What is the normal heterotrophic plate count?

Heterotrophic plate count levels in potable water should be <500 CFU/mL. These levels may increase on occasion, but counts consistently >500 CFU/mL would indicate a general decrease in water quality.

What is the standard plate count method used for?

The most commonly used microbiological count method is the standard plate count (SPC) agar method. This method is used by the dairy industry for estimating the microbial populations in most types of dairy products and samples and for determining quality and sources of contamination at successive stages of processing.

How do you count a standard plate count?

The standard plate count method consists of diluting a sample with sterile saline or phosphate buffer diluent until the bacteria are dilute enough to count accurately. That is, the final plates in the series should have between 30 and 300 colonies.

What is heterotrophic plate count used for?

Measuring the heterotrophic plate count (HPC) is an analytic method that is a useful operational tool for monitoring general bacteriological water quality throughout the treatment process and in the distribution system.

What is standard plate counting?

The Standard Plate Count (SPC) means the colony count of the mesophilic bacteria growing under aerobic condition on standard methods agar (Plate Count Agar), and SPC becomes the representative index indicating the degree of the microbial contamination of the food.

What is total heterotrophic bacteria count?

The heterotrophic plate count (HPC), formerly known as the standard plate count, is a procedure for estimating the number of live, culturable heterotrophic bacteria in water and for measuring changes in swimming pools or during water treatment and distribution.

What is a good standard plate count?

The raw plate count results for standard agar plates should be within 25 to 250 colony forming units (CFU) or reported as an estimate. The recommended counting range for Aspergillus niger and other filamentous colonies is between 8 and 80 CFU per plate.

What is the formula for calculating cfu?

To find out the number of CFU/ ml in the original sample, the number of colony forming units on the countable plate is multiplied by 1/FDF. This takes into account all of the dilution of the original sample. For the example above, the countable plate had 200 colonies, so there were 200 CFU, and the FDF was 1/4000.

What are the 2 types of heterotrophic bacteria?

There are two subcategories of heterotrophs: photoheterotrophs and chemoheterotrophs. Photoheterotrophs are organisms that get their energy from light, but must still consume carbon from other organisms, as they cannot utilize carbon dioxide from the air.

What is the formula for calculating CFU?

What is the difference between total plate count and total viable count?

The main difference between the two is that total count determines the count of all cells both dead and alive while viable count estimate the number of viable or live cells only capable of growing into distinct colonies.

What types of bacteria are heterotrophic?

Heterotrophic Bacteria Types and Examples

• Citrus canker – Xanthomonas axonopodis.
• Crown gall – Agrobacterium tumefaciens.
• Blight of beans – Xanthomonas campestris.
• Wildfire of Tobacco – Pseudomonas syringae.
• Granville wilt – Pseudomonas solanacearum.

How are heterotrophic plate counts used in drinking water?

HPC methods use colony formation on culture media to approximate the levels of heterotrophs in a drinking water sample, with bacteria being more common than moulds and yeasts. HPC methods do not provide an indication of the specific heterotrophic bacteria present or their sources.

Which is the best agar for heterotrophic plate count?

Plate count agar (also called tryptone glucose yeast agar ): This medium can be used to examine heterotrophic bacteria in a wide variety of matrices. It can be used for both pour- and spread-plate methods. This high-nutrient agar, widely used in the past, may give lower counts than R2A or NWRI agar.

Which is the best method for plate count?

Four methods and five media are described. 2. Selection of Method 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.

How many colonies are needed for a plate count?

The suitable colony counting range ( 10) is 25-250. The automated spiral plate count method for the examination of foods and cosmetics ( 5 ), outlined below, conforms to AOAC Official Methods of Analysis, sec. 977.27.