Day 1 :
Bonn-Rhein-Sieg University of Applied Sciences, Germany
Keynote: Lignin: A natural antioxidant isolated via selective extraction from lignocellulose feedstock to be used in packaging applications
Time : 09:30-10:15
Margit Schulze has received her PhD at Institute for Organic Chemistry from TH Merseburg/Martin Luther-Universität Halle-Wittenberg in 1990. Her had various position in her career as a Researcher at Martin Luther University Halle-Wittenberg in 1986, Project Leader at Max-Planck-Institute for Polymer Research Mainz in 1994, Senior Lecturer at Royal Institute of Technology (KTH) Stockholm in 1996, Head of Industrial Oils, Degussa/Evonik, Darmstadt during 1998-2000 and since 2001 she holds Professorship (C3) for Organic Chemistry and Polymers at Bonn-Rhein-Sieg University. She has received Research Award of the Hochschule Bonn-Rhein-Sieg together with Edda Tobiasch for “Optimaix Bone Regeneration”.
Lignins are byproducts of the paper and pulping industry. They are available in huge amounts in form of so called black liquor, mainly produced via Kraft-pulping. However, applications of technical lignins are still limited to low-quality products due to the chemical and structural inhomogeneity. Thus, the first goal is to develop an appropriate approach for lignin extraction and purification. The purified lignins are then studied with special focus on antioxidant and bioactivity properties depending on biomass source and pulping process. In collaboration with the “Cold Chain Management” group at the University Bonn, lignin-based polymers are developed for active bio-based packaging and biomedical applications. Black liquor produced from wood pulping is used as a source of Kraft lignin. The lignin is extracted from black liquor via acidic precipitation, monitored by Thin Layer Chromatography (TLC). Purification of Kraft lignin was carried out by selective extraction. Lignins are characterized by FTIR, UV-Vis, 31P NMR, SEC, XRD and microscopy (SEM). Antioxidant activity is studied using a DPPH assay. The phenol content of lignins is determined by the Folin-Ciocalteau Micro method. Bioactivity (antibacterial and antifungal) of extracted lignins is accomplished by disk diffusion method and solution shake method. The antimicrobial activity is tested by modifying the method ISO 22196 (2007), a quantitative method to determine the level of antimicrobial activity of plastic surfaces. Folin-Ciocalteu and DPPH-Assay results confirm the antioxidant ability of lignins. In addition, it could be shown that the antioxidant activity of the lignin fractions strongly depends on the source of the black liquor. Here, differences in biomass feedstock used for the Kraft pulping process could be the reason for this observation which still is under investigation.
Univerite de Liege, Belgium
Keynote: Pichia process optimisation by co-feeding procedure : How to reduce oxygen uptake and heat generation without loss of pAOX1 promoter induction
Time : 10:15-11:00
Patrick Fickers has completed his PhD in Biochemistry from Universite de Liege, Belgium and from Institut National Agronomique, Paris, France. In 2004, he was at Polytech’ Lille, France as a Post doctorate. In 2005, he has joined the Centre of Protein Engineering, Liege, Belgium as FNRS fellow. He was an Associate Professor at Universite libre de Bruxelles and the Head of the Biotechnology and Bioprocess Unit from 2009 to 2014. Since 2015, he is Professor at Gembloux Agro BioTech, University of Liege in the Microbial Processes and Interactions. He is also a Scientific Collaborator at University of Camaguey, Cuba and Adjunct Professor at TDT University (Ho Chi Minh City, Vietnam). He has published more than 40 research papers in peer-reviewed journals, 6 book chapters and several review articles. His researches focus on the development of yeast and bacterial strains by metabolic engineering. He is also interested in process development in bioreactor for the production of valuable compounds
Recombinant protein production driven by AOX1 promoter (pAOX1) is challenged by a high oxygen demand and heat production, especially in large-scale bioreactor. A promising solution relies on a methanol/sorbitol co-feeding strategy during the induction phase. In this work, transient continuous cultures were first performed to quantitatively assess the benefits of a methanol/sorbitol co-feeding process with a P. pastoris Mut+ strain bearing a pAOX1-lacZ construct served as a reporter gene. Our results demonstrated that cell-specific oxygen consumption (qO2) could be reduced by decreasing the methanol fraction in the feeding media. Optimal pAOX1 induction was achieved and maintained in the range of 0.45~0.75 C-mol/C-mol of methanol fraction. In addition, the qO2 was reduced by 30% at most in those conditions. Based on a simplified metabolic network, metabolic flux analysis was performed to quantify intracellular metabolic flux distributions during the transient continuous cultures, which further shed light on the advantages of methanol/sorbitol co-feeding process. Secondly, chemostat cultures were performed to investigate the cell growth, metabolism and regulation of pAOX1 regarding co-feeding rate of optimized methanol/sorbitol mixture. Our results highlight that methanol/sorbitol co-feeding allowed cells to adapt to oxygen transient limitation that often occur at industrial scale with reduced effect on pAOX1 induction and cell viability. The optimal feeding rate tested here was 6.6 mmolC (DCW h)-1 at an oxygen transfer rate (OTR) of 8.28 gO2 (l.h)-1 with over five-fold pAOX1 induction (probably directly associated with target protein productivity) compared with previous work.