Δ12 fatty acid desaturase gene from Geotrichum candidum in cheese: molecular cloning and functional characterization

Soft cheese with white rind lacks essential fatty acids (EFAs), and as a result its long-term consumption may lead to various kinds of cardiovascular and cerebrovascular diseases, such as hyperlipidemia, hypertension, and atherosclerosis. Geotrichum candidum is a dimorphic yeast that plays an important role in the ripening of mold cheese. A gene coding for Δ12 fatty acid desaturase, a critical bifunctional enzyme desaturating oleic acid (OA) and linoleic acid (LA) to produce LA and α-linolenic acid (ALA), respectively, was isolated from G. candidum, and then cloned and heterologously expressed in Saccharomyces cerevisiae. This gene, named GcFADS12, had an open reading frame of 1257 bp and codes for a protein of 419 amino acids with a predicted molecular mass of 47.5 kDa. Characterization showed that GcFADS12 had the ability to convert OA to LA and LA to ALA, and the conversion rates for OA and LA were 20.40 ± 0.66% and 6.40 ± 0.57%, respectively. We also found that the protein product of GcFADS12 catalyzes the conversion of the intermediate product (LA) to ALA by addition of OA as the sole substrate. The catalytic activity of GcFADS12 on OA and LA was unaffected by fatty acid concentrations. Kinetic analysis revealed that GcFADS12 had stronger affinity for the OA than for the LA substrate. This study offers a solid basis for improving the production of EFAs by G. candidum in cheese.

Molecular Genetic Analysis with Microsatellite-like Loci Reveals Specific Dairy-Associated and Environmental Populations of the Yeast Geotrichum candidum

Geotrichum candidum is an environmental yeast, also found as part of the cheese surface microbiota, where it is important in the ripening of many traditional cheeses, such as Camembert. We have previously developed a Multi Locus Sequence Typing (MLST) scheme, which differentiated five clades, of which one contained only environmental isolates, two were composed almost entirely of dairy isolates, and two others contained a mixture of dairy, environmental, and miscellaneous food isolates. In order to provide a simple method to uniquely type G. candidum strains, and in addition to permit investigation of the population structure at a fine level, we describe here a molecular analysis using a set of twelve highly discriminating microsatellite-like markers. The present study consolidates the previously suggested division between dairy and environmental strains, and in addition distinguishes a specifically European group of environmental strains. This analysis permitted the discrimination of 72 genotypes from the collection of 80 isolates, while retaining the underlying meaningful phylogenetic relation between groups of strains.

Uncovering the Biotechnological Importance of Geotrichum candidum

Fungi make a fundamental contribution to several biotechnological processes, including brewing, winemaking, and the production of enzymes, organic acids, alcohols, antibiotics, and pharmaceuticals. The present review explores the biotechnological importance of the filamentous yeast-like fungus Geotrichum candidum, a ubiquitous species known for its use as a starter in the dairy industry. To uncover G. candidum's biotechnological role, we performed a search for related work through the scientific indexing internet services, Web of Science and Google Scholar. The following query was used: Geotrichum candidum, producing about 6500 scientific papers from 2017 to 2022. From these, approximately 150 that were associated with industrial applications of G. candidum were selected. Our analysis revealed that apart from its role as a starter in the dairy and brewing industries, this species has been administered as a probiotic nutritional supplement in fish, indicating improvements in developmental and immunological parameters. Strains of this species produce a plethora of biotechnologically important enzymes, including cellulases, β-glucanases, xylanases, lipases, proteases, and α-amylases. Moreover, strains that produce antimicrobial compounds and that are capable of bioremediation were identified. The findings of the present review demonstrate the importance of G. candidum for agrifood- and bio-industries and provide further insights into its potential future biotechnological roles.