| Fumaric acid is a high value-added four-carbon dicarboxylic acid compound, which has been widely used in chemical, pHarmaceutical, food and other industries.In this paper, the RH 7-13# preserved in our lab was screened with bromocresol green as indicator. Bromocresol green is a new screening method, and it has a significant advantage of shorten the screening time. After isolation and purification, a new Arrhizus, RH 7-13-24#, was obtain. Compared with the original strain, the RH 7-13#, the new screened strain has a higher fumaric acid production, increased by 49.01%. In addition, the new Arrhizus is still stable after several passages.In this research, a new mixture medium including glycerol and glucose was choosed as the fermentation medium. After a series of experiments, the optimal fermentation conditions was identified:glycerol dosage 40 g/L, add time to the fermentation stage 24 h, inoculation amount was 30%(V/V), to 24 h seed age or inoculation amount was 20%(V/V), seed age was 36 h. Compared with the pure glucose medium (40 g/L), the production of fumaric acid increased by 55.63% and compared with the pure glycerol (40 g/L), the production of fumaric acid increased by 2437.75%. Meanwhile, compared with the pure glucose medium (80 g/L), the mixture medium can reduce those valueless byproducts, like lactic acid (reduced by 45.97%) and ethanol (reduced by 60.15%).After studying the membrane permeability of RH 7-13-24# in different conditions, the positive effect of mixture medium was identified, and it can enhance the membrane permeability, (increased by 17%). The high membrane permeability can help the small molecules go and out the membrane. At the same time, the addition of glycerol can improve the membrane liquidity and it could lead to the improvement of the content of unsaturated fatty acid significantly. Therefore, the Rhizopus can have a better ability of mass transfer and oxygen transfer. Additionally, the anaerobic respiration was reduced and the byproducts (ethanol and lactic acid) were lower.This paper attempts to study the mixture fermentation influence to cell shape, using the metabolomics analysis. After a series of optimization (cell quenching, extraction, and detection), the optimal condition of extraction the micromolecule from the RH 7-13-24# was established. Under this condition, more than 160 kinds of biological active micromolecule were obtained. Using the relevant statistical method to analyze the biological active micromolecule, the relation between the glycerol and the micromolecule was identified. When the microbe uses the glycerol, the amino acid increases, which is major used for the growth needs. When the microbe uses the glucose, the EMP pathway and the TCA cycle were strengthened, which can provide more ATP for the produce of fumaric acid. As a result, the mixed fermentation has a higher production of fumaric acid. But in this research, the content of alanine and lactic acid was lower in co-fermentation process. When 0.4 g/L alanine was added in the co-fermentation process, the yield of fumaric acid was improved by 9.3%. At the same time, when 0.4 g/L lactic acid was added in the co-fermentation process, the yield of fumaric acid improved by 8.4%. |
