Characterization of three different types of extracellular vesicles and their impact on bacterial growth

Recently body fluids have been found to contain a class of nanoparticles released from cells, referred to as extracellular vesicles; exosomes are a type of small-diameter extracellular vesicle. We selected three types of sample: milk-derived exosomes, adipose-derived stem cell exosomes, and nanoparticles extracted from coconut water, to investigate their morphology, particle size distribution, protein content, and microRNA expression levels. Among the vesicles investigated, coconut nanoparticles had the greatest size distribution, and the protein content of coconut nanoparticles differed from that of mammalian exosomes. Using fluorescence microscopy, we determined that DiI-labeled extracellular vesicles could be absorbed by bacteria. Prominently, milk-derived exosomes could promote the growth of Escherichia coli K-12 MG1655 and Lactobacillus plantarum WCFS1. The studied extracellular vesicles could alter bacterial gene expression. Overall, this study identified differences in exogenous extracellular vesicles from different sources and revealed their supportive effects on microbial growth to make better utilization of microbial resources.