Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein
Thesis (MEng)--Stellenbosch University, 2023.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2023
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614118628818944 |
|---|---|
| access_status_str | Open Access |
| author | Kasperski, Sasha Dalena |
| author2 | Van Rensburg, Eugene |
| author_browse | Kasperski, Sasha Dalena Van Rensburg, Eugene |
| author_facet | Van Rensburg, Eugene Kasperski, Sasha Dalena |
| author_sort | Kasperski, Sasha Dalena |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127267 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:46:57.306Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127267 Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein Kasperski, Sasha Dalena Van Rensburg, Eugene Gorgens, Johann Ferdinand Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Single cell proteins Sugarcane products Biomass conversion Lignocellulose -- Biotechnology Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Identifying affordable, environmentally friendly and sustainably produced proteins with high nutritional value is crucial to meet the increasing strain placed on global food production, driven by rapid population growth. Consequently, there is much opportunity in the bioconversion of low-value plant materials, such as sugarcane bagasse, into single-cell proteins (SCPs). This project investigated the bioconversion of steam-exploded sugarcane bagasse to produce SCPs using generally regarded as safe (GRAS) microbial strains. The sugarcane bagasse was steam-exploded at 185 °C for 10 minutes to produce a highly digestible product with low concentrations of inhibitors, such as furfural (0.25 ± 0.01 g/L), 5-hydroxymethylfurfural (5-HMF; 0.004 ± 0.002 g/L) and acetic acid (3.79 ± 0.22 g/L). The resulting steam-exploded sugarcane bagasse underwent separate hydrolysis and fermentation (SHF) for SCP production. Enzymatic hydrolysis was performed at a solid loading of 15% (w/v) pressed steam-exploded sugarcane bagasse and a Cellic® CTec3 enzyme dosage of 7.5 FPU/g dry weight (DW) substrate for 72 h, which resulted in a final glucose concentration of 42.26 ± 0.80 g/L, representing a 77.6% ± 0.4% conversion of cellulose to glucose. The resulting enzymatic hydrolysis product contained negligible concentrations of furfural and 5-HMF, together with 4.44 ± 0.56 g/L of acetic acid. Six GRAS microbial strains, Bacillus subtilis CAB1111, Lactobacillus delbrueckii, Streptococcus thermophilus (bacterial strains), Fusarium venenatum, Pleaurotus ostreatus CAB13 and Saccharomyces cerevisiae CAB79 (fungal strains), were screened as SCP candidates in undiluted enzymatic hydrolysate to determine which microbes were able to tolerate the inhibitor concentrations, such as acetic acid. S. cerevisiae, used as a control, tolerated the inhibitors best as it consumed all of the glucose and achieved a final biomass concentration of 20.37 ± 11.81 g/L after 48 h. Of the five alternative strains, S. thermophilus tolerated the inhibitors present best, as it consumed 47.48% ± 3.75% of the glucose and achieved a final biomass concentration of 1.28 ± 0.17 g/L after 48 h. Therefore, S. thermophilus was selected for comparison to S. cerevisiae in pulse fed-batch fermentations to maximise biomass formation by exposing the strain at lower initial inhibitor concentrations. Pulse fed-batch fermentations, with an initial and final hydrolysate concentration of 20% (v/v) and 80% (v/v), respectively, substantially increased the final biomass concentrations of both S. cerevisiae and S. thermophilus, as compared to batch fermentation in undiluted hydrolysate. S. cerevisiae achieved a higher final biomass concentration (52.65 ± 0.80 g/L) than S. thermophilus (6.57 ± 0.09 g/L). The protein contents of S. cerevisiae and S. thermophilus were 46.9% ± 2.6% (DW) and 66.1% ± 1.3% (DW), respectively. S. cerevisiae produced 24.71 ± 1.44 g/L of protein, while S. thermophilus produced 4.34 ± 0.10 g/L of protein. Therefore, S. cerevisiae is a promising strain to convert steam-exploded sugarcane bagasse to SCPs as it resulted in higher protein and biomass concentrations than S. thermophilus. Additionally, the maximum ethanol concentration produced by S. cerevisiae during pulse fed-batch fermentation was 8.13 ± 0.27 g/L after 36 h; therefore, the coproduction thereof with SCP may further enhance the economic attractiveness of this process. Although, it is likely to be at the expense of the latter. The technical and economic feasibility of producing SCPs from steam-exploded sugarcane bagasse on an industrial scale using S. cerevisiae and S. thermophilus were determined and compared. The minimum selling price (MSP) was used as the determining factor as it takes into consideration the biomass yield, the total capital investment (CAPEX) and the operating costs (OPEX) and was used to obtain the prespecified internal rate of return (IRR) of 20%. S. cerevisiae achieved the lowest MSP of 2 319 US$/tonne biomass (ZAR 41/kg), which was about ten times less than the MSP achieved by the production of S. thermophilus (20 436 US$/tonne biomass; ZAR 353/kg). Therefore, on an industrial scale, S. cerevisiae is the most promising strain for the bioconversion of steam-exploded sugarcane bagasse to SCPs. AFRIKAANS OPSOMMING: Om bekostigbare, omgewingsvriendelike en volhoubaar geproduseerde proteïene met hoë voedingswaarde te identifiseer, is krities om aan die verhoogde druk wat op globale kosproduksie, gedryf deur vinnige populasiegroei, te voldoen. Vervolgens, is daar baie geleentheid in die bio-omsetting van lae-waarde plantmateriale, soos suikerrietbagasse, na enkelselproteïene (SCPs). Hierdie projek het die bio-omsetting van stoomontplofde suikerrietbagasse om SCPs te produseer ondersoek deur algemeen beskou as veilige (GRAS) mikrobiese lyne. Die suikerrietbagasse is gestoomontplof by 185 °C vir 10 minute om ’n hoogs verteerbare produk met lae konsentrasies van inhibeerders te produseer, soos furforaal (0.25 ± 0.01 g/L), 5-hidroksielmetielfurfuraal (5-HMF; 0.004 ± 0.002 g/L) en asynsuur (3.79 ± 0.22 g/L). Die resulterende stoomontplofde suikerrietbagasse het aparte hidrolise en fermentasie (SHF) vir SCP-produksie ondergaan. Ensimatiese hidrolise is uitgevoer by ’n soliede lading van 15% (w/v) gedrukte stoomontplofde suikerrietbagasse en ’n Cellic® CTec3-ensiemdosering van 7.5 FPU/g droë gewig (DW) substraat vir 72 h, wat ’n finale glukosekonsentrasie van 42.26 ± 0.80 g/L tot gevolg gehad het, wat ’n 77.6% ± 0.4% omsetting van sellulose na glukose verteenwoordig. Die resulterende ensimatiese hidrouliese produk het weglaatbare konsentrasie furfuraal en 5-HMF bevat, saam met 4.44 ± 0.56 g/L asynsuur. Ses GRAS-mikrobiese lyne, Bacillus subtilis CAB1111, Lactobacillus delbrueckii, Streptococcus thermophilus (bakteriese lyne), Fusarium venenatum, Pleaurotus ostreatus CAB13 en Saccharomyces cerevisiae CAB79 (funguslyne), is gekeur as SCP-kandidate in onverdunde ensimatiese hidrolisaat om te bepaal watter mikrobes die inhibeerderkonsentrasies soos asynsuur, kon verdra. S. cerevisiae, gebruik as kontrole, het die inhibeerders die beste verdra omdat dit al die glukose verbruik het en ’n finale biomassakonsentrasie van 20.37 ± 11.81 g/L na 48 h bereik het. Van die vyf alternatiewe lyne het S. thermophilus die teenwoordige inhibeerders die beste verdra, omdat dit 47.48% ± 3.75% van die glukose verbruik het en ’n finale biomassakonsentrasie van 1.28 ± 0.17 g/L na 48 h bereik het. Daarom is S. thermophilus gekies vir vergelyking met S. cerevisiae in pulsvoerlotfermentasies om biomassaformasie te maksimeer deur die lyn bloot te stel aan laer aanvanklike inhibeerderkonsentrasies. Pulsvoerlotfermentasies, met ’n aanvanklike en finale hidrolisaatkonsentrasie van 20% (v/v) en 80% (v/v), onderskeidelik, het die finale biomassakonsentrasie van beide S. cerevisiae en S. thermophilus beduidend verhoog, in vergelyking met lotfermentasie in onverdunde hidrolisaat. S. cerevisiae het ’n hoër finale biomassakonsentrasie (52.65 ± 0.80 g/L) as S. thermophilus (6.57 ± 0.09 g/L) bereik. Die proteïeninhoud van S. cerevisiae en S. thermophilus was 46.9% ± 2.6% (DW) en 66.1% ± 1.3% (DW), onderskeidelik. S. cerevisiae het 24.71 ± 1.44 g/L proteïene produseer, terwyl S. thermophilus 4.34 ± 0.10 g/L proteïene geproduseer het. Daarom is S. cerevisiae ’n belowende lyn om stoomontplofde suikerrietbagasse na SCPs om te sit omdat dit hoër proteïen- en biomassakonsentrasie tot gevolg het as S. thermophilus. Daarby, die maksimum etanolkonsentrasie deur S. cerevisiae geproduseer word gedurende pulsvoerlotfermentasie was 8.13 ± 0.27 g/L na 36 h; daarom, die ko-produksie daarvan met SCP kan die ekonomiese aanloklikheid van hierdie proses verder vergroot. Dit is egter moontlik dat dit ten koste van die laasgenoemde sal wees.Die tegniese en ekonomiese uitvoerbaarheid van produsering van SCPs uit stoomontplofde suikerrietbagasse op ’n industriële skaal deur S. cerevisiae en S. thermophilus is bepaal en vergelyk. Die minimum verkoopsprys (MSP) is gebruik as die bepalende faktor omdat dit die biomassa-opbrengs, die totale kapitale belegging (CAPEX) en die bedryfskostes (OPEX) in ag neem. S. cerevisiae het die laagste MSP van 2 319 US$/ton biomassa (ZAR 41/kg) bereik, wat omtrent tien keer minder was as die MSP bereik met die produksie van S. thermophilus(20 436 US$/ton biomassa; ZAR 353/kg). Daarom, op ’n industriële skaal is S. cerevisiae die mees belowende lyn vir die bio-omsetting van stoomontplofde suikerrietbagasse na SCPs. Masters 2023-03-03T12:03:59Z 2023-05-18T07:13:05Z 2023-03-03T12:03:59Z 2023-05-18T07:13:05Z 2023-03 Thesis http://hdl.handle.net/10019.1/127267 en_ZA en_ZA Stellenbosch University xvi, 122 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Single cell proteins Sugarcane products Biomass conversion Lignocellulose -- Biotechnology Kasperski, Sasha Dalena Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein |
| title | Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein |
| title_full | Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein |
| title_fullStr | Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein |
| title_full_unstemmed | Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein |
| title_short | Bioconversion of steam-pretreated sugarcane bagasse to single-cell protein |
| title_sort | bioconversion of steam pretreated sugarcane bagasse to single cell protein |
| topic | Single cell proteins Sugarcane products Biomass conversion Lignocellulose -- Biotechnology |
| url | http://hdl.handle.net/10019.1/127267 |
| work_keys_str_mv | AT kasperskisashadalena bioconversionofsteampretreatedsugarcanebagassetosinglecellprotein |