Department of Environmental Engineering & Earth Sciences, Clemson University, Clemson, SC, 29634-0919, USA.
The Dow Chemical Company, Midland, MI, 48674, USA.
Biodegradation. 2022 Apr;33(2):157-168. doi: 10.1007/s10532-022-09971-4. Epub 2022 Jan 31.
1,4-Dioxane is a pervasive and persistent contaminant in numerous aquifers. Although the median concentration in most contaminant plumes is in the microgram per liter range, a subset of sites have contamination in the milligram per liter range. Most prior studies that have examined 1,4-dioxane concentrations in the hundreds of milligrams per liter range have been performed with industrial wastewater. The main objective of this study was to evaluate aerobic biodegradation of 1,4-dioxane in microcosms prepared with soil and groundwater from a site where concentrations range from ~ 1500 mg·L in the source zone, to 450 mg·L at a midpoint of the groundwater plume, and to 6 mg·L at a down-gradient location. Treatments included biostimulation with propane, addition of propane and a propanotrophic enrichment culture (ENV487), and unamended. The highest rates of biodegradation for each location in the plume occurred in the bioaugmented treatments, although indigenous propanotrophs also biodegraded 1,4-dioxane to below 25 µg·L. Nutrient additions were required to sustain biodegradation of propane and cometabolism of 1,4-dioxane. Among the unamended treatments, biodegradation of 1,4-dioxane was detected in the mid-gradient microcosms. An isolate was obtained that grows on 1,4-dioxane as a sole source of carbon and energy and identified through whole-genome sequencing as Pseudonocardia dioxivorans BERK-1. In a prior study, the same strain was isolated from an aquifer in the southeastern United States. Monod kinetic parameters for BERK-1 are similar to those for strain CB1190.
1,4-二恶烷是许多含水层中普遍存在且持久的污染物。尽管大多数污染物羽流的中位数浓度在微克/升范围内，但一部分地点的污染浓度在毫克/升范围内。大多数先前研究过每升数百毫克 1,4-二恶烷浓度的研究都是用工业废水进行的。本研究的主要目的是评估在一个浓度范围从源区的约 1500 mg·L 到地下水中游的 450 mg·L 再到 6 mg·L 的地点的土壤和地下水中制备的微宇宙中 1,4-二恶烷的好氧生物降解。处理方法包括用丙烷进行生物刺激、添加丙烷和丙烷营养物富集培养物（ENV487）以及不添加。羽流中每个位置的生物降解率最高的处理方法是生物强化处理，尽管土著丙烷营养物也将 1,4-二恶烷生物降解至低于 25μg·L。需要添加营养物质才能维持丙烷的生物降解和 1,4-二恶烷的共代谢。在未添加处理中，在中梯度微宇宙中检测到 1,4-二恶烷的生物降解。获得了一种能够以 1,4-二恶烷为唯一碳源和能源生长的分离物，并通过全基因组测序鉴定为假诺卡氏菌 dioxivorans BERK-1。在先前的研究中，同一菌株是从美国东南部的含水层中分离出来的。BERK-1 的 Monod 动力学参数与 CB1190 菌株相似。
