Utilize este identificador para referenciar este registo: http://hdl.handle.net/10362/46807
Título: Process optimization of cell-wall polysaccharides production by Komagataella pastoris
Autor: Farinha, Inês da Silva
Orientador: Freitas, Maria Filomena
Vilarinho, Pedro
Palavras-chave: Chitin-glucan complex (CGC)
Mannans
Komagataella pastoris
high cell density cultivation
bioprocess optimization
polysaccharides characterization
Data de Defesa: Set-2018
Resumo: This PhD thesis had the objective of optimizing the process developed by Pharma73 S.A. for cultivation of the yeast Komagataella pastoris to produce the cell-wall polysaccharides, chitin-glucan complex (CGC) and mannans. A repeated fed-batch strategy was developed that resulted in the stable and reproducible production of biomass and CGC. Seven consecutive fed-batch cycles were maintained, with a daily biomass production of 119-124 g/L and a CGC volumetric productivity of 13-20 g/L.day. Reducing the dissolved oxygen (DO) level from 50 to 15% was demonstrated to result in an overall volumetric productivity of 8.67 and 10.69 g/L.day, for CGC and mannans, respectively. The CGC and mannans composition was not significantly affected by the reduction of the DO level. Medium K was developed to avoid the operational problems associated with the use of Basal Salts Medium (BSM). Medium K was successfully implemented in the repeated fed-batch process, where the CGC and mannans productivities were improved to 17.5-26 and 19.2-26.4 g/L.day, respectively, without compromising the composition of the two polysaccharides. The downstream was optimized to obtain both polysaccharides with high extraction efficiency and purity. The optimized extraction conditions included treating the biomass with NaOH 4 M, at 84 ºC, during 4 h. The structural analysis of the polysaccharides revealed the presence of -glucans and -chitin, in the CGC, and -mannans. Both polysaccharides degraded at high temperatures: above 300 ºC for CGC and between 233-253 ºC for mannans. The work performed in this thesis resulted in a 3.4-fold increase of the CGC productivity and the extraction of mannans from K. pastoris was demonstrated for the first time. The optimization of this production process made the process simpler and resulted in considerable savings in terms of overall production costs.
URI: http://hdl.handle.net/10362/46807
Designação: Doutor em Engenharia Química e Bioquímica, Especialidade Engenharia Bioquímica
Aparece nas colecções:FCT: DQ - Teses de Doutoramento

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