Microbial growth curveIt is a dynamic model that describes the changes in the population size of microorganisms over time under specific environmental conditions, usually divided into four stages: lag period, logarithmic period, stable period, and decay period. By analyzing the growth curve, the metabolic characteristics, environmental adaptability, and growth regulation mechanisms of microorganisms can be revealed, providing theoretical basis for industrial fermentation, disease prevention and control, environmental governance, and other fields.
Microbial growth curveAnalysis method:
Direct counting method
Blood cell counting board: directly counting the total number of live and dead bacteria through a microscope, with simple operation but unable to distinguish between live and dead.
Fluorescence staining method: Use dyes such as propidium iodide (PI) to label dead bacteria, and use flow cytometry to distinguish between live and dead bacteria.
Indirect counting method
Plate colony counting (CFU method): Dilute the bacterial solution onto a plate and count the colony count (CFU/mL) to reflect the number of viable bacteria, but it takes a long time (18-24 hours of cultivation).
Turbidity method: Measure the optical density (OD ₆₀₀) of bacterial solution using a spectrophotometer to quickly reflect the concentration of bacterial cells, but it is affected by cell size and color of the culture medium.
Metabolic activity detection
Respiratory intensity measurement: Reflecting metabolic activity by measuring oxygen consumption or CO ₂ release.
ATP bioluminescence method: using luciferase to catalyze the reaction between ATP and luciferin to produce luminescence, with light intensity proportional to bacterial concentration, suitable for rapid detection.
Molecular biology methods
QPCR: Quantitatively detect the copy number of specific genes (such as 16S rRNA) to reflect changes in bacterial population.
Flow cytometry: Combining fluorescent labeling to detect cell size, DNA content, and metabolic activity, achieving single-cell level analysis.