Bioburden Assay

Bioburden Assay (Microbial Enumeration)

Bioburden testing determines the number of viable microorganisms present in peptide materials prior to sterilization or final use. This test supports microbial risk assessment and environmental control evaluation, particularly for materials used in sensitive research or regulated non-GMP workflows.

What Is Bioburden?

Bioburden refers to the population of viable bacteria and fungi present in a material. Unlike endotoxin testing, which measures bacterial lipopolysaccharide (LPS), bioburden testing measures living microorganisms capable of growth under defined culture conditions.

Why Bioburden Testing Matters for Peptides

• Evaluates microbial contamination risk during synthesis and handling
• Supports environmental monitoring and process control
• Provides documentation for research and regulated non-GMP programs
• Complements endotoxin testing for broader microbiological assessment

Testing Methodologies

1. Aerobic Plate Count (Direct Plating)

Samples are diluted under aseptic conditions and spread or poured onto appropriate agar media. After incubation, visible colonies are counted and reported as colony-forming units (CFU).

• Suitable for powders and solution samples
• Incubation typically performed under defined temperature ranges
• Reports total aerobic microbial count

2. Membrane Filtration Method

For low-bioburden or larger-volume samples, membrane filtration may be used. The sample is filtered through a sterile membrane that captures microorganisms. The membrane is then transferred to culture media and incubated.

• Improves sensitivity for low-level contamination
• Useful for dilute or solution-based materials
• Supports enhanced recovery under controlled conditions

Incubation & Enumeration

Incubation conditions are selected based on expected microbial types. After defined incubation periods, colonies are counted and expressed as:

• CFU per gram (powders)
• CFU per mL (solutions)
• Total aerobic microbial count (scope-dependent)

Bioburden vs. Endotoxin

Reporting

Results are reported as CFU per unit with documented method conditions and incubation parameters. Interpretation may be aligned with internal specifications or intended use requirements.

Bio-Synthesis, Inc. provides bioburden testing aligned with GLP / ISO 13485 quality systems for regulated peptide programs.