Prem N. Sharma

Bio: Prem N. Sharma is an academic researcher from Indian Institute of Chemical Technology. The author has contributed to research in topics: Population & Tephritidae. The author has an hindex of 9, co-authored 18 publications receiving 230 citations.

Isolation and characterization of gut bacteria of fruit fly, Bactrocera tau (Walker)

Abstract: Gut bacteria of fruit fly, Bactrocera tau (Walker) (Diptera: Tephritidae), were isolated and the isolates attractive to B. tau adults were characterized using morphological, biochemical and 16S rRNA analyses to determine their taxonomic position. Based upon morphological, biochemical and 16S rRNA sequences (on the basis of closest match), five gut bacterial species of B. tau were characterized as Delftia acidovorans, Pseudomonas putida, Flavobacterium sp., Defluvibacter sp. and Ochrobactrum sp., of which four bacterial isolates, viz., Delftia acidovorans, Flavobacterium sp., Defluvibacter sp. and Ochrobactrum sp. are new records from guts of the fruit fly species.

Molecular and biochemical characterization of three bacterial symbionts of fruit fly, Bactrocera tau (Tephritidae: Diptera).

Abstract: Characterization of three bacterial symbionts (BC1, BC2 and BC3) of fruit fly Bactrocera tau including morphological, biochemical and 16S rDNA (rrs gene) analysis was done to determine their taxonomic position. Morphological and biochemical characterization placed two bacteria (BC1, Klebsiella oxytoca and BC2, Pantoea agglomerans) into family Enterobacteriaceae and the third one (BC3, Staphylococcus sp.) into family Staphylococcaceae. 16S rDNA gene sequence comparison with the available NCBI database sequences further confirmed the characterizations of bacterial symbionts. Molecular phylogeny of Klebsiella oxytoca and Pantoea agglomerans closely related to the other free living enterobacterial members with 74 to 93% sequence homology (genetic distance 0.000 to 0.085); however, they showed only 74 to 87% similarity with other insect symbionts (genetic distance 0.090 to 0.121). Staphylococcus sp. showed 94% sequence homology with other members of family Staphylococcaceae with the genetic distance of 0.013. Population of these symbionts in adult fruit flies increased exponentially up to the 10th day of adult emergence and thereafter it became almost constant.

Population genetic structure of the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) based on mitochondrial cytochrome oxidase ( COI ) gene sequences

Abstract: Population genetic structure of melon fly analysed with mitochondrial cytochrome oxidase I gene suggested that melon fly populations across the globe is homogeneous with non-significant variation of 0.000–0.003 base substitutions per site. Test isolates representing various geographic situations across the world were placed in 26 mitochondrial haplotypes based on variations associated with a maximum of three mutational steps and the predominant haplotype i.e. H1 was present in all melon fly populations except Hawaiian population. Evolution of mtCOI gene suggested that the fly could have originated some 0.4 million years ago. The present study also indicated that the B. cucurbitae population expansion is an event of post Pleistocene warm climatic conditions with small number of founder population. The invasion of B. cucurbitae in Hawaii was associated with the large population size and the global presence of the fly is associated with human mediated dispersal. The very low genetic variation suggested that the fly management might be possible by large scale sterile insect techniques programme.

Differential Response of Extracellular Proteases of Trichoderma Harzianum Against Fungal Phytopathogens.

Abstract: In the present study, production of extracellular proteases by Trichoderma harzianum was evaluated based on the relative gene expression and spectrophotometric assay. The fungal isolates were grown in Czapek Dox Broth medium supplemented with deactivated mycelium of plant fungal pathogens such as Fusarium oxysporum, Colletotrichum capsici, Gloeocercospora sorghi, and Colletotrichum truncatum. The maximum protease activity was detected after 48 h of incubation against Colletotrichum spp. Similarly in qRT-PCR, the relative gene expression of four proteases varied from 48 to 96 h against host pathogens in a time-independent manner. Among proteases, statistically significant upregulation of asp, asp, and srp was observed against Colletotrichum spp., followed by F. oxysporum. But in the case of pepM22, maximum upregulation was observed against F. oxysporum. The variation in enzyme assay and qRT-PCR of proteases at different time intervals against various fungal phytopathogens could be due to the limitation of using casein as a substrate for all types of proteases or protease-encoding transcripts selected for qRT-PCR, which may not be true representative of total protease activity.

Solar Photocatalytic Detoxification and Disinfection of Water: Recent Overview

Abstract: During the last few years, there has been a plethora of research and development in the area of solar photocatalysis (TiO 2 and photo-Fenton). This overview, of the most recent papers on the use of sunlight to produce the ˙OH, comments on those most relevant to the development of the technology and summarizes most of the recent research related to the degradation of water contaminants, and how solar photocatalysis (coupled with biotreat-ment) could significantly contribute to the treatment of very persistent toxic compounds. Various solar reactors for photocatalytic water treatment based mainly on nonconcentrating collectors developed during the last few years are also described in detail. This review also reports the use of the photocatalytic processes (TiO 2 ) to inactivate microorganisms present in water, placing special emphasis on those applications that make use of sunlight. Work on water disinfection mechanisms in the last decade is summarized in the last part of this overview, with attention to some experimental systems developed to optimize this disinfection technology.

The 18mer peptaibols from Trichoderma virens elicit plant defence responses. Appl Soil Ecol 8:737-746

Abstract: SUMMARY Peptaibols, the products of non-ribosomal peptide synthetases (NRPS), are linear peptide antibiotics produced by Trichoderma and other fungal genera. Trichoderma virens strain Gv29-8, a well-known biocontrol agent and inducer of plant defence responses, produces three lengths of peptaibols, 11, 14 and 18 residues long, with several isoforms of each. Disruption of the NRPS gene, tex1, encoded by a 62.8-kb uninterrupted open reading frame, results in the loss of production of all forms of 18-residue peptaibols. Tex1 is expressed during all Trichoderma developmental stages (germinating conidia, sporulating and non-sporulating mycelia) examined on solid media. Expression analysis by reverse transcriptase PCR shows that in Gv29-8 wild-type the abundance of tex1 transcript is greater during co-cultivation with cucumber seedling roots than when grown alone. Cucumber plants co-cultivated with T. virens strains disrupted in tex1 show a significantly reduced systemic resistance response against the leaf pathogen Pseudomonas syringae pv. lachrymans, and reduced ability to produce phenolic compounds with inhibitory activity to the bacteria as compared with plants grown in the presence of wild-type. Two synthetic 18-amino-acid peptaibol isoforms (TvBI and TvBII) from Gv29-8 when applied to cucumber seedlings through the transpiration stream can alone induce systemic protection to the leaf pathogenic bacteria, induce antimicrobial compounds in cucumber cotyledons and up-regulate hydroxyperoxide lyase (hpl), phenylalanine ammonia lyase (pal1) and peroxidase (prx) gene expression. These data strongly suggest that the 18mer peptaibols are critical in the chemical communication between Trichoderma and plants as triggers of non-cultivar-specific defence responses.

Pepper mild mottle virus as a water quality indicator

Abstract: Pepper mild mottle virus (PMMoV) was recently found to be the most abundant RNA virus in human feces, and is a plant virus belonging to the genus Tobamovirus in the family Virgoviridae. When in human feces, it is of dietary origin from peppers and their processed products, and is excreted from a large proportion of healthy human populations, but rarely found in animal feces. Over the past decade, this virus has been increasingly attracting research attention as a potential viral indicator for human fecal pollution in aquatic environments and water treatment systems. Results presented in the literature reveal that PMMoV is globally distributed and present in various water sources in greater abundance than human pathogenic viruses, without substantial seasonal fluctuations. Several studies report that increased concentrations of PMMoV tend to be correlated with increased fecal contamination in general, along with more frequent detection of pathogenic enteric viruses. PMMoV also exhibits remarkable stability in water under various environmental conditions. Here, we review recent advancements in our understanding of the occurrence and persistence of PMMoV in natural and engineered water systems and discuss its advantages and limitations as a viral indicator for improved microbial water quality management.

TiO2/AC Composites for Synergistic Adsorption-Photocatalysis Processes: Present Challenges and Further Developments for Water Treatment and Reclamation

Abstract: Titanium dioxide supported on activated carbon, or TiO2/AC composite, exhibits bifunctionality of adsorption and photocatalysis in synergism. The authors review the TiO2/AC synthesis techniques, characteristics, and performances in removing organic pollutants in water. Practical issues pertinent to applications of the TiO2/AC composite in water treatment and reclamation are discussed. These include dispersing the particles and recovering from the product water, UV introduction and attenuation in the photoreactor, long-term photostability and mechanical stability of the composite, potential TiO2 deactivation by the organic and inorganic matrices, assessment of intermediates and byproducts, and regeneration techniques for the exhausted or fouled TiO2/AC. Coupling with a membrane separation process to recover and regenerate TiO2/AC in various continuous flow-through system configurations is proposed. There are also possible integrations of TiO2/AC treatment systems with other treatment processes that may res...