Pujar Namadev K, Laad Shruti, Premakshi H G, Pattar Shridhar V, Mirjankar Manisha, Kamanavalli Chandrappa M
1P. G. Department of Studies in Biochemistry, Karnatak University, Dharwad, Karnataka 580 003 India.
2P. G. Department of Studies in Chemistry, Karnatak University, Dharwad, Karnataka 580 003 India.
3 Biotech. 2019 Feb;9(2):52. doi: 10.1007/s13205-019-1589-8. Epub 2019 Jan 25.
An bacterial strain named as NC-1, capable of utilizing phenmedipham (PMP) herbicide as the sole of carbon source and energy for growth was isolated from pesticide-contaminated soil sample by enrichment culture technique. The isolated bacterial strain was identified as NC-1 (MH 796134) based on its morphological, cultural, biochemical characteristics and analysis of 16S rRNA gene sequence. The strain NC-1 could degrade more than 98.5% of PMP (2 mM) within 168 h. The optimal degradation pH and temperature were 7.0 and 30-35 °C, respectively. The strain NC-1 degraded PMP by a pathway involving its initial hydrolysis of their central amide carbamate linkage to yield -aminophenol via methyl--(3-hydroxyphenyl) carbamate and -toluidine were the major intermediates. However, -aminophenol was not further metabolized, because they neither supported the growth of organism nor stimulated oxygen uptake. But -toluidine released by dealkylation was followed by hydrolysis. Further, results also revealed that degradation of 4-methyl catechol proceeded via 2-hydroxy-5-methyl-6-oxohexa-2, 4-dienoate through cleavage ring processes. The formation of these compounds was confirmed by UV, TLC, HPLC, IR, NMR, and GC-MS spectral analysis. The cell-free extracts of NC-1 grown on PMP contained the activities of PMP hydrolase, toluidine dioxygenase, and 4-methyl catechol 1, 2-dioxygenase. These results demonstrate the biodegradation of PMP and promote the potential use of strain NC-1 to bioremediate PMP-contaminated environment.
通过富集培养技术，从受农药污染的土壤样本中分离出一株名为NC-1的细菌菌株，该菌株能够利用甜菜宁（PMP）除草剂作为唯一碳源和能量进行生长。根据其形态、培养、生化特性以及16S rRNA基因序列分析，将分离出的细菌菌株鉴定为NC-1（MH 796134）。菌株NC-1在168小时内可降解超过98.5%的PMP（2 mM）。最佳降解pH值和温度分别为7.0和30-35°C。菌株NC-1通过一条途径降解PMP，该途径包括其中心酰胺氨基甲酸酯键的初始水解，通过甲基-（3-羟基苯基）氨基甲酸酯生成对氨基苯酚，对甲苯胺是主要中间体。然而，对氨基苯酚没有进一步代谢，因为它们既不支持生物体的生长，也不刺激氧气摄取。但是脱烷基释放的对甲苯胺随后发生水解。此外，结果还表明，4-甲基邻苯二酚的降解是通过2-羟基-5-甲基-6-氧代己-2,4-二烯酸通过开环过程进行的。通过紫外、薄层色谱、高效液相色谱、红外、核磁共振和气相色谱-质谱光谱分析证实了这些化合物的形成。在PMP上生长的NC-1的无细胞提取物含有PMP水解酶、对甲苯胺双加氧酶和4-甲基邻苯二酚1,2-双加氧酶的活性。这些结果证明了PMP的生物降解，并促进了菌株NC-1在生物修复受PMP污染环境中的潜在应用。
