AS 4276.3:2021 pdf free download – Water microbiology Method 3: Enumeration of heterotrophic microorganisms — Pour plate,spread plate, membrane filtration and most probable number techniques

AS 4276.3:2021 pdf free download – Water microbiology Method 3: Enumeration of heterotrophic microorganisms — Pour plate,spread plate, membrane filtration and most probable number techniques.
(a) Pour plate.
(b) Spread plate.
(c) Spiral plate.
(d) Membrane filtration.
(e) Most probable number (MPN).
These techniques are Intended to measure the operational effectiveness of treatment processes and be used for the general examination of many types of water to evaluate and/or note changes in water quality.
This document does not cover the comparison of results obtained from different techniques.
1.2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document:
NOTE Documents br inlormative purposes are listed in the Bibliography.
AS 2031, Water quality — Sampling for microbiological analysis (ISO 19458:2006. MOD)
AS 5140, Microbiology offood. animal feed and water — Preparation, production, storage and perjormance testing of culture media (ISO 11133:2014, MOD)
AS 4276.1, Water microbiology. Method 1: Water quality — General requirements and guidance for niicrobtologtcal examinations by culture (ISO 8199:2018. MOD)
1.3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
1.3.1
count
observed number of ablacts, such as colonies, determined by direct countinK, or most probable number (MPN) estimation based on statistical calculation using the number of positive units in a dilution series of a test sample
1.3.2
may
indicates the existence ofan option
The major disadvantage of the spread plate technique is that the lower level of detection is increased due to the reduction in the volume of the Inoculum able to be applied to the surface of the plate.
NOTE A flow diagram of the procedure is shown in Figure Al.
7.2.2 Procedure
This procedure describes the technique [or enumerating microorganisms in water by inoculating a volume of sample onto the surface of an agar plate. Record the volume of sample inoculated.
The procedure for spread plating shall be In accordance with AS 4276.1.
7.2.3 Incubation
Plates should be Incubated at 36°C ± 2°C for 44 Ii ±4 hand/or 22°C ± 2 °C for 68 h ± 4 h, as required.
7.2.4 Counting of colonies
Colonies shall be counted and recorded after the incubation period.
72.5 CalculatIon of results
The calculation of results shall be carried out in accordance with AS 4276.1.
7.3 Spiral plate
7.3.1 General
This is a variation of the spread plate technique.
The spiral plater dispenses a known volume of the sample on the surface ol a rotating agar plate in an Archimedes spiral. The volume of sample deposited is decreased as the dispensing stylus moves from the centre to the edge of the plate, so that an exponential relationship exists between the volume deposited and the radius of the spiral. Following incubation, microorganisms present will develop on the surface of the agar. Using a counting grid, the number of colonies in a known area is calculated by referring to manufacturer’s instructions.
NOTE A flow diagram olihe procedure Is shown In EgurcA2.
7.3.2 Procedure
The procedure shall be in accordance with the manu1acturer.s instructions.
7.3.3 IncubatIon
Plates should be incubated at 36°C ± 2°C for 44 h ± 4 h and/or 22°C ±2 °C for 68 h ± 4 h, as required.
7.3.4 Reading of results
After the required £ncubation period, the reading of results shall he in accordance with the manufacturer’s instructions.
7.3.5 CalculatIon of results
The calculation of results shall be performed using the manufacturer’s instructions.