Bioaccumulation and distribution of selenium in Enterococcus durans

Area of Science:

• Microbiology
• Biochemistry
• Nutritional Science

Background:

• Selenium is a vital nutrient for all organisms.
• Lactic acid bacteria (LAB) can accumulate and organic-compound-integrate trace elements like selenium.
• Enterococcus durans LAB18s was investigated for selenium bioaccumulation capacity.

Purpose of the Study:

• To evaluate the selenium bioaccumulation potential of Enterococcus durans LAB18s.
• To analyze the distribution of organic selenium within the selenium-enriched biomass.
• To characterize the cellular localization and form of bioaccumulated selenium.

Main Methods:

• Cultivation of Enterococcus durans LAB18s under selenium-enriched conditions.
• Fractionation of biomass to determine selenium distribution (protein, polysaccharides, nucleic acids).
• Analysis of protein fractions using SDS-PAGE, SEM, SEM/EDS, and TEM.

Main Results:

• The highest percentage of organic selenium was found in the protein fraction.
• Alkali-soluble proteins exhibited the highest selenium content.
• Selenium was detected in proteins ranging from 23 to 100kDa, with bioaccumulation observed within and on the cells.

Conclusions:

• Enterococcus durans LAB18s demonstrates significant selenium bioaccumulation capabilities.
• The bioaccumulated selenium is primarily incorporated into the protein fraction.
• This selenium-enriched biomass holds promise as a functional ingredient or probiotic in feed applications.