RESUMO
Improved biofuels production requires a better understanding of industrial microorganisms. Some wild Saccharomyces cerevisiae strains, isolated from the fuel ethanol industry in Brazil, present exceptional fermentation performance, persistence and prevalence in the harsh industrial environment. Nevertheless, their physiology has not yet been systematically investigated. Here we present a first systematic evaluation of the widely used industrial strains PE-2, CAT-1, BG-1 and JP1, in terms of their tolerance towards process-related stressors. We also analyzed their growth physiology under heat stress. These strains were evaluated in parallel to laboratory and baker's strains. Whereas the industrial strains performed in general better than the laboratory strains under ethanol or acetic acid stresses and on industrial media, high sugar stress was tolerated equally by all strains. Heat and low pH stresses clearly distinguished fuel ethanol strains from the others, indicating that these conditions might be the ones that mostly exert selective pressure on cells in the industrial environment. During shake-flask cultivations using a synthetic medium at 37 °C, industrial strains presented higher ethanol yields on glucose than the laboratory strains, indicating that they could have been selected for this trait-a response to energy-demanding fermentation conditions. These results might be useful to guide future improvements of large-scale fuel ethanol production via engineering of stress tolerance traits in other strains, and eventually also for promoting the use of these fuel ethanol strains in different industrial bioprocesses.
Assuntos
Etanol/metabolismo , Microbiologia Industrial , Saccharomyces cerevisiae/fisiologia , Estresse Fisiológico , Ácido Acético/toxicidade , Brasil , Meios de Cultura/química , Etanol/toxicidade , Glucose/metabolismo , Concentração de Íons de Hidrogênio , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/efeitos da radiação , TemperaturaRESUMO
Lipase, protease, and amylase production by Penicillium restrictum in solid-state fermentation was investigated. The basal medium was an industrial waste of babassu oil (Orbignya oleifera) production. It was enriched with peptone, olive oil, and Tween-80. The supplementation positively influenced both enzyme production and fungal growth. Media enriched with Tween-80 provided the highest protease activity (8.6 U/g), whereas those enriched with peptone and olive oil led to the highest lipase (27.8 U/g) and amylase (31.8 U/g) activities, respectively.
Assuntos
Resíduos Industriais , Lipase/biossíntese , Penicillium/crescimento & desenvolvimento , Óleos de Plantas , Gerenciamento de Resíduos/métodos , Amilases/biossíntese , Endopeptidases/biossíntese , Fermentação , Indústria Alimentícia , Azeite de Oliva , Penicillium/enzimologia , Peptonas , PolissorbatosRESUMO
Mathematical models of the cellular metabolism have a special interest within biotechnology. Many different kinds of commercially important products are derived from the cell factory, and metabolic engineering can be applied to improve existing production processes, as well as to make new processes available. Both stoichiometric and kinetic models have been used to investigate the metabolism, which has resulted in defining the optimal fermentation conditions, as well as in directing the genetic changes to be introduced in order to obtain a good producer strain or cell line. With the increasing availability of genomic information and powerful analytical techniques, mathematical models also serve as a tool for understanding the cellular metabolism and physiology.
Assuntos
Células Eucarióticas/metabolismo , Modelos Biológicos , Células Procarióticas/metabolismo , Animais , Bactérias/citologia , Bactérias/enzimologia , Bactérias/metabolismo , Células Eucarióticas/enzimologia , Fermentação , Fungos/citologia , Fungos/enzimologia , Fungos/metabolismo , Cinética , Modelos Químicos , Células Procarióticas/enzimologiaRESUMO
The use of lactose as inducer of foreign gene expression under control of the lac UV5 promoter was investigated in recombinant Escherichia coli. Chicken muscle troponin C (TnC) gene was transcripted by T7 RNA polymerase and expressed in bioreactor cultivations after a feed-forward controlled fed-batch growth phase. Cell concentrations of 22 g l-1 dry cell weight (DCW)--before induction started--were used to achieve a TnC content of 19.5% of total cell protein through an induction strategy that combined the addition of a specific lactose amount of 4.7 g g-1 DCW divided into three pulses and the addition of yeast extract (1 g l-1) together with the second and the third lactose pulses. The results presented suggest that the residual lactose concentration plays an important role on the production of the heterologous protein.