Abstract
The aim of the present study is to isolate, characterize and identify a novel strain ZC from the Metlaoui phosphate laundries wastewater (MPLW). The chemical characterization of this phosphate rich effluent showed an alkaline pH and is saline, highly turbid and rich in suspended matter and total solids. The MPLW samples were loaded with potentially toxic metals, presented in decreasing order as follows: magnesium (5655 mg L−1), potassium (45 mg L−1), lead (1 mg L−1), iron (0.7 mg L−1), cadmium (0.5 mg L−1), copper (0.3 mg L−1) and zinc (0.1 mg L−1). Due to the high COD/BOD5 ratio, a poorly biodegradable organic load is underlining. The newly isolated strain was identified as Lysinibacillus fusiformis using 16S rDNA sequencing analysis. The viability of this new strain was tested in presence of the zinc, lead, cadmium, manganese and copper at 1, 10 and 100 mM. The L. fusiformis survival, under metallic stress, was inversely proportional to metal ion concentrations, while lead and zinc were the most toxic ones using MTT assay. Then, the newly isolated strain was characterized in terms of enzyme production, proteomic alteration and antibiotic resistance. The strain ZC revealed some modifications in the biochemical and enzymatic profiles by either the appearance or/and the disappearance of some activities. In addition, the increase in metal ions stress and concentrations was proportional to the adherence and to the hydrophobicity. The presence of the metal ions suggested the change of sensitivity to the resistance of this strain towards tobramycin, kanamycin, neomycin, netilmicin and cefoxitin, showing an increase in the MARindex. The strain ZC, used as a biological tool for MPLW treatment, showed a reduction in the metal ion contents. This reduction was due to accumulation and/or adsorption, showing a bioprocessing performance of the newly isolated L. fusiformis.
Highlights
Introduction conditions of the Creative CommonsThe Company of Phosphates of Gafsa (CPG, Gafsa, Tunisia), the world’s fifth largest phosphate producer, was producing up to 8 million metric tons (t) of phosphate a year until 2010
Heavy metals and cations concentrations were determined by flame atomic absorption spectrometry (Analytik Jena NOVA 400, Jena, Germany) of samples digested with an acid mixture of HCl and HNO3
The results showed a decrease in cell viability with an increase in metal ion concentrations (Figure showed a decrease in cell viability with an increase in metal ion concentrations (Figure 2)
Summary
The Company of Phosphates of Gafsa (CPG, Gafsa, Tunisia), the world’s fifth largest phosphate producer, was producing up to 8 million metric tons (t) of phosphate a year until 2010. Social unrest in Tunisia, has subsequently affected production [1]. The phosphate is “washed” in several phases, including the mechanical separation and treatment to increase the P2 O5 content [1], consuming 5 t of water per ton of phosphate. The production of 8 million tons per year of marketable phosphate consumes approximately 10.5 million tons of water. The CPG used water is paleowater from
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