Microscopy method for better biofuels


Rebecca Pool

Tuesday, June 12, 2018 - 15:00
Pikachu and Michael Jackson: the delivery of fluorogenic peptide aptamers into live microalgae is set to help biofuel production [Scientific Reports]
In a breakthrough for biofuel and drug manufacture, Japan-based researchers have developed a fluorescence microscopy method to study the production of metabolites - various molecules associated with metabolism - in living cells, at single-cell resolution.
Professor Yoichiroh Hosokawa from the Nara Institute of Science and Technology, and colleagues, first used a femtosecond laser to perforate holes into algae cells, before inserting fluorogenic aptamers, which fluoresce when binding to the metabolite, paramylon.
"We synthesised a peptide aptamer binding to paramylon, and introduced it into Euglena gracilis cells," highlights Hosokawa's colleague, Dr Takanori Maeno. "Paramylon is produced only by Euglena.... and can be refined into a biofuel."
The researchers went on to use laser scanning confocal microscopy to image the metabolite in single microalgae cells, measuring its accumulation over time to determine metabolising cells from unproductive neighbours.
Femtosecond laser photoporation of E. gracilis cells at single-cell resolution. (A) Bright-field and fluorescence images of an E. gracilis cell 20 min after the photoporation. (B) Fluorescence images of E. gracilis cells 20 min after the spatially patterned photoporation with the same aptamer. Patterned photoporation was performed on cells in the black and white patterns of Pikachu (left) and Michael Jackson. Each fluorescent dot corresponds to a single E. gracilis cell into which the aptamer was injected and bound to intracellular paramylon.
Engineering bacteria to efficiently metabolise is proving crucial to drug and biofuel production but researchers have struggled to identify productive cells.
The latest method will help researchers pinpoint the most productive algae for metabolic engineering.
"Our system gives spatial and temporal information about target intracellular paramylon, but should work for any kind of metabolite in the future... and will be useful for selecting high-performance cells," points out Hosokawa.
"Because the quantity of the metabolite is measured as the intensity of fluorescence, our method is also applicable to flow cytometry and fluorescence-activated cell sorting," he adds. "The remarkable advance of high-speed imaging and sorting technologies may assist the efficient selection of single cells with high specificity."
Research is published in Nature Scientific Reports.
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