Fact sheet on acetic acid bacteria

General information
Acetic acid bacteria belong to the family Acetobacteraceae. They are able to oxidize ethanol to acetic acid and therefore play an important role in product spoilage. For cosmetics they are mainly relevant with regard to quality and shelf life, as they can cause changes in odor and taste.

Characteristics

• Rod-shaped bacteria
• Gram-negative
• Strictly aerobic (require oxygen)
• Oxidize ethanol to acetic acid
• Tolerate low pH values (growth also possible in acidic environments)

Origin / occurrence

• Occur in the environment and on plant raw materials
• Typical entry routes into cosmetics:
  
  • contaminated plant raw materials (fruits, extracts, floral waters)
  • production environment
• Weaknesses in operational hygiene: colonization in product residues or deposits in pipes and tanks (biofilm formation)

Significance

• In cosmetics, acetic acid bacteria primarily cause sensory changes (odor, taste, acidification).
• In cosmetic production they can indicate hygienic weaknesses, e.g. inadequate cleaning of pipes or contaminated raw materials.
• Detection requires targeted test procedures, as they grow poorly on standard media (e.g. CASO). Acetic acid bacteria are often more visible on yeast and mold media, because these media have a lower pH and longer incubation times (acetic acid bacteria form only very small colonies that grow very slowly). If acetic acid bacteria are suspected, a targeted investigation with specialized media is recommended. Please contact our customer advisors specifically in such cases.

Inactivation by heating

• At +72 °C for a minimum exposure time of 2 minutes (Note: monitor core temperature)

1. Check the execution of cleaning and disinfection:
   1. Hygiene plan with details on how cleaning and disinfection are to be carried out, e.g. dosing, contact time, use of appropriate and clean materials and cleaning cloths
2. Train staff regarding potential errors and corrective measures
3. Repeat cleaning and disinfection
4. Verify effectiveness through on-site inspections and follow-up testing (e.g. contact plate and swab tests)

1. Check incoming goods for e.g. shelf life, packaging, deviations or microbiological abnormalities
2. This also applies to materials before use in production. Do not use raw materials in case of suspicion
3. Check microbiological specifications. If necessary, arrange laboratory testing of suspicious products or request results from the supplier
4. Verify effectiveness through follow-up testing

1. Ensure adherence to the formulation
2. If necessary, perform a preservative efficacy test (challenge test)
3. If necessary, adjust the preservative system
4. Verify effectiveness by performing a repeat preservative efficacy test

1. Review and document production processes
2. Train personnel
3. Verify effectiveness through regular microbiological product testing

1. Review work organization in the facility
   1. Separate work areas, equipment and utensils
   2. Separation of “clean” and “unclean” areas and activities
2. Train staff regarding potential errors and corrective measures
3. Verify effectiveness through on-site inspections and follow-up testing