Radiation-inducible radioprotective exopolysaccharides of <i>Bacillus siamensis</i> CV5 from irradiated roots of <i>Cistanche violacea</i> to decrease free radical damage produced by ionizing radiation

<b>Purpose:</b> To assess exopolysaccharides (EPS) of <i>Bacillus siamensis</i> CV5, isolated from irradiated roots of <i>Cistanche violacea</i>, for their induction by ionizing radiation (IR) and their antioxidant and radioprotective power. <b>Materials and methods:</b> Isolated bacteria from the roots of <i>C. violacea</i> were screened for EPS production. The most EPS-producing bacterium was selected and the response surface methodology (RSM) was applied to elucidate the IR dose effects on EPS production. Gamma irradiation effects on the morphology and functional groups of EPS were studied using microscopy and Fourier transform infra-red (FT-IR). The radioprotective potential of EPS on the survival of <i>B. siamensis</i> CV5 following IR was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Free radicals scavenging potentialities (FRSP) of non-irradiated and irradiated EPS were evaluated through 2, 2⁻-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and ferric reducing ability of plasma (FRAP) assays. <b>Results:</b> Twenty strains, isolated from irradiated roots of <i>C. violacea</i>, were screened for their EPS production. IR-resistant <i>B. siamensis</i> CV5 was the most EPS-producing strain. Its purified EPS contained rhamnose, fructose, mannose and glucose. RSM indicated that EPS of CV5 (CV5-EPS) are radiation inducible. Micrographs of CV5-EPS suggested an increase in the total area and a decrease in the Feret’s statistical diameter following exposure to IR. FT-IR spectra of these EPS revealed an increase of various functional groups. The MTT survival assay demonstrated a positive correlation between the added quantity of CV5-EPS and the viability of irradiated CV5 (<i>p</i> p <b>Conclusions:</b> CV5-EPS were demonstrated as radiation-inducible and radioprotective biomolecules. This radioprotective potential of CV5-EPS could be associated with their antioxidant activities. In the future, irradiated EPS could be tested as a gel in cancer radiotherapy for minimizing the damage caused by rays to surrounding healthy tissues.

研究目的：本研究旨在评估从辐照后的紫花肉苁蓉（Cistanche violacea）根系中分离得到的暹罗芽孢杆菌（Bacillus siamensis）CV5所产的胞外多糖（exopolysaccharides, EPS），探究其是否可被电离辐射（ionizing radiation, IR）诱导，并评估其抗氧化与辐射防护能力。
材料与方法：从紫花肉苁蓉的辐照根系中分离细菌菌株，并筛选其产EPS能力。选取产EPS量最高的菌株，采用响应面法（response surface methodology, RSM）解析电离辐射剂量对EPS合成的影响。通过显微镜观测与傅里叶变换红外光谱（Fourier transform infra-red, FT-IR）分析，探究γ辐照对EPS形貌与官能团的作用。采用3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT）法，评估EPS对经电离辐射处理后暹罗芽孢杆菌CV5存活率的辐射防护潜力。通过2,2-二苯基-1-苦基肼基（2,2-diphenyl-1-picrylhydrazyl, DPPH）、2,2'-联氮-双(3-乙基苯并噻唑啉-6-磺酸)（2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), ABTS）以及铁还原抗氧化能力（ferric reducing ability of plasma, FRAP）实验，测定未辐照与辐照EPS的自由基清除能力（free radicals scavenging potentialities, FRSP）。
结果：从紫花肉苁蓉的辐照根系中共分离得到20株细菌菌株，经EPS产率筛选后，耐电离辐射的暹罗芽孢杆菌CV5为产EPS能力最强的菌株。其纯化得到的EPS由鼠李糖、果糖、甘露糖与葡萄糖组成。响应面法分析结果显示，CV5所产EPS（CV5-EPS）可被电离辐射诱导。CV5-EPS的显微图像显示，经电离辐射处理后，其总覆盖面积增加，而费雷特统计直径（Feret’s statistical diameter）降低。该EPS的傅里叶变换红外光谱显示，多种官能团的信号强度有所提升。MTT存活率实验结果表明，CV5-EPS的添加量与经电离辐射处理的CV5菌株存活率呈正相关（p<0.05）。
结论：本研究证实CV5-EPS为可被电离辐射诱导的辐射防护生物活性物质。CV5-EPS的辐射防护潜力可能与其抗氧化活性相关。未来可将辐照后的EPS制备为凝胶制剂，用于癌症放射治疗中，以减轻射线对周围健康组织的损伤。

搜集汇总

背景与挑战

背景概述

该数据集研究了从辐照的Cistanche violacea根中分离的Bacillus siamensis CV5菌株产生的外多糖（EPS），发现这些EPS具有辐射诱导性和辐射防护潜力，其防护机制与抗氧化活性增强相关。研究通过实验验证了EPS对辐射损伤的减少作用，并探讨了其在癌症放疗中作为保护凝胶的潜在应用价值。数据集覆盖生物物理学、生物化学和癌症研究等交叉学科领域。