Bacterial community dynamics in horizontal flow constructed wetlands with different plants for high salinity industrial wastewater polishing

Abstract

This study is focused on the diversity of bacterial communities from two series of horizontal subsurface flow constructed wetlands (CW) polishing high salinity tannery wastewater. Each series was planted with Arundo donax or Sarcocornia sp. in a substrate composed by expanded clay and sand. Chemical and biochemical oxygen demand removal efficiencies were similar in each series, varying between 58 and 67% (inlet COD 218 ± 28 mg L(-1)) and 60 and 77% (inlet BOD(5) 37 ± 6 mg L(-1)), respectively. High numbers of culturable bacteria were obtained from substrate and root samples - 5.75 × 10(6)-3.95 × 10(8) CFU g(-1) recovered on marine agar and 1.72 × 10(7)-8.46 × 10(8) CFU g(-1) on nutrient agar. Fifty bacterial isolates were retrieved from the CW, related phylogenetically to Firmicutes, Actinobacteria, Bacteroidetes, α-, β-, and γ-Proteobacteria. Changes in the bacterial communities, from roots and substrate of each series, related to the plant species, hydraulic loading rates and along CW operation were examined using denaturating gradient gel electrophoresis (DGGE). The clustering analysis suggested that a diverse and distinct bacterial community inhabits each series, which was related to the type of plant present in each CW.

Microbial abundance and community in subsurface flow constructed wetland microcosms: role of plant presence

“…Initially, the water in each microcosm was completely drained through the bottom valve. Sand from a depth of 5 to 10 cm was collected at five different locations (four corners and the center of the microcosms) (Calheiros et al 2010;Wu et al 2013) in each parallel and then mixed into a composite sample. The sand samples from the three parallel microcosms were subsequently combined into a composite sample before DNA extraction.…”

Comparisons of microbial abundance and community among different plant species in constructed wetlands in summer

“…First, each microcosm was completely drained. Sand samples were then collected from the top layer 5-10 cm deep at five different plots (Calheiros et al, 2010) in each parallel and then mixed into a composite sample. The sand samples were stored in 5 mL aseptic Eppendorf tubes, immediately placed on ice and stored at À80 C before microbial analysis.…”

Effects of plant biomass on bacterial community structure in constructed wetlands used for tertiary wastewater treatment

“…Most of these studies reported that plants had little or no effect on the community structure or abundance of the overall bacteria (Ahn et al, 2007;Baptista et al, 2008) or particular functional groups, such as the ammonia oxidizing bacteria (Gorra et al, 2007), sulfate reducing bacteria (Baptista et al, 2008), and methane oxidizing communities (DeJournett et al, 2007). However, several studies revealed that the presence of plants had a significant effect on the species richness and the structure of bacterial communities in CWs (Calheiros et al, 2009(Calheiros et al, , 2010. To date, studies conducted to assess how plants affect the microbial community structure in CWs have used conventional molecular biology methods (e.g., PCR-DGGE and FISH).…”