Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov, Russia.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 Jan 1;100:171-5. doi: 10.1016/j.saa.2012.06.003. Epub 2012 Jun 15.
The integral bioluminescence (BL) intensity of live Photobacterium phosphoreum cells (strain 1883 IBSO), sampled at the stationary growth stage (20 h), was monitored for further 300 h in the absence (control) and presence of (241)Am (an α-emitting radionuclide of a high specific activity) in the growth medium. The activity concentration of (241)Am was 2 kBq l(-1); [(241)Am]=6.5×10(-11) M. Parallel experiments were also performed with water-soluble humic substances (HS, 2.5 mg l(-1); containing over 70% potassium humate) added to the culture medium as a possible detoxifying agent. The BL spectra of all the bacterial samples were very similar (λ(max)=481±3 nm; FWHM=83±3 nm) showing that (241)Am (also with HS) influenced the bacterial BL system at stages prior to the formation of electronically excited states. The HS added per se virtually did not influence the integral BL intensity. In the presence of (241)Am, BL was initially activated but inhibited after 180 h, while the system (241)Am+HS showed an effective activation of BL up to 300 h which slowly decreased with time. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, applied to dry cell biomass sampled at the stationary growth phase, was used to control possible metabolic responses of the bacteria to the α-radioactivity stress (observed earlier for other bacteria under other stresses). The DRIFT spectra were all very similar showing a low content of intracellular poly-3-hydroxybutyrate (at the level of a few percent of dry biomass) and no or negligible spectroscopic changes in the presence of (241)Am and/or HS. This assumes the α-radioactivity effect to be transmitted by live cells mainly to the bacterial BL enzyme system, with negligible structural or compositional changes in cellular macrocomponents at the stationary growth phase.
在生长培养基中不存在（对照）和存在（241）Am（高比活度的α-发射放射性核素）的情况下，监测处于静止生长阶段（20 h）的活发光菌（菌株 1883 IBSO）的整体生物发光（BL）强度，进一步监测 300 h。（241）Am 的活度浓度为 2 kBq l(-1)；[(241)Am]=6.5×10(-11) M。还在培养基中添加水溶性腐殖物质（HS，2.5 mg l(-1)；含有超过 70%的腐植酸钾）作为可能的解毒剂进行了平行实验。所有细菌样品的 BL 光谱非常相似（λ(max)=481±3 nm；FWHM=83±3 nm），表明（241）Am（也与 HS）在形成电子激发态之前的阶段影响细菌 BL 系统。单独添加的 HS 实际上对整体 BL 强度没有影响。在存在（241）Am 的情况下，BL 最初被激活，但 180 h 后被抑制，而系统（241）Am+HS 显示 BL 有效激活，持续 300 h，随后随时间缓慢下降。应用于静止生长阶段采集的干细胞生物质的漫反射红外傅里叶变换（DRIFT）光谱，用于控制细菌对α-放射性应激的可能代谢反应（早些时候在其他细菌在其他应激下观察到）。DRIFT 光谱都非常相似，显示细胞内聚-3-羟基丁酸的含量较低（占干生物质的几个百分点），并且在存在（241）Am 和/或 HS 的情况下，光谱没有或几乎没有变化。这表明α-放射性效应主要通过活细胞传递给细菌 BL 酶系统，在静止生长阶段细胞宏观成分的结构或组成没有变化或变化很小。
