Wittich R-M, Strömpl C, Moore E R B, Blasco R, Timmis K N
Division of Microbiology, GBF - National Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany.
J Ind Microbiol Biotechnol. 1999 Oct;23(4-5):353-358. doi: 10.1038/sj.jim.2900740.
We have studied the concerted degradation of two monochlorodibenzofurans by a bacterial consortium, consisting of the chlorodibenzofurans-cometabolizing and chlorosalicylates-excreting strain Sphingomonas sp RW16, and Pseudomonas sp RW10, which mineralized the released chlorosalicylates. Neither of the organisms was able to grow with chlorodibenzofurans alone. Degradation of 2-chloro- and 3-chlorodibenzofuran proceeded to the end products 5-chloro- and 4-chlorosalicylate, respectively, when the initial dioxygenase of Sphingomonas sp RW 16 attacked the unchlorinated aromatic ring of the heterocyclic dibenzofuran molecule. 2-Hydroxypenta-2,4-dienoate, formed upon meta-cleavage of the intermediary chlorotrihydroxybiphenyls, served as a growth substrate for the sphingomonad. Presumably, most of the chlorosalicylates were excreted and degraded further by Pseudomonas sp RW10. Mineralization of both chlorosalicylates proceeded through a converging pathway, via 4-chlorocatechol, and protoanemonin. Chlorosalicylates were mineralized by the pseudomonad only when their concentration in the culture medium was below 1.5 mM. In the case of initial dioxygenation taking place on the chlorinated aromatic ring, salicylate and chlorinated hydroxypentadienoates should be formed. The metabolic fate of putative chlorohydroxypentadienoates is not clear; ie, they may be channeled into unproductive catabolism and, thus, represent the critical point in the breakdown of the carbon of these two chlorodibenzofurans by Sphingomonas sp RW16.
我们研究了一个细菌群落对两种一氯二苯并呋喃的协同降解作用。该细菌群落由可共代谢氯代二苯并呋喃并分泌氯代水杨酸酯的鞘氨醇单胞菌属菌株Sphingomonas sp RW16和能使释放出的氯代水杨酸酯矿化的假单胞菌属菌株Pseudomonas sp RW10组成。这两种微生物单独在氯代二苯并呋喃环境中均无法生长。当鞘氨醇单胞菌属菌株Sphingomonas sp RW 16的初始双加氧酶攻击杂环二苯并呋喃分子的未氯化芳环时，2-氯二苯并呋喃和3-氯二苯并呋喃的降解分别生成终产物5-氯水杨酸酯和4-氯水杨酸酯。中间产物氯代三羟基联苯经间位裂解形成的2-羟基戊-2,4-二烯酸酯可作为鞘氨醇单胞菌的生长底物。据推测，大部分氯代水杨酸酯被分泌出来，并由假单胞菌属菌株Pseudomonas sp RW10进一步降解。两种氯代水杨酸酯均通过一条汇聚途径，经4-氯儿茶酚和原白头翁素实现矿化。只有当培养基中氯代水杨酸酯的浓度低于1.5 mM时，假单胞菌才能使其矿化。如果初始双加氧作用发生在氯化芳环上，则应形成水杨酸酯和氯代羟基戊二烯酸酯。假定的氯代羟基戊二烯酸酯的代谢归宿尚不清楚；也就是说，它们可能进入无生产性的分解代谢途径，因此，这可能是鞘氨醇单胞菌属菌株Sphingomonas sp RW16分解这两种氯代二苯并呋喃碳元素过程中的关键点。
