Iris Cornet associate professor

Research Iris Cornet

Research team

Expertise

I have experience in research into the valorisation of by-products of agriculture, horticulture, food industry and forestry. This biomass is used as a raw material for the production of chemicals and biofuels. My expertise lies in the application of microbial or enzymatic catalysis in the various industrial process steps in this conversion and the optimization thereof. Because of increasing oil prices lignocellulose originating from plants as an alternative raw material is extensively investigated, both in industry and research institutes. The use of enzymes and micro-organisms in the production of chemicals results in environmentally friendly processes without or with limited use of organic solvents, acids or bases and at ambient conditions, i.e. no high temperatures and pressures. This technology is called Industrial Biotechnology. Because lignocellulose has a compact and recalcitrant structure, in a first step the biomass must be pretreated in order to remove the lignin and make the cellulose available for the next step. The cellulose is enzymatically hydrolysed to sugars which are then fermented to the desired end product. We investigate the mechanisms that occur to optimize the processes using reactor operation and design. The mathematical description of the kinetics and mass balances in models is a help in the scaling up.

SMArT: Single-cell protein production from wastewater through renewable Methanol/ethanol-Assisted community engineering Technology 01/11/2023 - 31/10/2025

Abstract

Single-cell protein (SCP) production on food and beverage effluents is a resource-efficient water treatment approach, upgrading organics and nitrogen into protein for animal feed. These effluents are economically suitable for high-rate production of aerobic heterotrophic microorganisms (AHM) in open systems. However, fluctuations intrinsic to this approach lead to variability in nutritional quality of the SCP, and production costs of biomass downstream processing, still challenge the applicability of SCP technology. While an array of environmental biotech solutions showed the potential of biostimulation (co-substrate dosing) or bioaugmentation (target organism seeding), these tools have not yet been explored for SCP production on wastewater. SMArT aims to create a more stable and predictable microbial community leading to better nutritional quality using smart biostimulation and -augmentation strategies, based on renewable co-substrates, high-chance-to-thrive bacteria and yeast in a novel nursery concept. Biostimulant choice and dose will be tested with target AHM from enrichment cultures and literature. A sidestream nursery reactor is envisaged with optimal growth conditions to be coupled to the mainstream SCP reactor. Based on biomass yield and quality, the most prosperous configuration will be tested with real effluent. The advanced community engineering technology of SMArT aims a better SCP product that is attractive as a reliable and sustainable feed ingredient.

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  • Research Project

High-value products from FLAXseed through Innovative biocatalytic Technologies (FLAXIT). 01/01/2023 - 31/12/2024

Abstract

The aim of "FLAXIT" is to develop highly selective biocatalytic reactions for creating completely renewable molecules using flaxseed as the resource. For each ton of long flax fiber, 0.7 ton of flaxseed is produced in Belgium, which is considered a side stream, out of which 30-40% is oil and utilized mainly for low end technical applications. The other 60-70% is used as feed. With the intention of doubling the flax production to meet the growing fiber demand, flax growers in Belgium will produce higher volumes of flaxseed as by-product. In this project we will utilize the diverse biomolecules namely oil (consisting of polyunsaturated fatty acids), carbohydrates and proteins present in flaxseed to their best potential. With the help of extraction and biocatalytic transformations, we will create new value chains which open novel opportunities for farmers, industry, and society in Belgium. This project brings together a multidisciplinary team to use enzymatic- and microbial transformations to produce (i) methyl-, ethyl- and polyglycerol esters from flaxseed oil for personal care and cosmetic applications, (ii) long chain dicarboxylic acids from the flaxseed oil and carbohydrates for e.g. new polymers and cosmetic applications, and (iii) protein/peptides & water soluble dietary fibers from the defatted flaxseed cake for techno-functional applications in foods. In this way, we aim to obtain a zero-waste biorefinery for the valorization of flaxseed.

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  • Research Project

Waste oil to long-chain dicarboxylic acids (WODCA). 01/04/2022 - 31/03/2026

Abstract

The overall scientific goal of WODCA is to create new, sustainable, affordable long-chain dicarboxylic acids (LCDA) from waste oil that are relevant for industrial applications such as high-performance polymers, lubricants, coatings, corrosion inhibitors, etc. For this purpose, new non-pathogenic micro-organisms are developed as biocatalysts in an optimised fermentation process based on used frying oil, followed by an innovative membrane-based purification to obtain high purity LCDAs suitable for various Flemish chemical companies.

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  • Research Project

Technological innovation in the production of advanced biofuels applicable to the Belgian territory for road and air transport and technical, economic and environmental analyses (ADV_BIO) 01/10/2020 - 30/09/2025

Abstract

This project aims to develop innovative ways of producing advanced (bio)fuels from microalgae and lignocellulosic matrices for road or air transport and applicable on national territory. It focuses on the development of innovative and competitive technological production schemes in order to position Belgium as a differentiated strategic partner and player for the eco-efficient production of advanced alternative (bio)fuels of second and third generation. The project is a cooperation between ULiège, UGent, UCLouvain and UAntwerpen. Within this project, BioWAVE, UAntwerpen coordinates research on the biochemical conversion and fermentation of optimized and modified lignocellulosic matrices with the innovative goal to combine a unique pre-treatment approach with a unique detoxification process for the one-step production of second-generation bioethanol. Bioethanol will be produced from lignocellulose, such as poplar wood and maize straw, wild type and genetically modified with a lower lignin content as provided by UGent. This process is a multi-step approach involving unitary operations of pretreatment, hydrolysis (often enzymatic), fermentation and rectification/distillation to produce bioethanol that would be suitable for integration into transportation fuels. An option favoured in this ADV_BIO project is steam explosion. Although attractive at first glance because it uses only water and no chemical agents, steam explosion generates "toxic" compounds that inhibit the subsequent saccharification process and may also inhibit bioethanol fermentation, thus reducing production yields. The main inhibitors are furan compounds (2-furfural or 5-hydroxymethylfurfural), weak organic acids, but also phenolic compounds that come from the degradation of lignin. The latter are considered to be the most problematic and must be eliminated from the reaction media. A research action is aiming at preventing lignin from hindering the conversion of lignocellulosic biomass by, first of all, the application of plants, with a lower lignin content. In the steam explosion, the lignin bonds are broken and phenolic degradation products are released into the liquid. It has been proven that repolymerisation into lignin can occur after a very severe pre-treatment, with newly formed bonds that are more difficult to break down. The addition of renewable additives during the steam explosion process will be investigated to prevent this unwanted repolymerisation. Removal of the remaining phenolic compounds, and possibly other inhibiting compounds, can be achieved by using biological detoxification as an integrated or additional step. Laccase detoxification of lignocellulosic matrices treated by steam explosion has been shown to increase the sugar yield during enzymatic hydrolysis. During this detoxification process, furan compounds and organic acids are also eliminated. In this research part improved lignocellulose biomass (UGent) will be applied in a relevant industrial process for bioethanol production, using steam explosion and simultaneous saccharification and fermentation. In addition, innovative technologies, i.e. supplementation during steam explosion to improve depolymerisation, and laccase as well as microbial detoxification, are applied to increase overall conversion.

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  • Research Project

Valorisation of LIPid waste by Thermophilic Yeasts for the production of long chain Dicarboxylic Acids (LIPTYDA). 01/01/2022 - 31/12/2023

Abstract

In LIPTYDA we will create sustainable long-chain dicarboxylic acids (LCDAs) that are of great interest to several Flemish companies as they target different applications like high-grade polymers, plasticizers and lubricants. Current dicarboxylic acid production largely relies on fossil-based inputs and chemical processes, and is moreover limited to medium-chain products. In LIPTYDA we will focus on the novel long-chain dicarboxylic acids starting from grease trap waste (GTW); abundantly available in the food processing industry where it is collected during water treatment. GTW re-use is marginal as it is contaminated with food solids, and it is consequently mainly incinerated or deposited at landfills. Nevertheless, we see huge potential for GTW in biological fermentation processes: various LCDA producing yeast species thrive on lipids. First, we will thoroughly characterize the GTW and based on the outcome develop a suitable pretreatment. Next, we will apply advanced screening and synthetic biology approaches to obtain a yeast strain able to grow at high temperatures. Indeed, this is required to have GTW in the liquid state and guaranty good conversion to LCDAs. Finally, as we work with unusual temperatures and novel strains and feedstock, we will develop a new fermentation process using advanced reactor and cultivation technology.

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  • Research Project

Development of a reversible immobilised cell reactor for the valorisation of dilute phenol waste streams to microbial oil. 01/11/2019 - 31/10/2023

Abstract

Diluted phenol-rich streams occur regularly in lignocellulose-based biorefineries. Today, phenols are often regarded as waste. Some microorganisms can convert phenols into valuable intracellular components by fermentation. This makes the troublesome waste stream a raw material and an economic opportunity. To efficiently concentrate these dilute phenolic streams by conversion to intracellular components, it is necessary to speed up the process. In practice this often happens by increasing the amount of microorganisms, the biocatalyst, and consequently creating high cell concentrations. There is no efficient economic process for integrated fermentation and recovery of intracellular products. Our hypothesis is that the design of a new reactor type, namely a reversible immobilized cell reactor (RIR), offers a possible solution. In this reactor successively adhesion of the cells on a suitable support, fermentation, and finally desorption, to recover the intracellular components occurs. As a case study, the production of microbial oil is investigated starting from the phenolic hydrolysate obtained during the thermochemical treatment of lignocellulose. The aim of this project is to design an economically feasible process for valorising this phenolic flow. The new process will contribute to obtaining a biomass based circular economy.

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  • Research Project

A structured methodology for NADES selection and formulation for enzymatic reactions. 01/10/2019 - 30/09/2022

Abstract

Natural deep eutectic solvents (NADES) show great promise as media for enzymatic reactions in sectors where (bio)compatibility with natural or medical products is a must. Whereas in theory they can be tailored to the envisioned reaction, ensuring optimized yields, to date the knowledge is predominantly empirical, with some mechanistic reports giving a fragmented view at best. Therefore, even merely explaining experimental observations is not straightforward, let alone making predictions. This doctoral study aims at building a structured, holistic understanding of the effect of NADES media on enzymatic reactions, whereby effects on solubility, solvation, viscosity, inhibition and denaturation will be distinguished. The solubility, solvation energy and viscosity will be predicted by first principles and molecular dynamics calculations, serving as input for a group contribution model using machine learning. Experiments will train and validate the model, and learnings from observed reaction kinetics will be further benchmarked against molecular dynamics calculations of enzyme structures and interactions in NADES. Structural changes of the enzyme will be demonstrated using Raman optical activity spectroscopy. The combination of these methods ensures fundamental knowledge acquisition, while the group contribution model is part of a structured methodology. The findings of this project are transferable to other uses of NADES.

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  • Intelligence in PRocesses, Advanced Catalysts and Solvents (iPRACS)

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  • Research Project

Combined process of Steam Explosion and Microbial detoxification for improved PREtreatment of lignocellulose biomass (SEMPRE). 01/07/2019 - 31/12/2020

Abstract

During the thermochemical pretreatment biotechnological production of chemicals from the polysaccharides in lignocellulose, a solid fraction is obtained, consisting mainly of cellulose, and a lignin waste stream, the so-called, xylose rich fraction (XRF). XRF contains some residual sugar, toxic lignin-derived phenolic and sugar-derived furans. The goal of the research project is to investigate a technique to obtain almost complete removal of the lignin waste stream by using lipid producing bacteria, i.e., Rhodococcus sp. Rhodococcus is known to be able to metabolise phenol compounds. However to succeed, some hurdles have to be taken. (i) The furans and some phenolics can be toxic to the microorganism, (ii) repolymerisation of the lignin can occur (iii) the lignin is probably not completely converted, (iv) oligomers of lignin and lignin cellulose complexes can still be present, (v) it is not known if the Rhodococcus can degrade these oligomers. By analysis of the sugars, furans, phenolics, and the nature of the oligomers or particles, insight can be gained. Based on this knowledge, a toolbox of techniques to solve this will be applied, i.e. adaptation of the microorganism, commercial cellulases and laccases, alfa-naphtol to prevent repolymerisation of the lignin, using other bacteria, ….

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  • Research Project

Detoxification ability of Rhodococcus sp. on the lignin-rich waste stream after steam-explosion (DARLignin). 01/04/2019 - 30/03/2020

Abstract

During the thermochemical pretreatment biotechnological production of chemicals from the polysaccharides in lignocellulose, a solid fraction is obtained, consisting mainly of cellulose, and a lignin waste stream, the so-called, xylose rich fraction (XRF). XRF contains some residual sugar, toxic lignin-derived phenolic and sugar-derived furans. The goal of the research project is to investigate a technique to obtain almost complete removal of the lignin waste stream by using lipid producing bacteria, i.e., Rhodococcus sp. Rhodococcus is known to be able to metabolise phenol compounds. However to succeed, some hurdles have to be taken. (i) The furans and some phenolics can be toxic to the microorganism, (ii) repolymerisation of the lignin can occur (iii) the lignin is probably not completely converted, (iv) oligomers of lignin and lignin cellulose complexes can still be present, (v) it is not known if the Rhodococcus can degrade these oligomers. By analysis of the sugars, furans, phenolics, and the nature of the oligomers or particles, insight can be gained. Based on this knowledge, a toolbox of techniques to solve this will be applied, i.e. adaptation of the microorganism, commercial cellulases and laccases, alpha-naphtol to prevent repolymerisation of the lignin, using other bacteria, …. The present project focuses on the first part of this research, namely characterizing the xylose-containing waste stream and investigating the toxicity of the individual components for Rhodococcus.

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  • Research Project

Investigation of the effect of metal ions and mediators on the delignification selectivity during pretreatment of poplar wood by Phanerochaete chrysosporium. 01/10/2018 - 30/09/2022

Abstract

Microbial pretreatment of lignocellulosic biomass is performed to delignify the substrate for further use of the carbohydrates present. Typical applications of the pretreated substrate include its conversion to chemicals by subsequent hydrolysis and fermentation, or biopulping for use in the paper industry. In contrast to the traditional technologies at high temperature and high usage of solvents, microbial pretreatment is an environmentally friendly technology. The mold Phanerochaete chrysosporium is a good candidate for lignin degradation because of its fast growth and high optimal growth temperature. For delignification purposes, the mold excretes extracellular peroxidases, i.e. manganese peroxidase and lignin peroxidase, that catalyse the oxidation and depolymerisation of lignin. However, the major disadvantage is the non-selective degradation of the lignin over the present carbohydrates. Supplements, such as metal ions and aromatic compounds, can have an activating or inhibiting action on the delignification or hydrolysis process. Moreover, recent research showed that some metal ions and aromatic compounds can act as intermediates in the oxidation of non-phenolic compounds, such as carbohydrates. Delignification of lignocellulose and hydrolysis as well as oxidation of carbohydrates will determine the efficiency of the pretreatment, dependent on the desired application. Therefore, in this research, the influence of supplements on the different possible actors in the process, i.e. substrate, microorganism and enzymes, will be investigated. Better insights in the pretreatment will help to determine which combination and concentration of supplements will improve the application potential of the pretreated wood. Additionally, a improved method for easy determination of the growth rate and delignification rate based on FTIR will be developed. Finally, a mathematical model to describe the evolution of delignification process will be proposed.

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  • Research Project

Enzymatic reactions in NADES as new green media: activity and substrate/product solvation effects. 01/07/2018 - 31/12/2019

Abstract

This proposal aims at demonstrating the suitability and elucidating the effect of new green solvent media, natural deep eutectic solvents (NADES), on enzymatic reactions. NADES are eutectic mixtures of two or more biological primary metabolites (saccharides, amino and other organic acids, polyols, urea, choline) that are liquid at or slightly above room temperature, due to networking hydrogen bond interactions. Although they have been investigated earlier as green extraction media, reports on their use for enzymatic reactions are limited. For the first time, we will investigate their influence on enzymatic reactions by disaggregating the following effects: solvation energy, mass transfer in bulk and enzyme-substrate-intermediates stability. A well-known enzymatic conversion, i.e. deacetylation of a crude mannosylerythritol lipid (MEL) mixture aided by Novozym 435 (a commercial lipase), will be performed in selected NADES as a case example. Although no multi-parametric regression modeling will be done, qualitative (and semi-quantitative) insights will be gathered through coupling parametric solubility modeling (Hansen model, with experimental validation and input) with physicochemical characterization (viscosity, surface tension) of NADES systems, and concentration (substrate, enzyme) and temperature dependent kinetic experiments and modeling. The anticipated outcome of the project is a clear indication of enzymatic performance in fit for purpose NADES, and a breakdown of marginal efficiency change into solvation, activity and mass transfer differences with respect to traditional organic solvent systems.

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  • Research Project

Application of agro-industrial side-streams for the investigation of triggering effects on very-long-chain fatty acid production by Rhodococcus strains and process optimization. 01/01/2018 - 31/12/2018

Abstract

Very-long-chain fatty acids (VLCFAs) are fatty acids with a chain length of more than 20 carbons. They represent a valuable class of chemicals which can be used in several industries. Nowadays, these are produced from vegetable oils and petrochemical feedstock. In order to make the VLCFA production more sustainable, microbial VLCFA synthesis by Rhodococcus species seems to be a perfect tool. Unfortunately, current knowledge on VLCFA production with Rhodococcus is limited. Therefore, this project proposes to fill this gap. For investigation of the triggering effects to achieve high VLCFA production different agro-industrial substrates will be used as raw material. The triggering effect of the compounds on gene expression of the VLCFA pathway will be evaluated by RT-qPCR. The desired triggers should increase the VLCFA titer. Different Rhodococcus strains will be examined and evaluated for VLCFA synthesis. VLCFA production will be further optimized by screening of several medium compositions, optimization of environmental factors and, finally, the feeding pattern. Establishment of high VLCFA productivities can lead to a new production process of valuable building blocks for chemical industry.

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  • Research Project

Investigation of the mechanisms and optimal conditions during microbial pretreatment of lignocellulose biomass by using co-cultures. 01/04/2017 - 31/03/2018

Abstract

Pretreatment of lignocellulose biomass is necessary to degrade the lignin, decrease the cellulose crystallinity and increase the surface area for the subsequent required enzymatic hydrolysis. Fungal pretreatment is based on solid state cultivation where the fungal mycelia penetrate and attack the solid substrate through direct contact by releasing ligninolytic enzymes. In this project the mechanisms and optimal conditions of this complex process are investigated to enable a decrease in pretreatment time by using a stable consortium of collaborating microorganisms. Separate fungal strains are growing on polar wood chips in a computer controlled solid state fermenter. The process is followed up by measuring the deligninolytic enzyme activities, cellulase activities, carbohydrate concentrations in order to evaluate the capabilities of each strain. Also the growth rate will be determined by measuring the oxygen uptake rate of the solid state culture. All acquired information will be important to select the right strains that will enable a microbial consortium where a synergetic cooperation with high lignin removal will be obtained. This final pretreatment efficiency will be evaluated on ethanol productivity in a simultaneous saccharification and fermentation process of the pretreated poplar wood.

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  • Research Project

Modelling microbial growth during solid state fermentation 01/07/2014 - 31/12/2015

Abstract

Although good performance of solid state fermentation (SSF) on the lab scale, the industrial scale process has drawbacks, such as, poor heat transfer and difficult pH control. Bottleneck is the lack of information about the kinetics in SSF systems caused by the heterogeneous nature and complexity of the process. This project aims to model the kinetics of Monascus growth on rice based on experiments in a computer controlled solid state fermenter.

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  • Research Project