Physiological and morphological responses of the soil bacterium Rhodococcus opacus strain PD630 to water stress
Physiological and morphological responses of the soil bacterium Rhodococcus opacus strain PD630 to water stress
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DOI：
10.1016/j.femsec.2004.06.002
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发表时间：
2004-11-01
影响因子：
4.2
通讯作者：
Steinbüchel, A
中科院分区：
文献类型：
--
作者：
Alvarez, HM;Silva, RA;Steinbüchel, A
研究了不透明红球菌PD630在水分胁迫下的生理形态变化。葡萄糖酸盐和十六烷培养的细胞对这些条件具有极强的抵抗力，存活时间可达300天和400天；分别进行缓慢风干。本研究结果表明，菌株PD630具有特定的抗水胁迫机制。水分胁迫细胞对乙醇、高温和氧化胁迫敏感，而在施用前几个小时，它们仅对渗透胁迫表现出交叉保护。结果表明，不透明毛豆PD630对水分胁迫的抗性过程主要包括以下生理和形态变化：(1)能量调节，代谢活性急剧降低（在脱水的前24小时内下降约39%，在脱水190天后下降约90%）；(2)内源性代谢利用细胞内三酰基甘油产生能量和前体；(3)生物合成不同的渗透产物，如海藻糖、外托因和羟基外托因，可能通过渗透调节实现水分平衡，这可能解释了水和渗透胁迫之间的重叠。(4)通过霉菌酸种类的周转来调整细胞壁，初步实验显示细胞壁厚度没有明显变化，(5)形成短片段细胞，可能形成抗性形式，(6)产生覆盖菌落表面的细胞外黏液，可能调节水势的内外变化，(7)形成致密的细胞团。这有助于了解土壤细菌R. opacus PD630对水分胁迫的抗性过程。(C) 2004年欧洲微生物学会联合会。Elsevier B.V.版权所有。
Rhodococcus opacus PD630 was investigated for physiological and morphological changes under water stress challenge. Gluconate- and hexadecane-grown cells were extremely resistant to these conditions, and survival accounted for up to 300 and 400 days; respectively, when they were subjected to slow air-drying. Results of this study suggest that strain PD630 has specific mechanisms to withstand water stress. Water-stressed cells were sensitive to the application of ethanol, high temperatures and oxidative stress, whereas they exhibited cross-protection solely against osmotic stress during the first hours of application. Results indicate that the resistance programme for water stress in R. opacus PD630 includes the following physiological and morphological changes, among others: (1) energetic adjustments with drastic reduction of the metabolic activity (approximate to39% decrease during the first 24 h and about 90% after 190 days under dehydration), (2) endogenous metabolism using intracellular triacylglycerols for generating energy and precursors, (3) biosynthesis of different osmolytes Such as trehalose, ectoine and hydroxyectoine, which may achieve a water balance through osmotic adjustment and may explain the overlap between water and osmotic stress, (4) adjustments of the cell-wall through the turnover of mycolic acid species, as preliminary experiments revealed no evident changes in the thickness of the cell envelope, (5) formation of short fragmenting-cells as probable resistance forms, (6) production of an extracellular slime covering the surface of colonies, which probably regulates internal and external changes in water potential, and (7) formation of compact masses of cells. This contributes to understanding the water stress resistance processes in the soil bacterium R. opacus PD630. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.