d-Psicose production from d-fructose using an isolated strain, Sinorhizobium sp.

Abstract

Sinorhizobium sp., which can convert D-fructose into D-psicose, was isolated from soil. The optimal pH, temperature, and cell concentration for D-psicose production with the isolated strain were 8.5, 40°C, and 60 mg/ml, respectively. The toluene-treated cells showed 2.5-and 4.8-fold increases in the D-psicose concentration and productivity compared with untreated washed cells. Under the optimal conditions, the toluene-treated cells produced 37 g D-psicose/l from 70% (w/v) (3.9 M) D-fructose after 15 h.

Bioproduction of D-psicose using permeabilized cells of newly isolated Rhodobacter sphaeroides SK011

“…Only three bacteria, Pseudomonas cichorii [11], Agrobacterium tumefaciens [12], and Sinorhizobium sp. [13] had been used for D-psicose enzymatic production. The present study is the first report of the production of D-psicose using Rhodobacter sphaeroides cells.…”

“…The strains with D-psicose productivity were first selected by thin-layer chromatography (TLC) detection of D-psicose in the reaction mixture [13], and then, the mixture was assayed by HPLC to get the most promising strain. The 16S rDNA of the screened strain with the highest D-psicose productivity was amplified and sequenced by TaKaRa Biotechnology Co., Ltd (Dalian, China).…”

“…The retention time and concentrations of D-psicose was analyzed by a HPLC system (Waters 600, USA) equipped with a RID detector (Waters 2410, USA) and a Ca 2+ carbohydrate column (Waters Sugarpak-1, USA), which was eluted with water at 85°C and 0.4 mL/min. 13 C NMR spectra were measured with a Varian-Inova-400 NMR spectrometer at 400 MHz (in D 2 O, at 30°C; internal reference: 1,4-dioxane), respectively.…”

“…However, up to 30 g dry cell wt/L, productivity increased with increasing cell mass due to the increased amount of enzyme present. In Dpsicose production by resting cells of Sinorhizobium sp., the optimal cell mass was determined to be 60 mg/mL (dry or wet cell not shown in article) [13].…”

“…Only three bacteria, Pseudomonas cichorii [11], Agrobacterium tumefaciens [12], and Sinorhizobium sp. [13] have been used in its bioproduction from Dfructose, which as a biocatalyst could be used within a whole cell [13] or as isolated enzymes [10,12].…”