Yang Liqiong, Chen Xijuan, Zeng Xiangfeng, Radosevich Mark, Ripp Steven, Zhuang Jie, Sayler Gary S
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
Front Microbiol. 2019 Nov 26;10:2691. doi: 10.3389/fmicb.2019.02691. eCollection 2019.
Chemotaxis and haptotaxis are important biological mechanisms that influence microbial movement toward concentrated chemoattractants in mobile liquids and along immobile surfaces, respectively. This study investigated their coupled effect, as induced by naphthalene (10 mg L), on the transport and retention of two pollutant-degrading bacteria, 5RL (5RL) and DQ1 (DQ1), in quartz sand and natural soil. The results demonstrated that DQ1 was not chemotactic, whereas 5RL was chemotactic at 25°C but not at 4°C due to the restricted movement. In a quartz sand column, haptotaxis did not play a role in increasing the transport of 5RL as compared with chemotaxis. Compared with a naphthalene-free soil column, 5RL broke through naphthalene-presaturated soil columns to reach a stable effluent concentration 0.5 pore volumes earlier due to advective chemotaxis occurring behind the plume front in the bulk solution. 5RL also demonstrated greater retention (e.g., a doubled rate of attachment and a one-third smaller breakthrough percentage) due to along-surface haptotaxis and near-surface chemotaxis occurring in less mobile water near the soil surface. However, both chemotaxis and haptotaxis were weakened when 5RL co-transported with naphthalene due to reduced adsorption of naphthalene on the soil. This study suggests that surface adsorption of naphthalene can mediate the relative importance of advective chemotaxis (facilitating initial breakthrough), near-surface chemotaxis (increasing bacterial collision), and haptotaxis (increasing bacterial residence time).
趋化作用和趋触作用是重要的生物学机制，分别影响微生物在流动液体中向浓缩化学引诱剂移动以及沿固定表面移动。本研究调查了萘（10毫克/升）诱导的趋化作用和趋触作用的耦合效应，对两种污染物降解细菌5RL和DQ1在石英砂和天然土壤中的迁移和滞留的影响。结果表明，DQ1没有趋化性，而5RL在25°C时有趋化性，但在4°C时由于移动受限而没有趋化性。在石英砂柱中，与趋化作用相比，趋触作用在增加5RL的迁移方面没有发挥作用。与无萘土壤柱相比，由于在主体溶液中羽流前沿后方发生平流趋化作用，5RL提前0.5个孔隙体积突破萘预饱和土壤柱，达到稳定的流出浓度。由于在土壤表面附近流动性较小的水中发生沿表面趋触作用和近表面趋化作用，5RL也表现出更大的滞留（例如，附着率加倍，突破百分比小三分之一）。然而，当5RL与萘共同迁移时，由于萘在土壤上的吸附减少，趋化作用和趋触作用都减弱了。本研究表明，萘的表面吸附可以调节平流趋化作用（促进初始突破）、近表面趋化作用（增加细菌碰撞）和趋触作用（增加细菌停留时间）的相对重要性。
