Uttiya Dey

Green synthesis of silver nanoparticles and its application for mosquito control

Objective To synthesize and characterize silver nanoparticles from aqueous root extract of Parthenium hysterophorus (P. hysterophorus) and also to evaluate the potentiality of synthesized silver nanoparticles as larvacidal agent against Culex quinquefasciatus (Cx. quinquefasciatus).

An approach to polymer degradation through microbes

Inertness and indiscriminate uses as well as growing water and land pollution problems have lead to concern about plastics. Present paper investigates the possibility of plastic degradation by microbes isolated from forest soil and automobile washout sludge. The in-vivo degradation was studied by litter bag experiment by taking 1 g of each plastic and buried under forest soil and automobile wash-out sludge at a depth of 15 cm from the surface during the month of September to February, 20102011. An in-vitro experiment was started after collecting the plastic samples from the litter bag experiment and the microbes were isolated from the surface of the plastic. Then the isolated microbes inoculated in the Burk’s medium without carbon source in two sets, one with plastic and the other with polyethylene glycol (PEG). Result showed that no variety of plastic comfortable degraded under burial condition during six months. But interesting result was recorded from Scanning Electron Microscopy (SEM) study. The preliminary screening of biodegradation capability was done by Fourier Transform Infra Red (FTIR) Spectroscopy for surface changes. Again, degradation of PEG by microbes clearly indicates their existence in the said medium. Therefore it can be speculated that microbes has enough potential to degrade plastic with due course of time.

Isolation and characterization of arsenic-resistant bacteria and possible application in bioremediation

Highlights • Isolation of two rod-shaped Gram-positive bacteria.• Isolates tolerate up to 4500 ppm and 550 ppm concentration of arsenate and arsenite.• Bacteria mediated arsenic bioremediation.

Soil enzyme activity under arsenic-stressed area of Purbasthali, West Bengal, India

A study was conducted to assess the seasonal variations of soil enzymes (amylase, invertase, cellulase, and urease), and physicochemical parameters of soil in an arsenic (As)-contaminated area. Ten different sampling sites of Purbasthali, West Bengal, India, were chosen for this experiment, and the collected data were compared with that of the control area, Burdwan University Farm, Burdwan. The As concentrations were found to be high in all experimental soil samples. Only urease and amylase activities were found to vary significantly (p < 0.01) with organic carbon content during pre-monsoon season but nonsignificant (p > 0.05) relationships were recorded between soil enzyme activities and organic carbon content during the post-monsoon period. Again urease and cellulase activities were found to vary significantly (p < 0.05) with soil As content in both pre- and post-monsoon periods, respectively. Similar observations were recorded from cluster analysis in both the seasons. Moreover, all tested soil enzymes activities except urease in post-monsoon period have shown significant relationship (p < 0.01, p < 0.05) with soil moisture in both pre- and post-monsoon periods. Therefore, it is suggested that the study of enzymatic activities and physicochemical parameters of soil may be helpful in assessing the effects of As on the biochemical quality of soils.

Ultrastructural deformation of plant cell under heavy metal stress in Gram seedlings

Abstract Nowadays, heavy metal pollution has become a serious environmental problem on global scale. The heavy metals are non-biodegradable in nature, which can easily accumulate in the organisms of lower trophic level, and enter to the human body system through food chain. From this backdrop, the present experiment highlighted the effect of three heavy metals (Cr, Pb, and Mn) in different concentrations (25, 50, and 75 ppm) on Cicer arietinum in terms of growth physiology, metal uptake, biochemistry, and ultrastructural deformation. The results showed that with increasing metals (Cr and Pb) concentrations from 25 ppm to 75 mg/L both root and shoot length decreased along with root and shoot biomass. However, Mn showed little improvement in all growth physiological parameters at 50 ppm concentration. Biochemical parameters also revealed that both Cr and Pb reduced 64.94 and 69.61% total chlorophyll, respectively, with respect to control. Chlorophyll “a” to “b” ratio was highest in Mn followed by Cr and Pb at higher concentration (75 ppm). Metal accumulation pattern indicated that Cr is less accumulated in root shoot and leaf compared to Mn and Pb in all the studied concentrations. However, accumulation of Mn in shoot was always higher compared to Pb in all studied concentrations. Ultrastructural damage was recorded highest for Cr in root, shoot and leaf at both 25 and 50 ppm concentration. However, at 75 ppm Pb showed highest deformation in root and leaf was observed.

Investigation of Bioremediation of Arsenic by Bacteria Isolated from an Arsenic Contaminated Area

An interesting and popular topic of research is the development of modern, innovative and cost effective technologies for the decontamination of arsenic contaminated water. The main objective of the study was to isolate arsenic resistant bacteria which can be used to remove arsenic from the contaminated water of an arsenic affected area, so that clean drinking water can be provided to the affected people. In this present investigation, we are reporting three Gram positive, rod shaped bacteria, namely, S4, S7 and S8, isolated from arsenic contaminated soils of Purbasthali I block of Burdwan, West Bengal, India, which can tolerate high concentrations of both arsenate and arsenite. These three bacteria can remove more than 50% of arsenate and arsenite from arsenic amended media. The isolate S8 is an arsenic oxidizing bacterium which can oxidize arsenite to the less toxic form of arsenate. This particular strain, having both characteristics of removing and oxidizing arsenic was identified through 16S rRNA gene sequence analysis, as Aneurinibacillus aneurinilyticus DM-TSB-1. This particular bacterium, having these unique properties can be used for the bioremediation of arsenic contaminated water which will be highly beneficial for the human population as well as the livestock and vegetation of the affected area.