Effect of over-expression of multicopper oxidase and glyceraldehyde 3-phosphate dehydrogenase gene on histamine degradation by Lactiplantibacillus plantarum
Lactiplantibacillus plantarum is one of the common strains that degrade histamine in fermented foods,its key genes for his-tamine degradation have not been clarified,hindering the molecular breeding of L.plantarum with a high histamine degrading ability.To reveal the key genes for histamine degradation in L.plantarum,an L.plantarum with histamine degradation ability was screened from fer-mented vegetables,and its strain characterization and whole genome analysis were performed.Then the key histamine degradation genes of L.plantarum were mined through over-expression.Results showed that the maximum histamine degradation rate(20.16%)of the selected strain was obtained at the 48th hour.Morphological and molecular biological characterization results exhibited that the selected was L.plan-tarum and named L.plantarum CY087.L.plantarum CY087 had a good tolerance to high histamine content coupled with bad tolerances to low acid and high salt.Over-expression of the multicopper oxidase gene(mcO)and the glyceraldehyde 3-phosphate dehydrogenase gene(gapdH)in L.plantarum CY087 increased its histamine degradation rate.Compared with the strain CY087-36e,the histamine degradation rates of CY087-gapdH and CY087-mcO were increased by 31.94%and 16.14%,respectively,suggesting that the gapdH gene played a more critical role in the degradation of histamine in L.plantarum CY087.This study provides potential targets for the molecular modifica-tion of L.plantarum with a high histamine degradation ability.