Showing papers by "Kodiveri Muthukaliannan Gothandam published in 2015"

Synthesis and larvicidal activity of low-temperature stable silver nanoparticles from psychrotolerant Pseudomonas mandelii

Abstract: Applications based on silver nanoparticles (AgNPs) are limited by low temperatures, which cause aggregation of the nanoparticle fraction, leading to reduced efficacy of their products. We aimed at studying AgNP synthesis by psychrotolerant bacteria, its stability under long-term storage, and larvicidal activity under low-temperature conditions. Electron and atomic force microscopy studies revealed that 6 among 22 psychrotolerant isolates synthesized AgNPs with an average diameter of 1.9–14.1 nm. Pseudomonas mandelii SR1 synthesized the least-sized AgNPs with an average diameter of 1.9–10 nm, at temperatures as low as 12 °C without aggregate formation, and the synthesized nanoparticles were stable for up to 19 months of storage period. On studying their larvicidal activity, LC90 (lethal concentration) values against Anopheles subpictus and Culex tritaeniorhynchus larvae were at 31.7 and 35.6 mg/L, respectively. Stable non-aggregate AgNPs at low-temperature conditions from P. mandelii SR1, coupled with their larvicidal property, can be applied to control larval populations in water bodies located in seasonal or permanently cold environments.

Identification and analysis of the salt tolerant property of AHL lactonase (AiiATSAWB ) of Bacillus species.

Abstract: Bacterial biofilms communicate by a process called Quorum Sensing. Gram negative bacterial pathogens specifically talk through the production, detection, and response to the signal or autoinducer called Acyl Homoserine Lactones. Bacterial lactonases are important AHL hydrolysing or quorum quenching enzymes. The present study deals with ten endospore forming gram positive isolates of the saltern soil. Preliminary screening for Quorum Quenching activity with the QS Inhibition indicator strain Chromobacterium violaceum ATCC 12472, showed positive activity in four isolates namely TS2, TS16, TSAWB, and TS53B. AHL lactonase (AiiA) specific primers amplified Acyl Homoserine Lactone lactonase gene in the TSAWB genome alone. Phylogenetic relationship of the identified AiiATSAWB confirmed its evolutionary relationship with bacterial AiiA like AHL lactonase of the metallo-beta-lactamase super family. Our in vitro AHL hydrolysis assay under wide percentage (0–5) of salt solutions with TSAWB isolate and also its intracellular soluble protein fraction showed halotolerant AHL hydrolysis ability of the AiiATSAWB enzyme. In silico determination of putative tertiary structure, the ESBRI derived conserved salt bridges, aminoacid residue characterization with high mole percent of acidic and hydrophobic residues reaffirmed the halotolerant ability of the enzyme. So we propound the future use of purified AiiATSAWB, as hypertonic suspension for inhalation to substitute the action of inactivated host's paraoxonase in treating Pseudomonas aeruginosa infection in cystic fibrosis patients.

Insight on biochemical characteristics of thermotolerant amylase isolated from extremophile bacteria Bacillus vallismortis TD6 (HQ992818)

Abstract: Halotolerant bacterium Bacillus vallismortis (HQ992818) was isolated from saltern sediments in India, and produced significantly high levels extracellular amylase. A detailed investigation on the culture conditions including period of incubation, media pH, and inoculum size in addition to different sources of carbon and nitrogen, metal ions, NaCl, and amino acids was carried out for optimized production. Maximum amylase production (62 U/mL) was attained after 26 h of incubation. The optimized conditions for maximal production of amylase were found to be 1% NaCl, pH 8, temp 37°C, 1% starch, 1% sodium nitrate, phenyl alanine (0.01%) and calcium chloride (10 mM). The biochemical characteristics of the extracellular amylase were studied with respect to change in temperature, pH and metal ions. The enzyme was found to be optimally active in the temperature range of 40–70°C and pH 8. Activation of the enzyme by Ca2+ (135%), Fe2+ (113%) and Mg2+ (109%) occurred at 5 mM concentration and strongly inhibited by Hg2+, Zn2+ and Mn2+ occurred at 10 mM. Significant compatibility of the enzyme with the commercial laundry detergents and the results of washing performance test confirmed its effectiveness. Available data on the optimized culture conditions enables for easily adaptable setup of large scale production of the enzyme for use in detergent formulations.

Expression of Carotenoid Pathway Genes in Three Capsicum Varieties under Salt Stress

Abstract: Carotenoids pathway is one of decisive anabolic pathway which is responsible for diverse, vital functions such as absorption, dissipation and transfer of solar energy for photosynthesis. Change in environmental factors causes modulation in molecular as well physiological responses to acclimate altered conditions. The current study is designed to assess the difference in the expression pattern of carotenoid pathway genes as well as accumulation of β-carotene among three capsicum varieties having different sensitivity level against salt. To achieve this objective salt tolerant (G4), moderate, tolerant (K2) and sensitive (CO1) varieties were treated under different NaCl concentration (25, 50, 100, 150 and 200 mM) for 30 days. Differential expressions of five major genes of carotenoid pathway (phytoene synthase, phytoene desaturase, zeta carotene desaturase, lycopene β-cyclase and capsanthin/capsorubin synthase) were examined. Semi-quantitative real time PCR expression data have demonstrated the declined expression of genes under study as the salt concentration gradually increased. We also analyzed the impact of salt on chlorophyll content and β-carotene content.

Analysis of stress responsive genes in capsicum for salinity responses.

Abstract: Aims: This study is an endeavor to gain proper understanding about salt tolerance mechanism in plants; an attempt was made to characterize the differential expression of stress responsive genes, sodium potassium content proline content in three capsicum cultivars having different salt sensitivity level. Place and Duration of Study: School of Bio Sciences and Technology, VIT University, Vellore of India between June 2013 to May 2014. Methodology: Capsicum cultivars (salt tolerant, salt moderate sensitive and salt susceptible) were treated with different concentration of NaCl such as 25mM, 50mM, 100mM, 150mM and 200mM. Gene expression studies under different salt treatment were done for the following genes: osmotic adjustment (CaPROX1), osmotin like protein (CaOSM1), aquaporin (CaPIP2), dehydrin responsive gene (CaDREBLP1), ring domain zinc finger protein gene (CaKR1), membrane protein (CaChi2), endoplasmic reticulum ubiquitine ligase (CaRMa1H1) and cell death repressor (CaBI1). Proline Original Research Article Maurya et al.; ARRB, 6(1): xxx-xxx, 2015; Article no.ARRB.2015.064 67 content and sodium and potassium ion content also measured. Results: The result indicated that genes CaDREBLP1, CaRMa1H1, CaKR1, CaOSM1 were up regulated while CaPROX1, CaPIP2 genes were down regulated under salt stress. But no significant difference was noticed in gene expression level of CaBI1 and CaChi 2 gene. Conclusion: The higher gene expression level of stress responsive genes viz. CaDREBLP1, CaRMa1H1, CaKR1, CaOSM1 may involved in different level of salt tolerance among selected cultivars. Thus differential transcript modulation of these genes in capsicum cultivars indicates their role lending the salt tolerance in salt tolerant cultivar than sensitive.