Kanaly Robert A, Harayama Shigeaki, Watanabe Kazuya
Marine Biotechnology Institute, 3-75-1 Heita, Kamaishi City, Iwate 026-0001, Japan.
Appl Environ Microbiol. 2002 Dec;68(12):5826-33. doi: 10.1128/AEM.68.12.5826-5833.2002.
A bacterial consortium which rapidly mineralizes benzo[a]pyrene when it is grown on a high-boiling-point diesel fuel distillate (HBD) was recovered from soil and maintained for approximately 3 years. Previous studies have shown that mobilization of benzo[a]pyrene into the supernatant liquid precedes mineralization of this compound (R. Kanaly, R. Bartha, K. Watanabe, and S. Harayama, Appl. Environ. Microbiol. 66:4205-4211, 2000). In the present study, we found that sterilized supernatant liquid filtrate (SSLF) obtained from the growing consortium stimulated mineralization of benzo[a]pyrene when it was readministered to a consortium inoculum without HBD. Following this observation, eight bacterial strains were isolated from the consortium, and SSLF of each of them was assayed for the ability to stimulate benzo[a]pyrene mineralization by the original consortium. The SSLF obtained from one strain, designated BPC1, most vigorously stimulated benzo[a]pyrene mineralization by the original consortium; its effect was more than twofold greater than the effect of the SSLF obtained from the original consortium. A 16S rRNA gene sequence analysis and biochemical tests identified strain BPC1 as a member of the genus Rhodanobacter, whose type strain, Rhodanobacter lindaniclasticus RP5557, which was isolated for its ability to grow on the pesticide lindane, is not extant. Strain BPC1 could not grow on lindane, benzo[a]pyrene, simple hydrocarbons, and HBD in pure culture. In contrast, a competitive PCR assay indicated that strain BPC1 grew in the consortium fed only HBD and benzo[a]pyrene. This growth of BPC1 was concomitant with growth of the total bacterial consortium and preceded the initiation of benzo[a]pyrene mineralization. These results suggest that strain BPC1 has a specialized niche in the benzo[a]pyrene-mineralizing consortium; namely, it grows on metabolites produced by fellow members and contributes to benzo[a]pyrene mineralization by increasing the bioavailability of this compound.
从土壤中分离出一个细菌群落，该群落以高沸点柴油馏分（HBD）为生长基质时能快速使苯并[a]芘矿化，并维持了约3年。先前的研究表明，苯并[a]芘向上清液中的迁移先于此化合物的矿化过程（R. Kanaly、R. Bartha、K. Watanabe和S. Harayama，《应用与环境微生物学》66:4205 - 4211，2000年）。在本研究中，我们发现从生长的群落中获得的无菌上清液滤液（SSLF），当重新添加到不含HBD的群落接种物中时，能刺激苯并[a]芘的矿化。基于这一观察结果，从该群落中分离出8株细菌，并检测了它们各自的SSLF刺激原始群落进行苯并[a]芘矿化的能力。从一株命名为BPC1的菌株获得的SSLF对原始群落中苯并[a]芘矿化的刺激作用最为强烈；其效果比从原始群落获得的SSLF的效果高出两倍多。16S rRNA基因序列分析和生化测试确定菌株BPC1为红杆菌属的成员，该属的模式菌株林丹分解红杆菌RP5557因能在农药林丹上生长而被分离，现已不存在。菌株BPC1在纯培养中不能在林丹、苯并[a]芘、简单烃类和HBD上生长。相反，竞争性PCR分析表明菌株BPC1在仅以HBD和苯并[a]芘为食的群落中生长。BPC1的这种生长与整个细菌群落的生长同步，并先于苯并[a]芘矿化的开始。这些结果表明，菌株BPC1在苯并[a]芘矿化群落中具有特殊的生态位；也就是说，它以其他成员产生的代谢产物为食，并通过提高该化合物的生物利用度促进苯并[a]芘的矿化。
