Role of Snf-β in lipid accumulation in the high lipid-producing fungus Mucor circinelloides WJ11

BackgroundMucor circinelloides WJ11 is a high-lipid producing strain and an excellent producer of gamma -linolenic acid (GLA) which is crucial for human health. We have previously identified genes that encode for AMP-activated protein kinase (AMPK) complex in M. circinelloides which is an important regulator for lipid accumulation. Comparative transcriptional analysis between the high and low lipid-producing strains of M. circinelloides showed a direct correlation in the transcriptional level of AMPK genes with lipid metabolism. Thus, the role of Snf-beta, which encodes for beta subunit of AMPK complex, in lipid accumulation of the WJ11 strain was evaluated in the present study.ResultsThe results showed that lipid content of cell dry weight in Snf-beta knockout strain was increased by 32% (from 19 to 25%). However, in Snf-beta overexpressing strain, lipid content of cell dry weight was decreased about 25% (from 19 to 14.2%) compared to the control strain. Total fatty acid analysis revealed that the expression of the Snf-beta gene did not significantly affect the fatty acid composition of the strains. However, GLA content in biomass was increased from 2.5% in control strain to 3.3% in Snf-beta knockout strain due to increased lipid accumulation and decreased to 1.83% in Snf-beta overexpressing strain. AMPK is known to inactivate acetyl-CoA carboxylase (ACC) which catalyzes the rate-limiting step in lipid synthesis. Snf-beta manipulation also altered the expression level of the ACC1 gene which may indicate that Snf-beta control lipid metabolism by regulating ACC1 gene.ConclusionsOur results suggested that Snf-beta gene plays an important role in regulating lipid accumulation in M. circinelloides WJ11. Moreover, it will be interesting to evaluate the potential of other key subunits of AMPK related to lipid metabolism. Better insight can show us the way to manipulate these subunits effectively for upscaling the lipid production. Up to our knowledge, it is the first study to investigate the role of Snf-beta in lipid accumulation in M. circinelloides.

Automated summary

Our study revealed that the Snf-beta gene is crucial in regulating lipid accumulation in M. circinelloides WJ11. By manipulating the Snf-beta gene, we can alter lipid content in the strain. Furthermore, changes in GLA content were observed in Snf-beta knockout and overexpressing strains.