Use of supercritical CO2 to obtain extracts with antimicrobial activity from Chaetoceros muelleri microalga.: A correlation with their lipidic content

Supercritical CO2 extracts of the marine diatom Chaetoceros muelleri (gracilis) have been investigated for their potential use as food preservatives, namely, as antimicrobials. A screening of different pressures and temperatures for supercritical CO2 extraction was assayed in order to determine the main factors controlling the yield and antimicrobial activity of the extracts. Since the potential antimicrobial activity of these CO2 extracts is mainly induced by the lipidic fraction, HPLC with evaporative light scattering detection (HPLC-ELSD) and GC with flame ionization detection (GC-FID) were used to identify lipid families and fatty acids, respectively. Antimicrobial activity of the extracts was measured against Staphyloccocus aureus, Escherichia coli and Candida albicans. Possible correlations between antimicrobial activity of extracts and their chemical composition were investigated, concluding that the total triglycerides and the DPA content seem to be the main parameters controlling the antimicrobial activity of the studied extracts.