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Microbiological Testing Overview
Cultivation Techniques
Direct Methods
Combination Techniques

BioSpec Global A Better Way

BioSpec Global offers an array of products designed to perform microbiological testing of Water samples to detect contaminents such as Coliform including E.coli. How does microbiological work? Below are some basics to introduce you to various methods currently in use

Microbiological Testing - Overview

Current Methods of detection of microorganism can basically be divided into three categories.

  1. Cultivation Techniques
  2. Direct (non-cultivating) Techniques
  3. Combination of the above.

1. Cultivation Techniques

Cultivation techniques comprise of the MF method (Membrane Filtration), MPN method (Most Probable Number) and P/A (Presence Absence) testing. These methods of testing are considered Standard Methods as defined by the EPA (Environmental Protection Agencies), WHO (World Health Organization) and other regulating bodies internationally.

Some disadvantages of the MF, MPN techniques include:

  • Length of time to obtain results (1-6 days)
  • Increased warehousing cost (food industry)
  • Reduced shelf- life of products
  • The need for highly technical personnel
  • Labor intensive and the opportunity for human error

The use of chromogenic/fluorogenic reagents, (Rapid Test Method), has opened the doors for both detection and enumeration to be done using various detection technologies such as Spectrophotometers and Image Analyzers.

2. Direct Methods

Direct methods do not require any culturing to detect or measure the quantity of microbial parameters. The techniques generally uses labeling of the organisms or their components followed by detection of the labels. Techniques such as spectroscopy, electrophoresis, fluorescence microscopy, flow cytometry and laser scanning have been used in conjunction with the following methods:

  1. Immunological
  2. Bacteriophage
  3. Hybridization
  4. Polymerase Chain Reaction (PCR)

3. Combined Techniques

This category includes methods which utilize a certain amount of culturing (or enrichment) followed by techniques described under Direct Methods. Examples are:

  • Culture-PCR
  • Enzymatic immunoassay (EIA)
  • Enzyme-linked immunosorbent assay (ELISA)
  • Enzyme-linked fluorescent assay (ELFA)

Many technologies are emerging as rapid methods to replace the traditional ones. Such recent developments in the detection of pathogens are described on the next page.

For refrences or more information please visit our documentation page here

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