Abstract
Dihydroxyacetone production from glycerol has been studied. Cultures of Gluconobacter oxydans ATCC 621, a promising microorganism that is able to convert glycerol into dihydroxyacetone, has been employed. In this work, the influence of oxygen transport rate and the fluid dynamic conditions have been studied working with resting cells cultures. Several experiments were carried out at two different scales: 250 mL Erlenmeyer flasks and a 2 L stirred tank bioreactor, varying the agitation speed. Product and substrate concentration were determined employing high-performance liquid chromatography. Additionally, oxygen concentration was measured in the runs carried out in stirred tank reactors. Taking into account the results obtained in these experiments, three different behaviors were observed, depending on the mass transfer and chemical reactions rates. For experiments with low stirring speed (below 200 rpm for shake flasks and 300 rpm for reactors), the oxygen transport rate is the controlling step, while at high stirring speed (over 300 rpm in shake flasks and 560 rpm in the bioreactor), the chemical reaction is controlling the overall process rate. In some runs conducted at medium agitation, a mix control was found. All the kinetic models were able to reproduce experimental data and fulfill thermodynamic and statistical criteria, highlighting the importance of the mass transfer rate upon this system.
Highlights
Glycerol has become a waste due to the enormous availability caused by the huge growth of the biodiesel production industry [1], which produces glycerol as a by-product; approximately 10 kg of glycerol are produced per 100 kg of biodiesel [2]
Based on the results obtained in the aforementioned runs, three different kinetic modeling approaches have been used in order to describe
The strain employed in this work is Gluconobacter oxydans ATCC 621, which was provided by the Spanish Type Culture Collection (CECT 360)
Summary
Glycerol has become a waste due to the enormous availability caused by the huge growth of the biodiesel production industry [1], which produces glycerol as a by-product; approximately 10 kg of glycerol are produced per 100 kg of biodiesel [2]. An estimation of OECD-FAO (Organization for Economic Co-operation and Development—Food and Agricultural Organization) assumes that the global production of biodiesel will grow 4.5% annually, reaching 41 Mm3 in 2022 [2]. This makes the development of different sustainable processes that are able to transform the growing amount of glycerol produced into valuable products peremptory. Glycerol has been employed in many industries (food, pharmaceutical, cosmetic, chemical, etc.), due to its versatile physicochemical properties [3]. Amongst all these applications, one promising route is the bioconversion of glycerol into chemical products and precursors, such as 1,3-dihydroxyacetone (DHA). DHA is extensively used in the cosmetic industry due to its employment as a building block for the production of various fine chemicals such as 1,3-propanediol and citric acid (being an intermediate compound in this processes) [4], with microbial production being the preferred synthesis pathway, in contrast with the chemical processes, which have expensive safety requirements [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
