Résumé
IntroductionA filamentous strain, Nostoc sp. ATCC 53789 is known to produce a bioactive cyclo-depsipeptide, Cryptophycin (Cr) (1). The objective of this study is to enhance the green Cr yield through the utilisation of ecophysiological analysis of cyanobacteria cultures and the performance of unit operations involved in biomass treatment.Materials and MethodsThe strain is cultivated in a specially formulated, artificial medium, enabling precise modulation of its composition. Continuous or semi-continuous cultures are carried out in closed photobioreactors. It allows for precise control of the environmental parameters necessary for eco-physiological studies. Extraction and purification used liquid/ solid and liquid/liquid separative and preparative techniques (CPC and LC-prep). The focus is on achieving a criticalequilibrium of Cr between two immiscible bio-renewable solvents. Cr content is monitored by LC-DAD and LC-MS.ResultsOptimal values for the composition of the culture medium and light fluxes were determined to increase the biomass productivity of the cyanobacteria. An increase in Cr content is observed when dinitrogen is the only N-source (diazotrophy). Then Cr productivity was also improved.Studying the filamentous aggregation process of this species led to the implementation of a pre-harvest process.This involves the use of a simple fine filter screen, which reduces power consumption.The study demonstrated the potential for highly efficient extraction and purification, even with biorenewable solvents like limonene.ConclusionThe results demonstrate that biological production involves fewer steps than chemical synthesis and, most notably, utilises a range of bio-renewable inputs, including N2 and limonene. The scalability of the process is addressed in the context of the quantities requested for potential pharmaceutical applications.