Bioremediation and growth promoting effects of identified bacteria from different soil locations in Nigeria

Abstract

Soil contains diverse bacteria that are vital for maintaining soil health and fertility. While many soil bacteria are known for their plant  growth-promoting (PGP) abilities, combining this role with bioremediation is less common. The ability of the bacteria isolates to solubilize  phosphate, fix nitrogen and bioremediate environmental pollutants were investigated in this study. Isolated organisms were  further tested to know their ability to sequester toxicants such as heavy metals, pesticides and hydrocarbons while their capability to  produce growth hormones were also confirmed. The bacteria were molecularly identified using the 16S rDNA sequencing. The identified  isolates were: Bacillus species, Enterobacter species and Vagococcus fluvialis. Production of halo zones on the Pikovskaya's agar showed  the proficiency of the organisms to solubilize phosphate, change of Salkowiski's reagent to pink displayed their ability to produce Indole  acetic acid while their capability to produce siderophore was indicated by the change in the dark blue CAS indicator to orange. The heavy  metal tolerance test conducted showed that the organisms could resist metals at maximum concentration of: chromium (1.0mM), lead  (16.0mM), cadmium (1.6mM) and nickel (4.0mM). All the bacteria isolated and identified were found to have great biofertilizer potential.  At the same time, they also serve as bioremediators of polluted environment as well as biofertilizers.