1. Bacterial Contamination

• Rapid-growing, often visible within 24–48 hours
• Causes turbidity, pH changes (medium turns yellow), and cell death
• Common sources: non-sterile reagents, poor aseptic technique, airborne exposure

2. Fungal and Yeast Contamination

• Slower onset, visible as floating clumps or filaments
• Fungi often grow as mycelial mats; yeast appears as budding round cells
• Thrive in humid incubators and contaminated water trays

3. Mycoplasma Contamination

• Invisible to the naked eye and standard microscopy
• Alters DNA replication, metabolism, and gene expression
• Found in up to 15–35% of global cell cultures according to studies
• Requires PCR, DNA staining, or ELISA for detection

4. Viral Contamination

• Rare but dangerous in cell lines used for vaccine production or gene therapy
• May originate from contaminated serum or infected primary cells

5. Cross-Contamination Between Cell Lines



• Misidentified cell lines (e.g., HeLa overgrowth)
• Results in invalid data due to mixed genetic backgrounds

• Sudden pH changes (yellow or purple medium)
• Cloudy media or floating debris
• Unusual cell morphology
• Reduced growth rate
• Cell detachment or clumping
• Microscopic black dots or filaments

1. Aseptic Technique

• Always work in a certified biosafety cabinet (Class II BSC)
• Flame pipettes or use sterile, disposable tips
• Wipe surfaces and gloves with 70% ethanol before handling cell

 2. Use Antibiotic-Free Culture Whenever Possible

• Antibiotics can mask low-level contamination
• Routine use can cause resistant strains
• Ideal for early detection of contamination through observation

3. Quarantine and Test All New Cell Lines

• Always quarantine new cultures and screen for mycoplasma before use
• Keep a log of cell line origin, passage number, and test results

4. Maintain and Clean Incubators Regularly

• Clean water trays with antifungal agents (e.g., copper sulfate)
• Monthly decontamination with hydrogen peroxide or chlorine dioxide

5. Label and Track All Cell Lines and Reagents

• Use proper cell line authentication (STR profiling)
• Avoid reagent sharing between contaminated and clean lines

Bacterial or Fungal

• Discard contaminated culture immediately
• Clean all surfaces with 10% bleach followed by 70% ethanol
• Autoclave reusable materials

Mycoplasma

• Use anti-mycoplasma reagents like Plasmocin or BM-Cyclin
• Treat for 1–2 weeks, then confirm eradication via PCR
• Retreat or discard if contamination persists

Cross-contamination

• Discard mixed cultures unless genetically valuable
• Re-authenticate with short tandem repeat (STR) analysis

• Lost cell stocks and experimental data
• Delayed publications and funding deadlines
• Risk of publishing incorrect results
• Contaminated lines may still grow and appear normal — leading to false confidence

Contamination in cell culture is not just an inconvenience it’s a major scientific risk. The best approach is a proactive one: routine monitoring, aseptic practices, and authentication of every cell line used. With regular testing and proper lab protocols, researchers can safeguard their work, ensure data accuracy, and maintain long-term culture health.