Identification of NAD-Dependent Xylitol Dehydrogenase from Gluconobacter oxydans WSH-003

Abstract

Gluconobacter oxydans plays an important role in the conversion of d-sorbitol to l-sorbose, which is an essential intermediate for the industrial-scale production of vitamin C. In the fermentation process, some d-sorbitol could be converted to d-fructose and other byproducts by uncertain dehydrogenases. Genome sequencing has revealed the presence of diverse genes encoding dehydrogenases in G. oxydans. However, the characteristics of most of these dehydrogenases remain unclear. Therefore, the analyses of these unknown dehydrogenases could be useful for identifying those related to the production of d-fructose and other byproducts. Accordingly, dehydrogenases in G. oxydans WSH-003, an industrial strain used for vitamin C production, were examined. A nicotinamide adenine dinucleotide (NAD)-dependent dehydrogenase, which was annotated as xylitol dehydrogenase 2, was identified, codon-optimized, and expressed in Escherichia coli BL21 (DE3) cells. The enzyme exhibited a high preference for NAD+ as the cofactor, while no activity with nicotinamide adenine dinucleotide phosphate, flavin adenine dinucleotide, or pyrroloquinoline quinone was noted. Although this enzyme presented high similarity with NAD-dependent xylitol dehydrogenase, it showed high activity to catalyze d-sorbitol to d-fructose. Unlike the optimum temperature and pH for most of the known NAD-dependent xylitol dehydrogenases (30–40 °C and about 6–8, respectively), those for the identified enzyme were 57 °C and 12, respectively. The values of Km and Vmax of the identified dehydrogenase toward l-sorbitol were 4.92 μM and 196.08 μM/min, respectively. Thus, xylitol dehydrogenase 2 can be useful for the cofactor-reduced nicotinamide adenine dinucleotide regeneration under alkaline conditions, or its knockout can improve the conversion ratio of d-sorbitol to l-sorbose.

CRISPR interference-based gene repression in the plant growth promoter Paenibacillus sonchi genomovar Riograndensis SBR5

“…As an alternative explanation, it is possible that the genome of P. sonchi encodes other proteins with side activity as Dsorbitol dehydrogenase. For example, xylitol dehydrogenase from Gluconobacter oxydans (EC 1.1.1.-) catalyzes the conversion of D-sorbitol to D-fructose (Liu et al 2019). However, it remains to be studied if such enzymes exist in P. sonchi and/or whether ydjJ gene repression was incomplete.…”

Preparation of Hybrid Sol-Gel Materials Based on Living Cells of Microorganisms and Their Application in Nanotechnology

“…Timur et al developed a mediated whole-cell biosensor based on Gluconobacter oxydans cells [ 98 ]. G.oxydans are Gram-negative bacteria that are actively used in sensory systems to detect polyols, sugars, and alcohols [ 106 ]. Bacterial cells were immobilized on the surface of graphite electrodes via a sol-gel (tetraethyl orthosilicate)/chitosan hybrid composite modified with gold nanoparticles ( Figure 12 ).…”

Oxidative Fermentation of Acetic Acid Bacteria and Its Products

“…Meso-erythritol is changed to l -erythrulose [65] by AAB cells (Richtmyer et al, 1950 ). d -arabitol (the 2-epimer of eylitol) was firstly oxidized to d -xylulose [66] by d -arabitol dehydrogenase (AraDH), then reduced to xylitol [67] by NAD-dependent xylitol dehydrogenase (Suzuki et al, 2002 ; Liu et al, 2019 ). Xylitol, a natural pentahydroxy sugar alcohol, has a sweet compound similar to sucrose and serves as a substitute for natural sweeteners.…”