Removal of cadmium by heavy metal–resistant bacteria isolated from Hussain Sagar Lake—Hyderabad

Abstract

Hussain Sagar Lake (17.4239° N, 78.4738° E) located at the heart of the capital of Telangana state, Hyderabad, is well known by many as a tourist spot. However, during the recent years, this lake has been contaminated by various industries surrounding the lake, especially from the Kukatpally channel and NTR Marg. Such inflow and heavy dumping of wastes have led to huge amount of toxic silt at the bottom and have taken a toll on the holding capacity of the lake. This paper focuses on the effect of bacteria on the heavy metals in the lake soil samples. Cadmium sulfate was used to prepare the heavy metal sample and a cadmium-resistant bacterium was obtained after 48 h of treatment. Among the eight bacterial isolates, one showed cadmium absorption capacity with a minimal inhibitory concentration of 500 mg/l of synthetically prepared solution. The sample also showed resistance to other heavy metals like copper and zinc. The bacterium from this sample was identified to be Pseudomonas fluorescens which was used for optimization whose growth was assessed based on UV absorbance at 600 nm. The optimum solution was obtained at a pH of 6.01 and a temperature of 32.7 °C, and the removal rate for 50 mg/l of cadmium was observed to be 90% and that of 100 mg/l was found to be 72%.