Dairy Research Institute, IPLA, CSIC, C/ Francisco Pintado Fé, 26. 33011, Oviedo, Spain; Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Av. del Hospital Universitario s/n, 33011 Oviedo, Asturias, Spain.
Dairy Research Institute, IPLA, CSIC, C/ Francisco Pintado Fé, 26. 33011, Oviedo, Spain.
Int J Food Microbiol. 2025 Jan 16;427:110970. doi: 10.1016/j.ijfoodmicro.2024.110970. Epub 2024 Nov 9.
Agmatine, the decarboxylation product of arginine, is the precursor of putrescine - a harmful biogenic amine (BA) - that can accumulate in dairy products via bacterial metabolism involving the agmatine deiminase (AGDI) pathway. This first requires agmatine be produced via the decarboxylation of arginine and it remains unknown which microorganisms are responsible for this prior decarboxylation step. In addition, agmatine, as other BA, plays different physiological roles including those of co-transmitter and neuromodulator. Preclinical and clinical studies have shown agmatine to have a neuroprotective effect, rendering it of therapeutic interest being agmatine-producing bacteria proposed as psychobiotics. The identification of BA-producing microorganisms is based on the rise in pH due to the consumption of H during such decarboxylation reactions. However, in the detection of agmatine-producing microorganisms in cheese, this would lead to false positives since many bacteria possess arginine deiminase activity; this produces ornithine and ammonium from arginine, which also increases the pH. To overcome this problem, a whole-cell biosensor based on a previously developed agmatine-inducible transcription system was designed, and a protocol optimized for the successful identification of agmatine-producing microorganisms in cheese. The application of this protocol in cheese samples allowed for the isolation of agmatine-producing microorganisms identified as Hafnia spp. and unravels, for first time, the capacity of Hafnia paralvei to produce agmatine. This finding evidence the potential role of Hafnia spp. in putrescine accumulation in dairy products.
胍丁胺是精氨酸脱羧产物，是腐胺（一种有害生物胺（BA））的前体，可通过涉及胍丁胺脱亚氨酶（AGDI）途径的细菌代谢在乳制品中积累。这首先需要胍丁胺通过精氨酸的脱羧作用产生，目前尚不清楚哪些微生物负责这一前脱羧步骤。此外，胍丁胺与其他 BA 一样，发挥着不同的生理作用，包括共递质和神经调节剂。临床前和临床研究表明胍丁胺具有神经保护作用，因此具有治疗意义，产生胍丁胺的细菌被提议作为益生菌。BA 产生微生物的鉴定基于在这种脱羧反应中消耗 H 导致 pH 升高。然而，在奶酪中检测产生胍丁胺的微生物时，这会导致假阳性，因为许多细菌都具有精氨酸脱亚氨酶活性；这会从精氨酸产生鸟氨酸和铵，这也会增加 pH 值。为了解决这个问题，设计了一种基于先前开发的胍丁胺诱导转录系统的全细胞生物传感器，并优化了该系统，以成功鉴定奶酪中产生胍丁胺的微生物。该方案在奶酪样品中的应用允许分离出产生胍丁胺的微生物，鉴定为哈夫尼亚属，并首次揭示了哈夫尼亚 paralvei 产生胍丁胺的能力。这一发现证明了哈夫尼亚属在乳制品中腐胺积累中的潜在作用。
