| 摘要: |
| 从印度洋深海沉积物中分离出一株能够高效降解甲醛的假单胞菌（Pseudomonas sp. IOFA1），该菌株可在40 min内完全降解100 mg/cm3的甲醛.通过阴离子交换柱层析对菌株破碎液中的粗酶液进行纯化，得到一条具有甲醛降解活性的单一蛋白条带.经MALDITOF/TOF质谱鉴定，该蛋白为甲醛歧化酶蛋白（FM11）.序列分析表明FM11与其它物种已知醛脱氢酶的氨基酸序列最高相似性为65%；结构域分析表明FM11含有2个保守的锌结合位点和一个NAD结合位点.酶学性质分析结果显示，FM11的最适反应温度为40℃，在25～50℃范围内能够保留95%以上的酶活力，尤其是在高于70℃的高温环境下仍保有约50%的活力，表现出广泛的温度适应性.FM11具有非常广泛的最适反应pH值范围（pH值为5～9），且在pH值4和pH值10时仍分别保留50%和80%左右的酶活力，表现出广泛的pH适应性.在pH值为5～7的条件下孵育1 h后，FM11仍保有97%以上的酶活，且在pH值为7~10条件下孵育1 h后，仍保留90%以上的酶活，表现出极好的酸性和碱性稳定性.Ca2+、Mg2+在低浓度时（0.5 mmol/dm3）对FM11有较明显的激活作用.这些研究为我们进一步开发Pseudomonas sp. IOFA1甲醛歧化酶在降解甲醛方面的用途奠定了基础. |
| 关键词: 海洋生物学 深海 假单胞菌 甲醛歧化酶 甲醛降解 温度和pH适应性 pH稳定性 |
| DOI：10.3969/J.ISSN.2095-4972.2016.03.014 |
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| 基金项目:中国大洋矿产资源研究开发协会资助项目（DY125-15-T-06）；福建省科技计划资助项目（2013N0018） |
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| Purification and characterization of formaldehyde dismutase FM11 from deep-sea bacterium Pseudomonas sp. IOFA1 |
| YU Xiang,CHEN Xinglin,JIN Min,ZENG Runying |
| (State Key Laboratory Breeding Base of Marine Genetic Resources，Third Institute of Oceanography, SOA, Xiamen 361005，China;Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources， Xiamen 361005， China) |
| Abstract: |
| Pseudomonas sp. IOFA1， the strain isolated from the deep-sea sediments of Indian Ocean， was found to degrade formaldehyde efficiently. IOFA1 could rapidly degrade 100mg/cm3 formaldehyde within 40 min. The crude enzymes in cell lysate were purified with a DEAD-sepharose ion exchange column and analyzed with SDS-PAGE. After segregation， a pure protein with formaldehyde-degrading activity was obtained and was further identified as formaldehyde dismutase （FM11） by MALDI-TOF/TOF mass spectrum. Sequence analysis showed that FM11 shared 65% maximum amino acid sequence identity to known formaldehyde dismutase from other species. Domain analysis suggested the existence of two conserved zinc atom binding sites and one conserved NAD binding site in FM11. FM11 was most active at 40℃ and retained more than 95% of its maximum activity at temperatures ranging from 25℃ to 60℃， exhibiting well adaption to temperatures. FM11 displayed a broad range of optimal pHs （pH 5~9）， and could adapt to wide pH environments as it could retained more than 50% and 80% of its maximum activity in pH 4 and pH 10， respectively. FM11 could retained more than 97% and 90% of its initial activity after incubation for 1 h in pH 5~7 and pH 7~10 environments， respectively， displaying a excellent acidic and alkaline stability. The presence of Ca2+、Mg2++ at low concentration could significantly increase the activity of FM11. Collectively， our findings should provide a foundation for the utilization of Pseudomonas sp. formaldehyde dismutase in the decontamination of environmental formaldehyde． |
| Key words: marine biology Deep-sea Pseudomonas sp. formaldehyde dismutase formaldehyde degradation temperature and pH adaption pH stability |
