Browsing by Author "Radha Prasanna"

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Characterization of the Biocidal Spectrum of Extracellular Filtrates of Microcystis aeruginosa
(2011) Pranita Jaiswal; Radha Prasanna; Pawan K. Singh
The effect of dichloromethane (DCM) and ethyl acetate (EA) extract of a cyanobacterium, Microcystis aeruginosa was evaluated against unicellular cyanobacteria and the phytopathogenic fungus Rhizoctonia solani. Fractionation of the filtrate showed the presence of five spots of different Rf values on silica gel coated plates indicating the presence of a number of compounds in the extract. A marked reduction in growth (52%) of the fungus was recorded on the plates supplemented with cyanobacterial extract, indicating the involvement of anti-fungal metabolite(s). The extract did not show any negative influence on seed germination and growth of seedlings of wheat, rice and mung, emphasizing the suitability of the compound for use in agriculture. © 2011 Association of Microbiologists of India.
Cyanobacteria as a "green" option for sustainable agriculture
(Wiley Blackwell, 2013) Radha Prasanna; Anjuli Sood; Sachitra Kumar Ratha; Pawan K. Singh
The use of indigenous native technologies and environment-friendly supplements forms the basis of "green" technologies for environmentally safe and sustainable agriculture. This article discusses different aspects of the use of cyanobacterial inoculants to enhance crop productivity and improve/sustain soil fertility. The sustaining of fertility of rice fields is due to cyanobacteria, as they perform many roles in the soil ecosystem. The beneficial effects of algalization are attributed to the growth-promoting substances produced by cyanobacteria and the temporary immobilization of added nitrogen. There is a need to develop more effective formulations and useful markers for the widespread use of cyanobacterial biofertilizers. Studies undertaken to characterize the abundance, diversity, and metabolic capabilities of cyanobacteria isolated from the rice rhizosphere reveal that the isolates are efficient in enhancing the germination and growth of wheat and rice seeds. © 2014 John Wiley & Sons, Ltd.
Cyanobacterial bioactive molecules - An overview of their toxic properties
(2008) Pranita Jaiswal; Pawan Kumar Singh; Radha Prasanna
Allelopathic interactions involving cyanobacteria are being increasingly explored for the pharmaceutical and environmental significance of the bioactive molecules. Among the toxic compounds produced by cyanobacteria, the biosynthetic pathways, regulatory mechanisms, and genes involved are well understood, in relation to biotoxins, whereas the cytotoxins are less investigated. A range of laboratory methods have been developed to detect and identify biotoxins in water as well as the causal organisms; these methods vary greatly in their degree of sophistication and the information they provide. Direct molecular probes are also available to detect and (or) differentiate toxic and nontoxic species from environmental samples. This review collates the information available on the diverse types of toxic bioactive molecules produced by cyanobacteria and provides pointers for effective exploitation of these biologically and industrially significant prokaryotes. © 2008 NRC.
Evaluating the potential of N. calcicola and its bicarbonate resistant mutant as bioameleorating agents for 'usar' soil
(2010) Pranita Jaiswal; Ajai Kumar Kashyap; Radha Prasanna; Pawan Kumar Singh
The potential of Nostoc calcicola and its bicarbonate resistant mutant as bioameleorating agent was investigated, using laboratory simulation experiments, in terms of their growth potential, glutamine synthetase (GS) activity, heterocyst frequency and effect on pH of soil. Nostoc calcicola, exhibited a tendency to lower the pH of 'usar' soil significantly and showed better growth and pigment content at 20% soil extract as compared to basal medium. The bicarbonate resistant mutant (HCO3-R) exhibited a better ability to grow at higher percentage of soil extract (60%), besides bringing about a more significant change in soil pH as compared to wild type. The heterocyst frequency was much higher in the mutant strain, which was not significantly affected by growth in various concentrations of soil extract. The mutant strain holds promise as a potential bioameliorant for 'usar' soil after further evaluation of its reclamative properties at field level. © 2010 Association of Microbiologists of India.
Growth and biochemical characterization of associations between cyanobionts and wheat seedlings in co-culturing experiments
(2011) Anjuli Sood; Pawan K. Singh; Arun Kumar; Rajendra Singh; Radha Prasanna
N2-fixing cyanobacteria are unique in their capacity to form symbiotic associations with a wide range of eukaryotic hosts belonging to different plant groups. The present study was undertaken to analyze the interactions of the cyanobiont PI 01 (from Azolla pinnata) and Nostoc PCC 9229 (from Gunnera monoika) with wheat seedlings, in co-culturing experiments. Each of the cyanobionts enhanced significantly the volume of root and shoot biomass in the experimental cultures. The transverse sections of roots in the co-cultured seedlings revealed the presence of aseriate packets of cyanobionts below the root epidermis. The investigated cyanobionts excreted amino acids (His, Met, Val) and sugars into the medium, while indoleacetic acid was detected when the cyanobionts were grown in a tryptophan containing medium. During the co-culturing, sugars and proline were detected in the extracellular filtrates. It can be hypothesized that these sugars and amino acids may serve as signal substances in the development of functional associations between the relevant cyanobionts and the wheat seedlings. © 2011 Versita Warsaw and Springer-Verlag Wien.
Modulation of carbonic anhydrase activity in two nitrogen fixing cyanobacteria, Nostoc calcicola and Anabaena sp.
(Elsevier GmbH, 2005) Pranita Jaiswal; Radha Prasanna; Ajai Kumar Kashyap
The activity of enzyme carbonic anhydrase (CA) was investigated in two diazotrophic cyanobacteria, Anabaena sp. (ARM 629) and Nostoc calcicola, in the presence of CO2/NaHCO3 and different inhibitors. The CA activity increased when the cells were pretreated with a high concentration of CO2/NaHCO3 and then transferred to ambient level CO 2. Maximum activity of CA was observed after 8 h of incubation in light on transfer of cells from high Ci to ambient level CO 2, and was low when incubated in dark. Addition of the photosynthetic inhibitor DCMU brought about a differential reduction in CA activity, depending on the carbon source (NaHCO3/CO2). CA inhibitors - ethoxyzolamide (EZ) and acetazolamide (AZ) - inhibited the enzyme activity in both the genera, but the extent of inhibition was greater in Anabaena sp. than in N. calcicola. Such a variation in extent of inhibition/stimulation of CA activity being different in the two genera reflects differences in their inherent potential and genetic background. The relevance of such cyanobacterial strains as CO2 sinks is also discussed. © 2005 Elsevier GmbH. All rights reserved.
Physiological characterization and molecular profiling of toxic and non-toxic isolates of cyanobacterium microcystis
(Triveni Enterprises, 2013) Pranita Jaiswal; Radha Prasanna; Pawan K. Singh
Our investigation aimed to utilize physiological attributes and molecular tools for distinguishing the toxic strain of Microcystis from other non toxic strains, belonging to the same genus. Physiological characterization of five Microcystis isolates indicated that the toxic strain (Ml) exhibited significantly higher pigment accumulation (phycocyanin: 54.20 ng ml -1; allophycocyanin: 18.2 |ig ml-1 ) and sugar content (74.25 ng ml-1 ), which may be providing a competitive advantage for successful colonization and proliferation. Profiling using repeat sequence primers (STRR, Hip) was helpful in distinguishing different strains (M1-M5) and HIP TG profile was unique to Ml. SDS-PAGE profile of the five strains indicated the presence of a unique band (25kDa) in Ml. The combined use of SDS-PAGE and HipTG profiles can help in providing distinct fingerprint for the toxic strain, which can be useful in its identification. © Triveni Enterprises, Lucknow (India).