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Solvent toxicity in organic-aqueous systems analysed by multivariate analysis.
Carla C C R de Carvalho1, M Manuela R da Fonseca
1Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
Bioprocess and Biosystems Engineering
|September 21, 2004
Summary
Solvent toxicity in biphasic systems significantly impacts microbial cells like Rhodococcus erythropolis and Mycobacterium sp. Understanding these effects is crucial for optimizing bioremediation and fine chemical production using these microorganisms.
Area of Science:
- Biotechnology
- Microbial Physiology
- Bioremediation
Background:
- Biphasic reaction systems are widely used for microbial processes, including bioremediation and fine chemical synthesis.
- Several bacterial strains, including Rhodococcus erythropolis, Xanthobacter Py2, Arthrobacter simplex, and Mycobacterium sp., are employed in these systems.
- Solvent toxicity is a major challenge affecting cell viability and productivity in biphasic systems.
Purpose of the Study:
- To evaluate the impact of various organic solvents on the viability and morphology of four industrially relevant microbial strains.
- To identify key factors influencing solvent toxicity and microbial response in biphasic systems.
- To provide insights for designing more efficient and robust two-phase reaction systems.
Main Methods:
- Testing a range of organic solvents (e.g., ethyl butyrate, n-hexane, DMSO) with Rhodococcus erythropolis, Xanthobacter Py2, Arthrobacter simplex, and Mycobacterium sp.
- Monitoring cell population dynamics using fluorescence microscopy to assess viability and morphology at the single-cell level.
- Applying Principal Component Analysis (PCA) to interpret the complex relationships between solvent properties, cell responses, and experimental conditions.
Main Results:
- Solvent toxicity accounted for over one-third of the data variability across all tested strains.
- Rhodococcus erythropolis demonstrated resilience, maintaining viability under challenging conditions.
- Pre-adaptation to solvents affected strains differently: detrimental for R. erythropolis and A. simplex, but beneficial for X. Py2.
- Substrate transformation generally increased system toxicity, while specific compounds like hydrocortisone impaired A. simplex stress response.
Conclusions:
- Microbial response to solvents in biphasic systems is strain-specific and influenced by factors like adaptation time and substrate properties.
- Optimizing solvent selection and pre-treatment strategies is essential for enhancing microbial performance in industrial applications.
- The study provides a framework for mitigating solvent toxicity to improve cell productivity in two-phase bioreactors.