Interplay between interfacial behaviour, cell structure and shear enables biphasic lipid extraction from whole diatom cells (Navicula sp.)

Ultrasound-Assisted Extracellular Polymeric Substance Removal from the Diatom Navicula sp.: A Route to Functional Polysaccharides and More Efficient Algal Biorefineries

“…A previously studied strain of the diatom Navicula sp. was grown in a modified F medium with added silica . The cultures were grown in 15 L carboys and harvested after a 10 day growth period using a disk stack centrifuge (Separator OTC 2-02-137, GEA Westfalia, Italy) operated at 10,000 rpm.…”

“…The lipid-rich hexane layer was pipetted and diluted appropriately using n -hexane, and the absorbance was measured at 450 nm using an ultraviolet–visible (UV–vis) spectrophotometer (Cary 3E UV–vis absorbance spectrophotometer, Agilent Technologies, Mulgrave, VIC, Australia). The lipid concentration was obtained using a calibration curve obtained for known lipid concentrations versus the absorbance at 450 nm, following the same method as previously reported . In brief, the calibration curve was obtained by redissolving a known mass of lipids in hexane that was extracted from Navicula sp.…”

“…In a previous study, we showed that the bound EPS on the diatomNavicula sp. potentially hindered lipid extraction from these cells in a biphasic system and that ultrasound was capable of removing the bound EPS . Therefore, apart from the potential effect on the rheological properties and hence the processability, the presence of EPS appears to affect the lipid extraction efficiency as well.…”

Computer-aided solvent screening for the fractionation of wet microalgae biomass

“…However, solvents being practically immiscible with water usually attain low lipid yield without prior cell disintegration. 38,67 It is proposed, that the resulting phase boundary and extracellular polysaccharides act as a barrier to wet cells such that the waterimmiscible solvent has poor access to the target molecules. 67,68 In contrast to practically immiscible solvents, Liu et al experimentally identified a water-miscible solvent for wet lipid extraction 69 enabling contact of the solvent to the target molecules.…”

“…38,67 It is proposed, that the resulting phase boundary and extracellular polysaccharides act as a barrier to wet cells such that the waterimmiscible solvent has poor access to the target molecules. 67,68 In contrast to practically immiscible solvents, Liu et al experimentally identified a water-miscible solvent for wet lipid extraction 69 enabling contact of the solvent to the target molecules. In this approach however, the solvent does not induce phase separation such that co-extracted hydrophilic molecules, for example carbohydrates or proteins, cannot be easily separated from the lipid compounds.…”