Industrial Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan.
FEMS Microbiol Lett. 2009 Nov;301(1):95-102. doi: 10.1111/j.1574-6968.2009.01797.x. Epub 2009 Sep 17.
Out of 17 samples collected from diverse environments, 110 bacterial isolates of varied characteristics were screened for their dibenzothiophene-desulphurizing activity. A single isolate, Eu-32, originating from a soil sample taken from the roots of a eucalyptus tree, displayed dibenzothiophene-desulphurizing activity. This isolate metabolized dibenzothiophene to 2-hydroxybiphenyl (2-HBP), as detected by HPLC, and was also able to use other organic sulphur compounds as a sole sulphur source. Based on morphological, biochemical and molecular studies, it was found that the organism belongs to the genus Rhodococcus, with a maximum of 95% identity to species in this genus for the partial sequence of the 16S rRNA gene. Isolate Eu-32 could desulphurize 0.2 mM dibenzothiophene to 2-HBP in 72 h at a temperature of 30 degrees C and pH 7.0. The structure and molecular mass of metabolites produced from dibenzothiophene desulphurization were identified by GC-MS, and two sulphur-free products, 2-HBP and biphenyl, were detected in ethyl acetate extract. It was concluded that isolate Eu-32 is a unique desulphurizing biocatalyst that desulphurizes dibenzothiophene through an extended, sulphur-specific degradation pathway with the selective cleavage of C-S bonds.
从不同环境中采集的 17 个样本中，筛选了 110 个具有不同特征的细菌分离物，以检测其二苯并噻吩脱硫活性。从一棵桉树根部采集的土壤样本中分离出的单个分离物 Eu-32 显示出二苯并噻吩脱硫活性。该分离物通过 HPLC 检测到将二苯并噻吩代谢为 2-羟基联苯（2-HBP），并且还能够将其他有机硫化合物用作唯一的硫源。基于形态学、生化和分子研究，发现该生物属于 Rhodococcus 属，其 16S rRNA 基因部分序列与该属中的某些种具有高达 95%的同一性。分离物 Eu-32 在 30°C 和 pH 值为 7.0 的条件下，72 小时内可以将 0.2mM 的二苯并噻吩脱硫生成 2-HBP。通过 GC-MS 鉴定了从二苯并噻吩脱硫生成的代谢产物的结构和分子量，在乙酸乙酯提取物中检测到两种无硫产物，即 2-HBP 和联苯。因此，可以得出结论，分离物 Eu-32 是一种独特的脱硫生物催化剂，通过扩展的、特异性的硫降解途径脱硫，选择性地切割 C-S 键。
