Conditions promoting effective very high gravity sugarcane juice fermentation

Autor(es)

Monteiro, Bruno ^{[1, 2]} ; Ferraz, Pedro ^{[1, 3]} ; Barroca, Mario ^{[1, 3]} ; da Cruz, Sandra H. ^[2] ; Collins, Tony ^{[1, 3]} ; Lucas, Candida ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] Univ Minho, Ctr Mol & Environm Biol CBMA, P-4710057 Braga - Portugal

^[2] Univ Sao Paulo, ESALQ, Lab Food & Beverage Biotechnol, BR-13418900 Piracicaba, SP - Brazil

^[3] Univ Minho, Inst Sci & Innovat Biosustainabil IBS, CBMA, Campus Gualtar, P-4710057 Braga - Portugal

• Tipo de documento: Artigo Científico
• Fonte: BIOTECHNOLOGY FOR BIOFUELS; v. 11, SEP 18 2018.
• Citações Web of Science: 2

Resumo

Background: Applying very high gravity (VHG) fermentation conditions to the sugarcane juice (SCJ) bioethanol industry would improve its environmental and economic sustainability without the need for major infrastructure changes or investments. It could enable a decrease in the consumption of biological and natural resources (cane/land, water and energy) while maintaining acceptable production parameters. The present study attempts to demonstrate and characterise an effective industrially relevant SCJ-VHG fermentation process. Results: An industry-like SCJ-VHG bioethanol production process with 30 and 35 degrees Bx broth was employed to investigate the effects of both the yeast strain used and nitrogen source supplementation on process yield, process productivity, biomass viability, glycerol concentration and retention-associated gene expression. Process performance was shown to be variably affected by the different process conditions investigated. Highest process efficiency, with a 17% (w/v) ethanol yield and only 0.2% (w/v) sugar remaining unfermented, was observed with the Saccharomyces cerevisiae industrial strain CAT-1 in 30 degrees Bx broth with urea supplementation. In addition, efficient retention of glycerol by the yeast strain was identified as a requisite for better fermentation and was consistent with a higher expression of glycerol permease STL1 and channel FPS1. Urea was shown to promote the deregulation of STL1 expression, overcoming glucose repression. The consistency between Fps1-mediated ethanol secretion and ethanol in the extracellular media reinforces previous suggestions that ethanol might exit the cell through the Fps1 channel. Conclusions: This work brings solid evidence in favour of the utilisation of VHG conditions in SCJ fermentations, bringing it a step closer to industrial application. SCJ concentrated up to 30 degrees Bx maintains industrially relevant ethanol production yield and productivity, provided the broth is supplemented with a suitable nitrogen source and an appropriate industrial bioethanol-producing yeast strain is used. In addition, the work contributes to a better understanding of the VHG-SCJ process and the variable effects of process parameters on process efficiency and yeast strain response. (AU)

• Processo FAPESP: 11/12185-0 - Produção de etanol combustível: efeitos do nitrogênio livre na fermentação de mosto de caldo de cana com alta concentração de açúcares
• Beneficiário: Bruno Miguel dos Santos Monteiro
• Modalidade de apoio: Bolsas no Brasil - Doutorado