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Chemotaxis Increases the Retention of Bacteria in Porous Media with Residual NAPL Entrapment
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-06-13 , DOI: 10.1021/acs.est.8b01172
Joanna S. T. Adadevoh 1 , C. Andrew Ramsburg 2 , Roseanne M. Ford 1
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-06-13 , DOI: 10.1021/acs.est.8b01172
Joanna S. T. Adadevoh 1 , C. Andrew Ramsburg 2 , Roseanne M. Ford 1
Affiliation
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Chemotaxis has the potential to decrease the persistence of nonaqueous phase liquid (NAPL) contaminants in aquifers by allowing pollutant-degrading bacteria to move toward sources of contamination and thus influence dissolution. This experimental study investigated the migratory response of chemotactic bacteria to a distribution of residual NAPL ganglia entrapped within a laboratory-scale sand column under continuous-flow at a superficial velocity of 0.05 cm/min. Naphthalene dissolved in a model NAPL 2,2,4,4,6,8,8-heptamethylnonane partitioned into the aqueous phase to create localized chemoattractant gradients throughout the column. A pulse mixture of equal concentrations of Pseudomonas putida G7, a strain chemotactic to naphthalene, and Pseudomonas putida G7 Y1, a nonchemotactic mutant, was introduced to the column and effluent bacterial concentrations were measured with time. Breakthrough curves (BTCs) for the two strains were noticeably different upon visual inspection. Differences in BTCs (compared to nonchemotactic controls) were quantified in terms of percent recovery and were statistically significant (p < 0.01). Chemotaxis reduced percent recovery in the effluent by 45% thereby increasing the population of bacteria that were retained within the column in the vicinity of residual NAPL contaminants. An increase in flow rate to a superficial velocity of 0.25 cm/min did not diminish cell retention associated with the chemotactic effect.
中文翻译:
趋化性通过残留NAPL截留增加多孔介质中细菌的保留
趋化性有可能通过允许降解污染物的细菌移向污染源并因此影响溶解,来降低含水层中非水相液体(NAPL)污染物的持久性。这项实验研究调查了趋化细菌对在连续流动速度为0.05 cm / min的实验室规模砂柱中截留的残留NAPL神经节的分布的迁移反应。将萘溶于模型NAPL 2,2,4,4,6,8,8-七甲基壬烷中,分配到水相中以在整个色谱柱中产生局部趋化性梯度。相同浓度的恶臭假单胞菌G7(对萘具有趋化性的菌株)和恶臭假单胞菌的脉冲混合物将非趋化突变体G7 Y1引入色谱柱,并随时间测量出水细菌浓度。在目测中,两种菌株的穿透曲线(BTC)明显不同。BTC的差异(与非趋化性对照相比)以百分比回收率进行量化,并具有统计学意义(p <0.01)。趋化作用使流出物中的回收率降低了45%,从而增加了残留在色谱柱中残留在NAPL污染物附近的细菌数量。流速增加至表面速度0.25 cm / min不会减少与趋化作用相关的细胞滞留。
更新日期:2018-06-14
中文翻译:
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趋化性通过残留NAPL截留增加多孔介质中细菌的保留
趋化性有可能通过允许降解污染物的细菌移向污染源并因此影响溶解,来降低含水层中非水相液体(NAPL)污染物的持久性。这项实验研究调查了趋化细菌对在连续流动速度为0.05 cm / min的实验室规模砂柱中截留的残留NAPL神经节的分布的迁移反应。将萘溶于模型NAPL 2,2,4,4,6,8,8-七甲基壬烷中,分配到水相中以在整个色谱柱中产生局部趋化性梯度。相同浓度的恶臭假单胞菌G7(对萘具有趋化性的菌株)和恶臭假单胞菌的脉冲混合物将非趋化突变体G7 Y1引入色谱柱,并随时间测量出水细菌浓度。在目测中,两种菌株的穿透曲线(BTC)明显不同。BTC的差异(与非趋化性对照相比)以百分比回收率进行量化,并具有统计学意义(p <0.01)。趋化作用使流出物中的回收率降低了45%,从而增加了残留在色谱柱中残留在NAPL污染物附近的细菌数量。流速增加至表面速度0.25 cm / min不会减少与趋化作用相关的细胞滞留。