Center for Physical Sciences and Technology, Savanorių 231, 02300, Vilnius, Lithuania.
Nature Research Center, Akademijos 2, 08412, Vilnius, Lithuania.
J Biol Inorg Chem. 2021 May;26(2-3):299-311. doi: 10.1007/s00775-021-01853-z. Epub 2021 Feb 15.
In previous studies it was found that the antimicrobial properties of pulcherrimin-producing Metschnikowia species are related to the formation of a red pigment-pulcherrimin and sequestration of free iron from their growth medium. For strains of Metschnikowia pulcherrima, M. sinensis, M. shaxiensis, and M. fructicola, at a high, ≈80 mg/kg, elemental Fe concentration in agar growth media we observed the essentially different (metal luster, non-glossy rust like, and colored) yeast biomass coatings. For the studied strains the optical and scanning electron microscopies showed the increased formation of chlamydospores that accumulate a red pigment-insoluble pulcherrimin rich in iron. The chlamydospore formation and decay depended on the iron concentration. In this study pulcherrimin in biomass of the selected Metschnikowia strains was detected by Mössbauer spectroscopy. At ≈80 mg/kg elemental Fe concentration the Mössbauer spectra of biomass of the studied strains were almost identical to these of purified pulcherrimin. Iron in pulcherrimin reached ≈1% of biomass by weight which is very high in comparison with elemental Fe percentage in growth medium and is not necessary for yeast growth. The pulcherrimin in biomass was also observed by Mössbauer spectroscopy at lower, ≈5 mg/kg, elemental Fe concentration. Through chemical binding of iron pulcherrimin sequestrates the soluble Fe in the growth media. However, at high Fe concentrations, the chemical and biochemical processes lead to the pulcherrimin accumulation in biomass chlamydospores. When soluble iron is sequestrated or removed from the growth media in this way, it becomes inaccessible for other microorganisms.
在之前的研究中发现，产 pulcherrimin 的粘红酵母属物种的抗菌特性与红色色素 pulcherrimin 的形成以及从其生长介质中螯合游离铁有关。对于粘红酵母、中华粘红酵母、沙氏粘红酵母和裂殖酵母的菌株，在琼脂生长培养基中高浓度（约 80mg/kg）的元素铁浓度下，我们观察到基本不同的（金属光泽、非光泽铁锈状和有色）酵母生物量涂层。对于研究的菌株，光学和扫描电子显微镜显示出增加了厚垣孢子的形成，这些厚垣孢子积累了富含铁的不溶性 pulcherrimin。厚垣孢子的形成和衰减取决于铁浓度。在这项研究中，通过穆斯堡尔光谱法检测了所选粘红酵母菌株生物量中的 pulcherrimin。在约 80mg/kg 元素铁浓度下，研究菌株的生物量穆斯堡尔光谱几乎与纯化的 pulcherrimin 的光谱相同。铁在 pulcherrimin 中的重量百分比达到约 1%，这与生长培养基中元素铁的百分比相比非常高，并且不是酵母生长所必需的。在较低的（约 5mg/kg）元素铁浓度下，也通过穆斯堡尔光谱观察到生物量中的 pulcherrimin。通过铁的化学结合，pulcherrimin 螯合生长介质中的可溶性铁。然而，在高铁浓度下，化学和生物化学过程导致 pulcherrimin 在生物量厚垣孢子中积累。当以这种方式螯合或从生长介质中去除可溶性铁时，它就变得无法被其他微生物利用。
