Breeding Of High-Producing Erythritol Strain And Optimization Of Fermentation Condition

Erythritol is a kind of adding sweetener with edible safety and flavor like sucrose. There are several virtues in erythritol, such as low calory, high stability, appropriate sweet taste, non-cariogenic, non-hygroscopic, high tolerability and so on. It has great potential for application in food as an ideal assistant material for hygienical food. Erythritol produced by fermentation is more promising compared to chemical synthesis method.In this paper, we carried out a series of experiments, including screening, strains ultroviolating, and optimizing fermentation process. The main results are as follows:1. 7 strains were high erythritol-producers with the productivity higher than 20g/L were isolated from pollen, honey and honeycomb collected in apiary in Mountain Tai. Amongst 7 erythritol-producing strains, Strain K-23 produced 46.8g/L erythritol after 132h and based on glucose in a medium containing 20% glucose,1% yeast extract and 0.1% urea.2. Examinations were compared under various cultivation condition in the while of activating, collection and screening on the erythritol-producing strains. Setting up a method with a special TCL whi1e the plate was developed by the periodate sodium- benzidine as the color developing reagent and the solvent system of n-butanol a1coho1-aceticacid-water (4: 1: 5) as the mobi1e phase, that is, made a piece of normal TCL through the normal sample spoting samples with gradient and certain quantity. In the investigation, just requiring a result of TCL with samples that comparing with normal-board. So we can analized the erythritol that came from the sample with the qualitative and quantitive methods.3. Strain K-23 as the original strain was treated with U.V, one mutant ERY237 produced more than 70g/L was selected, and the hereditary stability of the mutant ERY237 was investigated in the shaking flask by pass-generation tests. The tests was showed that the genetic property of this mutant was stable.4. Through a series of orthogonal experiment, the effects of fermentation conditions on the production of erythritol from strain ERY237 such as carbon sources, nitrogen sources, initial pH, temperature and other factors were studied. The optimal fermentation media and culture condition were established. The optimal liquid medium consisted of 300g/L glucose was used as carbon source, 8g/L corn seed liquor as nitrogen source and other inorganic salts(g/L): CuSO4·5H2O 0.5,MnSO4·4H2O 5; The optimal culture condition were: inoculability quantity 9%, initial pH6.0, medium volume 55mL in 250mL flask,agitation speed 200r/min at 32℃。The yield of erythritol reached 91.7g/L in 120h.