Nutrients, surfactants, and aeration in constructed wetlands affect bacterial persistence and metabolic activity during the remediation of crude oil-contaminated water

The use of constructed wetlands (CWs) is one of the best options to treat wastewater. In CWs, microorganisms play a major role in the degradation of organic pollutants but the concentration of nutrients, surfactant, and aeration (NSA) in oil-contaminated water is one of the factors that affect the persistence and metabolic functioning of hydrocarbon-degrading microorganisms. In the present investigation, the influence of the addition of NSA on the persistence of the augmented bacteria, copy of (alkane hydroxylase gene) alkB gene, and its expression level in the water, soil, and plants of CWs were evaluated. The CWs mesocosms were developed by the vegetation of Typha latifolia and Cyperus laevigatus and inoculated with the bacterial consortium (Pseudomonas putida TYRI39, Acinetobacter junii TYRH47, Acinetobacter sp. CYRH17, Pseudomonas sp. CYSI27, and Pseudomonas sp. TYRH42). The mesocosms were provided with nutrients (20 mg l− 1 N, 2.6 mg l− 1 P, and 16.4 mg l− 1 K) in liquid form, surfactant Tween-20 (0.2