Mucor rouxii Δ9-desaturase gene is transcriptionally regulated during cell growth and by low temperature

Unsaturated fatty acids are essential lipid components of Mucor rouxii. g-Linolenic acid (GLA) is synthesized via the desaturase enzymes: D9-desaturase catalyzes mono-unsaturated fatty acids that are utilized as substrate for GLA biosynthesis. We cloned and characterized a M. rouxii gene highly homologous to D9-desaturase genes. This sequence encodes for a protein of 452 amino acids and contains two introns of 60 and 61 nucleotides. D9-desaturase of M. rouxii is expressed during cell growth when cells are subjected to temperature shifts. At 30°C, the mRNA level of late log phase is about 6.4-fold higher than that of early log phase. A shift from 30 to 15°C induced transcription of D9-desaturase gene in both early and late log phases. However, the pattern of increased transcription by cold induction varied depending on growth conditions: transcription of late log phase is higher than that of early log phase. These results indicate that cell growth and low temperature influence the expression of D9-desaturase gene and fatty acid composition of M. rouxii

Genome Characterization of Oleaginous Aspergillus oryzae BCC7051: A Potential Fungal-Based Platform for Lipid Production

The selected robust fungus, Aspergillus oryzae strain BCC7051 is of interest for biotechnological production of lipid-derived products due to its capability to accumulate high amount of intracellular lipids using various sugars and agro-industrial substrates. Here, we report the genome sequence of the oleaginous A. oryzae BCC7051. The obtained reads were de novo assembled into 25 scaffolds spanning of 38,550,958\ua0bps with predicted 11,456 protein-coding genes. By synteny mapping, a large rearrangement was found in two scaffolds of A. oryzae BCC7051 as compared to the reference RIB40 strain. The genetic relationship between BCC7051 and other strains of A. oryzae in terms of aflatoxin production was investigated, indicating that the A. oryzae BCC7051 was categorized into group 2 nonaflatoxin-producing strain. Moreover, a comparative analysis of the structural genes focusing on the involvement in lipid metabolism among oleaginous yeast and fungi revealed the presence of multiple isoforms of metabolic enzymes responsible for fatty acid synthesis in BCC7051. The alternative routes of acetyl-CoA generation as oleaginous features and malate/citrate/pyruvate shuttle were also identified in this A. oryzae strain. The genome sequence generated in this work is a dedicated resource for expanding genome-wide study of microbial lipids at systems level, and developing the fungal-based platform for production of diversified lipids with commercial relevance