Park W, Jeon C O, Cadillo H, DeRito C, Madsen E L
Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA.
Appl Microbiol Biotechnol. 2004 Apr;64(3):429-35. doi: 10.1007/s00253-003-1420-6. Epub 2003 Aug 20.
Survival of naphthalene-degrading Pseudomonas putida NCIB 9816-4 was measured in nonsterile soil samples (coal tar-contaminated and pristine) with and without added crystalline naphthalene over a period of 21 days. A 2-3 log decrease in cfu occurred in the presence, but not absence, of added naphthalene. We used aqueous suspensions of crystalline naphthalene to explore potential mechanisms of its toxicity on the test bacterium under aerobic conditions. Measurements of dissolved naphthalene in medium indicated that uptake by P. putida NCIB 9816-4 maintained naphthalene at concentrations well below saturation. Accumulation of catechol was documented by high-performance liquid chromatography and gas chromatography/mass spectrometry in the presence of 0.5% (w/v) naphthalene crystals. Transient catechol accumulation was highest when cells entered stationary phase. A decrease in catechol concentration correlated with the development of brown color in the medium. Brown pigment accumulation correlated with a decrease in viable cell counts. These results suggested that catechol, related compounds, and their condensation products can accumulate to toxic levels in stationary phase P. putida NCIB 9816-4 cells. We hypothesize that the same mechanism of toxicity may occur under the nutrient-limited conditions expected in soil.
在21天的时间里，对萘降解恶臭假单胞菌NCIB 9816 - 4在添加和未添加结晶萘的非无菌土壤样本（受煤焦油污染的和原始的）中的存活情况进行了测定。在添加萘的情况下，菌落形成单位（cfu）出现了2 - 3个对数级的下降，而在未添加萘的情况下则没有。我们使用结晶萘的水悬浮液来探究其在有氧条件下对受试细菌的潜在毒性机制。对培养基中溶解萘的测量表明，恶臭假单胞菌NCIB 9816 - 4的摄取使萘的浓度维持在远低于饱和浓度的水平。在存在0.5%（w/v）萘晶体的情况下，通过高效液相色谱和气相色谱/质谱法记录了儿茶酚的积累。当细胞进入稳定期时，儿茶酚的瞬时积累最高。儿茶酚浓度的降低与培养基中棕色的出现相关。棕色色素的积累与活细胞数量的减少相关。这些结果表明，儿茶酚、相关化合物及其缩合产物在恶臭假单胞菌NCIB 9816 - 4稳定期细胞中可积累到有毒水平。我们推测，在土壤中预期的营养限制条件下可能会发生相同的毒性机制。
