Search

Additional file 1: Table S1. Differentially expressed genes between growth on different media at 10 h. Table S2. Differentially expressed genes between growth on different media when glycerol consumption became visible. Table S3. Differentially expressed genes between growth on different media when glycerol concentration is lower. Table S4. Gene expression in TPM within central metabolic pathways. Figure S1. Principal Component Analysis based on expression level from the 500 highest expressed genes in each of the cultivation media and RNA sampling points. Figure S2. Overview of differential expression analysis between Rhodotorula toruloides CBS 14 cultivated on crude glycerol and a mixture of crude glycerol and hemicellulose hydrolysate, at 10 h cultivation. Figure S3. Overview of differential expression analysis between Rhodotorula toruloides CBS 14 grown on different media when glycerol consumption became visible. Figure S4. Overview of differential expression analysis between Rhodotorula toruloides CBS 14 grown on different media when about 20 g/l of glycerol were left. Figure S5. Differentially expressed genes in Rhodotorula toruloides CBS 14 within sampling time points in each of the growth media. Figure S6. Examples of upregulated genes in Rhodotorula toruloides CBS 14 grown on a mixture of crude glycerol (CG) and hemicellulose hydrolysate (CGHH) for 10 h of cultivation, whose expression is higher than CG 10 h. Figure S7. Examples of upregulated genes in Rhodotorula toruloides CBS 14 grown on a mixture of crude glycerol (CG) and hemicellulose hydrolysate (CGHH) for 10 h of cultivation, whose expression is higher than CG 30 h. Figure S8. Examples of upregulated genes in Rhodotorula toruloides CBS 14 grown on a mixture of crude glycerol (CG) and hemicellulose hydrolysate (CGHH) for 36 h of cultivation, whose expression is higher than CG 60 h. Figure S9. Distribution of shared ortholog clusters within differentially expressed genes in each of the three differential expression analyzes. The diagram was generated using OrthoVenn2.

Bioenergy will be one of the most important renewable energy sources in the conversion from fossil fuels to bio-based products. Short rotation coppice Salix could be a key player in this conversion since Salix has rapid growth, positive energy balance, easy to manage cultivation system with vegetative propagation of plant material and multiple harvests from the same plantation. The aim of the present paper is to provide an overview of the main challenges and key issues in willow genetic improvement toward sustainable biofuel value chains. Primarily based on results from the research project "Optimized Utilization of Salix" (OPTUS), the influence of Salix wood quality on the potential for biofuel use is discussed, followed by issues related to the conversion of Salix biomass into liquid and gaseous transportation fuels. Thereafter, the studies address genotypic influence on soil carbon sequestration in Salix plantations, as well as on soil carbon dynamics and climate change impacts. Finally, the opportunities for plant breeding are discussed using willow as a resource for sustainable biofuel production. Substantial phenotypic and genotypic variation was reported for different wood quality traits important in biological (i.e., enzymatic and anaerobic) and thermochemical conversion processes, which is a prerequisite for plant breeding. Furthermore, different Salix genotypes can affect soil carbon sequestration variably, and life cycle assessment illustrates that these differences can result in different climate mitigation potential depending on genotype. Thus, the potential of Salix plantations for sustainable biomass production and its conversion into biofuels is shown. Large genetic variation in various wood and biomass traits, important for different conversion processes and carbon sequestration, provides opportunities to enhance the sustainability of the production system via plant breeding. This includes new breeding targets in addition to traditional targets for high yield to improve biomass quality and carbon sequestration potential.

Additional file 3. Figure 3. Bioreactor cultivation of R. toruloides CBS 14 in triplicates, (A) CG50 medium, (B) HH10CG50 medium. Glucose, xylose and acetic acid are presented on secondary Y axis.

Additional file 2. Figure 2. R. toruloides CBS 14, HH40CG60 media grown in duplicates, dry weight and change of compounds concentration in media over time, average lipid concentration was 10.57 g/L after 70h. Glucose, xylose and acetic acid are presented on secondary y axis.

Additional file 1: Figure S1. Photographs of the investigated strains on agar plates.

Additional file 2: Table S1. Screening of Rhodotorula and Lipomyces strains for growth on glucose, xylose and a mixture of both. All strains were grown on either a glucose- (G), xylose (X) or a glucose/xylose mixture (M) containing media. Growth was measured by OD- determination, Lipids were measured using FTIR spectroscopy. Lipid content was not determined (n.d.) for some strains due to exclusion of these strains from further investigation based on their poor growth performance. Experiments were performed in duplicates and average deviation is displayed, (*) only one replicate available.

Additional file 1. Figure 1. Specific lipid production rates of R. toruloides CBS 14 and R. glutinis CBS 3044 in 55 g/L crude glycerol media and 55 g/L crude glycerol media with 10% hemicellulose hydrolysate. Negative values are due to a decrase of lipid concentrations during the measuring interval.