title: Safety assessment of Tetragenococcus halophilus isolates from doenjang, a Korean high-salt-fermented soybean paste.
abstract: We assessed the safety of 49 Tetragenococcus halophilus strains isolated from doenjang in Korea. Minimum inhibitory concentration assays showed that all strains can be considered as susceptible to ampicillin, erythromycin, penicillin G, tetracycline, and vancomycin, but resistant to ciprofloxacin based on the Enterococcus breakpoint values provided by the European Committee on Antimicrobial Susceptibility testing in 2015. Ciprofloxacin resistance was sufficiently high to consider the potential for acquisition of transmissible determinants. Two strains exhibiting potentially acquired resistance to chloramphenicol and gentamicin, and chloramphenicol alone, were identified. None of the strains exhibited α-hemolytic activity or biofilm formation; two strains exhibited weak β-hemolytic activity. Doenjang isolates produced an average of 3338.6 ppm of tyramine in the laboratory, considerably higher than the levels produced by two reference strains. All of the test strains exhibited similar cadaverine, histamine, and putrescine production patterns. Most T. halophilus strains could grow at a NaCl concentration >18%, exhibited acid production at 15% NaCl, and expressed strain-specific protease and lipase activities. The potential acquisition of transmissible determinants for antibiotic resistance and tyramine production identified in this study necessitate the need for a thorough safety assessment of T. halophilus before it can be considered for use in food fermentation processes.
authors.affiliation: Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 02707, Republic of Korea.
authors.forename: Do-Won
authors.initials: DW
authors.lastname: Jeong
authors.affiliation: Department of Food Science and Biotechnology, Kyonggi University, Suwon 16227, Republic of Korea.
authors.forename: Sojeong
authors.initials: S
authors.lastname: Heo
authors.affiliation: Department of Food Science and Biotechnology, Kyonggi University, Suwon 16227, Republic of Korea. Electronic address: jhl@kgu.ac.kr.
authors.forename: Jong-Hoon
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000254:growth & development; D001679:Biogenic Amines / Q000096:biosynthesis; D019149:Bioreactors; D002939:Ciprofloxacin / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D056569:Enterococcaceae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D005285:Fermentation; D005511:Food Handling; D005516:Food Microbiology; D059022:Food Safety; D006640:Histidine Decarboxylase / Q000235:genetics; D008826:Microbial Sensitivity Tests; D056910:Republic of Korea; D017673:Sodium Chloride, Dietary; D045730:Soy Foods / Q000382:microbiology*; D013025:Glycine max / Q000382:microbiology*; D014445:Tyrosine Decarboxylase / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001679:Biogenic Amines; D017673:Sodium Chloride, Dietary; D002939:Ciprofloxacin; D006640:Histidine Decarboxylase; D014445:Tyrosine Decarboxylase
keywords: Ciprofloxacin resistance; Doenjang; Salt-tolerance; Tetragenococcus halophilus; Tyramine decarboxylase