No abstract available

[en] Bacillus megaterium BM302 bred by ion-beam implantation produces L-sorbose dehydrogenase accelerative protein (SAP) to accelerate the activity of L-sorbose dehydrogenase (SDH) of Gluconobacter oxydans in the 2-keto-L-gulonic acid (2KLG) fermentation from L-sorbose by the mixed culture of B. megaterium BM302 and G. oxydans. The SAP purified by three chromatographic steps gave 35-fold purification with a yield of 13% and a specific activity of 5.21 units/mg protein. The molecular weight of the purified SAP was about 58 kDa. The SDH accelerative activity of SAP at pH 7 and 50 deg. C was the highest. Additionally, it retained 60% activity at a pH range of 6.5 ∼ 10 and was stable at 20 deg. C ∼ 60 deg. C. After 0.32-unit SAP was added to the single cultured G. oxydans strains, the SDH activity was apparently accelerated and the 2KLG yield of GO29, GO112, G0 and GI13 was enhanced 2.1, 3.3, 3.5 and 2.9 folds respectively over that of the strains without the addition of SAP.

[en] In the fulfillment of this study, pineapple of the spanish red variety, cut in 1.0 - 1.5 cm slices, were used. The product was sunken in a saccharose syrup with the addition of sodium methabisulphite and potassium sorbate and packed in polyethylene bags and latter irradiated with 0.2 and KGy doses. The behavior of potassium sorbate with two addition levels is similar during storage at room temperature for the studied irradiation doses. The degradation process of sodium methabisulphite takes place almost totally at one month storage. Unlike of potassium sorbate there exist no meaning differences between sulfur dioxide in irradiated and nonirradiated samples.It is concluded that the irradiation process cause an increasing in the degradation of potassium sorbate basically at the beginning of the storage, while seems no exert some effect on the sodium methabisulphite degradation. (Author)

[en] Graphical abstract: Catalytic conversion of carbohydrates into HMF and EMF in ethanol/DMSO with acid–base bifunctional hybrid nanospheres prepared from self-assembly of corresponding basic amino acids and HPA. - Highlights: • Acid–base bifunctional nanospheres were efficient for production of EMF from sugars. • Synthesis of EMF in a high yield of 76.6% was realized from fructose. • Fructose based biopolymers could also be converted into EMF with good yields. • Ethyl glucopyranoside was produced in good yields from glucose in ethanol. - Abstract: A series of acid–base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid–base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl glucopyranoside in good yields could be obtained from glucose in ethanol. Moreover, the nanocatalyst functionalized with acid and basic sites was able to be reused several times with no significant loss in catalytic activity

No abstract available

[en] D-[6-¹⁴C]Glucosone that had been prepared enzymically from D-[6-¹⁴C]glucose was used to compare relative efficiencies of these two sugars for L-ascorbic acid (AA) biosynthesis in detached bean (Phaseolus vulgaris L., cv California small white) apices and 4-week-old spinach (Spinacia oleracea L., cv Giant Noble) leaves. At tracer concentration, ¹⁴C from glucosone was utilized by spinach leaves for AA biosynthesis much more effectively than glucose. Carbon-14 from [6-¹⁴C]glucose underwent considerable redistribution during AA formation, whereas ¹⁴C from [6-¹⁴C]glucosone remained almost totally in carbon 6 of AA. In other experiments with spinach leaves, L-[U-¹⁴C]sorbosone was found to be equivalent to [6-¹⁴C]glucose as a source of ¹⁴C for AA. In the presence of 0.1% D-glucosone, conversion of [6-¹⁴C] glucose into labeled AA was greatly repressed. In a comparable experiment with L-sorbosone replacing D-glucosone, the effect was much less. The experiments described here give substance to the proposal that D-glucosone and L-sorbosone are putative intermediates in the conversion of D-glucose to AA in higher plants

No abstract available

[en] The uptake of [¹⁴C-UL] L-sorbose by yeast cells has been used as an energy-independent facilitated diffusion system to test near-UV inactivation of β-galactoside permease. The results showed that 365 nm light markedly diminished L-sorbose transport in Saccharomyce cerevisiae. It is concluded that the radiation directly modified the membrane carrier or some associated component in the membrane that is functionally linked to the carrier, since the transport of this sugar in yeast has been shown to be independent of metabolic energy. (U.K.)

[en] To obtain thermotolerant mutants of G. oxydans, which can enhance the transformation rate of L-sorbose to 2-Keto-L-gulonate (2-KLG) at 33 deg. C in a two-step process of vitamin C manufacture, ion beam was used as a mutation source. Gluconobacter oxydans G0 and Bacillus megaterium B0 were used in this study. The original strain Gluconobacter oxydans G0 was mutated by the heavy ion implantation facility at the Institute of Plasma Physics, Chinese Academy of Sciences. Several mutants including Gluconobacter oxydans GI13 were isolated and cocultured with Bacillus megaterium B0 at 33 deg. C in shaking flasks. The average transformation rate of the new mixed strain GI13-B0 in per gram-molecule reached 94.4% after seven passages in shaking flasks, which was increased by 7% when compared with the original mixed strain G0-B0 (Gluconobacter oxydans G0 and Bacillus megaterium B0). Moreover, the transformation rate of I13B0 was stable at 94% at temperatures ranging from 25 deg. C to 33 deg. C, which would be of much value in reducing energy consumption in the manufacture of L-ascorbic acid, especially in the season of summer. To clarify some mechanism of the mutation, the specific activities of L-sorbose dehydrogenase in both G0 and GI13 were estimated

No abstract available