What is the HPC method?
The Heterotrophic Plate Count tests (HPC) are flexible test methods for the presence and vitality of a diversity of microorganisms. As HPC analyzes measures and indicates pathogen removal and regrowth organisms, they are useful tools for evaluating drinking water samples.
What is pour plate technique?
Pour plate method is usually the method of choice for counting the number of colony-forming bacteria present in a liquid specimen. Because the sample is mixed with the molten agar medium, a larger volume can be used than with the spread plate. Each colony represents a “colony-forming unit” (CFU).
How do you reduce HPC in water?
HPC levels can be minimized in a distribution system by supplying water containing low levels of assimilable organic carbon and a disinfectant residual, and exercising best practices to ensure proper distribution system maintenance.
How do you calculate heterotrophic count?
To compute the heterotrophic plate count for pour plate, spread plate, and membrane filter methods (CFU/mL), divide either the total or average number of colonies per plate by the sample volume. (Use the average number of colonies if duplicate plates of the same dilution.)
How do you calculate HPC?
A second way to calculate the reduced levels is by using the Height (level) of collimation line (or plane). From the above numerical example, Height of Plane of Collimation (HPC) = +120.000 + 1.135 = +121.135m (as from Figure 2) => RLB = HPC – (Staff Reading at B)
How do the results of the pour plate method compare?
How do the results of the pour-plate method compare with those obtained using the streak-plate and spread-plate methods? The results should compare favorably with the streak plate and spread plate methods to obtain isolated colonies. The bacteria samples are diluted several times to ensure decrease # of microbes.
What does CFU stand for?
colony forming unit
A colony forming unit, or CFU, is a unit commonly used to estimate the concentration of microorganisms in a test sample.
What causes high HPC?
The density of HPC bacteria reached in the distribution system can be influenced by numerous parameters, including the bacterial quality of the finished water entering the system, temperature, residence time, presence or absence of disinfectant residual, construction materials, surface-to-volume ratio, flow conditions …
How does a heterotrophic Plate Count ( HPC ) work?
Heterotrophic Plate Count (HPC) is a microbial method that uses colony formation on culture media to approximate the levels of heterotrophic flora. HPC does not, however, give an indication of the types of organisms present or their sources.
What kind of media are used for HPC?
The three methods are the spread plate, pour plate and membrane filtration methods. Three different media can be used to enumerate HPC, including the Standard Methods Agar (SMA), R2A agar, and m-HPC agar. All three of these media are non-selective, in that they supply nutrients and support growth for a variety of heterotrophic bacteria.
What’s the pour plate method and how does it work?
a. Pour plate method: The pour plate method (9215B) is simple to perform and can accommodate sample or diluted-sample volumes ranging from 0.1 to 2.0 mL. It produces subsurface colonies that are relatively small, compact, and less apt to encroach on each other than surface colonies do.
When to use pour plate for bacteria enumeration?
The Pour Plate technique can be used on any type of liquefied sample for the enumeration of bacteria. Conditions vary depending upon the type (s) of bacteria being enumerated. Agar is prepared according to standard recipe and then held at 44-46°C in a water bath.