• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.696-699
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• 1998

Biological oxidation of D-sorbitol to L-sorbose using permeated and immobilized cells of Gluconobacter suboxydans was carried out to investigate the optimum reaction condition. The stabilization effect of cross-linking agents such as glutaraldehyde, tannic acid, and polyethylene imine to prevent the leakage of enzymes from beads containing permeated and immobilized cells of G. suboxydans was examined by the production of L-sorbose from the mixture of D-sorbitol and gluconic acid. The protein concentration effused from immobilized beads treated with only glutaraldehyde was $5.2\mug/m\ell$ after 20 h. The beads of G. suboxydans immobilized with alginate and cross-linked with 0.3% glutaraldehyde was the most useful for the oxidation of D-sorbitol to L-sorbose.

• Microbiology and Biotechnology Letters
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• v.8 no.2
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• pp.103-111
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• 1980

This studies were conducted to make vinegar from the physiologcical fallen persinmon during the ripening fruit. The main components of the persimmon mere investigated for the several focal valieties, Some microke acted on the fermentation of persimmon was isolated. The obtained results were as follows : 1) The hardness of fruit was the hithest for Jangjunsi (long persimmon) The hardness of Bansi and Soosi valieties was decreased vary fast after five or six weeks. 2) The total amount of pectin was increased a little in order of Jangjunsi, Bansi and Soosi. The amount of soluble pectin was increased considerably in order of Soosi, Bansi and Jangjunsi. 3) The amount of total sugar and reducing sugar were increased in order of Bansi, Jangjunsi and Soosi. After five or six weeks the amount of reducing sugar of Soosi and Bansi was increased much. The amount of starch was decreased in order of Bansi, Jangjunsi and Soosi, to trace amounts without significent differences. 4) The amount of Soluble tannin was decreased in order of Bansi, Jangjunsi and Soosi. 5) Main microbes on the fermentation of persimmon vinegar were identified as follows: yeast was proved to be Saccharomyces rouxii, CBS 726, and Acetobacters were Gluconobacter oxydans subsp. suboxydans, Gluconobacter oxyaans subsp, osydans, Acetobaeter pasteurians subsp. xylinum 6) During the fermentation, process of persimmon vinegar the amount of reducing sugar and alcohol were decresed, but that of acidity was increased.

• KSBB Journal
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• v.8 no.1
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• pp.10-16
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• 1993

The use of Jerusalem artichoke containing $\beta$-1, 2-fructose oligomer for the production of D-sorbitol and L-sorbose has been studied. The employment of inulinase(0.398%, v/v) for the hydrolysis of 40% (v/w) Jerusalem artichoke juice resulted in 36.7g/1 of glucose and 85.3g/1 of fructose at $50^{\circ}C$. These sugars were utilized as substrates for D-sorbitol and L-sorbose production. Coimmobilization of inulinase and permeabilized cells of Zymomonas mobilis in the mixture of chitin (5%, w/e) and x-carrageenan(4%, w/v) resulted in the production of 30.2g/1 of D-sorbitol by using inulin as a substrate. The process of L-sorbose production from D-sorbitol by Gluconobacter suboxydans was optimized with respect to the substrate concentration, level of dissolved oxygen and glucosic and concentration. Gluconlc acid produced by Zymomonas mobilis from glucose was found to inhibit Gluconobacter suboxtans in conversion of D-sorbitol to L-sorbose. In view of removing such inhibitory effect by gluconic acid, mutants were selected by the NTG (N-methyl-N'-N'-nitro-N-nitrosoguanidlne) treated method. Mutants selected by NTG mutagenesis showed no inhibitory effects of gluconic acrid against L-sorbone production when its concentration increased up to 100g/1. A mutant produced 40.1g/l of L-sorbose in the medium containing 100g/l D-sorbitol and 100g/l-gluconic acid. This result is consider able when compared with L-sorbose concentration (21.7g/1) obtained from the fermentation with wild type strain of Gluconobacter suboxnians.

• Preventive Nutrition and Food Science
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• v.2 no.1
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• pp.66-70
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• 1997

A mixed-culture of Gluconobacter suboxydans IFO 3172 and Saccharomyces uvarum IFO 0751 was per-formed in a synthetic medium. the optimal inculum ratio of G. suboydans and S. uvarum for mixed-culture fermentation was 150:1. The optimum pH, incubation temperature and aeration rate for mixed-culture fer- mentation were 5.0, 3$0^{\circ}C$ and 2.25vvm, reapectively. As a result of batch pure-and mixed-culture fer-mentation, specific growth rate in pure-culture of both strain was lower than that in mixed-culture. The yield of cell mass from S. uvarum exclusively decreased. The growth rate of the mixed-culture was very similar to the pure-culture in the begining of culture, but it has been decreased after 16hrs. In the mean time, S. uvarum in mixed-culture fermentation could grow due to fructose converted, but it could not row in pure-culture fermentation. Thus, the relationship was a sort of commensalism. The kinetic parameters cal-culated through steady-state results during continuous fermentations are as follows :{TEX}$$\mu$_{max1}${/TEX}=0.118({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{1}${/TEX}=0.330(g/L),:{TEX}$$\mu$_{max2}${/TEX}=0.162({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{2}${/TEX}=0.038(g/L). The yield of bacterial cell mass relatively constant, but yield of yest cell mass was gradually decreased.

• Microbiology and Biotechnology Letters
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• v.25 no.1
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• pp.68-74
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• 1997

The conversion of D-sorbitol to L-sorbose by Gluconobater suboxydans was analyzed, and continuous production of L-sorbose was carried out in immobilized cell reactors. L-Sorbose production by high densities of resting cells was more effective than by conventional batch fermentations. Sorbitol dehydrogenase, an enzyme converting D-sorbitol to L-sorbose, did not suffer from substrate inhibition, but from product inhibition. When L-sorbose production was carried out with Ca-alginate-immobilized cells, about 60 g/l of L-sorbose was obtained. On the other hand, when the corn steep liquor (CSL) concentration of medium was reduced to 0.08%, 80 g/l of L-sorbose was obtained. Outgrowth inside the immobilized carriers was thought to block the pores of the carriers so that substrate could not easily diffuse through the carriers. Continuous production of L-sorbose was well accomplished in a bubble column reactor, and 6. 5 g/l.h of productivity and 81.2% of yield were obtained at a substrate feeding rate of 0.08h$^{-1}$ under the optimum conditions with carrier volume of 55% and aeration rate of 3 vvm.