Avinash Mishra - Academia.edu (original) (raw)

Papers by Avinash Mishra

Isolation and characterization of extracellular polymeric substances from micro-algae Dunaliella salina under salt stress

Bioresource Technology - BIORESOURCE TECHNOL, 2009

Extracellular polymeric substances (EPSs), produced by Dunaliella salina strain, increase concomi... more Extracellular polymeric substances (EPSs), produced by Dunaliella salina strain, increase concomitantly with salt concentration and maximum (944mg/l) were obtained at 5M NaCl, whereas minimum (56mg/l) at 0.5M salinity. Emulsifying activity was measured in terms of strength to retain the emulsion and comparatively 85.76% retention was observed at 0.5M salinity thereafter it intends to decline. The FT-IR-spectra reveal characteristic functional groups NH stretching, asymmetrical CH stretching vibration of aliphatic CH2-group, CC stretching of aromatic, CN stretch of aliphatic amine, NH wag of primary amine and CX stretch of alkyl-halides with a stretching of COC, CO corresponding to the presence of carbohydrates. The FT-IR-spectra substantiated the presence of primary amine-group, aromatic-compound, halide-group, aliphatic alkyl-group and polysaccharides. Four monosaccharides (glucose, galactose, fructose and xylose) were also detected by HPLC analysis. Production of EPSs may allow fu...

A monoclonal antibody was derived from mice immunized with the native trimeric, photosystem I (PS... more A monoclonal antibody was derived from mice immunized with the native trimeric, photosystem I (PSI) complex from the cyanobacterium Synechococcus PCC 7002 which reacts with a conformational epitope of the PSI complex. As seen by immunoelectron microscopy, the mAb bound to the stromal side of the thylakoid membranes. The DNA sequence encoding variable regions of the mAb was cloned into recombinant plasmids, sequenced and expressed in Escherichia coli. ELISA, Western blots and immunoelectron microscopy provided evidence that the expressed paired variable domain (Fv) fragments bind to the antigen in the same way as the parent mAb.

Bioinformatics is a scientific discipline of discovering biological functions through analysis of... more Bioinformatics is a scientific discipline of discovering biological functions through analysis of molecular sequence information from DNA, RNA or proteins. It is the computer assisted data management discipline that enables one to understand life's processes precisely. It helps to discover better drug target after differentiating between healthy and diseased. Bioinformatics is being considered bedrock for the future of biotechnology and is being adopted worldwide by academicians, companies, national and international consortia. Statistical and computational analysis of the complex relationships between phenotypes and genotypes; animals and plants plays a crucial role in the future of biology.

Rheological Properties of Grain Sorghum Dough As Determined By Mixography

Studies on extensigraphic properties and effect of salt addition in grain sorghum dough

Diazotrophs are key players of the globally important biogeochemical nitrogen cycle, having a sig... more Diazotrophs are key players of the globally important biogeochemical nitrogen cycle, having a significant role in maintaining ecosystem sustainability. Saline soils are pristine and unexplored habitats representing intriguing ecosystems expected to harbour potential diazotrophs capable of adapting in extreme conditions, and these implicated organisms are largely obscure. Differential occurrence of diazotrophs was studied by the nifH gene-targeted clone library approach. Four nifH gene clone libraries were constructed from different soil niches, that is saline soils (low and high salinity; EC 3.8 and 7.1 ds m À1 ), and agricultural and rhizosphere soil. Additionally, the abundance of diazotrophic community members was assessed using quantitative PCR. Results showed environment-dependent metabolic versatility and the presence of nitrogen-fixing bacteria affiliated with a range of taxa, encompassing members of the Alphaproteobacteria, Betaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, Cyanobacteria and Firmicutes. The analyses unveiled the dominance of Alphaproteobacteria and Gammaproteobacteria (Pseudomonas, Halorhodospira, Ectothiorhodospira, Bradyrhizobium, Agrobacterium, Amorphomonas) as nitrogen fixers in coastal-saline soil ecosystems, and Alphaproteobacteria and Betaproteobacteria (Bradyrhizobium, Azohydromonas, Azospirillum, Ideonella) in agricultural/rhizosphere ecosystems. The results revealed a repertoire of novel nitrogen-fixing bacterial guilds particularly in saline soil ecosystems.

Non-targeted metabolomics implied that Salicornia brachiata contains essential and sulphurrich am... more Non-targeted metabolomics implied that Salicornia brachiata contains essential and sulphurrich amino acids, which are recommended by the FAO. Total phenolic content of the plant extract contains reducing capacity and reactive oxygen species (ROS) scavenging activity. A high content of nutritive indicator polyunsaturated fatty acids (PUFAs; 55-64%), including linoleic acid (C18:2; 22-27%) and alpha-linolenic acid (C18:3; 29-41%), was detected under both control and stress conditions. About 38% of saturated fatty acids, including 26% palmitic acid (C16:0), was found under the control conditions, which varied under stress. About 19 different metabolites with different bioactivities have, so far, been identified. Metabolites benzyl sulphate (m/z 93.04) and flavonoid myricatin (m/z 183.14 and 532.98) are known for their aroma and nutritive supplements. Bioactive metabolites of pharmaceutical importance, such as oxomefruside (m/z 131.07; to be used in hypertension), clonidine (m/z 210.19; to treat high blood pressure, anxiety and certain pain), carmustine (m/z 212.19; antineoplastic in nature) and gangliosides (m/z 879.48; anti-inflammatory), were detected in the plant extract. An important dietary supplement selenocystathionine (m/z 269.09) was identified, which is used in hyper-accumulation of anti-cancer agent selenium. Moreover, metabolites with antimicrobial (sodium cefazolin; m/z 459.82), insecticidal or fungicidal activities (dichlorophene, m/z 267.10; oxydisulfoton, m/z 271.10; sulfotep, m/z 303.41 and azothoate, m/z 355.48) were also detected. Non-targeted metabolomics, antioxidants and scavenging activities revealed the nutritional potential of the plant, making it a promising functional food for dietary supplements.

In this study, 115 marine bacterial isolates were screened for cellulase enzymatic activity and e... more In this study, 115 marine bacterial isolates were screened for cellulase enzymatic activity and enzyme with a molecular mass of 40 kDa was purified from culture supernatant of the marine bacterium Bacillus sp. H1666 using ion exchange and size exclusion chromatography method. Growth of bacterial strain H1666 with efficient cellulase enzyme production was observed on untreated wheat straw and rice bran. The biochemical properties of the extracted cellulase were studied and enzyme was found active over a range of pH 3-9. The optimum cellulase activity was observed at pH 7 and temperature 50 • C. The enzyme was also shown to be slightly thermo-stable with 40% residual activity at 60 • C for 4 h. The potential applicability of enzyme was tested on dried green seaweed (Ulva lactuca) and 450 mg/g increase in glucose yield was obtained after saccharification. MALDI TOF-TOF analysis of cellulase peptide fingerprint showed similarity to the sequence of the glycoside hydrolase family protein.

Peroxisomal ascorbate peroxidase gene (SbpAPX) of an extreme halophyte Salicornia brachiata impar... more Peroxisomal ascorbate peroxidase gene (SbpAPX) of an extreme halophyte Salicornia brachiata imparts abiotic stress endurance and plays a key role in the protection against oxidative stress. The cloned SbpAPX gene was transformed to local variety of peanut and about 100 transgenic plants were developed using optimized in vitro regeneration and Agrobacterium mediated genetic transformation method. The T 0 transgenic plants were confirmed for the gene integration; grown under controlled condition in containment green house facility; seeds were harvested and T 1 plants were raised. Transgenic plants (T 1 ) were further confirmed by PCR using gene specific primers and histochemical GUS assay. About 40 transgenic plants (T 1 ) were selected randomly and subjected for salt stress tolerance study. Transgenic plants remained green however non-transgenic plants showed bleaching and yellowish leaves under salt stress conditions. Under stress condition, transgenic plants continued normal growth and completed their life cycle. Transgenic peanut plants exhibited adequate tolerance under salt stress condition and thus could be explored for the cultivation in salt affected areas for the sustainable agriculture.

Microbial Exopolysaccharides

The early biofilm colonizing Vibrio campbellii and Vibrio fortis produced 400 and 134 mg L −1 ext... more The early biofilm colonizing Vibrio campbellii and Vibrio fortis produced 400 and 134 mg L −1 extracellular polymeric substances (EPS), respectively of distinct composition in planktonic cultures. The EPS of V. campbellii consisted of five monosaccharides: arabinose, galactose, glucose, mannose and rhamnose, however, that of V. fortis has only three monosaccharides: arabinose, galactose and mannose. The AFM topography analysis showed different morphology and physical characteristics of EPSs. FTIR and NMR spectral analyses revealed characteristic functional groups of the polysaccharides. EPSs were amorphous in nature and contained characteristic diffraction peaks. EPSs showed high emulsifying activity and pseudoplastic rheology. This is the first report of detailed characterization of EPS produced by V. campbellii and V. fortis, so far. Detailed analytical (FT-IR, 1 H NMR, PXRD, etc.) and bio-physicochemical characteristics (thermostability, emulsifying and rheological properties) of EPSs showed potential for industrial applications. (B. Jha). source for commercial application including drug discovery, however this area of research is unexplored (Laurienzo, 2010). Vibrio species are well known for biofilm formation and are ubiquitous in marine ecosystems . Exopolymers produced by Vibrio spp. display huge diversity in composition and potential applications. Despite the immense potential of exopolymers produced by Vibrio spp., the characterization of EPS by only few species, viz., Vibrio harveyi, Vibrio alginolyticus, Vibrio furnissii and Vibrio parahaemolyticus was attempted . Moreover, the EPS production and their biotechnological properties vary not only at species level but also at the strain level.

The production of biosurfactant by Bacillus subtilis LSFM-05 was carried out using raw glycerol, ... more The production of biosurfactant by Bacillus subtilis LSFM-05 was carried out using raw glycerol, obtained from a vegetable oil biodiesel plant in Brazil, as the sole carbon source. Production of the biosurfactant was carried out in a 15-L bench-top fermentor and the surfactant was obtained from the foam produced. The crude surfactant was purified by silica gel column chromatography with a yield of 230 mg of the purified biosurfactant per liter of foam. TLC, IR spectroscopy, 1 H and 13 C NMR and Fourier transform ion cyclotron resonance mass spectrometry with electrospray ionization (ESI-FTMS) were used to characterize the purified surfactant. The isolated surfactant was identified as a surfactin lipopeptide. MS/MS data identified the amino acid sequence as GluOMe-Leu-Leu-Asp-Val-Leu-Leu and showed that the fatty acid moiety contained 14 carbons in iso, anteiso or normal configurations. The critical micelle concentration of the C 14 /Leu 7 surfactin was 70 M, with emulsification efficiency after 24 h (E 24 ) of 67.6% against crude oil. Raw glycerol represents an abundant and renewable carbon source and provides an opportunity for reducing the cost of biosurfactant production and may add value to biodiesel production by creating new commercial applications for this by-product.

PloS one, 2014

Bacterial autotrophy contributes significantly to the overall carbon balance, which stabilises at... more Bacterial autotrophy contributes significantly to the overall carbon balance, which stabilises atmospheric CO2 concentration and decelerates global warming. Little attention has been paid to different modes of carbon/sulphur metabolism mediated by autotrophic bacterial communities in terrestrial soil ecosystems. We studied these pathways by analysing the distribution and abundance of the diagnostic metabolic marker genes cbbM, apsA and soxB, which encode for ribulose-1,5-bisphosphate carboxylase/oxygenase, adenosine phosphosulphate reductase and sulphate thiohydrolase, respectively, among different contrasting soil types. Additionally, the abundance of community members was assessed by quantifying the gene copy numbers for 16S rRNA, cbbL, cbbM, apsA and soxB. Distinct compositional differences were observed among the clone libraries, which revealed a dominance of phylotypes associated with carbon and sulphur cycling, such as Gammaproteobacteria (Thiohalomonas, Allochromatium, Chroma...

Carbohydrate Polymers, 2000

Production of biosurfactant from an alkaliphilic bacterium Cronobacter sakazakii (Accession No.JN... more Production of biosurfactant from an alkaliphilic bacterium Cronobacter sakazakii (Accession No.JN398668) was screened by haemolytic assay, emulsifying activity and surface tension measurement. Biosurfactant, comprised of total sugars (73.3%), reducing sugars (1.464%), protein (11.9%), uronic acid (15.98%) and sulfate (6.015%), showed low viscosity with pseudoplastic rheological behavior and exhibited significant emulsification activity with oils and hydrocarbons. A series of low and

Journal of Cereal Science, 2008

A gamma-kafirin gene of Sorghum bicolor L var. M35-1 was isolated using a PCR based approach by d... more A gamma-kafirin gene of Sorghum bicolor L var. M35-1 was isolated using a PCR based approach by designing specific primers. The primers gave highly reproducible amplification. The amplicons were then cloned and sequenced. Nucleotide sequences were subjected to the homology search and a comparative analysis was done with other prolamins. Amplified g-kafirin gene (accession no. AY566298-99) showed 99% homology with a g-kafirin gene of Sorghum vulgare. Compared to Sorghum vulgare, only 3 extra bases were present in Sorghum bicolor at position 40 nucleotide bases downstream of transcription initiation site. These sequences were related with prolamins of other genera, i.e. coix and maize with 84% sequence homology. The deduced protein sequence of g-kafirin gene of S. bicolor (accession no. AAS73290) gave significant similarity of 99%, 79% and 77% with gamma-kafirin protein of S. vulgare, g-zein and g-coixin proteins, respectively. All cysteine residues of g-kafirin were highly conserved. Probable secondary structure of gamma-kafirin protein was predicted using the online PSIPRED server. Study of temporal expression of the g-kafirin gene is needed for analysing the expression pattern of introgressed gene(s) driven by its promoter. Temporal expression of gamma-kafirin gene in endosperm studied by semi quantitative RT-PCR with specifically designed primers showed that g-kafirin expression started at 7 DAP (days after pollination). There was statistically a non-significant increase in expression up to 14 DAP, thereafter expression increased significantly (at the 5% level) and reached a maximum at 21 DAP.

APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY, 2009

Proteins are one of the targets for improving the nutritional quality, and attempts are being mad... more Proteins are one of the targets for improving the nutritional quality, and attempts are being made through manipulation of its native gene(s). Pigeonpea (Cajanus cajan L.) is one of the nutritionally important legumes of tropical and subtropical regions of the world, and studies of the structure of seed storage proteins and their interactions have been limited by the difficulty of isolating single-protein subunits in large amounts from a complex mixture of the seed endosperm. One way to overcome this problem is the expression of seed storage protein-encoded gene(s) in heterologous systems that have additional advantages wherein specific gene modifications can be made and the new gene constructs can quickly be expressed. Legumin protein was extracted from pigeonpea seeds of different developmental stages (5th to 25th day after flowering [DAF]) and characterized. The legumin gene (leg) of size 1.482 kb was screened, using the deoxygenin-labeled legumin probe, from the complementary deoxyribonucleic acid (cDNA) library, constructed from 18-day-old (DAF) immature seeds of pigeonpea and sequenced (accession no. AF3555403). The legumin gene was further characterized by DNA blotting, and its probable secondary structure was predicted using online ExPASy server. Significant Protein Data Bank (PDB) alignment of the deduced legumin protein by BLASTP was observed with proglycinin of soybean. Comparative 3D structural homology was predicted by Cn3D software, and the legumin protein showed the 3D structure alignment and interaction homology with proglycinin chain 1FXZA (PDB no. 1FXZ). The legumin gene was subcloned in vector pET-24a driven by the bacterial promoter, and its expression was detected in Escherichia coli by immunoblotting using polyclonal antibodies, raised against the purified legumin protein.

Botanica Marina, 2011

Differentially expressed genes in Dunaliella salina grown under super saturated salt stress (5.5 ... more Differentially expressed genes in Dunaliella salina grown under super saturated salt stress (5.5 M) were isolated by subtractive hybridization, cloned and classified for further biotechnological and industrial exploration. Sequence homology analysis showed that 26% of the library represented salt responsive genes for metabolic enzymes, viz., fructose-1,6-diphosphate aldolase (AldP), glucose-6-phosphate dehydrogenase, carbonic anhydrase, phosphoglycerate kinase etc., while 6% of library clones contained hypothetical/unknown genes. Six clones (8% of the library) contained genes that differentially expressed under salt stress, however, 6-8% of the library represented genes over expressed under salt stress and involved in photosynthesis, defense, cell rescue (chaperon/protease inhibitor) and protein sorting. About 39% were other genes of which 6% and 14% were transcription factors and house keeping genes (putative enzymes/signaling) respectively, while the remaining 19% of genes had miscellaneous functions.

Carbohydrate Polymers, 2011

We examined the chemical composition of extracellular polymeric substances (EPS) extracted from t... more We examined the chemical composition of extracellular polymeric substances (EPS) extracted from two natural microbial pellicle biofilms growing on acid mine drainage (AMD) solutions. The EPS obtained from a mid-developmental-stage biofilm (DS1) and a mature biofilm (DS2) were qualitatively and quantitatively compared. More than twice as much EPS was derived from DS2 as from DS1 (approximately 340 and 150 mg of EPS per g [dry weight] for DS2 and DS1, respectively). Composition analyses indicated the presence of carbohydrates, metals, proteins, and minor quantities of DNA and lipids, although the relative concentrations of these components were different for the two EPS samples. EPS from DS2 contained higher concentrations of metals and carbohydrates than EPS from DS1. Fe was the most abundant metal in both samples, accounting for about 73% of the total metal content, followed by Al, Mg, and Zn. The relative concentration profile for these metals resembled that for the AMD solution in which the biofilms grew, except for Si, Mn, and Co. Glycosyl composition analysis indicated that both EPS samples were composed primarily of galactose, glucose, heptose, rhamnose, and mannose, while the relative amounts of individual sugars were substantially different in DS1 and DS2. Additionally, carbohydrate linkage analysis revealed multiply linked heptose, galactose, glucose, mannose, and rhamnose, with some of the glucose in a 4-linked form. These results indicate that the biochemical composition of the EPS from these acidic biofilms is dependent on maturity and is controlled by the microbial communities, as well as the local geochemical environment.