A research team at KAIST has for the first time successfully visualised living bacteria actually making PHA inside the cell.
PHA is a polyester material that is synthesised by numerous different strains of bacteria as an energy and carbon storage material. The microbes start producing the substance under stress conditions and in the presence of excess carbon sources, accumulating it in the form of intracellular granules.
PHA materials are viewed as offering a good potential alternative to fossil fuel-based conventional resins. 100% bio-based, they are biodegradable and in some cases even marine degradable, with properties that are suitable for a range of different applications.
Previous studies investigating PHA granules inside microbial cells have been performed by using fluorescence microscopy, transmission electron microscopy (TEM), and electron cryotomography. Neither technique permitted living cells to be visualised in action. This made it difficult to fully understand the formation of PHA granules in cells. Until now, therefore, only various mechanism models based on observations had been proposed, without the process actually having been observed.
The Korean scientists - a team of metabolic engineering researchers led by Distinguished Professor Sang Yup Lee and Physics Professor YongKeun Park - used 3D holographic microscopy and optical diffraction tomography to study the formation and growth of PHA granules in the cells of live bacteria.