Tropical Candida Fermentation Grease 12 Carbon Dibasic Acid Production In The Study

Long chain dicarboxylic acid is a kind of dicarboxylic acid,which carbon chain has 10 to 18 carbon atoms and contains saturated or unsaturated dicarboxylic.It has a very wide range of uses in industrial raw materials and plays an important role in the plastics,fragrances,paint and synthetic pesticides pharmaceutical production areas.Dodecanedioic acid is a kind a long-chain dicarboxylic acid,it usually obtained by fermentation of alkanes directly.Because of the decline of crude oil reserves and the shortage of petrochemical raw materials resources required,the costs of dicarboxylic acid production is increasing,so it is essential for finding new sustainable alternatives.In this paper,Candida tropicalis genome-scale metabolic networks are constructed and analyzed,researching the possibility of using grease or oil hydrolyzate as fermentation feedstock of long-chain dicarboxylic acids.The fermentation test uses oil as the substrate for the shake flask cultrue to optimize the grease fermentation conditions in Candida tropicalis1798,and researching the effect on adding lipase for the production of dodecanedioic acid.This experiment analyzes the possible ways of producing dodecanedioic acid by the oleic acid fermentation test,and the result are as follows:Firstly,Candida tropicalis genome-scale metabolicnetwork models is based on the yeast genome-scale metabolic network model which has been published,combining comparative and Genomic Blast metabolic network diagram analysis to build the models quickly.In order to research the fermenting process of Candida tropicalis producing long-chain dicarboxylic acids,long chain dicarboxylic acid metabolism reaction added into the model and analyzed the effect on the process of using the basic unit as a substrate for long chain dicarboxylic acid fermentation.It was found that the demand for oxygen was decreased obviously in the process of fatty acid fermentation to produce long chain dicarboxylic acid than that in the alkane fermentation.This experiment proves the feasibility of using oil or grease enzymolysis as raw material to product long chain dicarboxylic acid.Secondly,experiment uses Candida tropicalis 1798 for fermentation,with oil as the substrate in shake flasks and measured the results by HPLC,it shows that long-chain dicarboxylic acid components present in the fermentation broth.This result proves oil instead of paraffin as a substrate for fermentation to produce dicarboxylic acids is feasible.The optimum fermentation conditions have been confirmed by the experiment as follows: the constant temperature shocks incubator at 200 r / min,triangle bottled liquid volume amount 50 mL,use of baffles bottles and the inoculation quantitu is controlled in 10% at 30℃ in pH5.0,the optimum substrate concentration is 7.5 fat,emulsifier optimum concentration of Tween 60 was 0.05% and the optimum concentration of urea was 0.12%.Under this condition of the fermentation,the conversion rate of oil could be up to 5%.In addition,the fermentation results shows that the utilization rate of oil is lower than paraffin in Candida tropicalis 1798.Finally,measuring the lipase has effect on oil conversion by adding extrac ellular lipase experiment,finding the production of lipase in strain itself is 11.1g/L by shake flask fermentation.The amount of output is lower than hydrolyze all of the oil needed lipase in the fermentation by the theoretical analysis.By adding quantity optimal experiment,finding that the long chain dibasic acid production reach the maximal when the adding quantity of the lipase is 0.9g/L.Previous oil fermentation product measured by HPLC shows that the product of dodecene is exist.It is speculated that unsaturated bond is generated in grea se.In order to further analysis the source of the dodecanedioic acid.The result is the Candida tropicalis 1798 can transform oleic acid to dodecanedioic acid by the shake flask fermentation tests.