Significance and Use 5.1 Biofilm characteristics such as thickness, matrix architecture, and population are dependent on factors such as shear and nutrient availability and composition. Additionally, sporulation can occur within biofilms, including those formed by Bacillus subtilis.5 The purpose of this test method is to define the parameters to grow and enumerate a B. subtilis biofilm comprised of vegetative cells and spores embedded in extracellular polymeric substance (EPS). This type of biofilm could provide a greater challenge to antimicrobials than vegetative biofilm or spores alone. The biofilm generated using this method is suitable for efficacy testing of antimicrobials.Scope 1.1 This test method specifies the operational parameters required to grow and quantify a Bacillus subtilis biofilm comprised of vegetative cells and endospores (spores) using the colony biofilm method (CBM).2,3 The resulting biofilm is representative of static environments that can develop a sporulating biofilm rather than being representative of one particular environment. 1.2 This test method utilizes a modified CBM to grow the biofilm. The CBM uses a semipermeable membrane on an agar plate as the biofilm growth surface and nutrient source.2,3 In this test method, membranes are inoculated and incubated for a total of 8 days to promote sporulation within the biofilm. 1.3 This test method describes how to sample and analyze the biofilm for vegetative cells and spores. Biofilm population is expressed as total colony forming units (CFU) and spores per membrane. 1.4 Basic microbiology training is required to perform this test method. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
