Khan Azmi, Singh Pratika, Kumar Ravinsh, Das Sujit, Singh Rakesh Kumar, Mina Usha, Agrawal Ganesh Kumar, Rakwal Randeep, Sarkar Abhijit, Srivastava Amrita
Department of Life Science, School of Earth, Biological and Environmental Sciences, Central University of South Bihar, Gaya, India.
Laboratory of Applied Stress Biology, Department of Botany, University of Gour Banga, Malda, India.
Front Microbiol. 2021 Nov 3;12:729032. doi: 10.3389/fmicb.2021.729032. eCollection 2021.
Microorganisms produce various secondary metabolites for growth and survival. During iron stress, they produce secondary metabolites termed siderophores. In the current investigation, antifungal activity of catecholate siderophore produced by has been assessed against . Exogenous application of the bacterial siderophore to fungal cultures resulted in decreased colony size, increased filament length, and changes in hyphal branching pattern. Growth inhibition was accompanied with increased intracellular iron content. Scanning electron microscopy revealed dose-dependent alteration in fungal morphology. Fluorescent staining by propidium iodide revealed cell death in concert with growth inhibition with increasing siderophore concentration. Antioxidative enzyme activity was also compromised with significant increase in catalase activity and decrease in ascorbate peroxidase activity. Siderophore-treated cultures showed increased accumulation of reactive oxygen species as observed by fluorescence microscopy and enhanced membrane damage in terms of malondialdehyde content. Antifungal property might thus be attributed to xenosiderophore-mediated iron uptake leading to cell death. STRING analysis showed interaction of MirB (involved in transport of hydroxamate siderophore) and MirA (involved in transport of catecholate siderophore), confirming the possibility of uptake of iron-xenosiderophore complex through fungal transporters. MirA structure was modeled and validated with 95% residues occurring in the allowed region. analysis revealed MirA-Enterobactin-Fe complex formation. Thus, the present study reveals a promising antifungal agent in the form of catecholate siderophore and supports involvement of MirA fungal receptors in xenosiderophore uptake.
微生物产生各种次生代谢产物以实现生长和存活。在铁胁迫期间，它们会产生被称为铁载体的次生代谢产物。在当前的研究中，已评估了由[具体产生菌]产生的儿茶酚型铁载体对[具体真菌]的抗真菌活性。将细菌铁载体外源施加到真菌培养物中导致菌落大小减小、菌丝长度增加以及菌丝分支模式改变。生长抑制伴随着细胞内铁含量的增加。扫描电子显微镜显示真菌形态发生剂量依赖性改变。碘化丙啶荧光染色显示随着铁载体浓度增加，细胞死亡与生长抑制同步。抗氧化酶活性也受到损害，过氧化氢酶活性显著增加，抗坏血酸过氧化物酶活性降低。通过荧光显微镜观察，铁载体处理的培养物显示活性氧物种积累增加，并且就丙二醛含量而言，膜损伤增强。因此，抗真菌特性可能归因于异源铁载体介导的铁摄取导致细胞死亡。STRING分析显示参与异羟肟酸型铁载体转运的MirB和参与儿茶酚型铁载体转运的MirA之间存在相互作用，证实了通过真菌转运蛋白摄取铁 - 异源铁载体复合物的可能性。对MirA结构进行建模并验证，95%的残基出现在允许区域。[具体分析]揭示了MirA - 肠杆菌素 - 铁复合物的形成。因此，本研究揭示了一种有前景的儿茶酚型铁载体形式的抗真菌剂，并支持MirA真菌受体参与异源铁载体摄取。
