Fact sheet on Bacillus sp.

General
Bacillus sp. are able to form resistant forms, so-called spores. These are very heat-stable and can survive heat treatment steps. In the cosmetics field, Bacillus sp. are generally considered to be of low concern, as the number of spores and vegetative cells in a contaminated product usually remains stable and proliferation over the product life cycle is considered unlikely.

The spores of Bacillus sp. can often survive the production process due to their heat resistance. Since they are neither among the "specified microorganisms" that should not be detectable in 1 g of product nor among the classical spoilage organisms, microbial counts below the limit are generally considered to be of low concern.

Characteristics

• Gram-positive, mostly motile rod-shaped bacteria
• Aerobic or facultatively anaerobic growth
• Highly resistant to environmental influences
• Characteristic is the formation of endospores

Origin / Occurrence

• Spore formers are widespread in our environment (e.g. soil/dust, plants, air, …).
• They can enter the product, for example, via plant-based raw materials or insufficient facility hygiene.

Significance

• In cosmetic products Bacillus sp. are usually of low concern, as the vegetative forms rarely proliferate in products
• Bacillus sp. form resistant spores that withstand environmental and production conditions well.

Conditions for Growth

• Temperature:
  • Optimum: +30 °C to +40 °C
  • Minimum: 0 °C
  • Generally no growth above +50 °C (exceptions are thermophilic bacteria)
• pH: Growth at pH 4.0 to 8.5 (for many the optimum is pH 6.0 to 8.0).
• a_w (water activity): According to ISO 29621, cosmetics with an a_w value of less than 0.75 are considered low-risk, as microorganisms generally cannot proliferate at this water activity.
• Oxygen requirement: Growth with and without oxygen (facultative anaerobe).

Killing by Heat

• Spores of Bacillus sp. are heat-resistant and can survive temperatures >100 °C for certain periods.
• Standardized heat treatments (e.g. pasteurization) often are not sufficient to inactivate the spores.
• Safe inactivation only at temperatures ≥121 °C for a period of at least 15 min.
• Vegetative forms are killed at 72 °C for 2 min (observe core temperature).

1. Check the performance of cleaning and disinfection:
   1. Hygiene plan with details on how to perform cleaning and disinfection, e.g. dosing, contact time, use of suitable and clean materials and cleaning cloths
2. Train employees regarding potential errors and possible improvements
3. Repeat cleaning and disinfection
4. Verification of effectiveness by
5. On-site inspections and follow-up testing (e.g. contact plates and swab tests)

1. Check water systems and piping for correct function and condition. Avoid stagnation of water in e.g. pipes, systems, hoses…
2. Regularly check the water system and piping microbiologically and technically (observe maintenance intervals)
3. In case of contamination of water systems, react immediately and implement measures. If necessary, involve appropriate specialist companies
4. Verification by regular follow-up testing

1. Inspect 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 if there is suspicion of contamination
3. Check microbiological specifications. If necessary, request laboratory testing of suspicious products or request results from the supplier
4. Verification by follow-up testing

1. Ensure adherence to the formulation
2. Possibly perform a preservative efficacy test (challenge test)
3. Possibly adjust the preservation system
4. Verification by a repeat preservative efficacy test

1. Check and document production processes
2. Train personnel
3. Verification by regular microbiological product testing

1. Review work organization in the facility
   1. Separate work areas, equipment and utensils
   2. Separation of "clean" and "dirty" areas and activities
2. Train employees regarding potential errors and improvement measures
3. Verification by on-site inspections and follow-up testing