A Cr(VI)-reducing Microbacterium sp. strain SUCR140 enhances growth and yield of Zea mays in Cr(VI) amended soil through reduced chromium toxicity and improves colonization of arbuscular mycorrhizal fungi

Pot culture experiments were conducted in a glasshouse to evaluate the effects of four efficient Cr(VI)-reducing bacterial strains (SUCR44, SUCR140, SUCR186, and SUCR188) isolated from rhizospheric soil, and four arbuscular mycorrhizal fungi (AMF—Glomus mosseae, G. aggregatum, G. fasciculatum, and G. intraradices) alone or in combination, on Zea mays in artificially Cr(VI)-amended soil. Presence of a strain of Microbacterium sp. SUCR140 reduced the chromate toxicity resulting in improved growth and yields of plants compared to control. The bioavailability of Cr(VI) in soil and its uptake by the plant reduced significantly in SUCR140-treated plants; the effects of AMF, however, either alone or in presence of SUCR140 were not significant. On the other hand, presence of AMF significantly restricted the transport of chromium from root to the aerial parts of plants. The populations of AMF chlamydospores in soil and its root colonization improved in presence of SUCR140. This study demonstrates the usefulness of an efficient Cr(VI)-reducing bacterial strain SUCR140 in improving yields probably through reducing toxicity to plants by lowering bioavailability and uptake of Cr(VI) and improving nutrient availability through increased mycorrhizal colonization which also restricted the transport of chromium to the aerial parts.     

In vitro Cr(VI) reduction by cell-free extracts of chromate-reducing bacteria isolated from tannery effluent irrigated soil

Four efficient Cr(VI)-reducing bacterial strains were isolated from rhizospheric soil of plants irrigated with tannery effluent and investigated for in vitro Cr(VI) reduction. Based on 16S rRNA gene sequencing, the isolated strains SUCR44, SUCR140, SUCR186, and SUCR188 were identified as Bacillus sp. (JN674188), Microbacterium sp. (JN674183), Bacillus thuringiensis (JN674184), and Bacillus subtilis (JN674195), respectively. All four isolates could completely reduce Cr(VI) in culture media at 0.2 mM concentration within a period of 24–120 h; SUCR140 completely reduced Cr(VI) within 24 h. Assay with the permeabilized cells (treated with Triton X-100 and Tween 80) and cell-free assay demonstrated that the Cr(VI) reduction activity was mainly associated with the soluble fraction of cells. Considering the major amount of chromium being reduced within 24–48 h, these fractions could have been released extracellularly also during their growth. At the temperature optima of 28 °C and pH?7.0, the specific activity of Cr(VI) reduction was determined to be 0.32, 0.42, 0.34, and 0.28 μmol Cr(VI)?min^?1?mg^?1 protein for isolates SUCR44, SUCR140, SUCR186, and SUCR188, respectively. Addition of 0.1 mM NADH enhanced the Cr(VI) reduction in the cell-free extracts of all four strains. The Cr(VI) reduction activity in cell-free extracts of all the isolates was stable in presence of different metal ions tested except Hg²⁺. Beside this, urea and thiourea also reduced the activity of chromate reduction to significant levels.     

Hepatotoxicity of graphene oxide in Wistar rats

Environmental Science and Pollution Research - Graphene oxide (GO) has a multitude of applications in areas of nanomedicine, electronics, textile, water purification, and catalysis among others. GO...     

Developmental Processes, Changing Lifestyle and Traditional Wisdom: Analyses from Western Himalaya

Traditional knowledge and practices are important in prudent resource use and biodiversity conservation. The implications of modernization and changing lifestyle are discussed in the context of agriculture and resource use, the two sectors in which maximum modernization has occurred. The information was gathered through observations and structured interviews over three years (July 1996 to July 1999) of field work in the western Himalaya. It was observed that forest based subsistence agriculture has given way to the market dependant cash crop cultivation. That apart from loss of genetic diversity, has also resulted in the degradation of forests. The use of wild plants in the day-to-day activities has also declined and dependence on high value market products has increased. Currently, wild plants are used only if no other cheap substitute is available in the market or if the use is economically beneficial to the people. Thus, the knowledge gathered through ages of experience is eroding because of the activities geared for short-term economic benefits which, in long run, may not be sustainable.     

Uptake of soil applied paclobutrazol in mango (Mangifera indica L.) and its persistence in fruit and soil

Paclobutrazol is a plant growth regulator that is used to counter alternate bearing habit of mango (Mangifera indica L.). The uptake and persistence of paclobutrazol residues in mango fruits and soil respectively, was studied following its application at tree basin soil @5 and 10 g a.i. per tree for three consecutive years. Residues of paclobutrazol were found in unripe mango fruits at levels below permissible level while the same was generally not detected in fully mature mango fruits ready for harvest. There was no effect of consecutive yearly applications on the amount of paclobutrazol residues in mango fruit. However, the residues of paclobutrazol were found in tree basin soil (0-15 cm) at the end of each season and there was a small increase in the amount of residues corresponding to the number of yearly applications that had been made. GC-MS analysis confirmed that the sample peaks obtained corresponded to paclobutrazol residues present in mango and soil.     

Behaviour of forchlorfenuron residues in grape,soil and water

Persistence of forchlorfenuron residues in grape berries at harvest following its dip application as single or split doses to grape berry clusters and periodic dissipation of forchlorfenuron residues in grape berries following foliar spray application were studied. Periodic dissipation of forchlorfenuron residues following its fortification in soil and water were also studied. Splitting the dip application concentration of forchlorfenuron to grape berries reduced its residues in the berries at harvest, which persisted for more than 65 days from all treatments. In case of foliar application, however, the residues of forchlorfenuron in/on the grape berries persisted for 15-20 days only from three treatment concentrations of 2, 3 and 4 ml/l and dissipated with half-lives of 3.4-4.5 days. The residues of forchlorfenuron dissipated faster in soils maintained at field capacity moisture condition than in air dry soils. There was wide variation in its residue persistence in soil (DT50 = 15.1-121.3 days) depending on soil type and moisture condition. Forchlorfenuron residues persisted for more than 30 days in water and its dissipation was fastest at a water salinity level of 3.85 mmho/ cm although the rate of dissipation was not significantly affected by the change in salinity level from <0.04 to 5.90 mmho/cm.     

Nanomaterials in Biology

Environmental Science and Pollution Research -     

Immunostimulants for shrimp aquaculture: paving pathway towards shrimp sustainability

Environmental Science and Pollution Research - At present, food security is a matter of debate of global magnitude and fulfilling the feeding requirement of?&gt;?8 billion human...     

UV-irradiation assisted functionalization and binding of Pd nanoparticles in polycarbonate membranes for hydrogen separation

Environmental Science and Pollution Research - For hydrogen-based energy systems development, purified hydrogen (H2) is a basic requirement and it can be achieved by using the H2-selective...     

General plume dispersion model (GPDM) for point source emission

Gaussian-based dispersion models are widely used to estimate local pollution levels. The accuracy of such models depends on stability classification schemes as well as plume rise equations. A general plume dispersion model (GPDM) for a point source emission, based on Gaussian plume dispersion equation, was developed. The program complex was developed using Java and Visual basic tools. It has the flexibility of using five kinds of stability classification schemes, i.e., Lapse Rate, Pasquill–Gifford (PG), Turner, σ–θ and Richardson number. It also has the option of using two types of plume rise formulations – Briggs and Holland’s. The model, applicable for both rural and urban roughness conditions, uses meteorological and emission data as its input parameters, and calculates concentrations of pollutant at the center of each cell in a predefined grid area with respect to the given source location. Its performance was tested by comparing with 4-h average field data of continuous releases of SO₂ from Dadri thermal power plant (Uttar Pradesh, India). Results showed that the Turner scheme used with Holland’s equation gives the best outcome having a degree of agreement (d) of 0.522.