Anaerobic growth and potential for amino acid production by nitrate respiration in Corynebacterium glutamicum
Anaerobic growth and potential for amino acid production by nitrate respiration in Corynebacterium glutamicum
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DOI：
10.1007/s00253-007-0926-8
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发表时间：
2007-07-01
影响因子：
5
通讯作者：
Ikeda, Masato
中科院分区：
文献类型：
--
作者：
Takeno, Seiki;Ohnishi, Junko;Ikeda, Masato
氧气限制是谷氨酸棒杆菌发酵氨基酸过程中的一个关键问题。针对这一课题，我们的研究始于对谷氨酸杆菌需氧特性的分析，该菌通常被认为是一种严格的好氧细菌。该菌在相对较低的氧浓度(0.5%O-2)下在琼脂平板上形成菌落，而在没有O-2的情况下没有明显的菌落形成。然而，在硝酸盐(NO3-)存在下，该菌在厌氧条件下表现出有限的生长和亚硝酸盐(NO2-)的产生，这表明谷氨酸杆菌可以利用硝酸盐作为最终的电子受体。无论硝酸盐水平如何，从好氧和低氧培养中提取的细胞提取物的分析都产生了相似的硝酸还原酶活性。基因组分析揭示了一个可能与硝酸还原酶和运输相关的narK2GHJI簇。对NarG和NarJ的干扰使依赖硝酸盐的厌氧生长消失，硝酸还原酶活性丧失。阻断可能的硝酸盐/亚硝酸盐逆向转运蛋白基因narK2不会影响酶的活性，但会损害厌氧生长。这些结果表明，该基因与硝酸盐呼吸有关。对L-赖氨酸和L-精氨酸产生菌的琼脂切片分析表明，这两种氨基酸的产生都是通过硝酸盐呼吸厌氧产生的，这表明谷氨酸杆菌具有厌氧生产氨基酸的潜力。
Oxygen limitation is a crucial problem in amino acid fermentation by Corynebacterium glutamicum. Toward this subject, our study was initiated by analysis of the oxygen- requiring properties of C. glutamicum, generally regarded as a strict aerobe. This organism formed colonies on agar plates up to relatively low oxygen concentrations ( 0.5% O-2), while no visible colonies were formed in the absence of O-2. However, in the presence of nitrate ( NO3-), the organism exhibited limited growth anaerobically with production of nitrite ( NO2-), indicating that C. glutamicum can use nitrate as a final electron acceptor. Assays of cell extracts from aerobic and hypoxic cultures yielded comparable nitrate reductase activities, irrespective of nitrate levels. Genome analysis revealed a narK2GHJI cluster potentially relevant to nitrate reductase and transport. Disruptions of narG and narJ abolished the nitrate-dependent anaerobic growth with the loss of nitrate reductase activity. Disruption of the putative nitrate/nitrite antiporter gene narK2 did not affect the enzyme activity but impaired the anaerobic growth. These indicate that this locus is responsible for nitrate respiration. Agar piece assays using L-lysine- and L-arginine-producing strains showed that production of both amino acids occurred anaerobically by nitrate respiration, indicating the potential of C. glutamicum for anaerobic amino acid production.