A halotolerant and thermotolerant <Emphasis Type="Italic">Bacillus</Emphasis> sp. degrades hydrocarbons and produces tensio-active emulsifying agent

A Bacillus sp. strain DHT, isolated from oil-contaminated soil, grew and produced biosurfactant when cultured in variety of substrate at salinities of up to 100 g l⁻¹ and temperatures up to 45°C. It was capable of utilizing crude oil, fuels, various pure alkanes and PAHs as a sole carbon and energy source across a wide range of temperature and salinity. Over the range evaluated, the degradation of hydrocarbon and biosurfactant production was not influenced by salinity (0–10% wv⁻¹) and temperature (30–45°C). The biosurfactant produced by the organism emulsified a range of hydrocarbons with hexadecane as the best substrate and toluene as the poorest. From 16S rDNA analysis, strain DHT was related to Bacillus licheniformis.     

Access of cellulase to cellulose and lignin for poplar solids produced by leading pretreatment technologies

Adsorption of cellulase on solids resulting from pretreatment of poplar wood by ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), controlled pH, dilute acid (DA), flowthrough (FT), lime, and sulfur dioxide (SO₂) and pure Avicel glucan was measured at 4°C, as were adsorption and desorption of cellulase and adsorption of β‐glucosidase for lignin left after enzymatic digestion of the solids from these pretreatments. From this, Langmuir adsorption parameters, cellulose accessibility to cellulase, and the effectiveness of cellulase adsorbed on poplar solids were estimated, and the effect of delignification on cellulase effectiveness was determined. Furthermore, Avicel hydrolysis inhibition by enzymatic and acid lignin of poplar solids was studied. Flowthrough pretreated solids showed the highest maximum cellulase adsorption capacity (σ_solids = 195 mg/g solid) followed by dilute acid (σ_solids = 170.0 mg/g solid) and lime pretreated solids (σ_solids = 150.8 mg/g solid), whereas controlled pH pretreated solids had the lowest (σ_solids = 56 mg/g solid). Lime pretreated solids also had the highest cellulose accessibility (σ_cellulose = 241 mg/g cellulose) followed by FT and DA. AFEX lignin had the lowest cellulase adsorption capacity (σ_lignin = 57 mg/g lignin) followed by dilute acid lignin (σ_lignin = 74 mg/g lignin). AFEX lignin also had the lowest β‐glucosidase capacity (σ_lignin = 66.6 mg/g lignin), while lignin from SO₂ (σ_lignin = 320 mg/g lignin) followed by dilute acid had the highest (301 mg/g lignin). Furthermore, SO₂ followed by dilute acid pretreated solids gave the highest cellulase effectiveness, but delignification enhanced cellulase effectiveness more for high pH than low pH pretreatments, suggesting that lignin impedes access of enzymes to xylan more than to glucan, which in turn affects glucan accessibility. In addition, lignin from enzymatic digestion of AFEX and dilute acid pretreated solids inhibited Avicel hydrolysis less than ARP and flowthrough lignin, whereas acid lignin from unpretreated poplar inhibited enzymes the most. Irreversible binding of cellulase to lignin varied with pretreatment type and desorption method. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Genetic characterization of Chikungunya virus from New Delhi reveal emergence of a new molecular signature in Indian isolates

ABSTRACT: BACKGROUND: Chikungunya (CHIK) is currently endemic in South and Central India and exist as co-infections with dengue in Northern India. In 2010, New Delhi witnessed an outbreak of CHIK in the months October-December. This was the first incidence of a dominant CHIK outbreak in Delhi and prompted us to characterize the Delhi virus strains. We have also investigated the evolution of CHIK spread in India. FINDINGS: Clinical samples were subjected to RT-PCR to detect CHIK viral RNA. The PCR amplified products were sequenced and the resulting sequences were genetically analyzed. Phylogenetic analysis based on partial sequences of the structural proteins E1 and E2 revealed that the viruses in the latest outbreak exhibited ECSA lineage. Two novel mutations, E1 K211E and E2 V264A were observed in all Delhi isolates. In addition, CHIKV sequences from eight states in India were analyzed along with Delhi sequences to map the genetic diversity of CHIKV within the country. Estimates of average evolutionary divergence within states showed varying divergence among the sequences both within the states and between the states. We identified distinct molecular signatures of the different genotypes of CHIKV revealing emergence of a new signature in the New Delhi clade. Statistical analyses and construction of evolutionary path of the virus within the country revealed gradual spread of one specific strain all over the country. CONCLUSION: This study has identified unique mutations in the E1 and E2 genes and has revealed the presence of ancestral CHIKV population with maximum diversity circulating in Maharashtra. The study has further revealed the trend of CHIK spread in India since its first report in 1963 and its subsequent reappearance in 2005.     

Salt Stress-induced Responses in Growth and Metabolism in Callus Cultures and Differentiating In Vitro Shoots of Indian Ginseng (Withania somnifera Dunal)

In vitro-grown shoots and calli of Withania somnifera, an important medicinal plant, were exposed to various types of salts under in vitro culture conditions. Membrane permeability, lipid peroxidation, and the antioxidant system increased in shoots as well as in unorganized callus tissues under all the three concentrations of KCl, NaCl, KNO₃, NaNO₃, and CaCl₂. The growth responses of shoots and callus cultures under various salt treatments revealed that the tissue could grow better under NaCl and KNO₃ compared to other salts and the in vitro shoots appeared healthy at 50?mM concentration of NaCl and KNO_3. The activity of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase, guaiacol peroxidase, lipoxygenase, polyphenol oxidase, and glutathione reductase increased under salt treatments, especially at higher concentrations. The greatest activity increase was recorded for peroxidases, whereas CAT was the least responsive. Only two isoforms, Mn-superoxide dismutase (Mn-SOD) and Fe-SOD, could be visualized in callus tissue while Cu/Zn-SOD was absent. Diaphorase 4 was totally missing in callus tissue and was detected only in shoots. Phenolics accumulated at all the concentrations of the salts tested as an induced protective response. The higher concentration of CaCl₂ produced maximum increases in antioxidants and enzymatic activities compared to other salts. Thus, for W. somnifera the presence of excess calcium in the growing medium is most deleterious compared to other salts. Results also suggest that the nonenzymatic and enzymatic antioxidant systems of both the tissues played a primary role in combating the imposed salt stress.     

Arsenic affects mineral nutrients in grains of various Indian rice (Oryza sativa L.) genotypes grown on arsenic-contaminated soils of West Bengal

The exposure of paddy fields to arsenic (As) through groundwater irrigation is a serious concern that may not only lead to As accumulation to unacceptable levels but also interfere with mineral nutrients in rice grains. In the present field study, profiling of the mineral nutrients (iron (Fe), phosphorous, zinc, and selenium (Se)) was done in various rice genotypes with respect to As accumulation. A significant genotypic variation was observed in elemental retention on root Fe plaque and their accumulation in various plant parts including grains, specific As uptake (29–167 mg kg^?1 dw), as well as As transfer factor (4–45%). Grains retained the least level of As (0.7–3%) with inorganic As species being the dominant forms, while organic As species, viz., dimethylarsinic acid and monomethylarsonic acid, were non-detectable. In all tested varieties, the level of Se was low (0.05–0.12 mg kg^?1 dw), whereas that of As was high (0.4–1.68 mg kg^?1 dw), considering their safe/recommended daily intake limits, which may not warrant their human consumption. Hence, their utilization may increase the risk of arsenicosis, when grown in As-contaminated areas.     

High level expression of soybean trypsin inhibitor gene in transgenic tobacco plants failed to confer resistance against damage caused byHelicoverpa armigera

Helicoverpa armigera is a major pest of many tropical crop plants. Soybean trypsin inhibitor (SBTI) was highly effective against the proteolytic activity of gut extract of the insect. SBTI was also inhibitory to insect growth when present in artificial diet. The gene coding for SBTI was cloned from soybean (Glycine max, CVBirsa) and transferred to tobacco plants for constitutive expression. Young larvae ofH. armigera, fed on the leaves of the transgenic tobacco plants expressing high level of SBTI, however, maintained normal growth and development. The results suggest that in certain cases the trypsin inhibitor gene(s) may not be suitable candidates for developing insect resistant transgenic plants.     

Colorimetric estimation of human glucose level using γ-Fe2O3 nanoparticles: An easily recoverable effective mimic peroxidase

This article reports simple, green and efficient synthesis of γ-Fe₂O₃ nanoparticles (NPs) (maghemite) through single-source precursor approach for colorimetric estimation of human glucose level. The γ-Fe₂O₃ NPs, having cubic morphology with an average particle size of 30 nm, exhibited effective peroxidase-like activity through the catalytic oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂ producing a blue-colored solution. On the basis of this colored-reaction, we have developed a simple, cheap, highly sensitive and selective colorimetric method for estimation of glucose using γ-Fe₂O₃/TMB/glucose–glucose oxidase (GOx) system in the linear range from 1 to 80 μM with detection limit of 0.21 μM. The proposed glucose sensor displays faster response, good stability, reproducibility and anti-interference ability. Based on this simple reaction process, human blood and urine glucose level can be monitored conveniently.     

Establishment of phosphate-solubilizing strains of Azotobacter chroococcum in the rhizosphere and their effect on wheat cultivars under green house conditions

A pot experiment was conducted in the green house to investigate the establishment of phosphate solubilizing strains of Azotobacter chroococcum, including soil isolates and their mutants, in the rhizosphere and their effect on growth parameters and root biomass of three genetically divergent wheat cultivars (Triticum aestivum L.). Five fertilizer treatments were performed: Control, 90 kg N ha(-1), 90 kg N + 60 kg P2O5 ha(-1), 120 kg N ha(-1) and 120 kg N + 60 kg P2O5 ha(-1). Phosphate solubilizing and phytohormone producing parent soil isolates and mutant strains of A. chroococcum were isolated and selected by an enrichment method. In vitro phosphate solubilization and growth hormone production by mutant strains was increased compared with soil isolates. Seed inoculation of wheat varieties with P solubilizing and phytohormone producing A. chroococcum showed better response compared with controls. Mutant strains of A. chroococcum showed higher increase in grain (12.6%) and straw (11.4%) yield over control and their survival (12-14%) in the rhizosphere as compared to their parent soil isolate (P4). Mutant strain M37 performed better in all three varieties in terms of increase in grain yield (14.0%) and root biomass (11.4%) over control.