The biological agriculture industry has made extraordinary advances in microbial discovery over the last decade. Improved screening methods, strain engineering, and novel formulation technologies have significantly expanded the palette of promising biological actives entering product development.
As a result, the primary technical challenge has changed.
Identifying a prospective microbial candidate able to provide desired effects used to be one of the key limiting factors, but today the greater challenge is what comes next: getting a biological active from a promising lab result to a reliable commercial product. This requires the ability to produce that organism consistently at commercial scale, while maintaining product quality, process efficiency, and economic viability.
A common (and costly) assumption is that scale-up follows a linear path – that a process validated in a 10-litre fermenter can be transferred directly to a 10,000-litre bioreactor by increasing volumes proportionally. In reality, living organisms are highly sensitive to their physical and chemical environment, and those environments don’t change linearly as production scales increase.
Processes that are tried and tested during laboratory development can generate inconsistent yields, variable product quality, or reduced biological performance once transferred to industrial manufacturing.
What Changes During Fermentation Scale-Up?
Scaling fermentation changes the conditions experienced by the microbe throughout cultivation. Although operating parameters such as temperature, pH, and nutrient composition may remain nominally the same, the physical environment within the bioreactor changes considerably.
Oxygen Transfer
Oxygen transfer is one of the most significant challenges in aerobic fermentation. Lab-scale fermenters generally provide efficient oxygen transfer because of their high surface-area-to-volume ratio and relatively short mixing times. As vessel size increases, maintaining the same oxygen transfer rate becomes progressively more difficult. Larger reactors exhibit longer mixing times and greater variation in dissolved oxygen concentration, creating localized microenvironments that microbes experience as they circulate through the vessel.
These fluctuations influence metabolite production, biomass formation, and overall process productivity. As a result, maintaining equal oxygen availability across scales requires more than proportional increases in aeration or agitation.
Shear Stress
Hydrodynamic conditions also change substantially during scale-up. Agitation systems, sparging strategies, and pumping operations generate mechanical forces that influence microbial physiology. While some organisms tolerate elevated shear without measurable effects, others exhibit reduced viability, altered morphology, or changes in metabolic activity.
Because sensitivity varies between species, and even between strains, shear conditions that appear acceptable at laboratory scale may become limiting factors during industrial production.
Heat Transfer
Microbial metabolism continuously generates heat that must be removed to maintain stable cultivation conditions. Heat removal becomes increasingly challenging as reactor volume increases. Large vessels typically exhibit lower surface-area-to-volume ratios, making temperature control less responsive than in laboratory systems. Even modest temperature changes can alter growth rates, enzyme activity, and metabolite formation, contributing to increased batch variability.
Growth Kinetics
Changes in mass transfer, mixing behavior, and environmental heterogeneity influence microbial growth kinetics throughout fermentation. Cells within large bioreactors do not experience uniform cultivation conditions. Instead, they cycle through regions with different oxygen concentrations, nutrient availability, pH values, and temperatures. These dynamic conditions affect gene expression, metabolic pathways, and product formation, resulting in behavior that differs from observations made at laboratory scale. For this reason, successful laboratory fermentation cannot be assumed to predict equivalent industrial performance.
Downstream Processing Introduces Additional Scale-Dependent Challenges
The technical challenges associated with scale-up go beyond fermentation – downstream operations like cell separation, concentration, drying, and formulation are also affected by increasing process volumes. Equipment that performs efficiently during laboratory development may become throughput limitations or introduce additional variability when processing industrial batches.
Separation technologies illustrate this well. Centrifugation and filtration systems must balance process efficiency with preservation of microbial viability or metabolite integrity. Process parameters that maximize recovery at laboratory scale frequently require substantial optimization before achieving the same performance at commercial capacity.
Formulation presents another important factor. An active ingredient that demonstrates excellent stability during formulation development may behave differently when upstream production introduces subtle batch-to-batch variation. Small differences in biomass composition, physiological state, and metabolite profile can influence formulation stability, shelf life, dispersibility, and ultimately field performance. At commercial production volumes, these sources of variability become cumulative rather than isolated.
The Cumulative Nature of Scale-Up Effects
One of the key aspects of biological manufacturing is that process variation accumulates across successive production stages. A relatively small deviation during fermentation may influence downstream separation efficiency, which subsequently affects formulation performance and final product stability. By the time a product reaches the customer, identifying the original source of variability can be extremely challenging. Effective process development therefore requires understanding the manufacturing process as an integrated system rather than a series of independent operations.
Why Scale-Up Expertise Is So Difficult to Develop
Scale-up expertise sits at the intersection of several disciplines – microbiology, biochemical engineering, downstream processing, formulation science, and industrial process development. As a result, it is largely acquired through practice and experience. Fundamental engineering principles provide the framework for process design, but successful commercialization depends on understanding how different microbes respond to changing cultivation environments across multiple production scales. This knowledge is accumulated through repeated process development, pilot-scale validation, commercial manufacturing, and systematic analysis of process performance.
What This Means For Companies Planning Commercial Production
Scale-up is not just a phase that happens after product development – it is part of product development itself, and the companies that reach market fastest are the ones that understand its challenges from the beginning.
The decisions that determine whether scale-up succeeds are made earlier than most realise. Companies that treat scale-up as an afterthought consistently spend more fixing it than they would have spent anticipating it. The investment needed to get it right early – in process design, in the right manufacturing partner, in realistic timelines – is almost always smaller than the cost of getting it wrong late, especially in biological agriculture, where commercial windows are seasonal and a single missed launch can set a product back by a year.
For companies producing biologicals at commercial scale, evaluating scale-up capability is therefore as important as evaluating production capacity. Consistent commercial manufacturing depends on the ability to reproduce biological performance across scales while controlling process variability throughout both upstream and downstream operations. That continuity is what scale-up capability actually is about. Everything else is infrastructure.
Evologic has developed its manufacturing platform around this principle, integrating laboratory development, pilot production, and industrial fermentation within a single process development framework. Supported by more than 200 years of combined team experience, this integrated approach is designed to maintain process integrity and product quality at every step – from first fermentation run to commercial supply.
