Production of 2-phenylacetic acid and phenylacetaldehyde by oxidation of 2-phenylethanol with free immobilized cells of Acetobacter aceti
ABSTRACT Acetobacter aceti MIM 2000/28 was employed for the oxidation of 2-phenyl-1-ethanol. Oxidation in aqueous systems gave phenylacetic acid with high yields, while the use of a two-liquid phase system (composed of water and isooctane) allowed for the production of the corresponding aldehyde. Free cells showed poor operational stability and were immobilized in calcium alginate; immobilized cells had specific activity, substrate tolerance and stability higher than that obtained with free cells. Simple fed-batch operation with immobilized cells in an air-lift reactor allowed for the production of 23 g l−1 phenylacetic acid in 9 days without foam formation.
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ABSTRACT: The genus Gluconobacter comprises some of the most frequently used microorganisms when it comes to biotechnological applications. Not only has it been involved in "historical" production processes, such as vinegar production, but in the last decades many bioconversion routes for special and rare sugars involving Gluconobacter have been developed. Among the most recent are the biotransformations involved in the production of L-ribose and miglitol, both very promising pharmaceutical lead molecules. Most of these processes make use of Gluconobacter's membrane-bound polyol dehydrogenases. However, recently other enzymes have also caught the eye of industrial biotechnology. Among them are dextran dextrinase, capable of transglucosylating substrate molecules, and intracellular NAD-dependent polyol dehydrogenases, of interest for co-enzyme regeneration. As such, Gluconobacter is an important industrial microbial strain, but it also finds use in other fields of biotechnology, such as biosensor-technology. This review aims to give an overview of the myriad of applications for Gluconobacter, with a special focus on some recent developments.Critical Reviews in Biotechnology 01/2007; 27(3):147-71. · 5.10 Impact Factor
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ABSTRACT: The Gluconobacter oxydans M5 with disruption of the pyrroloquinoline quinine-dependent membrane-bound aldehyde dehydrogenase (ALDH) was used for the oxidation of benzyl alcohol. The selectivity toward benzaldehyde showed an obvious increase for the engineered strain, which reached the 67.3%, while the wild strain had only 2.8%. Meantime, the aqueous/isooctane (1:1) biphasic system was used for the further improvement of selectivity. By these methods, nearly 100% selectivity and conversion rate could be obtained within 1 h at the optimum initial benzyl alcohol concentration of 5.0 g/l.Current Microbiology 12/2010; 62(4):1123-7. · 1.52 Impact Factor
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ABSTRACT: The hexanol oxidation catalyzed by alcohol dehydrogenase from baker's yeast (YADH) has been investigated with two different forms of the biocatalyst: the isolated YADH as well as the YADH in the permeabilized whole cells. It was found that in this reaction, equilibrium is shifted to the reduction side. Hence, to increase the conversion it was necessary to regenerate NAD+. For that purpose, enzyme NADH oxidase isolated from Lactobacillus brevis was used. All biocatalysts were kinetically characterized. The overall reaction rate was described by the mathematical model which consisted of kinetics and balance equations. Due to the deactivation of NADH oxidase, only 50–58% hexanol was converted to hexanal in the batch reactor where the hexanol oxidation was catalyzed by isolated YADH. In the case of permeabilized baker's yeast cells, no enzyme deactivation occurred and 100% hexanol conversion in the hexanoic acid was detected.Process Biochemistry. 01/2009;