What are the differences between gram stain and culture?

Question

Accepted Answer

Gram stain and culture are two completely different techniques with several significant differences between them.

Basis of differentiation
Gram stain
Culture

Definition
Is a differential staining technique used to identify the presence of bacteria and differentiate between types of bacteria
Is a method of preparing and maintaining microorganism in a laboratory

Purpose
Is used to differentiate bacteria into two main groups – gram positive bacteria and gram negative bacteria
Is used to multiply microorganisms for various purposes such as testing, chemical purification, and storage among others

Components used in the procedure
Uses two stains – crystal violet and safranin, mordant such as iodine solution, decolorizer such as ethanol, and water
Uses an array of nutrient-rich culture media that may be solid, semi-solid or liquid

Basis of technique
Based on the differences in the thickness of the peptidoglycan layer of the cell wall
Based on the ability of microorganisms to grow and multiply inside a favorable culture media

Outcome
Gram positive bacteria appear purple in color and gram negative bacteria appear pink in color 
Colonies of the microorganisms are visible on solid and semi-solid media. In liquid media, microorganisms are visible in suspended form

Basis of differentiation	Gram stain	Culture
Definition	Is a differential staining technique used to identify the presence of bacteria and differentiate between types of bacteria	Is a method of preparing and maintaining microorganism in a laboratory
Purpose	Is used to differentiate bacteria into two main groups – gram positive bacteria and gram negative bacteria	Is used to multiply microorganisms for various purposes such as testing, chemical purification, and storage among others
Components used in the procedure	Uses two stains – crystal violet and safranin, mordant such as iodine solution, decolorizer such as ethanol, and water	Uses an array of nutrient-rich culture media that may be solid, semi-solid or liquid
Basis of technique	Based on the differences in the thickness of the peptidoglycan layer of the cell wall	Based on the ability of microorganisms to grow and multiply inside a favorable culture media
Outcome	Gram positive bacteria appear purple in color and gram negative bacteria appear pink in color	Colonies of the microorganisms are visible on solid and semi-solid media. In liquid media, microorganisms are visible in suspended form

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