Detection and Identification
These 2 words normally used in conjunction in the rapid method. However, they mean two different things. Identification refers to determine the identity of the pure culture isolate whereas detection is the detecting of the microorganisms directly from the food.
In the past, the analysis of the microbiology involves 3 steps. The 1st step is the pre-enrichment step in which the food are incubated in non selective media for microbial cell repair. The 2nd step is the selective enrichment whereby the culture (pathogen of the interest) are then transferred to the selective media for growth while limiting the growth of undesirable pathogen. Lastly, the last step is the post enrichment. In this steps, the pathogen of the interest are isolate in to pure culture for growth in order for the identification method to take place. However, this conventional method is time-consuming and labor intensive. Therefore, rapid methods are created to speed up the identification and detection for effective analysis.
Identification techniques or methods
A. Miniaturized Biochemical and other identification Assay
The identification assays usually involve the use of pure isolate of unknown pathogen and it is mostly identify based on the biochemical characteristics of the micro-organisms. Identification based on the microbials’ biochemical characteristic is tedious and require time-consuming which may take weeks or months to analysis. The introductions of the miniaturized biochemical kits enable to analysis the biochemistry of the micro-organisms in a faster time. These kits contain 115 to 30 types of media or substrates and only require 18-24 hrs of incubation before the result can be obtained. Beside using the biochemistry for the accessing the type of organisms, test kits can also make use of the fatty acid or nucleic acid for the identification.
Corn flour may contain Salmonella and maybe B. cereus. Note: Salmonella spp. belong to Enterobacteriaceae family.
Antibody-Based Assays and Nucleic Acid-Based Assays can also used to detect and identify the micro-organisms and toxins.
The Nucleic Acid- Based Assays include the DNA probes, PCR and Bacteriophage. These assay is used to detect pathogen in the food. Examples of DNA probes are the GENE-TRAK asaay in which 2 types of method are applied- DNA hybridization and enzyme immunoassay. PCR involves hybridization and amplification. It is effective and fast, however, it can be easily distributed by the composition of the food. Lastly, Bacteriophage is used to detect specific pathogen in the foods. Examples of it are the bioluminescence and the ice nucleation.
The simplest test of the Antibody-Based Assay is the Latex Agglutination in which antibody-coated colored latex beads or colloidal gold particles are used to test the bacterial cell suspension. For the analysis of toxin, Reverse Passive Latex Agglutination is normally used.
There are many other Antibody-Based Assay test which include Immunodiffusion, Immunoprecipitation, ELISA (Enzyme-Linked Immunosorbent Assay) and Immunomagnetic Separation (IMS).
Some of the tests mentioned above are now currently being improved with new technologies and to able to give resulting in a much shorter time with high accuracy and sensitively
PCR has been improved to rtPCR (real-time PCR) in which the results can be obtained in real time, meaning the data can be collected immediately during the certain processing or analysis steps.
Moreover, Biosenors and DNA Microarrays are also developed. Biosensors make use of the minute fluctuations resulting from the biological interactions into measureable digital electronic reading. On the other hand, DNA Microarrays uses DNA chips, biochips , gene chips or genome chips, which capable of analysize thousand of gene simultaneously
These 2 words normally used in conjunction in the rapid method. However, they mean two different things. Identification refers to determine the identity of the pure culture isolate whereas detection is the detecting of the microorganisms directly from the food.
In the past, the analysis of the microbiology involves 3 steps. The 1st step is the pre-enrichment step in which the food are incubated in non selective media for microbial cell repair. The 2nd step is the selective enrichment whereby the culture (pathogen of the interest) are then transferred to the selective media for growth while limiting the growth of undesirable pathogen. Lastly, the last step is the post enrichment. In this steps, the pathogen of the interest are isolate in to pure culture for growth in order for the identification method to take place. However, this conventional method is time-consuming and labor intensive. Therefore, rapid methods are created to speed up the identification and detection for effective analysis.
Identification techniques or methods
A. Miniaturized Biochemical and other identification Assay
The identification assays usually involve the use of pure isolate of unknown pathogen and it is mostly identify based on the biochemical characteristics of the micro-organisms. Identification based on the microbials’ biochemical characteristic is tedious and require time-consuming which may take weeks or months to analysis. The introductions of the miniaturized biochemical kits enable to analysis the biochemistry of the micro-organisms in a faster time. These kits contain 115 to 30 types of media or substrates and only require 18-24 hrs of incubation before the result can be obtained. Beside using the biochemistry for the accessing the type of organisms, test kits can also make use of the fatty acid or nucleic acid for the identification.
Corn flour may contain Salmonella and maybe B. cereus. Note: Salmonella spp. belong to Enterobacteriaceae family.
Antibody-Based Assays and Nucleic Acid-Based Assays can also used to detect and identify the micro-organisms and toxins.
The Nucleic Acid- Based Assays include the DNA probes, PCR and Bacteriophage. These assay is used to detect pathogen in the food. Examples of DNA probes are the GENE-TRAK asaay in which 2 types of method are applied- DNA hybridization and enzyme immunoassay. PCR involves hybridization and amplification. It is effective and fast, however, it can be easily distributed by the composition of the food. Lastly, Bacteriophage is used to detect specific pathogen in the foods. Examples of it are the bioluminescence and the ice nucleation.
The simplest test of the Antibody-Based Assay is the Latex Agglutination in which antibody-coated colored latex beads or colloidal gold particles are used to test the bacterial cell suspension. For the analysis of toxin, Reverse Passive Latex Agglutination is normally used.
There are many other Antibody-Based Assay test which include Immunodiffusion, Immunoprecipitation, ELISA (Enzyme-Linked Immunosorbent Assay) and Immunomagnetic Separation (IMS).
Some of the tests mentioned above are now currently being improved with new technologies and to able to give resulting in a much shorter time with high accuracy and sensitively
PCR has been improved to rtPCR (real-time PCR) in which the results can be obtained in real time, meaning the data can be collected immediately during the certain processing or analysis steps.
Moreover, Biosenors and DNA Microarrays are also developed. Biosensors make use of the minute fluctuations resulting from the biological interactions into measureable digital electronic reading. On the other hand, DNA Microarrays uses DNA chips, biochips , gene chips or genome chips, which capable of analysize thousand of gene simultaneously
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