Prof. Yuanda Song, Director, Colin Ratledge Center for Microbial Lipids; Director, SDUT-UM International Joint Laboratory on Microbial Cell Factories for Bioactive Natural Products, Shandong University of Technology, Zibo, Shandong, China
Biograph: Dr. Y Song is a professor of biochemistry at Shandong University of Technology. He got his BS degree in chemistry from Suzhou University in 1987, and ME degree in chemical engineering from Beijing Institute of Technology and BGRIMN in 1990. From 1997-2001 He did his PhD study in microbial lipid biochemistry with Prof. Colin Ratledge at the University of Hull in England. Then Dr Song went to Ohio State University, University of Michigan and Virginia Commonwealth University for his postdoctoral training from 2001 to 2007. In Oct 2007, Dr Song joined Central South University (China), as a Shenghua Scholar, Professor of biochemistry, and associate chair of the Department of Biochemistry. In Nov. 2010，Dr Song joined Jiangnan University as a Tai Lake Scholar and Distinguished Professor. In Nov. 2015 Dr Song joined Shandong University of Technology as a Distinguished Professor and Director of Colin Ratledge Center for Microbial Lipids. His research has been supported by both national (NSFC etc), international (Merieux Fr), and industrial funds. He has published more than 70 peer-reviewed articles, and filed 15 patents. He is also the member of the editorial board of two international journals.

Speech Title: The molecular mechnism of high oleaginicity in oleaginous fungus Mucor circinelloides WJ11
Abstract: The oleaginous fungus, Mucor circinelloides, is one of few fungi that produce high amounts of γ-linolenic acid (GLA); however, it usually only produces <25% lipid. Nevertheless, a new strain (WJ11) isolated in this laboratory can produce lipid up to 36% of (w/w) cell dry weight (CDW). We have investigated the potential mechanism of high lipid accumulation in WJ11 by genomic, proteomic, comparative biochemical analysis and ¹³C labeled metabolic flux analysis with a low lipid accumulating strain CBS 277.49, which accumulates less than 15% (w/w) lipid. Comparative genomic analysis showed that the genome of WJ11 is highly similar to CBS277.49, however, the different numbers of genes encoding the enzymes in central carbon pathways between WJ11 and CBS 277.49 may have an effect on the lipid accumulation. Some unique genes were identified for each strain using OrthoMCL clustering procedure, which may play a role in different cell growth and lipid accumulation in these two strains. Comparative proteomic analysis between strains WJ11 and CBS 277.49 at the fast lipid accumulation stage indicated the expression of proteins related to branched chain amino acid metabolism were significantly increased in WJ11, this may provide more substrates for fatty acid synthesis. The expression of proteins involved in glycolytic pathway were up-regulated while that involved in tricarboxylic acid cycle were down-regulated in WJ11 compared with CBS 277.49, which resulted in a greater flux of carbon into fatty acid biosynthesis. In addition, some proteins taking part in pentose phosphate pathway were up-regulated, leading to more NADPH production in WJ11 than CBS 277.49. Biochemical analysis showed that strain WJ11 had enhanced activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase by 46% and 17%, respectively, which is similar to proteomic results, but with decreased activities of NAD+:isocitrate dehydrogenase, NADP+:isocitrate dehydrogenase and citrate synthase by 43%, 54% and 16%, respectively, which lead to the decreased tricarboxylic acid cycle, and then provided more substrate for ATP:citrate lyase (ACL) to produced acetyl-CoA. Also, the activities of ACL and fatty acid synthase in the high lipid-producing strain, WJ11, were increased by 25% and 56%, respectively. Consistent with this result, metabolic flux analysis showed that carbon flux through pentose phosphate pathway, malic enzyme and ACL were higher, while TCA was lower, in WJ11 compared to CBS277.49. Taken together, comparing to CBS 277.49, the metabolic pathways in WJ11 is cooperatively regulated to provide more substrate aceyl-CoA, and reducing power NADPH for lipid production.

In addition, our recent work has shown that Mucor circinelloides has abundant lipase genes. Some of the lipases has bifunctional roles, i.e. with both lipase and acyl-transferase activity, which were involved in TAG metabolism and modification respectively.