Characterization of ornithine decarboxylase with histidine decarboxylase activity in natural histidine decarboxylase gene deletion Enterobacter hormaechei RH3

• Published in: Food microbiology Vol. 125; p. 104644
• Main Authors: Pei, Huijie, Wang, Yilun, He, Wei, Zhang, Yue, Yang, Lamei, Li, Jinhai, Ma, Yixuan, Hu, Xinjie, Li, Shuhong, Li, Jianlong, Hu, Kaidi, Liu, Aiping, Ao, Xiaolin, Teng, Hui, Li, Ran, Li, Qin, Zou, Likou, Liu, Shuliang, Yang, Yong
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2025
• Subjects: Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Enterobacter - enzymology; Enterobacter - genetics; Enterobacter - metabolism; Enterobacter hormaechei; Expression; Gene Deletion; Histamine; Histamine - metabolism; Histidine Decarboxylase - genetics; Histidine Decarboxylase - metabolism; Hydrogen-Ion Concentration; Inoculation; Meat Products - microbiology; Ornithine decarboxylase; Ornithine Decarboxylase - genetics; Ornithine Decarboxylase - metabolism; Histamine; Enterobacter hormaechei; Inoculation; Ornithine decarboxylase; Expression
• ISSN: 0740-0020; 1095-9998; 1095-9998
• DOI: 10.1016/j.fm.2024.104644

Histamine is predominantly produced in sausages via the decarboxylation of histidine by bacteria. Furthermore, histamine-producing bacteria usually possess the enzyme histidine decarboxylase (hdc). Enterobacter hormaechei RH3 isolated from sausages exhibited significant levels of histamine production despite the absence of hdc. In this study, we elucidated the previously unidentified mechanism underlying histamine production by RH3. We identified an enzyme, NehdX-772, exhibiting the hdc activity from the cell lysate supernatant of RH3, which was annotated as ornithine decarboxylase. The optimal activity of NehdX-772 was recorded at 35 °C and pH 6.0, and it could tolerate a salt concentration of 2.5% (w/v) NaCl. Moreover, artificial inoculation revealed that NehdX-772 was synthesized at significant levels in sausages, leading to an increase in histamine levels. The discovery of NehdX-772 explains the underlying mechanism of histamine production by RH3 and can be applied to decrease histamine production in sausages. •The ornithine decarboxylase (NehdX-772) converts histidine into histamine.•NehdX-772 was resistant to acid and alkali, but sensitive to heating.•NehdX-772 was present and highly expressed in fermented sausages.