Institute of Nutritional and Food Science, Food Microbiology and Hygiene, University of Bonn, Friedrich-Hirzebruch-Allee 7, 53115, Bonn, Germany.
Arch Microbiol. 2021 Aug;203(6):3353-3360. doi: 10.1007/s00203-021-02322-6. Epub 2021 Apr 19.
Listeria monocytogenes is a food-borne pathogen with the ability to grow at low temperatures down to - 0.4 °C. Maintaining cytoplasmic membrane fluidity by changing the lipid membrane composition is important during growth at low temperatures. In Listeria monocytogenes, the dominant adaptation effect is the fluidization of the membrane by shortening of fatty acid chain length. In some strains, however, an additional response is the increase in menaquinone content during growth at low temperatures. The increase of this neutral lipid leads to fluidization of the membrane and thus represents a mechanism that is complementary to the fatty acid-mediated modification of membrane fluidity. This study demonstrated that the reduction of menaquinone content for Listeria monocytogenes strains resulted in significantly lower resistance to temperature stress and lower growth rates compared to unaffected control cultures after growth at 6 °C. Menaquinone content was reduced by supplementation with aromatic amino acids, which led to a feedback inhibition of the menaquinone synthesis. Menaquinone-reduced Listeria monocytogenes strains showed reduced bacterial cell fitness. This confirmed the adaptive function of menaquinones for growth at low temperatures of this pathogen.
李斯特菌是一种食源性病原体，能够在低至-0.4°C的温度下生长。在低温下生长时，通过改变脂质膜组成来维持细胞质膜流动性非常重要。在李斯特菌中，主要的适应效应是通过缩短脂肪酸链长使膜流化。然而，在某些菌株中，低温生长时menaquinone 含量的增加是另一种反应。这种中性脂质的增加导致膜的流化，因此代表了与脂肪酸介导的膜流动性修饰互补的机制。本研究表明，与未受影响的对照培养物相比，李斯特菌菌株menaquinone 含量的降低导致在 6°C 下生长后对温度应激的抵抗力显著降低和生长速率降低。menaquinone 含量通过补充芳香族氨基酸来降低，这导致了menaquinone 合成的反馈抑制。menaquinone 减少的李斯特菌菌株显示出降低的细菌细胞适应性。这证实了menaquinones 对该病原体低温生长的适应性功能。
