Fungal Mn oxides supporting Mn(II) oxidase activity as effective Mn(II) sequestering materials
Fungal Mn oxides supporting Mn(II) oxidase activity as effective Mn(II) sequestering materials
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DOI：
10.1080/09593330.2013.790066
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发表时间：
2013-04
影响因子：
2.8
通讯作者：
Jianing Chang;Y. Tani;H. Naitou;N. Miyata;H. Seyama
中科院分区：
文献类型：
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作者：
Jianing Chang;Y. Tani;H. Naitou;N. Miyata;H. Seyama
本文研究了一株含锰氧化真菌KR21-2菌株培养形成的生物氧化锰(BMO)对锰的氧化能力。在空气平衡条件下，新形成的BMO主要通过将Mn(II)氧化成难溶的Mn来有效地隔离溶解的Mn(II)，这种能力可持续至少8天。对BMO进行脱氧、NaN3中毒或加热都容易削弱它们的Mn(II)氧化能力，这表明酶促Mn(II)氧化参与了这一过程。不含Mn(II)的菌丝体和BMO相溶解后的残余菌丝体均未观察到对Mn(II)的氧化能力，表明需要氧化相。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法表明，氧化相嵌入了Mn(II)氧化酶，从而保持了BMOS的酶活性。在−80℃下冷冻保存至少4周的BMO中的Mn(II)氧化能力，而冷冻干燥则导致这种能力完全丧失。基于这些结果，我们认为支持锰(II)氧化酶活性的真菌锰氧化物是一种有效的锰(II)隔离材料，能够从不含额外营养的溶液中连续氧化锰(II)以保持生物活性。
We examined the Mn(II)-oxidizing ability of the biogenic Mn oxide (BMO) formed in cultures of a Mn(II)-oxidizing fungus, Acremonium strictum strain KR21-2. The newly formed BMO effectively sequestered dissolved Mn(II) mainly by oxidizing Mn(II) to insoluble Mn under air-equilibrated conditions, and this ability lasted for at least 8 days. Deaerating the BMOs, poisoning them with NaN3, or heating them all readily weakened their Mn(II) oxidation ability, indicating the involvement of enzymatic Mn(II) oxidation. There was no Mn(II)-oxidizing ability observed for mycelia cultivated without Mn(II) or for residual mycelia after the BMO phase was dissolved, suggesting the need for the oxide phase. A sodium dodecyl sulphate-polyacrylamide gel electrophoresis assay demonstrated that the oxide phase embeds the Mn(II) oxidase and thereby maintains the enzymatic activity in BMOs. Freezing at−80°C preserved the Mn(II)-oxidizing ability in BMOs for at least 4 weeks, while lyophilization caused a complete loss of this ability. Based on these results, we propose that fungal Mn oxides supporting Mn(II) oxidase activity are an effective Mn(II)-sequestering material capable of oxidizing Mn(II) continuously from solutions containing no additional nutrients to maintain biological activity.