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Microthrix parvicella, a filamentous bacterium from activated sludge: growth on Tween 80 as carbon and energy source
Abstract:
Microthrix parvicella, cultivated in a medium with Tween 80 and Casamino acids, utilized only the oleic acid moiety of Tween 80 as carbon and energy source. The cell yield from Tween 80 was about 0.32 g dry weight of cells per g of Tween 80 consumed. As only the oleic acid moiety of Tween 80 was utilized, the cell yield from oleic acid was 1.3 g dry weight of cells per g oleic acid consumed. The amount of carbon produced as CO2 was less than 30% of the oleic acid-carbon and this low value was in agreement with the high cell yield. In batch culture M. parvicella stored large amounts of lipid material during the early growth phase. The fatty acids of the lipid globules were similar to the fatty acids supplied as carbon source. The percentage composition of the biomass changed to give C/N percentage ratios of about 15 during the early growth phase due to the high concentration of internal lipids and the low concentration of protein. The growth rate in batch culture was about 0.016 h-1 but was affected by the concentration of Casamino acids in the medium.
Insights
Microthrix parvicella efficiently uses oleic acid from Tween 80 for energy, achieving high cell yields. This bacterium stores lipids, impacting its biomass composition during growth.
Area of Science:
- Microbiology
- Biochemistry
- Environmental Science
Background:
- Microthrix parvicella is a filamentous bacterium found in wastewater treatment systems.
- Understanding its metabolic capabilities is crucial for optimizing biological processes.
Purpose of the Study:
- To investigate the utilization of Tween 80 by Microthrix parvicella.
- To determine the carbon and energy source of Tween 80 for M. parvicella.
- To analyze the cell yield and biomass composition.
Main Methods:
- Cultivation of M. parvicella in a medium containing Tween 80 and Casamino acids.
- Analysis of Tween 80 utilization and CO2 production.
- Determination of cell yield and biomass composition, including lipid content and C/N ratio.
Main Results:
- Microthrix parvicella exclusively utilized the oleic acid component of Tween 80.
- High cell yields were observed: 0.32 g dry weight/g Tween 80 and 1.3 g dry weight/g oleic acid.
- Low CO2 production (<30% of oleic acid carbon) indicated efficient substrate conversion.
- Significant lipid accumulation occurred during early growth, with fatty acids mirroring the supplied carbon source.
- Biomass C/N ratio shifted to ~15 due to high lipid and low protein content.
- Observed growth rate was approximately 0.016 h-1, influenced by Casamino acid concentration.
Conclusions:
- Microthrix parvicella demonstrates efficient oleic acid metabolism for growth and energy.
- Lipid storage is a key characteristic of M. parvicella's growth phase, affecting biomass composition.
- Casamino acid concentration plays a role in regulating the growth rate of M. parvicella.