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In the recent times, plants are facing certain types of environmental stresses, which give rise to formation of reactive oxygen species (ROS) such as hydroxyl radicals, hydrogen peroxides, superoxide anions and so on. These are required by the plants at low concentrations for signal transduction and at high concentrations, they repress plant root growth. Apart from the ROS activities, hydrogen sulfide (H2S) and nitric oxide (NO) have major contributions in regulating growth and developmental processes in plants, as they also play key roles as signaling molecules and act as chief plant immune defense mechanisms against various biotic as well as abiotic stresses. H2S and NO are the two pivotal gaseous messengers involved in growth, germination and improved tolerance in plants under stressed and non‐stress conditions. H2S and NO mediate cell signaling in plants as a response to several abiotic stresses like temperature, heavy metal exposure, water and salinity. They alter gene expression levels to induce the synthesis of antioxidant enzymes, osmolytes and also trigger their interactions with each other. However, research has been limited to only cross adaptations and signal transductions. Understanding the change and mechanism of H2S and NO mediated cell signaling will broaden our knowledge on the various biochemical changes that occur in plant cells related to different stresses. A clear understanding of these molecules in various environmental stresses would help to confer biotechnological applications to protect plants against abiotic stresses and to improve crop productivity. [ABSTRACT FROM AUTHOR]

The current study deals with Cr(VI) removal using unmodifiedaluminananoparticles of two different sizes (NA1: mean hydrodynamic diameter= 75.3 ± 2.8 nm; NA2: mean hydrodynamic diameter = 229.8 ±3.3 nm). The equilibrium adsorption capacities, 73.2 and 59.4 mg ofCr(VI)/g of adsorbent, were noted for NA1 and NA2, respectively, underoptimized conditions (pH 7.0, temperature = 27 °C, initial Cr(VI)concentration = 20 mg L–1, adsorbent dosage = 0.1gL–1) but different contact times (120 min for NA1,180 min for NA2). For both sorbents, the equilibrium adsorption datafitted well with the Langmuir isotherm model. The adsorbent NA1 followeda pseudo-second-order kinetics, whereas NA2 followed pseudo-first-orderkinetics. Surface characterization studies (zeta potential measurement,scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy(EDX), and Fourier transform infrared (FTIR) spectroscopy) substantiatedoxyanionic binding on the sorbent surface. The EPR and XRD spectroscopyconfirmed the existence of reduced Cr(III) on the adsorbent surface.The applicability of the sorbent in Cr(VI)-contaminated water wasstudied. [ABSTRACT FROM AUTHOR]

Indigenous isolates from the waters of chromite miningsites at Sukinda Valley, Orissa, India, showed a considerable enhancementin Cr (VI) bioreduction rate through adaptation and consortia development.On the basis of 16S-rRNA sequencing, these isolates were identifiedas Bacillus subtilisVITSUKMW1, AcinetobacterjuniiVITSUKMW2, and Escherichia coliVITSUKMW3.The native isolates showed a high tolerance at 500–1000 mgL–1of Cr (VI). An increase in the reduction ratefrom 0.199–0.477 mg L–1h–1to 0.5–1.16 mg L–1h–1at 5–20 mg L–1of initial Cr (VI) concentrationwas achieved by the adapted isolates. An increase in the growth rateand Cr (VI) reduction rate [0.86–2.6813 mg L–1h–1at 5–100 mg L–1ofinitial Cr (VI) concentration] was observed in the ternary consortiumof adapted isolates. The FT-IR spectra revealed the active participationof the bacterial surface groups in the reduction. The developmentof sequential processes (native → adapted → consortia)employing Cr (VI) tolerant isolates, proves to be a potential bioremediationstrategy for specific chromite mine sites. [ABSTRACT FROM AUTHOR]

The Cr(VI) removal capability of Acinetobacter junii VITSUKMW2 isolated from the Sukinda chromite mine site was evaluated and enhanced using statistical design techniques. The removal capacity was evaluated at different pH values (5-11) and temperatures (30-40 degrees C) and with various carbon and nitrogen sources. Plackett- Burman design was used to select the operational parameters for bioremediation of Cr(VI). Three parameters (molasses, yeast extract, and Cr(VI) concentration) were chosen for further optimization using central composite design. The optimal combination of parameters was found to be 14.85 g/l molasses, 4.72 g/l yeast extract, and 54 mg/l initial Cr(VI), with 99.95% removal of Cr(VI) in 12 h. A. junii VITSUKMW2 was shown to have significant potential for removal of Cr(VI).