Microbially mediated redox transformations of manganese (II) along with some other trace elements: a study from Antarctic lakes |
| |
Authors: | K P Krishnan Rupesh Kumar Sinha Kiran Krishna Shanta Nair S M Singh |
| |
Institution: | (1) National Centre for Antarctic and Ocean Research, Headland Sada, Vasco da Gama, Goa, 403804, India;(2) National Institute of Oceanography, Dona Paula, Goa, India |
| |
Abstract: | The significance of freshwater systems in global manganese cycles is well appreciated. Yet, the polar systems, which encompass
the largest freshwater repository in the world, have been least studied for their role in manganese cycling. Here, we present
results from a study that was conducted in the brackish water lakes in the Larsemann Hills region (east Antarctica). The rate
of in situ manganese oxidation ranged from 0.04 to 3.96 ppb day−1. These lakes harbor numerous manganese-oxidizing bacteria (105 to 106 CFU l−1), predominantly belonging to genera Shewanella, Pseudomonas and an unclassified genus in the family Oxalobacteriaceae. Experiments were conducted with representatives of predominant
genera to understand their contribution to Mn cycling and also to assess their metabolic capabilities in the presence of this
metal. In general, the total and respiring cell counts were stimulated to a maximum when the growth medium was amended with
10 mM manganese. The addition of manganese promoted the use of d-mannitol, maltose, etc., but inhibited the use of maltotriose, l-serine and glycyl l-glutamic acid. The bacterial isolates were able to catalyze both the redox reactions in manganese cycling. In vitro manganese
oxidation rates ranged from 3 to 147 ppb day−1, while manganese reduction rates ranged from 35 to 213 ppb day−1. It was also observed that the maximum stimulation of manganese oxidation occurred in the presence of cobalt (81 ± 57 ppb day−1), rather than iron (37 ± 16 ppb day−1) and nickel (40 ± 47 ppb day−1). Our studies suggest that cobalt could have a more profound role in manganese oxidation, while nickel promoted manganese
reduction in polar aquatic systems. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|