Microbial Formulation and Stabilization

To optimize the physiological state

The tolerance of the microorganisms to drying can be improved by optimizing the physiological state of the cells prior to desiccation. Two principal approaches can help to achieve this. The first one is to optimize the growth conditions with respect to medium composition and abiotic cultivation parameters so that maximum stress tolerance in stationary phase is obtained. The second approach is that of pre-conditioning or stressing the cells after cultivation through exposure to non-lethal environmental stressors. In other words, microorganisms can sometimes be trained to better cope with adverse conditions. Little stress results in increased fitness and better chances of surviving stress levels that would be lethal for a non-preconditioned cell.

Additive compounds to protect from freezing or drying

Biological adaptations alone are not sufficient to ensure high survival in dry biological products. Addition of compounds that provide outside protection from harmful effects of freezing or drying is also necessary. These additives are often substances that the microorganisms can produce themselves and use for protection inside, such as disaccharides, amino acids and various amino acid derivates. Production of these compounds is often a response to stress or pre-conditioning and by including these compounds in the formulation, survival can often be improved. However, each new microorganism will very likely require individual formulation optimization with regards to preconditioning regimes and formulations additives.

On-going and finished projects

• CBC - Center for Biological Control
• The novel species Thorsellia anophelis - Towards a self-sustainable anti-malarial system in mosquitoes
• Stabilization of a Sphingobium species as a bioprophylaxis for pesticide degradation
• Development of new on-seed formualtions of rhizobacteria
• BACSIN - Bacterial Abiotic Stress and Survival Improvement Network
• Impact of biopolymers on biological and physico-chemical characteristics of technical powder containing freeze-dried microorganisms
• Freeze-drying and storage stability of Lactobacillus coryniformis Si3 in sucrose-based formulatons
• Dry and water-based stabilisation of the biocontrol yeast Pichia anomala

Past and present members of the group

• Sebastian Håkansson - Associate Professor, group leader
• Joakim Bjerketorp - Researcher
• Per Wessman - Post-Doc
• Åsa Begenholtz (Schoug) - Ph.D-student
• Mirela Jonson - Researcher
• Jens Levenfors - Researcher
• Lisa Fredlund - Post-Doc