Cadmium bioremediation by metal-resistant mutated bacteria isolated from active sludge of industrial effluent

Bioremediation of metal pollutants from industrial wastewater using metal resistant bacteria is a very important aspect of environmental biotechnology. In this study, three species of Pseudomonas aeruginosa were isolated from active sludge of a food factory in the city of Kerman. The bacterial identity was determined by various biochemical tests. Among them, isolate number one could grow on Muller-Hinton agar medium containing 6mM cadmium ion [Cd[2+]] and was therefore selected for further study. The isolates were subjected to mutation by two mutagenic agents [Acridine Orange and Acriflavine] using gradient plate and SIC techniques. The Minimum Inhibitory Concentration of Cd[2+] for the isolate one after mutation was increased to 7mM. Removal of Cd[2+] using mutated and wild type strains of this bacterium was carried out at different time intervals [10-300 minutes]. It was observed that within 60 minutes, 94.7% of cadmium was removed in 30mg/L of Cd[2+] solution. However, with 60mg/L Cd[2+] solution, only 53.58% and 38.68% Cd[2+] removed were achieved by mutated and wild type bacteria, respectively. The equilibrium data was fitted by Langmuir isotherm equation and the related parameters for Cd[+2] were derived. Based on the data obtained in this study, it can be concluded that biomass of this bacterium can be used for bioremediation of cadmium from industrial waste processing plants with high efficiency

[Elimination of copper and zinc from industrial wastes by mutated bacteria]

Today, toxic effluents have created ecological and health problems in and around the industrial cities resulting in death of nearby living organisms. The aim of this research was to increase the elimination of copper and zinc from copper factory effluents in Kerman/Iran through mutation inducing in metal-resistant bacteria by using Acriflavine, Acridine orange and Ethidium bromide. A total of 20 strains of Pseudomonas spp. were isolated from water and soil of the factory and subjected to microbiological identification. Maximum Inhibitory Concentration [MIC] to Cu and Zn were determined by agar dilution method. Those strains with the highest MIC to these metals [5mM] were subjected to 400-3200mg/L of the above mutagenic agents. After determination of MIC those colonies which were capable to grow on 20mM copper were selected for atomic absorption spectroscopy. According to the atomic absorption spectroscopy of dried biomass obtained from resistant strains after exposure to mutagenic agents, strains 6,7,8,9,10,13 and 16 showed the highest accumulation of CU and Zn [10mM for Cu and 20mM for Zn]. Strain 13 had the highest absorption of Cu [0.35%/mg biomass] and strain 10 showed the highest accumulation of Zn [0.33%/mg biomass]. Elimination of heavy metals by artificially mutated bacteria can be suggested as a cost effective solution to this environmental health issue

Application of metal resistant bacteria by mutational enhancment technique for bioremediation of copper and zinc from industrial wastes

In this research, using mutation in the metal resistant bacteria, the bioremediation of the copper and zinc from copper factory effluents was investigated. Wastewater effluents from flocculation and rolling mill sections of a factory in the city of Kerman were collected and used for further experiments. 20 strains of Pseudomonas spp. were isolated from soil and effluents surrounding factory and identified by microbiological methods. Minimum inhibitory concentrations for copper [Cu] and zinc [Zn] were determined by agar dilution method. Those strains that exhibited highest minimum inhibitory concentrations values to the metals [5mM] were subjected to 400-3200 mg/L concentrations of the three mutagenic agents, acriflavine, acridine orange and ethidium bromide. After determination of subinhibitory concentrations, the minimum inhibitory concentrations values for copper and zinc metal ions were again determined, which showed more than 10 fold increase in minimum inhibitory concentrations value [10 mM for Cu and 20 mM for Zn] with P