Constraints on anaerobic respiration in the hyperthermophilic archaea Pyrobaculum islandicum and Pyrobaculum aerophilum
Constraints on anaerobic respiration in the hyperthermophilic archaea Pyrobaculum islandicum and Pyrobaculum aerophilum
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DOI：
10.1128/aem.02033-07
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发表时间：
2008-01-01
影响因子：
4.4
通讯作者：
Holden, James F.
中科院分区：
文献类型：
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作者：
Feinberg, Lawrence F.;Srikanth, R.;Holden, James F.
Pyrobaculum islandicum使用铁，硫代硫酸盐和元素硫进行厌氧呼吸，而Pyrobaculum aeraphilum使用铁和硝酸盐;然而，对这些过程的限制及其铁和硫还原的生理机制尚不清楚。含硫化合物的生长速率在pH 5至6和高度还原（< -420-mV）条件下最高，而硝酸盐和铁的生长速率在pH 7至9和更氧化（> -210-mV）条件下最高。在铁上生长扩大了这两种生物已知的生长pH范围。P. islandicum与P. aerophilum的不同之处在于，它需要与不溶性氧化铁直接接触以生长，当在不溶性铁上生长时，它不产生任何胞外化合物，并且它缺乏2，6-蒽氢醌二磺酸氧化酶活性。此外，铁还原P. islandicum似乎是完全独立的C型细胞色素。与嗜氧假单胞菌中的情况一样，岛假单胞菌中的NADH依赖性铁还原酶活性在铁生长培养物中相对于非铁生长培养物显着增加。蛋白质组学分析表明，有一个假定的膜结合的硫代硫酸盐还原酶的量在P. islandicum培养上生长的硫代硫酸盐相对于那些在铁和元素硫的培养物中的显着增加。这是第一个证据表明这种酶被用于超嗜热菌或古细菌。砷化焦杆菌和加州焦杆菌也能在柠檬酸铁和不溶性氧化铁上生长，但只有砷化焦杆菌能在不溶性铁上生长，而不直接接触。
Pyrobaculum islandicum uses iron, thiosulfate, and elemental sulfur for anaerobic respiration, while Pyrobaculum aeraphilum uses iron and nitrate; however, the constraints on these processes and their physiological mechanisms for iron and sulfur reduction are not well understood. Growth rates on sulfur compounds are highest at pH 5 to 6 and highly reduced (< -420-mV) conditions, while growth rates on nitrate and iron are highest at pH 7 to 9 and more-oxidized (> -210-mV) conditions. Growth on iron expands the known pH range of growth for both organisms. P. islandicum differs from P. aerophilum in that it requires direct contact with insoluble iron oxide for growth, it did not produce any extracellular compounds when grown on insoluble iron, and it lacked 2,6-anthrahydroquinone disulfonate oxidase activity. Furthermore, iron reduction in P. islandicum appears to be completely independent of c-type cytochromes. Like that in P. aerophilum, NADH-dependent ferric reductase activity in P. islandicum increased significantly in iron-grown cultures relative to that in non-iron-grown cultures. Proteomic analyses showed that there were significant increases in the amounts of a putative membrane-bound thiosulfate reductase in P. islandicum cultures grown on thiosulfate relative to those in cultures grown on iron and elemental sulfur. This is the first evidence of this enzyme being used in either a hyperthermophile or an archaeon. Pyrobaculum arsenaticum and Pyrobaculum calidifontis also grew on Fe(111) citrate and insoluble iron oxide, but only P. arsenaticum could grow on insoluble iron without direct contact.