ABSTRACT
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.
Subject(s)
Cells, Immobilized/metabolism , Dihydroxyacetone/metabolism , Glycerol/metabolism , Waste Products , Cell Extracts , Cells, Immobilized/chemistry , Gluconobacter oxydans , Biofuels , Recycling , Renewable Energy , Glycerol/chemistryABSTRACT
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.
Subject(s)
Dihydroxyacetone/metabolism , Gluconobacter/metabolism , Glycerol/metabolism , Oxygen/metabolism , Biotransformation , Bioreactors/microbiology , Carbon/metabolismABSTRACT
1,3-Dihydroxyacetone is widely used in cosmetics, medicines and food products. We reviewed the recent progress in metabolic pathways, key enzymes, as well as metabolic engineering for microbial production of 1,3-dihydroxyacetone. We addressed the research trend to increase yield of 1,3-dihydroxyacetone by improving the activity of glycerol dehydrogenase with genetic engineering, and regulating of fermentation process based on metabolic characteristic of the strain.
Subject(s)
Dihydroxyacetone , Fermentation , Genetic Engineering , Methods , Gluconobacter oxydans , Genetics , Metabolism , Industrial Microbiology , Methods , Metabolic Engineering , Methods , Sugar Alcohol Dehydrogenases , MetabolismABSTRACT
We reviewed the fermentation for dihydroxyacetone production. Microbial fermentation is better for dihydroxyacetone production as compared to chemical methods. Gluconobacter oxydans was recognized as the most important strain for industrial production of dihydroxyacetone. The dihydroxyacetone yield is associated with many factors such as substrate, product, oxygen and biomass concentration. Repeated fed-batch fermentation and immobilization fermentation were recognized as the most potential process in various fermentation mode. Construction of recombinant microorganism and optimization of process are future directions of dihydroxyacetone production.
Subject(s)
Dihydroxyacetone , Fermentation , Gluconobacter oxydans , Metabolism , Industrial MicrobiologyABSTRACT
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.
Subject(s)
Humans , Blister , Clinical Protocols , Racial Groups , Dihydroxyacetone , Hand , New Jersey , Pigmentation , Skin , Suction , Thigh , Transplants , VitiligoABSTRACT
El envejecimiento induce marcados cambios de la superficie cutánea y particularmente de la capa córnea. La aplicación de lipo-hidroxi-ácido, un derivado lipofílico del ácido salicílico, aporta una mejoría de ciertas alteraciones asociadas al envejecimiento. Produce una eliminación más uniforme de los corneocitos y un aumento del espesor de las capas basal y de Malpighi, dentro de los límites fisiológicos