Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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Permeabilization of Kluyveromyces marxianus with Mild Detergent for Whey Lactose Hydrolysis and Augmentation of Mixed Culture

Cheese whey is a by-product of cheese-manufacturing industries, and the utilization of whey is a challenging problem either to use it or dispose it, because only few microorganisms can metabolize the whey lactose. Enzymatic hydrolysis of whey lactose to glucose and galactose by β-galactosidase is the approach for biotechnological application. Kluyveromyces marxianus cells were permeabilized with non-toxic, biodegradable, anionic detergent N-lauroyl sarcosine (N-LS) for the enzyme activity. The permeabilization process parameters (N-LS concentration, solvent volume, temperature and incubation time) were optimized. The maximum β-galactosidase activity of 1,220 IU/g dry weight was obtained using permeabilized cells under optimized conditions. Moreover, viability of the permeabilized cells was also evaluated, which showed that cells were alive; however, viability was reduced by two log cycles. The permeabilized cells were evaluated for whey lactose hydrolysis. The maximum lactose hydrolysis of 91 % was observed with 600 mg (dry cell weight/100 mL) in whey powder (5 % w/v) solution at 180-min incubation, pH 6.5 and 30°C. Further, the hydrolyzed whey was evaluated for amelioration of growth of non-lactose-consuming yeast Saccharomyces cerevisiae. S. cerevisiae was able to grow in hydrolyzed whey simultaneously with K. marxianus. The study confirmed that N-LS could be used to permeabilize K. marxianus cells to make available the enzyme activity

Production of galacto-oligosaccharides by the β-galactosidase from kluyveromyces lactis : comparative analysis of permeabilized cells versus soluble enzyme

8 páginas, 5 figuras, 3 tablas -- PAGS nros. 10477-10484The transgalactosylation activity of Kluyveromyces lactis cells was studied in detail. Cells were permeabilized with ethanol and further lyophilized to facilitate the transit of substrates and products. The resulting biocatalyst was assayed for the synthesis of galacto-oligosaccharides (GOS) and compared with two soluble β-galactosidases from K. lactis (Lactozym 3000 L HP G and Maxilact LGX 5000). Using 400 g/L lactose, the maximum GOS yield, measured by HPAEC-PAD analysis, was 177 g/L (44% w/w of total carbohydrates). The major products synthesized were the disaccharides 6-galactobiose [Gal-β(1→6)-Gal] and allolactose [Gal-β(1→6)-Glc], as well as the trisaccharide 6-galactosyl-lactose [Gal-β(1→6)-Gal-β(1→4)-Glc], which was characterized by MS and 2D NMR. Structural characterization of another synthesized disaccharide, Gal-β(1→3)-Glc, was carried out. GOS yield obtained with soluble β-galactosidases was slightly lower (160 g/L for Lactozym 3000 L HP G and 154 g/L for Maxilact LGX 5000); however, the typical profile with a maximum GOS concentration followed by partial hydrolysis of the newly formed oligosaccharides was not observed with the soluble enzymes. Results were correlated with the higher stability of β-galactosidase when permeabilized whole cells were usedProjects BIO2007-67708-C04-01, BIO2007-67708-C04-03, BIO2010-20508-C04-01, and BIO2010-20508-C04-04 from the Spanish Ministry of Science and Innovation supported this research. B.R.-C. and M.A.d.A. were supported by fellowships from the Spanish Ministries of Science and Innovation (FPI program) and Education and Culture (FPU program), respectivelyPeer reviewe