Wastes generated from the industries have created big crisis and it is big challenge to convert them in into the eco-friendly compounds by sustained methods. Industrial wastes (effluents) contain various toxic metals, harmful volatile compounds, along with several organic and inorganic compounds. There is a continuous demand of development of new strategies and novel sustained methods to overcome industrial waste management due to increasing urbanization (Evelyne et al., 2014). Long-term exposure of industrial effluents in the atmosphere can cause infectious diseases, neurological disorders, cancer, etc (Megharaj et al., 2003). The liberation of these toxic compounds, there is big losses in all the domains of society (Deepali, 2011).
In the industries effluents many toxic pollutants have been noticed e.g. chromium, sulfides, phenolic compounds, magnesium, sodium, potassium etc. One of the important toxic compounds known as chromium is also a necessary micronutrient for the development of many microorganisms (Thacker et al., 2005). But higher amount of chromium is highly toxic in all the environment e.g. air, water and soil. In nature, soil may retain Cr concentration ranges from 10 to 50 mg/kg (Pechova et al., 2007). In a survey, Indian tannery industries alone about 2000-3000 tons of chromium emits into the environment with high chromium concentrations from 2000 and 5000 mg/l. Through, it was a safe recommended permissible discharge limits is 2 mg/l (Belay, 2010).
In the nature, some microbes (especially blue green algae) have been reported for biological reduction (Biotransformation) of Cr (VI) into Cr (III). In the several studies it has been tried to identify chromium reductant microorganisms. Some fungi were also studied for their chromium (VI) reducing capacity (Deepali, 2011; Jayalakshmi et al., 2013). The ability of microbes to survive under Cr (VI) metal exposure and perform detoxification mechanism into Cr (III) is being trying to rectify globally. Every microbe has its own specific metal tolerance ability (capacity) under environmental conditions. In the literature, some mechanisms of Cr (VI) reducing strategies have been mentioned e.g. exclusion by permeability barrier, active transport efflux pumps, intra and extra cellular appropriation, enzymatic methods etc (Bruins et al., 2000). One of the bacteria which have been convert toxic Cr (VI) to nontoxic Cr (III) had been mentioned earlier (Jayalakshmi et al., 2013; Qian 2013]. Similarly, one of the fungus which has performed Cr (VI) bio-absorptive property has been explored. During biosorption Cr (VI) gets bound to the functional groups present on the surface of microbes and gets percolated inside (Noorjahan et al., 2014).
In nature vast varieties of cyanobacteria grows on soil surfaces and morphologically phylogenetically might be different (Joo et al., 2007). Well known microbe Leptolyngbya, which is a filamentous form of cyanobacterium and have characterized by the thin width of their cylindrical trichomes. Leptolyngbya have been isolated from various industrial effluents in the soil. Leptolyngbya boryana species is phylogenetically connected to Leptolyngbya sp (Anagnostidis et al., 2014).
In the present study, research was performed to search novel Cr (VI) reductant bacteria of microbes in tannery effluent soil. The finding of this research may be more suitable, effective, eco-friendly, sustainable and cost-effective biological treatment of leather industry wastewater. In the many studies Leptolyngbya boryana has been exposed in the nitrogen fixation and other related genomic analysis (VI) to nontoxic Cr (III) is not mentioned anywhere. So, in the study we have focused on its potential roles for the reduction of Cr (VI) to Cr (III).