Diverse Arbuscular Mycorrhizal Fungi (AMF) Communities Colonize Plants Inhabiting a Constructed Wetland for Wastewater Treatment

Abstract

Constructed wetlands (CWs) are biological wastewater treatment systems that comprise several components where plants and associated organisms play an important role in water depuration. Microbial studies emphasize bacterial dynamics, whereas studies of arbuscular mycorrhizal fungi (AMF) are scarce and the functional role of AMF in aquatic and wetland plants is poorly understood. The aim of this study was to analyze the AMF communities colonizing the roots of Canna indica, Canna flaccida, and Watsonia borbonica inhabiting a CW treating wastewater of a tourism unit. The dynamics of the AMF communities were evaluated by Denaturing Gradient Gel Electrophoresis (DGGE) of 18S rRNA gene amplification products along cold (C) and hot (H) seasons for three consecutive years. DGGE profiles allowed the estimation of AMF species richness (S), and Shannon-Wienner (H) and Pielou (J) indexes, for the different plant species, showing differences between species and along the years. Excised bands from DGGE were analyzed and identified through sequencing for arbuscular mycorrhiza, revealing the presence of AMF strains closely related to Glomus sp., Rhizophagus sp. and Acaulospora sp. genera. Concomitant water quality analyses showed that the system was effective in organic and nutrient removal during the sampling period. Findings from this study suggest that AMF diversity found in the CW is influenced by the water constituents, season, and plant species.

Toxicity Abatement of Wastewaters from Tourism Units by Constructed Wetlands

“…Wastewater at the inlet and outlet of the CW and the water of the pond can be considered as easily treatable by biological approaches, based on the BOD/COD ratio [28]. These findings are in alignment with what has been reported in literature for the operation of these systems, with a high organic loading in the period with a higher number of overnight stays, which usually occurs in the summer [6,29]. This gives rise to a typical low-medium strength untreated domestic wastewater, concerning its organic and nutrient contents.…”

“…However, its forecasted concentration, based on the concentration of the ionized ammonia detected, the pH of the samples, and the water temperature during the exposures [31], was likely lower than the 48 h LC 50 value and the corresponding 95% confidence interval reported for D. magna of 2.94 (2.70-3.22) mg NH 3 -N/L in sample B [32]. The toxicity of ammonia has been mainly attributed to nonionized ammonia, which is kept in equilibrium with the ionized form [29]. An EC 50 value of 1.5 mg/L NH 3 -N was reported for D. magna and an EC 50 value for NH 4 + -N of 95.2 mg/L was estimated by Villamar et al [33].…”

Responses of Rhizosphere Fungal Communities to the Sewage Sludge Application into the Soil

“…These primers amplified, in addition to AMF, also non-AMF sequences to a small extent [28,29,47,48,49,50], like Ascomycota and Basidiomycota with a higher incidence of Ascomycota (14% from all sequences) in our case. However, many studies using these primers have significantly increased our knowledge about AMF communities in various environments [51,52,53,54,55,56]. In our case, more than 86% of the DNA sequences in the control sample and more than 69% in the sludge sample belonged to some group of AM fungi.…”

Heavy-Metal Phytoremediation from Livestock Wastewater and Exploitation of Exhausted Biomass

“…Yadav et al [ 89 ] showed that the wetland bed depth has direct significant effect on HMs removal efficiencies in vertical flow CWs. In fact, the removal of Cr, Ni, Cu, Zn and Co increased by 16.6%, 22.9%, 20.4%, 21.5%, and 21.8%, respectively, when the gravel bed depth of CWs was increased from 0.3 to 1.5 m. In addition, the presence of various microorganisms and the initial concentration of HMs also affect plant performance [ 127 ]. The higher HMs concentration in water induces the higher uptake by plants [ 95 ].…”