ABSTRACT
Milking is a method for simultaneous production and extraction of target compounds directly from live cells without harvesting or killing them. The extraction relies on an aqueous-organic biphasic system where the organic solvent is in direct contact with the cells and therefore must be biocompatible. Zhang et al. (2011) performed a screening of biocompatible solvents for enhancement of lipid milking from Nannochloropsis sp. The solvents tested were hexanol, heptanol, octanol, hexane, heptane, octane, nonane, decane, dodecane, tetradecane, and hexadecane, with partition coefficient (Log Poct), ranging from 2.03 for hexanol to 8.80 for hexadecane. This study concluded that on the one hand hydrophilic solvents with Log Poct > 5.5 (the alcohols and the alkanes with C-6 to C-8) were not biocompatible with the microalgae Nannochloropsis sp. due to deactivated dehydrogenase and increased cell membrane permeability. On the other hand, dodecane, tetradecane, and hexadecane (10% v/v) were biocompatible with the microalgae investigated, with hexadecane allowing extraction (22%) of the biomass total lipids. Furthermore, it was possible to recover 89% of the solvent used in the milking process.
