Utilization of a waste glycerol fraction using and reusing immobilized Gluconobacter oxydans ATCC 621 cell extract

Background: Depletion of petroleum resources has enforced the search for alternative sources of renewable energy. Introduction of biofuels into the market was expected to become a solution to this disadvantageous situation. Attempts to cover fuel demand have, however, caused another severe problem­the waste glycerol generated during biodiesel production at a concentration of approximately 10% w/w. This, in turn, prompted a global search for effective methods of valorization of the waste fraction of glycerol. Results: Utilization of the waste fraction at 48 h with an initial glycerol concentration of 30 g·L-1 and proceeding with 62% efficiency enabled the production of 9 g·L-1 dihydroxyacetone at 50% substrate consumption. The re-use of the immobilized biocatalyst resulted in a similar concentration of dihydroxyacetone (8.7 g·L-1) in two-fold shorter time, with an efficiency of 85% and lower substrate consumption (35%). Conclusions: The method proposed in this work is based on the conversion of waste glycerol to dihydroxyacetone in a reaction catalyzed by immobilized Gluconobacter oxydans cell extract with glycerol dehydrogenase activity, and it could be an effective way to convert waste glycerol into a valuable product.

Effects of oxygen transfer coefficient on dihydroxyacetone production from crude glycerol

Abstract The principal objective of this study was to evaluate the kinetics of dihydroxyacetone production by Gluconobacter frateurii CGMCC 5397 under different oxygen volumetric mass transfer coefficient (kLa) conditions in submerged bioreactors using biodiesel-derived crude glycerol as the carbon source. kLa is a key fermentation parameter for the production of dihydroxyacetone. Cultivations were conducted in baffled- and unbaffled-flask cultures (the kLa values were 24.32 h−1 and 52.05 h−1, respectively) and fed-batch cultures (the kLa values were held at 18.21 h−1, 46.03 h−1, and 82.14 h−1) to achieve high dihydroxyacetone concentration and productivity. The results showed that a high kLa could dramatically increase dihydroxyacetone concentrations and productivities. The baffled-flask culture (with a kLa of 52.05 h−1) favored glycerol utilization and dihydroxyacetone production, and a dihydroxyacetone concentration as high as 131.16 g/L was achieved. When the kLa was set to 82.14 h−1 in the fed-batch culture, the dihydroxyacetone concentration, productivity and yield were 175.44 g/L, 7.96 g/L/h and 0.89 g/g, respectively, all of which were significantly higher than those in previous studies and will benefit dihydroxyacetone industrial production.

Clinical Effects of Dihydroxyacetone Solution for Vitiligo Patients / 대한피부과학회지

BACKGROUND: Vitiligo is a common, acquired, progressive depigmenting disorder. It is not physically destructive, however often leaves patients visibly disfigured by uneven color of the exposed areas such as the face or hands, especially in colored races. Most treatment protocols for vitiligo usually require a long treatment duration and do not result in complete repigmentation. Therefore, cosmetically-acceptable and easily-usable alternatives are needed. OBJECTIVE: The purpose of this study was to evaluate the clinical effects of dihydroxyacetone (DHA) solution for Korean vitiligo patients. METHODS: Thirty eight patients were treated with DHA, who suffered from vitiligo affecting the face, hands, trunk and thighs. They were instructed to apply DHA once every other day. Thereafter, the number of applications and intervals were adjusted according to the status of coloring. We surveyed the grade of subjective satisfaction, and also measured the L*, a* and b* values of normal skin, vitiligo lesion, DHA-applied site (n=10) and autologous suction blister graft site (n=6) and compared color difference between those areas using the Minolta Chromoameter gap (Minolta, Ramsey, New Jersey, USA). RESULTS: The characteristic pigmentation showed an acceptable cosmetic improvement in 27 of the 38 patients after 4-6 weeks of treatment. L* value was improved after DHA application, while a* and b* values showed more discrepancy than normal skin color. As a whole, the color difference between normal skin and vitiligo lesion was decreased after DHA application. CONCLUSION: The results suggest that DHA could be used for Korean vitiligo patients as an additional option for cosmetic correction.

Determination of Dihydroxyacetone in Fermentation Broth by HPLC / 中国生物工程杂志

A method to determine dihydroxyacetone (DHA) in fermentation broth was developed by high performance liquid chromatography (HPLC). DHA was separated on a Alltima C18(5?m,250?4.6mm). The mobile phase was 0.5% methanol solution (pH adjusted to 3.0 with H3PO4), the flow-rate was 1.0 ml/min and the detective wavelength was 200 nm. The detection limits of DHA was 0.1 g/L～10.0 g/L. 6.2 g/L DHA in the fermentation broth was detected by HPLC, which was in agreement with the result by spectrophotometric method.The method was applicable for DHA determination in the fermentation process.

Screening and Identification of a Strain Producing Dihydroxyacetone During Oxidation of Glycerol / 微生物学通报

More than 20 strains capable of producing dihydroxyacetone from glycerol were isolated from 4 different natural environment samples by using two detection methods. The strain 6-8 which could grow on medium containing glycerol as sole carbon source had a higher converting capability. Under a better culture, the highest DHA production of the strain 6?8 reached 6.4 g/L. In addition to general morphological and bio-chemical characteristics, the strain 6?8 was identified by 16S rDNA sequence and systematic analysis. The results showed that 16S rDNA sequence of the strain 6-8 had similarity of 99.7% with Acinetobacter sp. suggesting that the strain 6-8 is one of subspecies of Acinetobacter sp.