1 Université de Nantes, Laboratoire Mer Molécules Santé, EA 21 60, BP 92208, 44322 Nantes, France
2 Université de Nantes, GEPEA, UMR CNRS-6144, Bât.CRTT, 37 Boulevard de l’Université, BP406, 44602 Saint-Nazaire Cedex, France
3 Le Mans Université, Laboratoire Mer Molécules Santé, EA 21 60, Avenue Olivier Messiaen, 72085 Le Mans, France
Estuaries and coastal areas are amongst the most productive marine ecosystems on earth mainly due to microscopic algae that inhabit intertidal sediments, the microphytobenthos, forming at the sediment surface dense biofilms. Since the past decade, its key roles in the ecosystem functioning started to be studied: ecology, biology and physiology. But the assessment of useful metabolites remains little known. Microphytobenthos diversity remains a ‘secret garden’ with a powerful potential in biotechnology.
The Nantes Cultures Collection (NCC), is dedicated to the preservation, storage and assessment of benthic diatoms. With more than 100 strains, including ‘blue diatoms’, the NCC is a real conservatory of microphytobenthos diversity. To determine lipid profiles of the NCC strains and supply new and original strains for biotechnology, an integrated screening approach based on FTIR spectroscopy has been developed. Five strains were found to present total lipid rate up to 15% DW: Amphora sp. NCC169, Nitzschia sp. NCC109, Nitzschia alexandrina NCC33, Opephora sp. NCC366 and Staurosira sp. NCC182. Two of them, Nitzschia alexandrina NCC33 and Staurosira sp. NCC182, as well Entomoneis paludosa NCC18.2 have been grown under different conditions of light and nitrogen concentration with photosynthetic performance and macromolecular content survey. Results suggest that under high light and nitrogen limitation, photosynthetic machinery is negatively impacted, and cells accumulate lipids and/or carbohydrates. However, lipids of interest as PUFA, ARA and EPA decreased. Culture conditions to optimize production of such as fatty acids for these three original benthic diatom strains leads to an adequacy between economical and ecophysiological constraints: low light and no nitrogen limitation.
