Biology subjects

Aggelis, G.

Publications and source records attributed to Aggelis, G..

3 recordsLinked to original sources

bioRxiv2021

Bioconversion of pomegranate residues into biofuels and bioactive lipids

Pomegranate residues (PRs) (i.e. the solid residues remaining after juice extraction), generated currently in abundance in Greece, contain a variety of carbon sources and therefore can be regarded as a potential feedstock for chemical and biotechnological processes rather than as waste materials. In the current project, the polysaccharides contained in PRs were extracted and hydrolyzed in a one-step process without the use of chemical reagents and the resulting broth was used as substrate in biotechnological applications, including ethanol and single cell oil (SCO) production. The yeasts Meyerozyma guilliermondii, Scheffersomyces coipomoensis, Sugiyamaella paludigena and especially Saccharomyces cerevisiae, were able to efficiently convert PR derived reducing sugars into bioethanol. Ethanol production under anaerobic conditions ranged from 3.6 to 12.5 g/L. In addition, the oleaginous yeasts Lipomyces lipofer and Yarrowia lipolytica as well as M. guilliermondii, S. coipomoensis and S. paludigena were tested for their ability to accumulate lipids suitable as feedstock for biodiesel production. Lipids were accumulated at concentrations up to 18% and were rich in palmitic acid (C16:0) and oleic acid (C18:1). Finally, the oleaginous fungus Cunnichamella echinulata was cultivated on PR based solid substrates for {gamma}-linolenic acid (GLA) production. The fermented bio-products (i.e. fermented substrate plus fungal mycelia) contained up to 4.8 mg GLA/g of dry weight. Phenolic removal (up to 30%) was achieved by several of the above mentioned microorganisms, including C. echinulata, L. lipofer, M. guilliermondii, S. paludigena and Y. lipolytica. We conclude that PRs can be used as a raw material for microbial growth, ethanol and SCO production, which is of economic and environmental importance.

microbiology↗

bioRxiv2020

Singe cell oil (SCO) based bioactive compounds: II. Enzymatic synthesis of glucose fatty acid esters using SCOs as acyl group-donors and their biological activities

Sugar fatty acid esters, especially glucose fatty acid esters (GEs), have broad applications in food, cosmetic and pharmaceutical industries. In this research the fatty acid moieties derived from polyunsaturated fatty acid containing single cell oils (SCOs), i.e. those produced from Cunninghamella echinulata, Umbelopsis isabellina and Nannochloropsis gaditana as well as from olive oil and an eicosapentaenoic acid (EPA) concentrate were converted into GEs by enzymatic synthesis, using lipases as biocatalysts. The GE synthesis was monitored using thin-layer chromatography, FT-IR and in situ NMR. It was found that GE synthesis carried out using immobilized Candida antarctica B lipase was very effective reaching high yields, near to 100%. It was shown that EPA-GEs were very effective against several pathogenic bacteria and their activity can be attributed to their high EPA content. Furthermore, C. echinulata-GEs were more effective against pathogens comparing to U. isabellina-GEs, probably due to the presence of gamma linolenic acid (GLA) in the lipids of C. echinulate, which is known for its antimicrobial activity, in higher concentrations. C. echinulata-GEs also showed a strong insecticidal activity against Aedes aegypti larvae, followed by EPA-GEs, olive oil-GEs, and N. gaditana-GEs. All synthesized GEs induced apoptosis of the SKOV-3 ovarian cancer cell line, with the apoptotic rate increasing significantly after 48 h. A higher percentage of apoptosis was observed in the cells treated with EPA-GEs, followed by C. echinulata-GEs, U. isabellina-GEs and olive oil-GEs. We conclude that SCOs can be used in the synthesis of GEs with interesting biological properties.

biochemistry↗

bioRxiv2020

Enzymatic synthesis of fatty acid amides using microbial lipids as acyl group-donors and their biological activities

Fatty acid amides (FAAs) are of great interest due to their broad industrial applications. They can be synthesized enzymatically with many advantages over chemical synthesis. In this study, the fatty acid moieties of lipids of Cunninghamella echinulata ATHUM 4411, Umbelopsis isabellina ATHUM 2935, Nannochloropsis gaditana CCAP 849/5, Olive oil and an eicosapentaenoic acid (EPA) concentrate were converted into their fatty acid methyl esters and used in the FAA (i.e. ethylene diamine amides) enzymatic synthesis, using lipases as biocatalysts. The FAA synthesis, monitored using in situ NMR, FT-IR and thin-layer chromatography, was catalyzed efficiently by the immobilized Candida rugosa lipase. The synthesized FAAs exhibited a significant antimicrobial activity, especially those containing oleic acid in high proportions (i.e. derived from Olive oil and U. isabellina oil), against several human pathogenic microorganisms, insecticidal activity against yellow fever mosquito, especially those of C. echinulata containing gamma linolenic acid, and anti-cancer properties against SKOV-3 ovarian cancer cell line, especially those containing EPA in their structures (i.e. EPA concentrate and N. gaditana oil). We conclude that FAAs can be efficiently synthesized using microbial oils of different fatty acid composition and used in specific biological applications.

biochemistry↗