Requirement of a relatively high threshold level of Mg2+ for cell growth of a rhizoplane bacterium, Sphingomonas yanoikuyae EC-S001
Requirement of a relatively high threshold level of Mg2+ for cell growth of a rhizoplane bacterium, Sphingomonas yanoikuyae EC-S001
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DOI：
10.1128/aem.70.9.5214-5221.2004
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发表时间：
2004-09-01
影响因子：
4.4
通讯作者：
Tahara, S
中科院分区：
文献类型：
--
作者：
Hoo, H;Hashidoko, Y;Tahara, S
Mg2+是细菌细胞生长的必需元素之一。不同浓度的镁离子（Mg2+）的存在经常影响植物相关细菌的细胞生长恢复。本研究试图确定鞘单胞菌EC-S001中的Mg2+水平是否影响寄主植物的细胞生长恢复以及阈值水平是多少。S. yanoikuyae EC-S001从无菌条件下表面灭菌的菠菜幼苗的根面分离得到，在寄主幼苗的根面和叶平面上表现出均匀的分散和附着。S. yanoikkuyae EC-S001在马铃薯葡萄糖肉汤培养基中不能生长，但在菠菜叶的水提取物中生长良好。对菠菜叶提取物中的生长因子进行化学研究，确定其活性成分为镁离子。约0.10 mM Mg2+或更高的浓度允许S. yanoikkuyae EC-S001在马铃薯葡萄糖肉汤培养基中生长。在我们的实验中发现一些腐生和/或重氮营养细菌对Mg2+的需求有不同的阈值水平。例如，洋葱伯克霍尔德菌EC-K014，最初从一种植物的根际分离出来，甚至可以在不含Mg2+的Hoagland's no生长。2培养基与糖和谷氨酰胺（HSG培养基），需要微量的Mg2+水平的生长。相比之下，S. yanoikuyae EC-S001和枯草芽孢杆菌IFO12113在不含Mg2+的HSG培养基中添加0.98 mM Mg2+后，恢复效果最为显著。我们的研究得出结论，Mg2+不仅仅是S. yanoikuyae EC-S001细胞生长恢复所需的必需微量元素，某些不可培养的细菌可能需要更高浓度的Mg2+或其他特定的必需元素来生长。
Mg2+ is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg2+) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg2+ levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg2+ or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg2+ requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the rhizoplane of a Melastoma sp., could grow even in Mg2+-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg2+ for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg2+ to Mg2+-free HSG medium. Our studies concluded that Mg2+ is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg2+ or another specific essential element for their growth.