Abstract
Cadmium resisting bacteria (CRB) were present in all water and sediments (samples) collected from Alexandria Eastern Harbor, Egypt. The occurrences of CRB in sediments samples were higher than in water samples and reached up to 77.22% of total counts. Five isolates were selected to be the most resistant to cadmium with minimal inhibitory concentration of 60 ppm. The most potent isolate that accumulates a maximum Cd2+ concentration of 23.3 mg Cd2+/ g dry cells wasidentified as Vibrio harveyi. Medium components affecting metal removal by V. harveyi were explored based on the application of Plackett-Burman design. The growth of V. harveyi in the optimized culture conditions, recorded cadmium biosorption of 1.52 fold increase. Immobilized living cells of V. harveyi on hazelnut shells increased the uptake of cadmium to 49.35 mg Cd2+/g dry cells and removal efficiency up to 84%. Transmission electron microscope study confirmed the accumulation of Cd2+ by V. harveyi cells. Key words: Cadmium resisting bacteria, Vibrio harveyi, bioaccumulation, Plackett-Burman design.
Highlights
A variety of microbes inhabit extreme environments (Satyanarayana et al, 2005)
Cadmium resisting bacteria were present in all water and sediments samples and tolerated 20 ppm of Cd2+
The abundance of Cadmium resisting bacteria (CRB) that tolerate 40 ppm of Cd2+ were lower and no occurrence of cadmium resisting bacteria were in half of the samples, the occurrence in the remaining samples ranged from 0.11 to 4.39% in water samples and from 0.46 to 10.81% in sediments samples (Figure 3)
Summary
A variety of microbes inhabit extreme environments (Satyanarayana et al, 2005). Extreme habitats lie outside the range of conditions in which most of organisms live (Oarga, 2009). Extreme environments include high and low temperature, pH, pressure, salt concentration, nutrient concentration and water availability and conditions having high levels of radiation, harmful heavy metals and toxic compounds (organic solvents) (Satyanarayana et al, 2005). Soluble metal compounds can be deleterious to human health as well as to aquatic and marine environments (Semerjian, 2010; Srinivasa-Rao et al, 2010). The Eastern Harbor presents a natural laboratory site to study the effect of pollutants on the ecosystem. This Harbor receives about 230×103 m3 of untreated domestic sewage daily, beside minor wastes input from a local shipyard (Emara et al, 2008). The study extended to evaluate the efficiency of immobilized cells on agriculture waste
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
