Chu K H, Alvarez-Cohen L
Department of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, California 94720-1710, USA.
Appl Environ Microbiol. 1998 Sep;64(9):3451-7. doi: 10.1128/AEM.64.9.3451-3457.1998.
The effect of nitrogen source on methane-oxidizing bacteria with respect to cellular growth and trichloroethylene (TCE) degradation ability were examined. One mixed chemostat culture and two pure type II methane-oxidizing strains, Methylosinus trichosporium OB3b and strain CAC-2, which was isolated from the chemostat culture, were used in this study. All cultures were able to grow with each of three different nitrogen sources: ammonia, nitrate, and molecular nitrogen. Both M. trichosporium OB3b and strain CAC-2 showed slightly lower net cellular growth rates and cell yields but exhibited higher methane uptake rates, levels of poly-beta-hydroxybutyrate (PHB) production, and naphthalene oxidation rates when grown under nitrogen-fixing conditions. The TCE-degrading ability of each culture was measured in terms of initial TCE oxidation rates and TCE transformation capacities (mass of TCE degraded/biomass inactivated), measured both with and without external energy sources. Higher initial TCE oxidation rates and TCE transformation capacities were observed in nitrogen-fixing mixed, M. trichosporium OB3b, and CAC-2 cultures than in nitrate- or ammonia-supplied cells. TCE transformation capacities were found to correlate with cellular PHB content in all three cultures. The results of this study suggest that the nitrogen-fixing capabilities of methane-oxidizing bacteria can be used to select for high-activity TCE degraders for the enhancement of bioremediation in fixed-nitrogen-limited environments.
研究了氮源对甲烷氧化菌细胞生长和三氯乙烯（TCE）降解能力的影响。本研究使用了一种混合恒化器培养物以及两种纯的II型甲烷氧化菌株，即甲基弯曲菌OB3b和从恒化器培养物中分离出的菌株CAC-2。所有培养物都能够利用三种不同的氮源（氨、硝酸盐和分子氮）中的每一种进行生长。在固氮条件下生长时，甲基弯曲菌OB3b和菌株CAC-2的净细胞生长速率和细胞产量略低，但甲烷摄取速率、聚-β-羟基丁酸酯（PHB）产生水平和萘氧化速率较高。通过测量有无外部能源时的初始TCE氧化速率和TCE转化能力（降解的TCE质量/失活的生物量）来测定每种培养物的TCE降解能力。在固氮的混合培养物、甲基弯曲菌OB3b和CAC-2培养物中观察到的初始TCE氧化速率和TCE转化能力高于供应硝酸盐或氨的细胞。在所有三种培养物中，发现TCE转化能力与细胞PHB含量相关。本研究结果表明，甲烷氧化菌的固氮能力可用于选择高活性TCE降解菌，以增强在固定氮受限环境中的生物修复。
