Which of the following statements about biofilms is NOT true?

• A. Biofilms are always composed of a single microbial species.
• B. Biofilms are composed of microorganisms embedded in a self-produced matrix.
• C. Biofilms can form on both living and non-living surfaces.
• D. Biofilms can contribute to antibiotic resistance.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what a biofilm is. A biofilm is a community of microorganisms that adhere to a surface and are embedded within a self-produced extracellular matrix composed of polysaccharides, proteins, and nucleic acids.
2. Step 2: Analyze the statement 'Biofilms are always composed of a single microbial species.' Consider that biofilms often consist of multiple microbial species living together, which can interact and provide mutual benefits.
3. Step 3: Review the other statements: biofilms are composed of microorganisms embedded in a self-produced matrix, can form on both living and non-living surfaces, and can contribute to antibiotic resistance. These are well-established characteristics of biofilms.
4. Step 4: Identify the statement that contradicts the typical nature of biofilms. Since biofilms are usually multispecies communities, the statement claiming they are always single-species is incorrect.
5. Step 5: Conclude that the statement 'Biofilms are always composed of a single microbial species' is NOT true, while the other statements accurately describe biofilms.