Ethanol production in Brazil: a bridge between science and industry

Abstract

In the last 40 years, several scientific and technological advances in microbiology of the fermentation have greatly contributed to evolution of the ethanol industry in Brazil. These contributions have increased our view and comprehension about fermentations in the first and, more recently, second-generation ethanol. Nowadays, new technologies are available to produce ethanol from sugarcane, corn and other feedstocks, reducing the off-season period. Better control of fermentation conditions can reduce the stress conditions for yeast cells and contamination by bacteria and wild yeasts. There are great research opportunities in production processes of the first-generation ethanol regarding high-value added products, cost reduction and selection of new industrial yeast strains that are more robust and customized for each distillery. New technologies have also focused on the reduction of vinasse volumes by increasing the ethanol concentrations in wine during fermentation. Moreover, conversion of sugarcane biomass into fermentable sugars for second-generation ethanol production is a promising alternative to meet future demands of biofuel production in the country. However, building a bridge between science and industry requires investments in research, development and transfer of new technologies to the industry as well as specialized personnel to deal with new technological challenges.

Nisin incorporation enhances the inactivation of lactic acid bacteria during the acid wash step of bioethanol production from sugarcane juice

“…However, acid treatments reduce yeast efficiency and selects for contaminant bacteria that are resistant to acid treatments (Lopes et al . ). Several antibiotics have been investigated for use in bioethanol fermentation including virginiamycin, penicillin, erythromycin, tylosin, monensin and tetracycline (Muthaiyan et al .…”

Model‐based evaluation of continuous bioethanol production plant

“…However, yeasts, and in particular strains of Saccharomyces cerevisiae , are the primary microorganisms for bioethanol production and are capable of fermenting the main sugar feedstock such as glucose, fructose, and sucrose under large‐scale industrial production conditions . Ethanol tolerance and high ethanol yield make S. cerevisiae a promising and economically feasible strain for large‐scale bioethanol production …”

“…In recent studies, continuous systems have gained attention, because of their steady‐state condition, simple process control, high productivity, and simple design with smaller fermenters, lower capital and operational costs, and higher output . However, bioethanol production in continuous mode can be optimized by better operational conditions to decrease stress conditions, sugar loss, and contamination with wild strains …”

Recuperação e tratamento de água proveniente de vinhaça biodigerida e sua utilização em processos de produção de bioenergia

“…No processo Melle-Boinot dado ao ambiente não estéril e o reciclo das leveduras, a contaminação em escala industrial é cerca de 2,0 a 3,9 10 7 UFC mL -1 (LOPES et al, 2016). As bactérias contaminantes competem com as leveduras pelo açúcar e outros nutrientes do mosto (CHIN; INGLEDEW, 1994) e produzem ácidos lático e acético que intoxicam as leveduras (CHERUBIN, 2003), afetando a produção de etanol.…”

“…Os teores de frutose no vinho do T1 ao decorrer dos ciclos, apesar não apresentarem diferença estatística, aumentou nos ciclos 3 e 4, e no T2 não se observa diferença significativa nos ciclos 1, 2 e 3, apenas o ciclo 4 difere dos demais, devido a maior concentração residual (1838,53 mg L -1 ). O aumento de açúcar residual observado no último ciclo de fermentação pode ser decorrente do estresse pelo qual a levedura sofre ao decorrer dos reciclos (LOPES et al, 2016) e no caso do T2 aos teores de sais superiores podem ter ocasionaram esse aumento na concentração de frutose. Comparando os vinhos dos dois tratamentos há diferença significativa entre eles em todos os ciclos, em que assim como no mosto do T1 os teores eram maiores, no vinho também se observa essa relação.…”