Bioremoval of Cu(II), Zn(II), Pb(II) and Cd(II) by Nostoc muscorum isolated from a coal mining site Jayeeta Hazarika & Kannan Pakshirajan & Arindam Sinharoy & Mayashree B. Syiem Received: 30 May 2014 /Revised and accepted: 24 November 2014 # Springer Science+Business Media Dordrecht 2014 Abstract This study evaluated the potential of the cyanobac- terium Nostoc muscorum isolated from a mining environment for the removal of the heavy metals Cu(II), Zn(II), Pb(II) and Cd(II) from a constituent aqueous solution of different initial concentrations (5 to 50 mg L -1 ). Prior to the metal bioremoval experiments, the effect of three main culture parameters, i.e. inoculum volume, inoculum age and pH, on N. muscorum growth was assessed and their levels optimized employing the Taguchi experimental design technique. The batch metal re- moval kinetics showed a maximum removal of Pb(II) (98 %) and Cu(II) (87.8 %), followed by Cd(II) (82 %) and Zn(II) (67.2 %) at 5 mg L -1 initial metal concentration. Furthermore, estimation of protein, carbohydrate and biomass contents of the metal-exposed N. muscorum revealed that Zn(II) and Cd(II) are more toxic compared to Cu(II) at all initial metal concentrations, whereas it was more tolerant towards Pb(II). Keywords Cyanobacteria . Nostoc muscorum . Heavy metals . Bioremoval . Taguchi design Introduction Environmental pollution is a consequence of various anthro- pogenic activities, and amongst the different forms of envi- ronmental pollution, heavy metal contamination of surface water is a serious matter of concern primarily due to its direct influence over the food chain in the ecosystem (Bashan and Bashan 2010). Heavy metals are potent toxicity-causing agents in most living organisms, including humans (Rai 2010). Low concentrations of few heavy metals like Cu, Zn, Mg, Mn, etc. are required as vital micronutrients in many biological systems, but these heavy metals are potentially very toxic at an elevated level (Sunda and Huntsman 1998; Pinto et al. 2003). Thus, there is a need to control heavy metal release by treating metal-contaminated wastewater prior to its discharge. Conventional methods to treat heavy metals include chem- ical precipitation, ion exchange, electrochemical treatment, etc. which are either energy consuming, expensive or ineffi- cient, particularly at low initial metal concentrations. Hence, there is a constant search for novel techniques to reduce heavy metal levels below permissible limits (Schiewer and Volesky 2000). Bioremediation using microorganisms is viewed as an economically viable alternative in the interest of ecologically sound, effective and feasible treatment processes (Babu and Gupta 2008). Bioremoval involves the use of biological materials such as algae, bacteria, fungi, peat moss, agricultural waste, etc. in the removal of inorganic or organic pollutants (Madgwick 1994). Algae, in particular, act as a bioindicator of polluted surface water as they grow and reproduce in polluted sites (Rawat et al. 2011). Though most bacteria and fungi can be used for metal removal, the need for an additional organic carbon source and other nutrients severely limits their application potential (Prasanna et al. 2008). On the other hand, photosyn- thetic organisms like blue green algae (cyanobacteria) exhibit abundant growth and limited growth requirements, even under stressed environmental conditions, which make them highly suitable for bioremoval of heavy metals (Cain et al. 2008). Cyanobacteria have also been reported to efficiently scavenge heavy metals (Chaisuksant 2003; Akhtar et al. 2004; Dixit and Singh 2014) owing to their large surface area, high mucilage volume, presence of functional groups on their cell surface J. Hazarika : K. Pakshirajan (*) : A. Sinharoy Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India e-mail: pakshi@iitg.ernet.in M. B. Syiem Department of Biochemistry, North Eastern Hill University, Shillong, Meghalaya 793022, India J Appl Phycol DOI 10.1007/s10811-014-0475-3