Breeding Of A High Yield ε-polylysine Producing Strain And Studies On Fermentation

ε-Polylysine is a new source of microbial food preservatives, which is created throughthe microbial synthesis of poly (L-lysine monomer polymer. As a new type of antibacterial peptide,epsilon, poly lysine has a wide antimicrobial spectrum, strong heat resistance, and good water solubility.And is also safe, easy to use, and can be degradated into amino acids necessary to human body to beabsorbed. Therefore it has been called a “nutricious food preservative”, and has the prospect to be widelyapplied in the field of food processing. The furthering the study of ε-polylysine, the extensions of itsapplication to medicine and chemical engineering, and its global demand of hundreds of tons have giventhe production of ε-polylysine profound importance and impactThis paper uses a ε-polylysine producing strain selected from nature, and tests its ability to produceε-polylysine through fermentation, and optimizes its process of fermentation. At the same time, this strainwas mutated through ultra violet radiation to achieve the following results.(1) Filter to attain5strains of ε-polylysine producing bacterium, shake flask culture to compare theε-polylysine fermentation production of the5strains of bacteria, select a high yielding and stable strainand cultivated it to0.47g/L in shaking flasks to set out as a subsequent test strain, and the strain wasidentified.(2) By testing the fermented liquid of ε-polylysine bacteriostatic activity, ε-polylysine wide spectrumcharacteristics are obtained.(3) Using a double screening ε-polylysine producing bacterium, the method of rapid screening canquickly from the nature to ε-polylysine production strains, compared with the traditional method to savesteps, simplify operation, more fast.(4) Through single factor test, carbon source, nitrogen source, initial pH, temperature, inoculationquantity, fermentation time and rotating speed on ε-polylysine production, and the influence key controlfactors in the fermentation process, then orthogonal experiment and response surface optimizationexperiments, finally determine the optimum fermentation culture medium formula:23g/L glucose, beefpaste4g/L, peptone8g/L, C6H14N2O7is1.84g/L and pH4, temperature28℃, inoculation amount8%,6d, shake flask fermentation production of ε-polylysine reached a maximum of0.86g/L.(5) Mutation was initiated simultaneously with culture medium optimization, and a strain that yielded aε-polylysine production rate of0.59g/L was attained, increasing the production by25.5%. This strainwas cultivated under optimized conditions, and when cultivated in shake flasks, the yield was as high as1.07g/L.