Biosorption of arsenic (III) from aqueous solution using calcium alginate immobilized dead biomass of Acinetobacter sp. strain Sp2b.

This study presents a novel biosorbent developed by immobilizing dead Sp2b bacterial biomass into calcium alginate (CASp2b) to efficiently remove arsenic (AsIII) from contaminated water. The bacterium Sp2b was isolated from arsenic-contaminated industrial soil of Punjab, a state in India. The strain was designated Acinetobacter sp. strain Sp2b as per the 16S rDNA sequencing, GenBank accession number -OP010048.The CASp2b was used for the biosorption studies after an initial screening for the biosorption capacity of Sp2b biomass with immobilized biomass in both live and dead states. The optimum biosorption conditions were examined in batch experimentations with contact time, pH, biomass, temperature, and AsIII concentration variables. The maximum biosorption capacity (qmax = 20.1 ± 0.76 mg/g of CA Sp2b) was obtained at pH9, 35 ̊ C, 20 min contact time, and 120 rpm agitation speed. The isotherm, kinetic and thermodynamic modeling of the experimental data favored Freundlich isotherm (R2 = 0.941) and pseudo-2nd-order kinetics (R2 = 0.968) with endothermic nature (ΔH° = 27.42) and high randomness (ΔS° = 58.1).The scanning electron microscopy with energy dispersive X-ray (SEM-EDX) analysis indicated the As surface binding. The reusability study revealed the reasonable usage of beads up to 5 cycles. In conclusion, CASp2b is a promising, efficient, eco-friendly biosorbent for AsIII removal from contaminated water.

Effect of Arsenic on Fluoride Tolerance in Microbacterium paraoxydans Strain IR-1.

Fluoride (F) and arsenic (As) are two major contaminants of water and soil systems around the globe, causing potential toxicity to humans, plants, animals, and microbes. These contaminated soil systems can be restored by microorganisms that can tolerate toxic stress and provide rapid mineralization of soil, organic matter, and contaminants, using various tolerance mechanisms. Thus, the present study was undertaken with the arsenic hyper-tolerant bacterium Microbacterium paraoxydans strain IR-1 to determine its tolerance and toxicity to increasing doses of fluoride, either individually or in combination with arsenic, in terms of growth inhibition using a toxicity unit model. The minimum inhibitory concentration (MIC)and half maximal inhibitory concentration (IC50) values for fluoride increased, from 9 g/L to 11 g/L and from 5.91 ± 0.1 g/L to 6.32 ± 0.028 g/L, respectively, in the combination (F + As) group. The statistical comparison of observed and expected additive toxicities, with respect to toxicity unit (TU difference), using Student's t-test, was found to be highly significant (p < 0.001). This suggests the antagonistic effect of arsenic on fluoride toxicity to the strain IR-1. The unique stress tolerance of IR-1 ensures its survival as well as preponderance in fluoride and arsenic co-contaminated sites, thus paving the way for its possible application in the natural or artificial remediation of toxicant-exposed degraded soil systems.

Efficacy and tolerability of injectable sodium valproate in patients with mania.

BACKGROUND: Sodium valproate is among the newer mood stabilizers and is also an anticonvulsant. AIM: To assess the effect of intravenous sodium valproate in patients with acute manic episodes of bipolar disorder. METHODS: A 1-week open trial was conducted in the year 2004-2005 at the emergency ward of the Psychiatric Centre, SMS Medical College, Jaipur, in which 30 patients participated. CONCLUSION: Substantial improvement was seen. No major side-effects were noted except marginal elevation of the SGOT and SGPT. The findings suggest that injectable sodium valproate is a safe and effective mood stabilizer for patients with mania.