# Microbial testing

> Microbial testing counts or detects bacteria and fungi in a cannabis sample, including total aerobic count (TAMC), total yeast and mould count (TYMC) and specific pathogens.

- Canonical: https://genetixbay.com/knowledge/glossary/microbial-testing.html
- Also written: micro testing, microbial panel, TYMC, TAMC, total yeast and mould count, total aerobic microbial count, total yeast and mold count
- Glossary category: Lab testing · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Microbial testing checks how many living microorganisms a sample carries and whether specific harmful ones are present. Count-based tests include total aerobic microbial count (TAMC) and total yeast and mould count (TYMC), reported in colony-forming units per gram (CFU/g). Pathogen tests look for organisms such as *Salmonella*, Shiga-toxin-producing *E. coli* and pathogenic *Aspergillus* species, usually reported as detected or [not detected](https://genetixbay.com/knowledge/glossary/non-detect.md) in a set sample mass.

## In practice

A [COA](https://genetixbay.com/knowledge/glossary/coa.md) might show TYMC 2,000 CFU/g against a limit of 10,000 CFU/g: pass. Mould counts rise with slow, humid drying, dense buds, poor airflow and storage at high [water activity](https://genetixbay.com/knowledge/glossary/water-activity.md). Labs use either culture plating or DNA-based (qPCR) methods; the two can give different counts on the same sample, so check the method. Limits vary by jurisdiction; check local rules.

## Units and formula

CFU/g (colony-forming units per gram), often written as powers of ten, e.g. 10^4 CFU/g = 10,000 CFU/g.

## Don't confuse with

- **Mycotoxins**: toxic chemicals some moulds leave behind, which can persist after the mould is killed.
- **Visible mould**: a lab count can fail before anything is visible.
- **Water activity**: a risk indicator for growth, not a microbe count.

## Related terms

[Mycotoxins](https://genetixbay.com/knowledge/glossary/mycotoxins.md), [Water activity test](https://genetixbay.com/knowledge/glossary/water-activity-test.md), [COA](https://genetixbay.com/knowledge/glossary/coa.md), [Batch](https://genetixbay.com/knowledge/glossary/batch.md), [Homogenisation (sampling)](https://genetixbay.com/knowledge/glossary/homogenisation.md)

## Read more

- [Botrytis (bud rot / grey mould) in cannabis](https://genetixbay.com/knowledge/diseases/botrytis-bud-rot.md)
- [Drying cannabis: the 60/60 method and water activity](https://genetixbay.com/knowledge/harvest-cure/drying.md)

## Sources

1. United States Pharmacopeia. General Chapter <61> Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests.