Hermosinda Varela

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Antarctic environments can sustain a great diversity of well-adapted microorganisms known as psychrophiles or psychrotrophs. The potential of these microorganisms as a resource of enzymes able to maintain their activity and stability at low temperature for technological applications has stimulated interest in exploration and isolation of microbes from this(More)
Proteases able to unhair sheep skins were produced from Bacillus subtilis. Protease activity was increased from 640 to 990 U/mL by using a fed-batch culture with glucose added sequentially up to 10 g/L. The crude enzyme prep-aration was mainly a mixture of metallo- and serine-proteases with optimal pH and temperature for protease activity at 7 and 50-55°C,(More)
Fed-batch fermentation of non-supplemented concentrated whey permeate resulted in high ethanol productivity for feeds of lactose for which batch fermentation had a poor performance. At an initial lactose concentration of 100 g/L and a constant lactose feeding rate of 18 g/h we have obtained: ethanol concentration 64 g/L, ethanol productivity 3.3 g/Lh,(More)
In a search for microorganisms producing extracellular protease with unhairing activity, Bacillus subtilis IIQDB32 was isolated. Protease formation was significantly stimulated by glucose, tryptone, yeast extract, Ca(2+) and Mn(2+), but was repressed by ammonia and Fe(2+).
The substitution of chemical depilatory agents in the leather industry by proteolytic enzymes produced by Bacillus species has an important economical and environmental impact. In previous assays, a Bacillus sp. showing a promising depilatory activity was isolated. In this paper, a culture medium that stimulated the synthesis and segregation of depilatory(More)
In this paper, the influence of aeration rate on the alcoholic batch fermentation of whey by Kluyveromyces fragilis NRRL Y-2415 was investigated. Assays in 1.5-L fermentor using concentrated whey permeate containing 100 g/L of lactose were carried out at different oxygen supply rate (KLaC*) from 0 to 82 mmol/Lh. Optimum response was obtained at 14 mmol/Lh:(More)
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