Ogunseitan O A, Delgado I L, Tsai Y L, Olson B H
Program in Social Ecology, University of California, Irvine 92717.
Appl Environ Microbiol. 1991 Oct;57(10):2873-9. doi: 10.1128/aem.57.10.2873-2879.1991.
The addition of specific nontoxic inducers of catabolic operons to contaminated sites is an approach that may enhance the efficiency of in situ biodegradation. We determined the genetic response of six pseudomonads to salicylate (also known as 2-hydroxybenzoate) added directly to 50 g of nonsterile soil samples. The strains, isolated from a polyaromatic hydrocarbon-contaminated soil, metabolized naphthalene as the sole source of available carbon, and their DNA sequences show significant homology to the nahAB genes of the degradative plasmid NAH7. Duplicate nonsterile soil cultures were incubated for up to 30 days. Experimental soil cultures were seeded with naphthalene-degrading strains (10(8) CFU g-1) originally isolated from the soil and amended with salicylate (16 or 160 micrograms g-1). Soil samples were analyzed periodically for the population density of heterotrophic bacteria and naphthalene degraders and for the abundance of the naphthalene-degradative genotype in the bacterial community. At 160 micrograms g-1, salicylate sustained the density of naphthalene degraders at the introduced density for 30 days in addition to producing a two- to sixfold increase in the occurrence in the bacterial community of DNA sequences homologous to the nah operon. No change in recoverable bacterial population densities was observed when soil samples were amended with 16 micrograms of salicylate g-1, but this concentration of salicylate induced a significant increase in the level of nah-related genes in the population.
向受污染场地添加分解代谢操纵子的特定无毒诱导剂是一种可能提高原位生物降解效率的方法。我们测定了六种假单胞菌对直接添加到50克非无菌土壤样品中的水杨酸盐（也称为2-羟基苯甲酸）的遗传反应。这些菌株从多环芳烃污染的土壤中分离得到，以萘作为唯一可用碳源进行代谢，并且它们的DNA序列与降解性质粒NAH7的nahAB基因具有显著同源性。将非无菌土壤重复培养物孵育长达30天。实验土壤培养物接种了最初从土壤中分离得到的萘降解菌株（10(8) CFU g-1），并用水杨酸盐（16或160微克 g-1）进行改良。定期分析土壤样品中异养细菌和萘降解菌的种群密度，以及细菌群落中萘降解基因型的丰度。在160微克 g-1时，水杨酸盐除了使细菌群落中与nah操纵子同源的DNA序列出现频率增加两到六倍外，还能使萘降解菌的密度在引入密度下维持30天。当用16微克水杨酸盐 g-1改良土壤样品时，未观察到可恢复细菌种群密度的变化，但该浓度的水杨酸盐诱导种群中nah相关基因水平显著增加。
