Fact sheet on lactic acid bacteria

General
Lactic acid bacteria mostly belong to the family Lactobacillaceae (e.g. Lactobacillus, Leuconostoc, Pediococcus). They are able to break down sugars and other carbohydrates into lactic acid. In cosmetics they mainly play a role in the spoilage of water- and sugar-containing products, as they can cause sensory changes.

Characteristics

• Rod-shaped or coccus-shaped bacteria
• Gram-positive
• Facultatively anaerobic
• Fermentative metabolism → production of lactic acid (homo- or heterofermentative)
• Tolerate low pH values (growth possible in acidic environments)

Origin / occurrence

• Found in the environment and e.g. on plants
• Typical entry routes into cosmetics:
• contaminated plant raw materials (fruits, herbs, extracts, floral waters)
• production environment
• Hygiene weaknesses in the facility: colonization in product residues or deposits in pipes and tanks (biofilm formation)

Significance

• In cosmetics lactic acid bacteria primarily cause sensory changes (odor, taste, acidification).
• In cosmetic production they can indicate hygienic weaknesses, e.g. insufficient cleaning of pipes or contaminated raw materials.
• Detection requires targeted test methods, since they grow poorly on standard media (e.g. CASO). Lactic acid bacteria often become more visible on yeast and mold media, because these media have a lower pH and the incubation time is longer. If lactic acid bacteria are suspected, a targeted examination using specialized media is recommended. Please specifically consult our customer advisors in such cases.

Growth conditions

• Temperature:
  
  • Optimum: +25 °C to +30 °C
  • Minimum: +5 °C
  • Generally no growth above +50 °C
• pH value: growth possible even in acidic environments
• a_w value: Generally growth at a water activity of at least 0.95
• Oxygen requirement: facultatively anaerobic

Inactivation by heating

• At +72 °C for at least 2 minutes of exposure time (Note: check core temperature)

1. Check how cleaning and disinfection are carried out:
   1. Hygiene plan with details on how cleaning and disinfection are to be performed, e.g. dosing, contact time, use of appropriate and clean materials and cleaning cloths
2. Training of staff regarding potential errors and corrective measures
3. Repeat cleaning and disinfection
4. Effectiveness checks through on-site inspections and follow-up tests (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 the goods prior to use in production. Do not use raw materials if contamination is suspected
3. Check microbiological specifications. If necessary, arrange laboratory testing of suspicious products or request results from the supplier
4. Effectiveness check through follow-up testing

1. Ensure adherence to the formulation
2. If necessary, perform a preservative challenge test
3. If necessary, adjust the preservation system
4. Effectiveness check by repeating the preservative challenge test

1. Check and document production processes
2. Train staff
3. Effectiveness control 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. Training of staff regarding potential errors and corrective measures
3. Effectiveness checks through on-site inspections and follow-up testing