GB/T 38480-2020 PDF English
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Determination of antifungal activity for microbial secondary metabolites - Mycelial growth rate method
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GB/T 38480-2020: PDF in English (GBT 38480-2020) GB/T 38480-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 07.080
A 21
GB 38480-2020
Determination of Antifungal Activity for Microbial
Secondary Metabolites - Mycelial Growth Rate Method
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: NOVEMBER 19, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 4
4 Principal ... 4
5 Reagents and Materials ... 5
6 Apparatus ... 5
7 Operation Procedures ... 5
8 Calculation of the Results ... 6
9 Repeatability ... 7
Determination of Antifungal Activity for Microbial
Secondary Metabolites - Mycelial Growth Rate Method
1 Scope
This Standard specifies a method for determining the antifungal activity of secondary
metabolites of antibiotics derived from microorganisms by the mycelial growth rate
method.
This Standard applies to the determination of antifungal activity of secondary
metabolites of antibiotics derived from microorganisms.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) is applicable to this document.
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Median inhibitory concentration; IC50
The concentration at which the inhibition rate of fungal growth reaches 50%.
3.2 Antifungal activity
The ability to resist the growth and reproduction of fungi.
4 Principal
Mix the tested secondary metabolites with the culture medium; use the growth rate of
the colonies on the culture medium to measure the ability of the secondary metabolites
to inhibit filamentous fungi, and judge the activity by calculating IC50.
7.2 Preparation of tested samples
The polar sample is directly dissolved in water (the non-polar sample is fully dissolved
by adding a certain concentration of surfactant); prepare it into a certain concentration
of mother liquor; filter through a sterile 0.45μm filter membrane. And then use the sterile
water (or the corresponding surfactant) to dilute step by step by 2 times or 5 times
concentration to prepare at least 5 different concentrations of the tested solution. When
diluting step by step, ensure that there is concentration point with the inhibition rate
greater than 50% distribution, and there is also concentration point with the inhibition
rate less than 50% distribution; prepare immediately before use.
7.3 Preparation of test plate
Respectively dilute the tested samples prepared in 7.2 with the PDA medium cooled
to 55°C±1°C at a ratio of 1:9; mix well and transfer 10 mL each with a sterile pipette to
a sterile petri dish; gently shake the petri dish to make it evenly flat. After it has solidified,
it shall be made into a test plate. The plate prepared by mixing the corresponding
solvent and PDA is used as a blank control plate for later-use.
7.4 Determination of antibacterial activity
Use a sterile punch (inner diameter of 5mm±0.1mm) to punch holes in the same radius
edge of the activated indicator bacteria plate; and use sterile forceps to take the
bacterial cake and place it in the middle of the detection plate prepared in 7.3. Each
treatment is repeated for 5 times. Place the plate in a constant temperature incubator
at 28°C±1°C for 24h~48h, take it out; and measure the colony diameter by the cross
method. The average value of two measurements is the colony diameter.
8 Calculation of the Results
The inhibition rate is calculated according to Formula (1):
Where:
I – inhibition rate;
D1 – diameter of colony formed in the blank control plate, in mm;
D2 – diameter of colony formed in the tested secondary metabolite plate, in mm.
Take the average of five parallel samples as the final result, and keep the calculated
result to two digits after the decimal point.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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