Biodegradation kinetics testing of two hydrophobic UVCBs – potential for substrate toxicity supports testing at low concentrations,Environmental Science: Processes & Impacts

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Biodegradation kinetics testing of two hydrophobic UVCBs – potential for substrate toxicity supports testing at low concentrations
Environmental Science: Processes & Impacts ( IF 4.3 ) Pub Date : 2020-09-04 , DOI: 10.1039/d0em00288g
Rikke Hammershøj _{1,

2,

3,

4} , Karina K. Sjøholm _{1,

2,

3,

4} , Heidi Birch _{1,

2,

3,

4} , Kristian K. Brandt _{4,

5,

6,

7} , Philipp Mayer _{1,

2,

3,

4}

Affiliation

The biodegradation kinetics of UVCB substances (unknown or variable composition, complex reaction products or biological materials) should be determined below the solubility limit to avoid experimental artefacts by the non-dissolved mixture. Recently, we reported delayed biodegradation kinetics of single petroleum hydrocarbons even at concentrations just below the solubility limit and attributed this to toxicity. The present study aimed to determine the concentration effect on biodegradation kinetics for constituents in two UVCBs, using surface water from a rural stream as the inoculum. Parallel biodegradation tests of diesel and lavender oil were conducted at concentrations just below the solubility limit and two orders of magnitude lower. The biodegradation kinetics of diesel oil constituents were generally similar at the two concentrations, which coincided with the stimulation of bacterial productivity (growth) at both concentrations, determined by [³H]leucine incorporation. By contrast, the biodegradation of lavender oil constituents was significantly delayed or even halted at the high test concentration. This was consistent with lavender oil stimulating bacterial growth at low concentration but inhibiting it at high concentration. The delayed biodegradation kinetics of lavender oil constituents at high concentration was best explained by mixture toxicity near the solubility limit. Consequently, biodegradation testing of hydrophobic UVCBs should be conducted at low, environmentally relevant concentrations ensuring that mixture toxicity does not affect the biodegradation kinetics.

中文翻译：

两种疏水UVCB的生物降解动力学测试-潜在的底物毒性支持低浓度测试

UVCB物质（未知或可变的组成，复杂的反应产物或生物材料）的生物降解动力学应确定在溶解度极限以下，以避免不溶混合物造成的实验伪像。最近，我们报道了即使在浓度仅低于溶解度极限的情况下，单一石油烃的生物降解动力学也被延迟，并将其归因于毒性。本研究的目的是使用农村溪流的地表水作为接种物，确定浓度对两种UVCB中生物降解动力学的影响。柴油和熏衣草油的平行生物降解测试是在浓度刚好低于溶解度极限且降低了两个数量级的条件下进行的。在两种浓度下，柴油成分的生物降解动力学通常相似，³ H]亮氨酸掺入。相反，在高测试浓度下，薰衣草油成分的生物降解被显着延迟甚至停止。这与薰衣草油在低浓度下刺激细菌生长但在高浓度下抑制细菌生长是一致的。薰衣草油成分在高浓度下延迟的生物降解动力学可以用溶解度极限附近的混合物毒性来最好地解释。因此，疏水性UVCB的生物降解测试应在低，与环境有关的浓度下进行，以确保混合物毒性不会影响生物降解动力学。

更新日期：2020-11-03

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