Isolation, Antioxidant Activity Analysis And Characterization Of Antioxidant Paenibactin Produced By Paenibacillus B28

Paenibacillus is a genus of bacteria with various of metabolic products. For the purpose of Screening new antioxidants, We measured the total antioxidant capacity of fermentation broth of Paenibacillus B28using FRAP (Ferric reducing antioxidant potential) method, found that it has antioxidant activity. Through16S rDNA sequencing, B28was identified as Paenibacillus ehimensis. And then target antioxidant was isolated and purified from the culture broth by using macroporous resin absorption, C18SPE column and preparation scale HPLC after choosing proper culture medium.Antioxidant activity in vitro was assayed by using several methods next. VC and Trolox(VE analog) were used as control in the experiment. By using FRAP total antioxidant capacity determination method, paenibactin’s relative oxidant capacity was calculated to be28.73, much higher than torlox(10.79). Then using DPPH method to analysis its free radical scavenging capacity in vitro, results indicated that its free radical scavenging capacity capacity was7.01times as VC. DNA supercoiling damage experiment was carried out next, giving out a result that paenibactin has significantly higher ability to prevent DNA molecular from oxidative damaging than VC. At last, temperature and pH experiment were carried out to test the stability of paenibactin’s antioxidation capacity, experiment results indicate that paenibactin has strong tolerance against temperature and pH, only show up obvious activity reduction after treated with100℃water bath for2h.To ascertain the fact whether this material was new antioxidant, structural analysis were carried out with ESI-MS, amino acid tests and NMR. The results show that its molecular structure is same as paenibactin which was found in strain Paenibacillus elgii B69previously. The primary structure of its monosome is DHB-[L-Ala]-[L-Thr] as well, and mainly exist with trimer form, A small amount of monomer and dimer nay also exist. Trimer’s molecular weight is924Da, and it’s a kind of catecholate siderophore. Based on its molecular structure, we speculate that its antioxidant capacity mainly ascribed to its catechol structure, similar to the widely used botanical antioxidant flavonoid. Considering its iron chelating ability, paenibactin can help enrichment medium trace iron meanwhile. we can expect it to be used as a new kind of natural antioxidant with multifunction after further research later.This study isolated a kind of catecholate siderophore from Paenibacillus ehimensis and researched on its antioxidant activity for the first time, can be used for reference in developing new multifunction antioxidants.