Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China.
School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
Environ Microbiol. 2017 Sep;19(9):3638-3648. doi: 10.1111/1462-2920.13864. Epub 2017 Aug 24.
Magnetotactic bacteria (MTB) demonstrate photoresponse. However, little is known about the biological significance of this behaviour. Magnetosomes exhibit peroxidase-like activity and can scavenge reactive oxygen species (ROS). Magnetosomes extracted from the Magnetospirillum magneticum strain AMB-1 show enhanced peroxidase-like activity under illumination. The present study investigated the effects of light irradiation on nonmagnetic (without magnetosomes) and magnetic (with magnetosomes) AMB-1 cells. Results showed that light irradiation did not affect the growth of nonmagnetic and magnetic cells but significantly increased magnetosome synthesis and reduced intracellular ROS level in magnetic cells. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to analyse the expression level of magnetosome formation-associated genes (mamA, mms6, mms13 and mmsF) and stress-related genes (recA, oxyR, SOD, amb0664 and amb2684). Results showed that light irradiation upregulated the expression of mms6, mms13 and mmsF. Furthermore, light irradiation upregulated the expression of stress-related genes in nonmagnetic cells but downregulated them in magnetic cells. Additionally, magnetic cells exhibited stronger phototactic behaviour than nonmagnetic ones. These results suggested that light irradiation could heighten the ability of MTB to eliminate intracellular ROS and help them adapt to lighted environments. This phenomenon may be related to the enhanced peroxidase-like activity of magnetosomes under light irradiation.
趋磁细菌（MTB）表现出光响应性。然而，这种行为的生物学意义知之甚少。磁小体具有过氧化物酶样活性，可以清除活性氧（ROS）。从趋磁螺菌 AMB-1 菌株中提取的磁小体在光照下表现出增强的过氧化物酶样活性。本研究探讨了光照对非磁性（无磁小体）和磁性（有磁小体）AMB-1 细胞的影响。结果表明，光照不会影响非磁性和磁性细胞的生长，但会显著增加磁小体的合成并降低磁性细胞内的 ROS 水平。进行定量逆转录聚合酶链反应（qRT-PCR）分析磁小体形成相关基因（mamA、mms6、mms13 和 mmsF）和应激相关基因（recA、oxyR、SOD、amb0664 和 amb2684）的表达水平。结果表明，光照上调了 mms6、mms13 和 mmsF 的表达。此外，光照上调了非磁性细胞中应激相关基因的表达，但下调了磁性细胞中应激相关基因的表达。此外，磁性细胞表现出比非磁性细胞更强的趋光行为。这些结果表明，光照可以提高 MTB 消除细胞内 ROS 的能力，并帮助它们适应光照环境。这种现象可能与光照下磁小体增强的过氧化物酶样活性有关。
