Ravintoagar

Ravintoagar, commonly known as nutrient agar, is a general-purpose solid growth medium used in microbiology to culture non-fastidious microorganisms. It supports the growth of a wide range of bacteria and fungi, making it a standard baseline medium in clinical, educational, and research settings. Composition typically includes extracted nitrogen sources such as peptones and yeast extract, a gelling agent (agar), water, and often a small amount of inorganic salts to maintain osmotic balance. The exact recipe varies, but the medium is non-selective and non-differential, meaning most non-fastidious organisms can grow on it without selective pressure or differentiation.

Preparation involves dissolving the dry components in water, adjusting the pH to about 7.0, and sterilizing by autoclaving. After cooling to about 45-50°C, the medium is poured into sterile Petri dishes and allowed to solidify. Plates are usually inverted after solidification and stored at 4°C if not used immediately.

Uses include routine cultivation and maintenance of microbial isolates, preliminary assessment of colony morphology (size, shape, color, texture), and educational demonstrations. Limitations include its non-selective nature, which allows overgrowth by fast-growing species and poor recovery of fastidious organisms. For isolation or identification, nutrient agar is typically used in combination with selective or differential media and appropriate biochemical tests. Ravintoagar serves as a fundamental tool in microbiology for general growth and observation tasks.