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Gamage, Shiromini
Publications (3 of 3) Show all publications
Gamage, S., Norström, S., Olofsson, M., Bylund, D., Asadollahi, M. & Hedenström, E. (2025). Pulp and paper industry side-stream materials as feed for the oleaginous yeast species Lipomyces starkeyi and Rhodotorula toruloides. Nordic Pulp & Paper Research Journal
Open this publication in new window or tab >>Pulp and paper industry side-stream materials as feed for the oleaginous yeast species Lipomyces starkeyi and Rhodotorula toruloides
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2025 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669Article in journal (Refereed) Epub ahead of print
Abstract [en]

The pulp and paper industry in Sweden annually produce millions of tons of side-stream materials as black liquor, pulp and paper mill sludge, sulfite liquor and lignosulfonate. These lignocellulosic based materials can be more utilized today in biorefinery processes with microorganisms to produce high-value products as lipids, proteins and biofuels. In this work, we used five side-stream materials as carbon source in fermentation with two oleaginous yeasts, Lipomyces starkeyi and Rhodotorula toruloides. We analyzed lipid production, fatty acid profiles, inhibitors, phenolics, free sugars and metals before and after batch fermentation in 2 L bioreactors. Steam-exploded hardwood media was used as reference as it's known to be a good substrate for the oleaginous yeast species and after fermentation the lipid yield for R. toruloides was 17 % (w/w) and for L. starkeyi 13 % (w/w). The side-stream materials contained less than 30 % of free sugar compared to the reference media and the total lipid yield was thus less than 2.7 %, (w/w). R. toruloides utilized various sugars during fermentation and L. starkeyi mostly consumed glucose and xylose. Both yeast species also showed a possible ability to utilize various phenolics indicating their metabolic potential to convert depolymerized lignin along with wood-based sugars to lipids and proteins.

Place, publisher, year, edition, pages
Walter de Gruyter GmbH, 2025
Keywords
Fatty acid methyl esters (FAMEs) analysis, fermentation, industrial waste, lipid production, oleaginous yeast
National Category
Bioprocess Technology
Identifiers
urn:nbn:se:miun:diva-53611 (URN)10.1515/npprj-2024-0039 (DOI)001392576900001 ()2-s2.0-85215954607 (Scopus ID)
Available from: 2025-01-16 Created: 2025-01-16 Last updated: 2025-02-04Bibliographically approved
Jiang, B., Zhang, D., Hu, X., Söderlind, U., Paladino, G., Gamage, S., . . . Yu, C. (2023). Low-Grade Syngas Biomethanation in Continuous Reactors with Respect to Gas–Liquid Mass Transfer and Reactor Start-Up Strategy. Fermentation, 9(1), Article ID 38.
Open this publication in new window or tab >>Low-Grade Syngas Biomethanation in Continuous Reactors with Respect to Gas–Liquid Mass Transfer and Reactor Start-Up Strategy
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2023 (English)In: Fermentation, ISSN 2311-5637, Vol. 9, no 1, article id 38Article in journal (Refereed) Published
Abstract [en]

In order to utilize a wider range of low-grade syngas, the syngas biomethanation was studied in this work with respect to the gas–liquid mass transfer and the reactor start-up strategy. Two reactors, a continuous stirred tank (CSTR) and a bubble column with gas recirculation (BCR-C), were used in the experiment by feeding an artificial syngas of 20% H2, 50% CO, and 30% CO2 into the reactors at 55 °C. The results showed that the CH4 productivity was slightly increased by reducing the gas retention time (GRT), but was significantly improved by increasing the stirring speed in the CSTR and the gas circulation rate in the BCR-C. The best syngas biomethanation performance of the CSTR with a CH4 productivity of 22.20 mmol·Lr−1·day−1 and a yield of 49.01% was achieved at a GRT of 0.833 h and a stirring speed of 300 rpm, while for the BCR-C, the best performance with a CH4 productivity of 61.96 mmol·Lr−1·day−1 and a yield of 87.57% was achieved at a GRT of 0.625 h and a gas circulation rate of 40 L·Lr−1·h−1. The gas–liquid mass transfer capability provided by gas circulation is far superior to mechanical stirring, leading to a much better performance of low-grade syngas biomethanation in the BCR-C. Feeding H2/CO2 during the startup stage of the reactor can effectively stimulate the growth and metabolism of microorganisms, and create a better metabolic environment for subsequent low-grade syngas biomethanation. In addition, during the thermophilic biomethanation of syngas, Methanothermobacter is the dominant genus. 

Keywords
bubble column reactor, continuous stirred tank reactor, low-grade syngas, start-up strategy, syngas fermentation
National Category
Energy Engineering
Identifiers
urn:nbn:se:miun:diva-47520 (URN)10.3390/fermentation9010038 (DOI)000915136300001 ()2-s2.0-85146808770 (Scopus ID)
Available from: 2023-02-07 Created: 2023-02-07 Last updated: 2023-03-03Bibliographically approved
Haller, H., Paladino, G., Dupaul, G., Gamage, S., Hadzhaoglu, B., Norström, S., . . . Jonsson, A. (2023). Polluted lignocellulose-bearing sediments as a resource for marketable goods—a review of potential technologies for biochemical and thermochemical processing and remediation. Clean Technologies and Environmental Policy, 25, 409-425
Open this publication in new window or tab >>Polluted lignocellulose-bearing sediments as a resource for marketable goods—a review of potential technologies for biochemical and thermochemical processing and remediation
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2023 (English)In: Clean Technologies and Environmental Policy, ISSN 1618-954X, E-ISSN 1618-9558, Vol. 25, p. 409-425Article in journal (Refereed) Published
Abstract [en]

Lignocellulose-bearing sediments are legacies of the previously unregulated wastewater discharge from the pulp and paper industry, causing large quantities of toxic organic waste on the Baltic Sea floor and on the bottom of rivers and lakes. Several km2 are covered with deposits of lignocellulosic residues, typically heavily contaminated with complex mixtures of organic and inorganic pollutants, posing a serious threat to human and ecological health. The high toxicity and the large volume of the polluted material are challenges for remediation endeavours. The lignocellulosic material is also a considerable bioresource with a high energy density, and due to its quantity, it could appeal to commercialization as feedstock for various marketable goods. This study sets out to explore the potential of using this polluted material as a resource for industrial production at the same time as it is detoxified. Information about modern production methods for lignocellulosic material that can be adapted to a polluted feedstock is reviewed. Biochemical methods such as composting, anaerobic digestion, as well as, thermochemical methods, for instance, HTC, HTL, pyrolysis, gasification and torrefaction have been assessed. Potential products from lignocellulose-bearing sediment material include biochar, liquid and gaseous biofuels, growing substrate. The use of a contaminated feedstock may make the process more expensive, but the suggested methods should be seen as an alternative to remediation methods that only involve costs. Several experiments were highlighted that support the conception that combined remediation and generation of marketable goods may be an appropriate way to address polluted lignocellulose-bearing sediments. Graphic abstract: [Figure not available: see fulltext.] 

Keywords
Circular Economy, Cleaner Production, Ecotechnology, Lignocellulose-bearing sediments, Sediment Mining
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:miun:diva-42751 (URN)10.1007/s10098-021-02147-3 (DOI)000669151800001 ()2-s2.0-85109309486 (Scopus ID)
Available from: 2021-08-10 Created: 2021-08-10 Last updated: 2023-02-21
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