ABSTRACT
Selenium (Se) and tellurium (Te) belong to the chalcogen group (periodic table group 16) and share many common characteristics. Both are metalloids and exist in four oxidation states, i.e. +VI, +IV, 0, and -II in nature (Mal et al., 2016a; Zannoni et al., 2008). Often the Se and Te oxyanion contamination occurs through anthropogenic activities such as mining, refinery industries and coal combustion and electronic industries (Belzile & Chen, 2016; Mal et al., 2016a). Oxyanions (selenate, selenite and tellurate, tellurite) of both elements are soluble and mobile, thus bioavailable and toxic (Nancharaiah & Lens, 2015; Turner et al., 2012). Compared to that, elemental Se and Te are non-soluble and less toxic. Bioreduction of Se/Te oxyanions to elemental Se(0) and elemental Te(0), respectively, can be achieved using both aerobic and anaerobic microorganisms and microbial reduction of chalcogen oxyanions is gaining considerable interest for bioremediation and treatment of Se/Te wastewaters due to their relatively low cost, non-toxic and environmental friendly approach (Mal et al., 2016b; Nancharaiah & Lens, 2015; Nancharaiah et al., 2016; Turner et al., 2012).
