Biologicals Under Control: Managing Contaminants Without Sacrificing Field Performance
As microbial products scale up, manufacturers face a critical challenge: controlling contaminants while preserving viability, quality and field efficacy.
Microbial crop protection products are reaching a stage where agronomic efficacy alone is no longer enough to secure commercial success. In 2026, as bacteria, fungi, viruses and other microorganisms expand across biological crop protection programs, manufacturers face a critical challenge: preventing unwanted microbial contamination without damaging the living active ingredient responsible for product performance. The issue matters across the U.S. biologicals industry because failures in microbial quality can affect registration, shelf life, manufacturing consistency, grower confidence and ultimately performance in the field.
The difficulty comes from the product itself. Many microbial biopesticides contain living organisms, meaning manufacturing is not simply about reaching a target concentration. Producers must preserve identity, purity and viability while preventing unwanted microorganisms from entering during fermentation, formulation, packaging or storage. Contaminants of concern can include pathogenic bacteria such as Salmonella and E. coli, as well as opportunistic microorganisms and organisms capable of producing unwanted metabolites. Microbial quality control therefore begins long before the finished product reaches a container.
From detecting contamination to understanding actual risk
Contaminant control in microbial products increasingly incorporates a risk-based approach that considers the identity of the microorganism, its concentration and potential exposure rather than treating every microbial detection as equivalent. International guidance from the Organisation for Economic Co-operation and Development (OECD) provides a framework for assessing microbial contaminants in microbial pest control products and distinguishing between situations that can present very different levels of concern.
One reference is the OECD's Series on Pesticides No. 65, which addresses microbial contaminant limits in microbial pest control products. Its approach considers hazard identification, exposure, dose-response and overall risk characterization. For manufacturers, the distinction is significant: finding an unintended microorganism does not by itself define the level of risk. What matters is what organism was detected, at what concentration, whether it presents a relevant hazard and under what circumstances workers, growers, consumers or the environment could be exposed.
Critical controls in microbial biological manufacturing
| Control point | What manufacturers need to assess | Commercial relevance |
|---|---|---|
| Microbial identity | Which microorganism is present | Prevents release of problematic lots |
| Concentration | Level of microbial contamination | Supports action thresholds |
| Manufacturing process | Fermentation, hygiene and handling | Reduces cross-contamination |
| Batch testing | Quality before product release | Improves consistency and traceability |
| Monitoring | Changes over production cycles | Identifies recurring deviations |
Good Manufacturing Practices and robust quality systems become particularly important as companies move from laboratory and pilot production toward commercial volumes. Regular batch testing, predefined action levels and corrective procedures can help identify deviations before products reach growers. The commercial consequence is substantial: microbial quality is becoming part of a company's ability to manufacture biologicals consistently and at scale, rather than simply another regulatory requirement at the end of product development.
Detection itself also presents challenges. Traditional culture-based methods remain important, but they have limitations because microorganisms that do not grow under the selected culture conditions may escape detection. Molecular identification and other analytical technologies can therefore complement conventional microbiology. The objective is not simply to conduct more tests, but to build a system capable of identifying contaminants that materially change the product's risk profile while avoiding unnecessary manufacturing disruptions.
That balance has direct economic consequences. Discovering contamination late can mean holding or discarding batches, investigating equipment and raw materials, modifying fermentation procedures or delaying shipments. At the same time, poorly targeted testing can add unnecessary production costs. The commercial challenge is to combine microbial safety with manufacturing efficiency, particularly as biological crop protection moves from specialized production toward the volumes required by mainstream U.S. agriculture.
Keeping the right microorganism alive is only half the challenge
Contamination control is only one side of the equation. A product may leave the manufacturing facility with consistent microbial quality and still need to demonstrate what happens when its active microorganism reaches species that were not targeted by the treatment. In the United States, the Environmental Protection Agency (EPA) has specific data requirements and test guidelines for microbial pesticides, including considerations for terrestrial and aquatic non-target organisms. This creates an important distinction between accidental contamination during manufacturing and environmental assessment of the microorganism intentionally used as the active ingredient.
Two different risks within a microbial product
| Assessment | Core question | Commercial or regulatory decision |
|---|---|---|
| Contamination | Did unwanted microorganisms enter the product? | Release, investigate or reject a batch |
| Environmental risk | Can the active affect non-target organisms? | Establish safety and use conditions |
| Active quality | Is the microorganism viable and functional? | Confirm product consistency |
| Exposure | Who could encounter the microorganism? | Characterize potential risk |
| Monitoring | Does quality remain consistent over time? | Detect manufacturing deviations |
For microbial pesticides, environmental assessment can extend beyond conventional measures of immediate toxicity. Depending on the organism and exposure scenario, regulators may also need to consider infectivity, pathogenicity, persistence and effects on non-target organisms. That effectively creates two complementary quality and safety barriers: controlling microorganisms that should not be present and understanding the behavior of the microorganism deliberately included in the formulation.
For U.S. developers, this increasingly argues for integrating quality and regulatory considerations earlier in R&D. Strain selection, fermentation design, microbial specifications, analytical methods, formulation, storage stability and environmental testing should not be treated as disconnected stages. A contamination or viability problem discovered when a biological is already moving toward registration or commercial scale can be far more expensive to solve than one identified during development.
The issue also connects the U.S. market with Latin America, where biological inputs are expanding and manufacturers increasingly operate across multiple regulatory jurisdictions. Companies capable of demonstrating identity, purity, viable concentration, stability, traceability and environmental safety will be better positioned to move microbial technologies between markets. Quality consistency may therefore become as important commercially as discovering the next promising microbial strain.
The future of microbial biologicals will depend on maintaining that balance. Requirements that are poorly matched to microbial products can increase development costs, while insufficient quality control can undermine grower and regulatory confidence. The direction points toward risk-proportionate standards, controlled manufacturing, better analytical tools and scientifically appropriate environmental assessment. For a microbial biological to succeed commercially, keeping the right microorganism alive is essential-but controlling what else may be growing alongside it is becoming just as important.
