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"Microthrix parvicella": a new approach for kinetic and physiological characterization
S Rossetti1, M C Tomei, C Levantesi
1CNR, Water Research Institute, Rome, Italy.
Summary
Microthrix parvicella exhibits versatile physiological traits, including storage capabilities and low-temperature growth, making it a competitive organism in activated sludge. Its high substrate affinity, indicated by low Ks values, classifies it as a Ks-strategist.
Area of Science:
- Environmental microbiology
- Wastewater treatment microbiology
Background:
- Microthrix parvicella is a filamentous bacterium found in activated sludge.
- Understanding its physiology and kinetics is crucial for managing wastewater treatment processes.
Purpose of the Study:
- To physiologically and kinetically characterize two strains of Microthrix parvicella (RN1 and 4B).
- To evaluate a new method for studying slow-growing bacteria.
Main Methods:
- Utilized a novel technique measuring Total Extended Filament Length (TEFL) on agar surfaces.
- Conducted kinetic characterization under various conditions, including low temperatures and different oxygen availabilities.
- Performed tests on both pure cultures and mixed populations from activated sludge.
Main Results:
- Microthrix parvicella demonstrates versatile capabilities: storage under diverse oxygen conditions, resistance to anoxia/anaerobia, and growth at low temperatures.
- Observed low Ks values, indicating high substrate affinity and classifying Microthrix parvicella as a Ks-strategist.
- Pure culture studies accurately reflect the microorganism's behavior, as co-culturing with activated sludge did not enhance growth rates.
Conclusions:
- The new TEFL method facilitates easier and faster study of slow-growing bacteria.
- Microthrix parvicella possesses significant competitive advantages in activated sludge due to its physiological flexibility.
- Physiological and kinetic data from pure cultures are reliable for understanding Microthrix parvicella in complex systems.