Metagenomic analysis of bacterial communities of Wadi Namar Lake, Riyadh, Saudi Arabia

Abstract

Wadi Namar lake is a new touristic attraction area in the south of Riyadh. Human activities around the lake may lead to changes in water quality with subsequent changes in microenvironment components including microbial diversity. The current study was designed to assess possible changes in bacterial communities of the water at Wadi Namar Lake. Therefore, water samples were collected from three different locations along the lake: L1 (no human activities, no plants), L2 (no human activity, some plants) and L3 (human activities, municipal wastes and some plants). The total DNA of the samples was extracted and subjected to 16S rDNA sequencing and metagenomic analysis; water pH, electrical conductivity (EC), total dissolved solids (TDS) as well as the concentration of Na⁺¹, K⁺¹, Cl^-1 and total N were analysed. Metagenomic analysis showed variations in relative abundance of 17 phyla, 31 families, 43 genera and 19 species of bacteria between the locations. Proteobacteria was the most abundant phylum in all locations; however, its highest abundance was in L1. Planctomycete phylum was highly abundant in L1 and L3, while its abundance in L2 was low. The phyla Acidobacteria, Candidatus Saccharibacteria, Nitrospirae and Chloroflexi were associated with high TDS, EC, K⁺¹ and Cl^-1 concentrations in L3; various human activities around this location had possibly affected microbial diversity. Current study results help in recognising the structure of bacterial communities at Wadi Namar Lake in relation to their surroundings for planning to environment protection and future restoration of affected ecosystems.

Keywords: 16S rRNA gene; Bacterial abundance; Environment; Metagenomics; Water microbiome.

Fig. 1

Map of Wadi Namar Lake displaying the three locations (L1, L2 and L3) of water samples collection. The map was prepared using ArcGIS programme (Esri, Redlands, California, U.S.).

Fig. 2

Richness and alpha diversity results of the microbial sequence data of the water samples collected from the three different locations (L1, L2 and L3) of Wadi Namar Lake, Riyadh, SA.

Fig. 3

Krona charts representation of metagenomic and taxonomic classification of bacterial communities in water samples collected from three different locations: L1 (A), L2 (B) and L3 (C), at Wadi Namar Lake, Riyadh, SA. Indicated numbers are the bacterial abundance (%).

Fig. 3

Krona charts representation of metagenomic and taxonomic classification of bacterial communities in water samples collected from three different locations: L1 (A), L2 (B) and L3 (C), at Wadi Namar Lake, Riyadh, SA. Indicated numbers are the bacterial abundance (%).

Fig. 4

Relative abundance (%) of the bacterial phyla identified by 16S metagenomics in water samples taken from three different locations (L1, L2 and L3) of Wadi Namar Lake, Riyadh, SA. Numbers indication the relative abundance of the top.

Fig. 5

Heat map representing relative abundance of the bacterial phyla identified by 16S metagenomic sequencing in water samples taken from three different locations (L1, L2 and L3) of Wadi Namar Lake, Riyadh, SA.

Fig. 6

Relative abundance (%) of the bacterial families identified by 16S metgenomic sequencing in water samples taken from three different locations (L1. L2 and L3) of Wadi Namar Lake, Riyadh, SA.

Fig. 7

Relative abundance (%) of the bacterial genera identified by 16S metagenomic sequencing in water samples taken from three different locations (L1, L2 and L3) of Wadi Namar Lake, Riyadh, SA.

Fig. 8

Relative abundance (%) of the bacterial species identified by 16S metagenomic sequencing in water samples taken from three different locations (L1, L2 and L3) of Wadi Namar Lake, Riyadh, SA.