Tetracycline residue alters profile of lactic acid bacterial communities and metabolites of ginger pickle during spontaneous fermentation.

Antibiotic residue, an emerging contaminant, has been an increasing concern worldwide in vegetables. However, the focus is still limited to its accumulation in vegetables and its adverse health effect on humans, with little mention of its impact on the vegetable process. Fermentation is an important method of the vegetable process. Tetracycline (TC) is the most widely used antibiotic, and its residue is often higher than other antibiotics in ginger. Therefore, current research was to characterize how the TC residue affected the lacticacidbacterial (LAB) communities and metabolites during the salted fermentation of ginger. The TC residue, organic acids, volatile compounds and LABs were analyzed during the fermentation, and the correlations between the LABs and compounds were also revealed. The results suggested that the hetero-lactic fermentation did not happen under the TC residue although the TC residue decreased from 4 mg/kg to 2.56 mg/kg in salt brine of ginger fermentation. Meanwhile, TC residue affected the occurrence, propagation and succession of LABs. The LAB biomarkers shifted to Lab. parafarraginis, Lab. buchneri and Lab. kisonensis under TC residue. Responded to LAB communities, the organic acids and volatile compounds were also markedly changed under the TC residue. And the important volatile compound variables shifted to citronellol, allylsenevol, geranyl acetate, vinylstearylether, isothiocyanic acid phenethyl, 3-octanol, geraniol, bingpian, citral and camphor. The transformation of LAB biomarkers induced by TC residue was the main cause of the change of important volatile compound variables, but interestingly, not all of them had significant positive or negative correlations. These results indicated that the antibiotic residue has an adverse ecological effect on the vegetable fermentation process.Therefore, the antibiotic residue should be listed as a quality control index in fermented vegetable raw materials.