Thursday, January 8, 2026

Serial dilution of bacterial culture MIC

 Serial dilution of bacterial culture


Broth Microdilution assay - How to determine the MIC (Minimum Inhibitory Concentration)

Henrik's Lab




MIC (Broth Microdilution) Testing

By TheRubinLab

McFarland Standard

In microbiology, McFarland standards are used as a reference to adjust the turbidity of bacterial suspensions so that the number of bacteria will be within a given range to standardize microbial testing.
McFarland nephelometer standards:

McFarland Standard No.0.51234
1.0% barium chloride (ml)0.050.10.20.30.4
1.0% sulfuric acid (ml)9.959.99.89.79.6
Approx. cell density (1X10^8 CFU/mL)1.53.06.09.012.0
% transmittance*74.355.635.626.421.5
Absorbance at 600nm*0.08 to 0.10.2570.4510.5820.669
  • Preparation of 1.0% Barium chloride suspension: 
  • 0.05 mL of 1.175% barium chloride dihydrate (BaCl2•2H2O)

How to perform serial dilutions and make microbial suspensions using McFarland Standards