Method for detecting and counting relative content of microorganism

A method for determining the relative content of a microorganism, comprising the following steps:

• i) adding a redox indicator to a medium to obtain an indicator medium;
• the color change range of the redox indicator includes three or more colors;
• ii) diluting a test sample 3-15 times with 3-15 replicates of each dilution to produce diluted test samples, and culturing the diluted test samples using the indicator medium;
• iii) reading the color or absorbance of the indicator medium in each diluted test sample during culture and/or after the completion of culture;
• and
• iv) calculating the relative content of the microorganism in the test sample according to color change or absorbance change value of the indicator medium by:
• according to the correlation between the color of the indicator medium and the content of microorganism, reading the color of the indicator medium in each diluted test sample and giving different color a numerical value, and the numerical value of the reading is positively correlated with the content of microorganism;
• and
• calculating the relative content of the microorganism in the test sample by a formula of:
• Z=(X1-1+X1-2+ . . . +X1-n)×Y1+(X2-1+X2-2+ . . . +X2-n)×Y2+ . . . +(Xm-1+Xm-2+ . . . +Xm-n)×Ym,
• wherein, Z is the relative content of the microorganism in the test sample;
• m is the mth dilution, 3≤m≤15;
• n is the nth replicate sample, 3≤n≤15;
• X is the value of a color reading, X≥0;
• Xm-n represents the value of the reading of the nth replicate sample of the mth dilution;
• Y represents a dilution coefficient, Y>0;
• Ym represents the dilution coefficient of the mth dilution, and Ym≥Ym-1≥Ym-2≥Y2≥Y1;
• or,
• according to the absorbance change value of the indicator medium, calculating the relative content of the microorganism in the test sample by a formula of:
• Z=(X1-1+X1-2+ . . . +X1-n)×Y1+(X2-1+X2-2+ . . . +X2-n)×Y2+ . . . +(Xm-1+Xm-2+ . . . +Xm-n)×Ym,
• wherein, Z is the relative content of the microorganism in the test sample;
• m is the mth dilution, 3≤m≤15;
• n is the nth replicate sample, 3≤n≤15;
• X is the absorbance change value of the indicator medium;
• Xm-n represents the absorbance change value of the nth replicate sample of the mth dilution;
• Y represents a dilution coefficient, Y>0;
• Ym represents the dilution coefficient of the mth dilution, and Ym≥Ym-1≥Ym-2≥Y2≥Y1.