Characterization of novel thorium tolerant Ochrobactrum intermedium AM7 in consort with assessing its EPS-Thorium binding.

Currently, radioactive waste is disposed primarily by burial in a deep geological repository. Microorganisms thriving in such contaminated environment show tolerance to radionuclides. In the present study the bacterial flora, from soil sample collected from an area around atomic power station exposed to radionuclides and heavy metals, was cultivated and assessed for thorium (Th) tolerance. Of all the isolates, strain AM7 identified as O. intermedium was selected since it could thrive at high levels of Th (1000 mg L-1). AM7 was characterized physico-chemically and its culture medium was optimized using central composite design of response surface methodology for assessing its growth properties in presence of Th. The strain also showed exceptional exopolysaccharide (EPS) production and its yield was further analyzed using one factor study to investigate the influence of each medium component. On supplementing the EPS medium with Th, no significant decrease in yield was observed. FTIR spectroscopy revealed the functional groups of EPS involved in EPS-Th binding. To the best of our knowledge, this is the first report showing exceptional Th-tolerance by any bacteria. Such study will help other researchers to strategize an environment-friendly way of radwaste disposal.

Impact of environmental stress on biochemical parameters of bacteria reducing chromium.

Chromium pollution is produced in connection with industrial processes like in tanneries. It has been suggested that bioremediation could be a good option for clean up. The stress effect of variable chromate levels, pHs and growth temperatures on biochemical parameters of two Cr(VI) reducing bacterial strains Pseudomonas aeruginosa Rb-1 and Ochrobactrum intermedium Rb-2 was investigated. Transmission electrone microscopy (TEM) was performed to study the intracellular distribution of Cr(VI). It was observed that initial stress of 1000 µgmL(-1) caused significant enhancement of all studied biochemical parameters at pH 7.0 and growth temperature of 37 °C showing great bioremediation potential of the strains. Transmission electron microscopy revealed that the distribution of chromium precipitates was not uniform as they were distributed in the cytoplasm as well as found associated with the periplasm and outer membrane. Fourier transform infrared spectroscopy showed the possible involvement of carboxyl, amino, sulpohonate and hydroxyl groups present on the bacterial cell surface for the binding of Cr(VI) ions. Cr(VI) stress brought about changes in the distridution of these functional groups. It can be concluded that the investigated bacterial strains adjust well to Cr(VI) stress in terms of biochemical parameters and along that exhibited alteration in morphology.

Impact of environmental stress on biochemical parameters of bacteria reducing chromium

Chromium pollution is produced in connection with industrial processes like in tanneries. It has been suggested that bioremediation could be a good option for clean up. The stress effect of variable chromate levels, pHs and growth temperatures on biochemical parameters of two Cr(VI) reducing bacterial strains Pseudomonas aeruginosa Rb-1 and Ochrobactrum intermedium Rb-2 was investigated. Transmission electrone microscopy (TEM) was performed to study the intracellular distribution of Cr(VI). It was observed that initial stress of 1000 µgmL-1 caused significant enhancement of all studied biochemical parameters at pH 7.0 and growth temperature of 37 °C showing great bioremediation potential of the strains. Transmission electron microscopy revealed that the distribution of chromium precipitates was not uniform as they were distributed in the cytoplasm as well as found associated with the periplasm and outer membrane. Fourier transform infrared spectroscopy showed the possible involvement of carboxyl, amino, sulpohonate and hydroxyl groups present on the bacterial cell surface for the binding of Cr(VI) ions. Cr(VI) stress brought about changes in the distridution of these functional groups. It can be concluded that the investigated bacterial strains adjust well to Cr(VI) stress in terms of biochemical parameters and along that exhibited alteration in morphology.