Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), 4 Place Jussieu, 75005 Paris, France.
Sorbonne Université, CNRS, Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), 4 Place Jussieu, 75005 Paris, France.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Oct 5;278:121262. doi: 10.1016/j.saa.2022.121262. Epub 2022 Apr 30.
While the formation of intracellular amorphous calcium carbonate (ACC) by living organisms is widespread, its detection in prokaryotes remains difficult owing to its susceptibility to transform or dissolve upon sample preparation. Because of these challenges, a large number of ACC-forming prokaryotes may have been undetected and their abundance in the natural environment is possibly underestimated. This study identifies diagnostic spectral markers of ACC-forming prokaryotes that facilitate their detection in the environment. Accordingly, ACC formed by cyanobacteria was characterized using Fourier transform infrared (FTIR) spectroscopy in near-IR, mid-IR, and far-IR spectral regions. Two characteristic FTIR vibrations of ACC, at ∼ 860 cmand ∼ 306 cm, were identified as reliable spectral probes to rapidly detect prokaryotic ACC. Using these spectral probes, several Microcystis strains whose ACC-forming capability was unknown, were tested. Four out of eight Microcystis strains were identified as possessing ACC-forming capability and these findings were confirmed by scanning electron microscopy (SEM) observations. Overall, our findings provide a systematic characterization of prokaryotic ACC that facilitate rapid detection of ACC forming prokaryotes in the environment, a prerequisite to shed light on the role of ACC-forming prokaryotes in the geochemical cycle of Ca in the environment.
虽然生物体内形成细胞内无定形碳酸钙（ACC）的现象很普遍，但由于其在样品制备过程中容易转化或溶解，因此在原核生物中检测到它仍然具有挑战性。由于这些挑战，大量形成 ACC 的原核生物可能未被检测到，它们在自然环境中的丰度可能被低估。本研究确定了形成 ACC 的原核生物的诊断光谱标记物，以促进其在环境中的检测。因此，使用傅里叶变换红外（FTIR）光谱法在近红外、中红外和远红外光谱区域对蓝藻形成的 ACC 进行了表征。鉴定出 ACC 的两个特征 FTIR 振动，在∼860 cm 和∼306 cm 处，作为快速检测原核 ACC 的可靠光谱探针。使用这些光谱探针，对几种 ACC 形成能力未知的微囊藻菌株进行了测试。在 8 种微囊藻菌株中，有 4 种被鉴定为具有形成 ACC 的能力，这些发现通过扫描电子显微镜（SEM）观察得到了证实。总的来说，我们的研究结果提供了对原核 ACC 的系统表征，有助于快速检测环境中形成 ACC 的原核生物，这是阐明形成 ACC 的原核生物在环境中 Ca 地球化学循环中的作用的前提。
