Abstract
The comparative effects of nickel (Ni2+) and arsenite (As(III)) on two diazotrophic cyanobacterial species were investigated in terms of photosynthetic attributes. Both metals demonstrated inhibitory effects on growth, pigments (chl a and phycocyanin) and photosystem II (PS II) photochemistry. However As(III) exerted severe effects as compared to Ni reflected by (1) reduced growth (2) significant inhibition of chl a and phycocyanin, (3) reduction in maximum photochemical efficiency of PSII and (4) depleted plastoquinone pool, thus suggesting it as more toxic. Moreover, comparative analysis of two species also demonstrated interspecies variation in terms of stress adaptive strategies reflected through higher sensitivity of Anabaena doliolum over Anabaena PCC7120. Thus the study recommends application of A. PCC7120 as biofertilizer in Ni and As(III) contaminated paddy fields. Key words: Anabaena sp. PCC7120, Anabaena doliolum, Nickel, As(III), maximal photochemical yield (Fv/Fm).
Highlights
Anthropogenic activities have altered the global biogeochemistry due to release of metals in recent years (Bhagat et al, 2016)
A. doliolum appears to be more sensitive as compared to Anabaena sp
The average IC50 determined for Ni was 9 and 15 μM and for arsenite 11 and 17 mM respectively for A. doliolum and Anabaena sp
Summary
Anthropogenic activities have altered the global biogeochemistry due to release of metals in recent years (Bhagat et al, 2016). Few metals hold prime importance for all living organisms due to their key role in basic life processes like photosynthesis and respiration, their elevated concentration in cells causes either their inappropriate binding to metal binding sites of enzymes or undesirable redox reactions causing lethal effects (Waldron et al, 2009a, b, 2010). Nickel is one such metal that plays a vital role in the cellular physiology of living organism (Poonkothai and Vijaywathi, 2012).
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