Fuchs K, Schreiner A, Lingens F
Institut für Mikrobiologie, Universität Hohenheim, Stuttgart, FRG.
J Gen Microbiol. 1991 Aug;137(8):2033-9. doi: 10.1099/00221287-137-8-2033.
Rhodococcus rhodochrous strain CTM co-metabolized 2-methylaniline and some of its chlorinated isomers in the presence of ethanol as additional carbon source. Degradation of 2-methylaniline proceeded via 3-methylcatechol, which was metabolized mainly by meta-cleavage. In the case of 3-chloro-2-methylaniline, however, only a small proportion (about 10%) was subjected to meta-cleavage; the chlorinated meta-cleavage product was accumulated in the culture fluid as a dead-end metabolite. In contrast, 4-chloro-2-methylaniline was degraded via ortho-cleavage exclusively. Enzyme assays showed the presence of catechol 1,2-dioxygenase and catechol 2,3-dioxygenase as inducible enzymes in strain CTM. Extended cultivation of strain CTM with 2-methylaniline and 3-chloro-2-methylaniline yielded mutants, including R. rhodochrous strain CTM2, that had lost catechol 2,3-dioxygenase activity; these mutants degraded the aromatic amines exclusively via the ortho-cleavage pathway. DNA hybridization experiments using a gene probe revealed the loss of the catechol 2,3-dioxygenase gene from strain CTM2.
在以乙醇作为额外碳源的情况下，红平红球菌CTM菌株能够共代谢2-甲基苯胺及其一些氯化异构体。2-甲基苯胺的降解通过3-甲基儿茶酚进行，3-甲基儿茶酚主要通过间位裂解进行代谢。然而，对于3-氯-2-甲基苯胺，只有一小部分（约10%）进行间位裂解；氯化间位裂解产物作为终产物在培养液中积累。相比之下，4-氯-2-甲基苯胺仅通过邻位裂解进行降解。酶分析表明，CTM菌株中存在儿茶酚1,2-双加氧酶和儿茶酚2,3-双加氧酶这两种可诱导酶。用2-甲基苯胺和3-氯-2-甲基苯胺对CTM菌株进行长期培养产生了突变体，包括红平红球菌CTM2菌株，该菌株失去了儿茶酚2,3-双加氧酶活性；这些突变体仅通过邻位裂解途径降解芳香胺。使用基因探针进行的DNA杂交实验表明，CTM2菌株中儿茶酚2,3-双加氧酶基因缺失。
