Molecular and physiological basis of Saccharomyces cerevisiae tolerance to adverse lignocellulose-based process conditions

Lignocellulose-based biorefineries have been gaining increasing attention to substitute current petroleum-based refineries. Biomass processing requires a pretreatment step to break lignocellulosic biomass recalcitrant structure, which results in the release of a broad range of microbial inhibitors, mainly weak acids, furans, and phenolic compounds. Saccharomyces cerevisiae is the most commonly used organism for ethanol production; however, it can be severely distressed by these lignocellulose-derived inhibitors, in addition to other challenging conditions, such as pentose sugar utilization and the high temperatures required for an efficient simultaneous saccharification and fermentation step. Therefore, a better understanding of the yeast response and adaptation towards the presence of these multiple stresses is of crucial importance to design strategies to improve yeast robustness and bioconversion capacity from lignocellulosic biomass. This review includes an overview of the main inhibitors derived from diverse raw material resultants from different biomass pretreatments, and describes the main mechanisms of yeast response to their presence, as well as to the presence of stresses imposed by xylose utilization and high-temperature conditions, with a special emphasis on the synergistic effect of multiple inhibitors/stressors. Furthermore, successful cases of tolerance improvement of S. cerevisiae are highlighted, in particular those associated with other process-related physiologically relevant conditions. Decoding the overall yeast response mechanisms will pave the way for the integrated development of sustainable yeast cell--based biorefineries.This study was supported by the Portuguese Foundation for Science and Technology (FCT) by the strategic funding of UID/BIO/04469/2013 unit, MIT Portugal Program (Ph.D. grant PD/BD/128247/ 2016 to Joana T. Cunha), Ph.D. grant SFRH/BD/130739/2017 to Carlos E. Costa, COMPETE 2020 (POCI-01-0145-FEDER-006684), BioTecNorte operation (NORTE-01-0145-FEDER-000004), YeasTempTation (ERA-IB-2-6/0001/2014), and MultiBiorefinery project (POCI-01-0145-FEDER-016403). Funding by the Institute for Bioengineering and Biosciences (IBB) from FCT (UID/BIO/04565/2013) and from Programa Operacional Regional de Lisboa 2020 (Project N. 007317) was also receiveinfo:eu-repo/semantics/publishedVersio

Estratégia profissional e mimetismo empresarial: os planos de saúde odontológicos no Brasil Professional strategy and institutional isomorphism: the dental health insurance industry in Brazil

O artigo analisa o modelo organizacional das empresas de planos de saúde odontológicos das modalidades de cooperativas de profissionais e a odontologia de grupo para compreender a dinâmica da oferta de serviços odontológicos no país. Adotou-se como referência a formulação institucionalista de Di Maggio e Powell. O mercado de planos de saúde odontológico é pulverizado, com o predomínio de empresas de pequeno porte, e apresenta um grande dinamismo, que favorece as empresas de pequeno, médio e alto porte. As modalidades analisadas concentram a maior proporção de beneficiários e receitas. A análise geral do desempenho do setor revela impressionante dinamismo na captação de clientes, mesmo após a criação da ANS. O regime de regulação tem imposto um novo padrão institucional à entrada, permanência e saída das empresas no mercado, que não afeta o desempenho setorial. Os dados analisados evidenciam que o setor de planos de saúde odontológicos é altamente rentável, apresentando uma grande capacidade na geração de receitas que explica o crescimento e a permanência destas modalidades no mercado. Os padrões de rentabilidade média, principalmente das empresas de odontologia de grupo, são extremamente elevados, ficando muito acima de qualquer atividade empresarial do Brasil.<br>This article analyzes the organizational model of the dental health industry. The main organizational leaders in this industry are the professional cooperatives and group dental insurance companies. The theoretical basis of the article is the organizational theory developed by Di Maggio and Powell. The dental health industry consists of a great number of small and very dynamic companies, however an expressive part of clients and profit are concentrated in a few large companies. The results show that the industry has expanded the number of clients after the creation of the National Health Insurance Agency. The regulation regime has forced institutional changes in the firms with regard to the market entry, permanence or exit patterns. There was no evidence that the regulatory rules have interfered with the development and financial conditions of the industry. The average profitability of the sector, especially among the group dental insurance companies, is extremely high