Microbial abundance, diversity and physicochemistry of sediments of Iko River Estuary, Akwa Ibom State

Abstract

Microbial abundance, diversity and physicochemistry of the sediments of Iko River Estuary in Akwa Ibom State, Nigeria were evaluated using standard plate count, analytical, whole bacterial community analyses and DNA sequencing techniques. The total hetrotrophic bacteria ranged from 2.1 × 106 to 3.6 × 106 CFU/g and sulphate reducing bacteria (SRB) from 2.1 × 101CFU/g to 4.1 × 101CFU/g. Culture dependent analysis revealed 16 bacterial genera with Bacillus subtilis, Kleibsiella sp, Pseudomonas aeruginosa and P. flourescens as the most abundant species (100%). Metagenomic analysis showed that the phyla Proteobacteria and Acidobacteria had the highest and lowest counts respectively for bacterial species. The two top spots were occupied by Unknown organisms with read counts of 582.0 (33.88%) and 562 (33.26%). Top known bacteria in sediments were Thiomicrospira frisia 20.0 (1.36%), Fusibacter 15.0 (1.02%), Thiomicrospira chilensis 13.0 (0.88%) and Sulfurimonas 13.0 (0.88%). Physicochemical analyses revealed slight decrease in sediment pH (6.20) upstream, (6.40) midstream, (6.50) downstream, Temperature (28oC for upstream and 29oC for downstream) and Electrical conductivity (130μScm-1) towards the downstream. The rich organic matter and microbial population in the sediments of Iko River Estuary provide nutrients and niches for commercially and ecologically important flora and fauna. These data may form the baseline during future ecological evaluation, monitoring and assessment of estuaries in the Niger Delta