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Disappearance of plasmalogen-containing phospholipids in Megasphaera elsdenii
A E Kaufman1, J N Verma, H Goldfine
1Department of Microbiology, University of Pennsylvania, School of Medicine, Philadelphia 19104-6076.
Abstract:
The plasmalogen content of phospholipids isolated from Megasphaera elsdenii ATCC 17752 decreased markedly in cultures passed serially at intervals of 3 to 6 weeks. From the wild-type ratio of vinyl ether to lipid phosphorus of 0.8, clones were isolated with ratios less than 0.05. Clonal analysis, as well as the reproducibility of the phenomenon and the long time course, suggest that the loss of plasmalogens is an adaptive process. Although small variations in cell morphology and ratios of end products of fermentation were detected, plasmalogen-rich and -deficient cells were virtually indistinguishable with respect to growth rates, range of fermentable carbohydrates, activities of selected enzymes, and electrophoretic patterns in both membrane and soluble proteins. Large decreases in saturated fatty acid production accompanied the decline of plasmalogens.
Insights
The study found that plasmalogen levels in Megasphaera elsdenii ATCC 17752 decrease over time, suggesting an adaptive process. This reduction in plasmalogens, a type of phospholipid, correlated with decreased saturated fatty acid production.
Area of Science:
- Microbiology
- Biochemistry
- Cell Biology
Background:
- Plasmalogens are a subclass of phospholipids with a unique vinyl ether linkage.
- Megasphaera elsdenii is a ruminal bacterium relevant to understanding microbial adaptation.
- The role and regulation of plasmalogen synthesis in bacteria are not fully understood.
Purpose of the Study:
- To investigate the changes in plasmalogen content in Megasphaera elsdenii during serial cultivation.
- To determine if the observed changes in plasmalogen levels are an adaptive response.
- To characterize the physiological and biochemical differences between plasmalogen-rich and plasmalogen-deficient cells.
Main Methods:
- Serial passage of Megasphaera elsdenii cultures over extended periods (3-6 weeks).
- Isolation and characterization of bacterial clones with varying plasmalogen content.
- Analysis of phospholipid composition, including vinyl ether to lipid phosphorus ratios.
- Assessment of cell morphology, growth rates, fermentable carbohydrate utilization, enzyme activities, and protein profiles.
- Quantification of fatty acid production.
Main Results:
- Plasmalogen content in Megasphaera elsdenii significantly decreased with serial passage.
- Clones with very low plasmalogen ratios (<0.05) were isolated from wild-type strains (ratio 0.8).
- The observed plasmalogen loss appeared to be an adaptive process, confirmed by clonal analysis and reproducibility.
- Plasmalogen-rich and deficient cells showed minimal differences in growth, metabolism, and protein expression.
- A substantial reduction in saturated fatty acid production was associated with plasmalogen decline.
Conclusions:
- The decrease in plasmalogen content in Megasphaera elsdenii is an adaptive response to prolonged cultivation.
- Despite significant changes in plasmalogen levels, core physiological functions remain largely unaffected.
- Plasmalogen deficiency in this bacterium is linked to altered fatty acid metabolism, specifically reduced saturated fatty acid synthesis.