Fluorescence spectroscopy: a rapid tool for assessing tetracycline resistance in Bifidobacterium longum

Do mitochondria use efflux pumps to protect their ribosomes from antibiotics?

Fungal environments are rich in natural and engineered antimicrobials, and this, combined with the fact that fungal genomes are rich in coding sequences for transporters, suggests that fungi are an intriguing group in which to search for evidence of antimicrobial efflux pumps in mitochondria. Herein, the range of protective mechanisms used by fungi against antimicrobials is introduced, and it is hypothesized, based on the susceptibility of mitochondrial and bacterial ribosomes to the same antibiotics, that mitochondria might also contain pumps that efflux antibiotics from these organelles. Preliminary evidence of ethidium bromide efflux is presented and several candidate efflux pumps are identified in fungal mitochondrial proteomes.

Coomassie Blue G250 for Visualization of Active Bacteria from Lake Environment and Culture

Bacteria play a fundamental role in the cycling of nutrients in aquatic environments. A precise distinction between active and inactive bacteria is crucial for the description of this process. We have evaluated the usefulness of Coomassie Blue G250 for fluorescent staining of protein containing potentially highly active bacteria. We found that the G250 solution has excitation and emission properties appropriate for direct epifluorescence microscopy observations. It enables fast and effective fluorescent visualization of living, protein-rich bacteria, both in freshwater environment and culture. Our results revealed that the number of G250-stained bacteria from eutrophic lake was positively correlated with other standard bacterial activity markers, like number of bacteria containing 16S rRNA, bacterial secondary production or maximal potential leucine-aminopeptidase activity. In case of the E. coli culture, the percentage of bacteria visualized with G250 was similar to that of bacteria which accumulated tetracycline. Compared to other common methods utilizing fluorogenic substances for bacteria staining, the approach we evaluated is inexpensive and less hazardous (for example mutagenic) to the environment and researchers. It can be regarded as an additional or alternative method for protein rich, active bacteria staining.