RESUMO
A fused protein composed of a carbohydrate-binding module and green fluorescence protein (GFP) was developed to measure the exopolysaccharides (EPShs) present in Escherichia coli microcolonies. The cleavage of the GFP part of this protein using a site-specific protease allowed for the non-invasive and quantitative evaluation of the EPShs.
Assuntos
Escherichia coli/química , Escherichia coli/crescimento & desenvolvimento , Polissacarídeos Bacterianos/análise , Genes Reporter , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/genética , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
Improvements in pyruvate production process were examined using Escherichia coli BW25113Dpta/ pHfdh strain carrying the formate dehydrogenase gene of Mycobacterium vaccae to change the redox status of the cells. Glucose and formate concentrations, and oxygenation levels determined previously in a shake-flask culture were applied for pyruvate production in a 1 l fermenter. However, pyruvate was not produced under the examined conditions. Detailed pH measurements during the fermenter culture using CaCO3 revealed that maintaining the pH value around 6.0 plays an important role in stabilizing the pyruvate accumulation. In the pH-adjusting culture around 6.0 with NaOH solution, the concentration and yield of pyruvate were 8.96 g l-1 and 0.48 g pyruvate g glucose-1, respectively, which were significantly higher than the values reported in the shake-flask culture (6.79 g l-1 and 0.32 g pyruvate g glucose-1).
