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Polyethylene glycol-induced internalization of bacteria into fungal protoplasts: electron microscopic study and
I Guerra-Tschuschke1, I Martín, M T González
1Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Spain.
Abstract:
We studied the mechanism of internalization of Escherichia coli into Saccharomyces cerevisiae induced by polyethylene glycol (PEG) and optimized the experimental conditions. Transmission electron microscope studies revealed that the principal factor involved in the internalization was the degree of cell aggregation attained. Internalization occurred mainly by an endocytosis-like mechanism and took place during the elimination of PEG. The optimum conditions were to treat a mixed pellet of both microorganisms with 15% PEG and then gradually dilute the polymer. The same conditions were applied to E. coli and Aspergillus nidulans, with similar results.
Insights
Polyethylene glycol (PEG) induces internalization of Escherichia coli into Saccharomyces cerevisiae via an endocytosis-like process. Optimal conditions involve 15% PEG treatment and gradual polymer dilution, promoting cell aggregation.
Area of Science:
- Microbiology
- Cell Biology
- Biotechnology
Background:
- Investigating microbial interactions and cellular uptake mechanisms is crucial for understanding symbiotic relationships and developing biotechnological applications.
- Escherichia coli (E. coli) and Saccharomyces cerevisiae (baker's yeast) are model organisms frequently used in biological studies.
- Polyethylene glycol (PEG) is a polymer known to induce cell fusion and affect cell membranes.
Purpose of the Study:
- To elucidate the mechanism by which polyethylene glycol (PEG) mediates the internalization of Escherichia coli into Saccharomyces cerevisiae.
- To optimize the experimental conditions for efficient PEG-induced microbial internalization.
- To assess the applicability of the optimized method to other microbial pairings, such as E. coli and Aspergillus nidulans.
Main Methods:
- Utilizing transmission electron microscopy (TEM) to visualize and analyze the cellular interactions and internalization processes.
- Systematically varying polyethylene glycol (PEG) concentrations and dilution protocols to determine optimal conditions.
- Co-culturing microbial pairs (E. coli with S. cerevisiae, and E. coli with A. nidulans) under optimized PEG treatment.
Main Results:
- Transmission electron microscopy confirmed that cell aggregation is the primary factor driving microbial internalization.
- The internalization process was identified as predominantly an endocytosis-like mechanism.
- Internalization was observed to occur during the elimination phase of polyethylene glycol (PEG).
- Optimal conditions were established as treating a mixed microbial pellet with 15% PEG, followed by gradual polymer dilution.
Conclusions:
- Polyethylene glycol (PEG)-induced internalization of E. coli into S. cerevisiae is facilitated by increased cell aggregation.
- An endocytosis-like mechanism is responsible for the observed internalization, occurring as PEG is removed.
- The optimized protocol, using 15% PEG and gradual dilution, is effective for E. coli internalization into S. cerevisiae and shows promise for other microbial pairings like E. coli and A. nidulans.