochemical Reactions to Identify Probiotics
- Certain metabolic activities are unique to certain species. Biochemical reactions can be used to demonstrate specific metabolic diversity in probiotics.
- Biochemical traits often represent additional phenotypic traits of the strain and are easily observed. Biochemical characteristics make it possible to identify strains by matching the phenotype to that of a known reference organism.
The Biochemical Identification Methods We Offered
Creative Enzymes offers our clients a variety of biochemical based methods to identify strains, our methods include but are not limited to the following.
| Methods | Description | Applications |
|---|---|---|
| Sugar fermentation test | Identification of strains by analyzing the ability of strains to break down sugars and by detecting the end-products of sugar breakdown. | Especially important for the identification of Enterobacteriaceae. |
| Oxidation-fermentation test | Strain types are distinguished according to the presence or absence of molecular oxygen involved in the breakdown of glucose. | Mainly used for the identification of Enterobacteriaceae and non-fermenting bacteria. |
| β-galactosidase test | The principle is based on the fact that some strains can produce β-galactosidase, which can break down o-nitrophenol-β-D-galactoside (ONPG) and produce yellow o-nitrophenol. | Mainly used for rapid identification of delayed fermentation lactose strains. |
| Bile esculin test | The principle is based on the fact that some strains can break down hesperidin into glucose and hesperidin, which reacts with the divalent iron of iron citrate in the medium to produce a black compound that makes the medium black. | Mainly used for the identification of group D Streptococci from other Streptococci. |
| Methyl red test | The principle is based on the analysis of the amount of acid produced by the breakdown of glucose during the sugar metabolism of certain strains of bacteria. Methyl Red reagent is added to the culture medium to identify the type of bacteria based on the change in color of the medium. | Mainly used to identify Escherichia coli and Enterobacter aerogenes. |
| V-P test | Bacteria are identified based on the production of acetylmethylmethanol from pyruvate under decarboxylation during sugar metabolism. In an alkaline environment, it is oxidized to diacetyl by oxygen in the air, which in turn interacts with the guanidine group contained in arginine in the peptone within the medium to produce a red compound to identify the strain. | Usually used in conjunction with the methyl red test to identify gram-negative bacteria. |
| Starch hydrolysis test | Certain bacteria can produce enzymes that break down starch, and strains are identified based on the principle that starch no longer turns blue when it is hydrolyzed with iodine. | It can be used for the identification of certain species of Bacillus spp. and anaerobic bacteria. |
| Catalase test | Bacteria with hydrogen peroxidase catalyze the generation of water and new ecological oxygen from hydrogen peroxide, followed by the formation of molecular oxygen to appear as bubbles. | Commonly used for the identification of gram-positive cocci. |
Creative Enzymes is a professional and experienced probiotic supplier and service provider. We offer a variety of biochemical-based tests to provide our clients with efficient and accurate strain identification results. To get more information, please contact us or fill out the online inquiry below, we will be happy to serve your research demands.
Reference
- Samad, A. A.; et al. Prevalence of Salmonella spp. in chicken meat from Quetta retail outlets and typing through multiplex PCR. Romanian Biotechnological Letters. 2019, 24(2).
