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In aquatic environments, excessive amounts of inorganic nutrients, such as heavy metals, pose a metabolic risk and threaten to halt microbial activity. Metal-resistant bacteria, through various metabolic activities, can treat and detoxify harmful inorganic compounds. Thus, higher energy and electron transport system (ETS) demands may be necessary for metal bioremediation, but cell viability may be affected. Therefore, the metabolic respiration activity of cells in the presence of Cu, Zn, Ni, and Cr individually and in the quaternary is an important aspect of this study that relies on estimating the action of respiration enzymes responsible for metabolic activity and glucose reduction over periods of metallic stress and growth phases. Three species of bacteria, including B. megaterium, S. ginsenosidimutans, and K. rhizophila, were isolated from the electroplating effluent and used to determine the activity level of catalase, dehydrogenase enzymes, and glucose reduction. Their ability to sustain metabolic activity and understand their role in conferring tolerance and bioremediation capabilities to bacteria was evaluated. The findings revealed that metabolic activity was greater during the exponential phase than during the stationary phase. Catalase production was less affected by high metal levels; additionally, sugar reduction was improved but decreased with increased metal levels, and growth progressed, in comparison to dehydrogenase activity, which was more sensitive to high metal levels. Although respiratory metabolism activity decreased with increasing cell age and high metal concentrations, metabolism and viability persisted under metallic stress. This establishes the tolerability of bacteria and recommends them for potential bioremediation of metallic pollutants and environmental clean-up. [ABSTRACT FROM AUTHOR]

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Treatment of acid mine drainage (AMD) has been tested in batch experiments to evaluate the efficiency of both single and mixed substrates for mine-impacted waters. Synthetic mine water was used in all experiments. The single treatment was performed using limestone (LS), activated sludge (AS), and spent mushroom compost (SMC). In addition, different ratios of treatment media combined as mixed substrates were also tested for AMD in an anoxic condition. Physico-chemical parameters and heavy metals (Mn, Fe, Cu, Pb, Zn) were analyzed throughout 120 h. Hence, SMC showed great contribution in the process of AMD treatment in this study. The results showed that the mixed substrates were effective in removing heavy metals and sulfate i.e. uncrushed limestone mixed with AS, SMC and woodchips at 12 hours contact time with 88.15% of removal efficiency. [ABSTRACT FROM AUTHOR]

Heavy metals tolerant bacteria were isolated from electroplating industry. The activities of electroplating and metal processing industries are regarded as one of the major source of heavy metal pollution. This paper present about the role of microorganisms in heavy metal removal from industrial waste water. In this study 21 bacterial colonies were isolated and tested in the presence of different metals. After screening five best isolates which showed high resistances were selected. The result reveals that all isolates MH1, MH4, MH6 MH15 and MH21 were able to tolerate 50 mg/l of cr, cu, pb and cd. Isolates MH1 and MH21 tolerate 200 mg/l of cadmium while isolate MH4 also showed high degree of resistance to copper. These indicated that the isolates can be used efficiently in removal of heavy metals in contaminated industrial effluents. [ABSTRACT FROM AUTHOR]