Use of a Gluconobacter frateurii Mutant to Prevent Dihydroxyacetone Accumulation during Glyceric Acid Production from Glycerol
ABSTRACT To prevent dihydroxyacetone (DHA) by-production during glyceric acid (GA) production from glycerol using Gluconobacter frateurii, we used a G. frateurii THD32 mutant, ΔsldA, in which the glycerol dehydrogenase subunit-encoding gene (sldA) was disrupted, but ΔsldA grew much more slowly than the wild type, growth starting after a lag of 3 d under the same culture conditions. The addition of 1% w/v D-sorbitol to the medium improved both the growth and the GA productivity of the mutant, and ΔsldA produced 89.1 g/l GA during 4 d of incubation without DHA accumulation.
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ABSTRACT: The considerable increase in biodiesel production worldwide in the last 5 years resulted in a stoichiometric increased coproduction of crude glycerol. As an excess of crude glycerol has been produced, its value on market was reduced and it is becoming a "waste-stream" instead of a valuable "coproduct". The development of biorefineries, i.e. production of chemicals and power integrated with conversion processes of biomass into biofuels, has been singled out as a way to achieve economically viable production chains, valorize residues and coproducts, and reduce industrial waste disposal. In this sense, several alternatives aimed at the use of crude glycerol to produce fuels and chemicals by microbial fermentation have been evaluated. This review summarizes different strategies employed to produce biofuels and chemicals (1,3-propanediol, 2,3-butanediol, ethanol, n-butanol, organic acids, polyols and others) by microbial fermentation of glycerol. Initially, the industrial use of each chemical is briefly presented; then we systematically summarize and discuss the different strategies to produce each chemical, including selection and genetic engineering of producers, and optimization of process conditions to improve yield and productivity. Finally, the impact of the developments obtained until now are placed in perspective and opportunities and challenges for using crude glycerol to the development of biodiesel-based biorefineries are considered. In conclusion, the microbial fermentation of glycerol represents a remarkable alternative to add value to the biodiesel production chain helping the development of biorefineries, which will allow this biofuel to be more competitive.Biotechnology for Biofuels 07/2012; 5(1):48. DOI:10.1186/1754-6834-5-48 · 6.22 Impact Factor
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ABSTRACT: Gluconobacter oxydans IFO12528 is able to produce glyceric acid (GA) from glycerol through the action of a membrane-bound alcohol dehydrogenase (mADH), which is required for GA production. To determine whether membrane-bound aldehyde dehydrogenase (mALDH) also plays a role in GA production in G. oxydans, we constructed an aldH-disrupted mutant of G. oxydans (ΔaldH). ΔaldH was unable to produce acetic acid from ethanol, but was able to produce GA at a level approximately half that of the wildtype strain, suggesting the involvement of another ALDH in GA production. We also investigated the enantiomeric composition of GA produced by the IFO12528 and ΔaldH strains. No difference in GA composition was evident in the ΔaldH mutant, with ~73% d-GA enantiomeric excess observed in both strains.Journal of oleo science 09/2014; 63(9):953-7. DOI:10.5650/jos.ess14112 · 1.24 Impact Factor
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ABSTRACT: Previously, Lešová et al. reported the isolation and identification of metabolite OR-1, showing antitrypsin activity, produced during fermentation by Penicillium funiculosum. The structure of OR-1 was a mixture of glyceric acid (GA), esterified with C(14)-C(18) fatty acids, and oleic acid (C18:1) as the most predominant fatty acid (Folia Microbiol. 46, 21-23, 2001). In this study, dioleoyl D-GA and dioleoyl L-GA were synthesized via diesterification with oleoyl chloride, and their antitrypsin activities were evaluated using both a disk diffusion method and spectral absorption measurements. The results show that both compounds and their equivalent mixtures possess antitrypsin activities; however, their IC(50) values (approximately 2 mM) are much higher than that of OR-1 (4.25 µM), suggesting that dioleoyl GA does not play a major role in the OR-1 antitrypsin activity.Journal of oleo science 06/2011; 60(6):327-31. DOI:10.5650/jos.60.327 · 1.24 Impact Factor