A wide range of prokaryotes, as well as eukaryotic cells, release nanoparticles composed of proteins and phospholipid bilayers into the extracellular milieu. These bacterial sphere particles are called as membrane vesicle (MV). MV is biologically active and contain various components including genetic materials and proteins. Recent progress in MV studies has indicated that MV plays an important role in microbial interaction including horizontal gene transfer, predatory and cell-to-cell communication. However, it is not fully understood which bacterial cells uptake MV in microbial community. In this review, we described a recent finding that MV selectively interacts with specific family of bacterial cells. Moreover, antibiotic-associated MV enabled effective killing of target bacterial species. These results would offer a new avenue in the application of MV for biotechnical tools such as drug delivery system.

Bacteria release membrane vesicles (MV) into the environment, which has diverse functions. Here we introduce our latest study on a factor that induce MV formation in structurally distinct bacteria.

Oligotrophs means the bacteria that can utilize a very low concentration of carbon source and we are attempting to isolate oligotrophs from various environments. Among them, Rhodococcus erythropolis N9T-4, isolated from stored crude oil, shows super oligotrophic features and can grow on a basal medium without any additional carbon, nitrogen, sulfur, and energy sources, but requires CO₂ for its oligotrophic growth. Transmission electron microscopic observation showed that a relatively large and spherical nanostructure was observed in a N9T-4 cell grown under oligotrophic conditions. We termed this unique bacterial nanostructure an oligobody. The oligobody was not observed, or very rarely observed in small sizes under nutrient rich conditions, whereas additional carbon sources did not affect oligobody formation. Energy dispersive X-ray spectroscopy analysis suggested that the oligobody is composed of inorganic polyphosphate and is a type of acidocalcisome. Two genes encoding polyphosphate kinases, ppk1 and ppk2, were found in the N9T-4 genome: ppk1 disruption caused a negative effect on the formation of the oligobody. Although it was suggested that the oligobody plays an important role for the oligotrophic growth, both ppk-deleted mutants showed the same level of oligotrophic growth as the wild-type strain.

Thylakoid is the nanostructure that can be found through photosynthetic prokaryote cyanobacteria to chloroplasts of plants. This membrane system has conserved composition of membrane lipids and protein complexes, and provides sites for photosynthetic electron transport. Although, functions of photosynthetic protein complexes have been well characterized, there is only few report describing mechanism of the thylakoid development. In this review, we summarized recent advances in thylakoid research on the proteins involved in thylakoid development and the enzymes for thylakoid lipid synthesis.