High Yield5-Aminolevulinic Acid Strains Screening And The Optimization Of The Conditions Of Fermentation

5-aminolevulinic acid (ALA) is widely found in microbes, plants and animal cells. It isbiosynthetic precursors of hemoglobin, porphyrins, chlorophyll and vitamin B12and othertetrapyrrole. Low concentrations of ALA can be used as plant growth regulators to improve cropquality and resistance, extend the shelf life of agricultural products; while high concentrations ofALA can be widely used as a herbicide. At the same time in the field of medicine, ALA hasaroused a lot of attentions as a photosensitive material. There are many reports on the treatmentof cancer and other diseases. At present the ALA production is mainly dependent on the chemicalsynthesis. In the face of its growing demand, an efficient method to accumulate ALAmicroorganisms has become a research focus.With the rise of the pH value of ALA solution, the stability down quickly, especially in thefermented liquid contain complex material, so keep fermenting liquid in the acid environment isvery important for the protection of the ALA. Currently lack of high performance liquidchromatography (HPLC) method for detection and identification solution of the ALA in PPMlevel.1. This essay focused on the ways of isolation and screening and detection of ALA. And themain research contents are as follows.The writer explored the pre-column derivatizationRP-HPLC method for the detection of the trace of ALA and the detection methodoptimization. The results show that if the pre-column derived temperature, detectionwavelength and mobile phase pH are changed, the detection sensitivity can be significantlyimproved, and the ALA sensitivity can also be improved to5mg/L2. The writer isolated from different ecological environments10strains that can accumulateALA, four of which can yield more than1.5mg/L. By analyzing the16S rDNA sequenceand phospholipid fatty acid of the four strains, and combing the morphological andphysiological characteristics, the writer determined their taxonomic status. The strain thatyeilds LA-10most is defined as Staphylococcus cohnii, whose fermentation period is24hwith the yeilding volumn up to6.88mg/L. Besides, at the end of fermentation, thefermentation broth was in acidic environment in order to prevent rapid decomposition. 3. The author tried to optimize the medium response surface and fermentation conditions oftheLA-10strains. The experiment showed that the optimum fermentation conditions of LA-10are as follows: initial PH value is5.0,250mL flask is installed with fluid volume of80mL,the rotation speed is100rpm with inoculation ratio of1%, and the fermentation time is24h;the optimum medium components are as follows: beef extract6.14g/L, glucose6.97g/L,tryptone5.15g/L, magnesium sulfate1g/L, sodium chloride1g/L, sodium dihydrogenphosphate1g/L, disodium hydrogen phosphate1g/L. Under this optimum conditions, theyielding volumn increased to19.8mg/L. The author conducted RP-HPLC method to definethe composition of ALA in the LA-10fermentation broth, which set the basis of furtherresearch and development for the LA-10strain.