📋 Workflow
Full workflow, products add-to-cart directly1
Media preparation
30 minPrepare and sterilize plate count agar and selective media
💡 Tip Autoclave at 121°C for 15 min
⚠️ Caution Aseptic technique to avoid contamination
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2
Sampling & dilution
20 minAseptically collect the water sample and make ten-fold serial dilutions
💡 Tip Refrigerate and test promptly
⚠️ Caution Freshly prepare dilution water
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3
Inoculation & incubation
48 hInoculate sample onto media and incubate at 36±1°C for 24-48 h
💡 Tip Use pour plate or spread plate
⚠️ Caution Include blank to verify sterility
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4
Colony counting
30 minCount colonies on plates with a colony counter
💡 Tip Count plates with 30–300 colonies
⚠️ Caution Distinguish typical vs atypical colonies
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5
Calculation & report
20 minCalculate count per dilution and report against the limit
💡 Tip Express as CFU/mL or CFU/100mL
⚠️ Caution Check dilution factor
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⚠️ 5 Common Beginner Mistakes
- ① Improperly sterilized media contaminating results
- ② Inaccurate dilution affecting count
- ③ Improper incubation temperature/time
- ④ Sample held too long allowing growth
- ⑤ Overlapping colonies hard to count
❓ FAQ
+Total count vs coliforms?
Total reflects overall load; coliforms reflect fecal contamination.
+How soon to test?
Test within 6 h under refrigeration.
+Why count 30-300?
This range gives most accurate counts.