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Papers by Vignesh Sivanandham

Domestic sewage discharge and live stocks are the main sources of pathogenic contaminations in ri... more Domestic sewage discharge and live stocks are the main sources of pathogenic
contaminations in rivers. The river Tamiraparani in southern India is affected by such nonpoint
source pollution throughout the year. We collected a total of 264 samples (water and
sediment) from 22 locations in 2-month intervals during a period of 1 year. Bacteriological
analysis such as total viable counts (TVC), total coliform (TC), total Streptococcus (TS),
Vibrio like organisms (VLO) and five pathogens as well as 12 geochemical parameters
(pH, EC, TDS, Cl, HCO3, Ca, Mg, Na, K, PO4, other nutrients and total hardness) were
studied. Principal Component Analysis (PCA) and correlation analysis proved that microbial
communities were separated with geochemical parameters in order to gain their
efficacy. Factor analysis confirmed separate loading rates of microbial (32.3 %) and
geochemical (32.7 %) parameters representing ‘allochthonous – geochemical’ and ‘fecal
matters – microbial’ interactions, respectively. We used geographical information systems
(GIS) for mapping the occurrence of indicator organisms from non-point sources
throughout the river basin.

Pollutant free and eco-friendly synthetic route using herbal plant A. indica, which can be used a... more Pollutant free and eco-friendly synthetic route using herbal plant A. indica, which can be used as an effective capping as well as reducing agent, is used for the synthesis of silver nanoparticles (Ag NP’s) and their antimicrobial activity is studied. Silver nanoparticles formation is confirmed from surface plasmon absorption identified from optical absorption studies. Functional groups present in the crude neem extract and synthesized nanoparticles (NP’s) with neem extract are analyzed by using FTIR studies. The antimicrobial screening of six different bacteria and four fungi strains were challenged against biosynthesized Ag NP’s by using A. Indica.

We report, synthesis and antifungal activities of CuO nanoparticles. Particles are prepared throu... more We report, synthesis and antifungal activities of CuO nanoparticles. Particles are prepared through sol-gel method. X-ray diffraction studies show the particles are monoclinic (crystalline) in nature. Scanning electron microscopic measurements are carried out to understand the morphology of the prepared particles. Energy-dispersive X-ray spectroscopic measurements show that the prepared particles containing Cu and O. To identify the local structure of the particles Fourier transform infra red (FTIR) spectroscopic measurements were carried out showing vibrational bands of Cu-O and O-H band. Anti fungal studies were performed on the set of fungal using disk diffusion method and found that the prepared particles are suitable for antifungal activities.

Silver nanoparticles are known to have inhibitory antimicrobial properties. In this letter, we re... more Silver nanoparticles are known to have inhibitory antimicrobial properties. In this letter, we report the synthesis of silver nanoparticles by using biocompatible, water soluble polymer through polyol method. Optical absorption spectrum of the prepared particles shows an absorption peak around 433 nm which is because of Surface Plasmon Resonance (SPR) of silver nanoparticles. Fourier transform infrared (FTIR) studies were done to identify the interaction of the nanoparticle and polymer. Transmission Electron Microscopic (TEM) studies con¯rm that the prepared particles are $ 100 nm in size. Antifungal activity was studied through standard disk di®usion method. Studies show the prepared particles are potential candidates for the antifungal activity.

A total of 176 (water and sediment) samples from 22 stations belonging to four different (urban, ... more A total of 176 (water and sediment) samples from 22 stations belonging to four different (urban, semi-urban, rural, and holy places) human habitations of Tamil Nadu beaches were collected and analyzed for physiochemical and microbial parameters during 2008-2009. Bacterial counts were two-to tenfold higher in sediments than in water due to strong bacterial aggregations by dynamic flocculation and rich organic content. The elevated bacterial communities during the monsoon explain rainfalls and several other wastes from inlands. Coliform counts drastically increased at holy and urban places due to pilgrimage and other ritual activities. Higher values of the pollution index (PI) ratio (>1) reveals, human fecal pollutions affect the water quality. The averaged PI ratio shows a substantial higher microbial contamination in holy places than in urban areas and the order of decreasing PI ratios observed were: holy places>urban areas>semi-urban areas>rural areas. Correlation and factor analysis proves microbial communities were not related to physicochemical parameters. Principal component analysis indicates 55.32 % of the total variance resulted from human/animal fecal matters and sewage contaminants whereas 19.95 % were related to organic contents and waste materials from the rivers. More than 80 % of the samples showed a higher fecal coliform and Streptococci by crossing the World Health Organization's permissible limits.

The levels of 17 organochlorine pesticides residues (OCPs) in surface water and sediments from Ta... more The levels of 17 organochlorine pesticides residues (OCPs) in surface water and sediments from Tamiraparani river basin, South India were investigated to evaluate their potential pollution and risk impacts. A total of 96 surface water and sediment samples at 12 sampling stations were collected along the river in four seasons during 2008-2009. The ΣOCP concentrations in surface water and sediments were in the range of 0.1 to 79.9 ng l −1 and 0.12 to 3,938.7 ng g −1 dry weight (dw), respectively. Among the OCPs, the levels of dichlorodiphenyltrichloroethanes (DDTs), aldrin, dieldrin, cis-chlordane, transchlordane, and mirex were dominant in the sediments. The dominant OCPs in water samples are heptachlor, o,p′-DDE, dieldrin, o,p′-DDD, and mirex, which show different source of contamination pattern among sampling seasons. The distribution pattern of DDTs, hexachlorocyclohexane, and other OCPs in the present study shows heterogenic nature of nonpoint source of pollution. Notable contamination of water and sediment sample that was observed in upstream (S2) 58 ng l −1 and downstream (S11) 1,693 ng g −1 dw explains agricultural and municipal outfalls, whereas frequent damming effect reduces the concentration level in the midstream. The overall spatial-temporal distribution pattern of ΣOCP residues are illustrated by GIS package.

We assessed the occurrence of pollution indicators and antibiotic resistant bacterial isolates fr... more We assessed the occurrence of pollution indicators and antibiotic resistant bacterial isolates from water and sediment samples of three different eco-regions of the Chennai coast between March -May of 2010. Total of 960 bacterial strains belonging to four genera were isolated which show the highest frequencies of resistance to vancomycin (53.6%) and penicillin (52.6%) (except Enterococcus sp., which is highly resistant to erythromycin) and lowest frequencies of resistance to chloramphenicol (3.43%), ciprofloxacin (3.95%), gentamicin (4.68%), and tetracycline (6.97%). The E. coli, Vibrio sp., Salmonella sp. and Enterococcus sp. show high frequency of resistance to 2-5 antibacterials of 60.4%, 45.83%, 69.16% and 46.6%, respectively. High pollution indices (PI -6.66-14.06) and antibiotic resistance indices (ARI -0.29-0.343) indicate that the coastal environment is highly exposed to antibiotic sources that suggesting to avoid direct contact.

We report, synthesis and antibacterial activities of CuO nanoflakes. CuO nanoparticles are prepar... more We report, synthesis and antibacterial activities of CuO nanoflakes. CuO nanoparticles are prepared at room temperature through sol-gel method. X-ray diffraction studies show the particles are monoclinic (crystalline) in nature. Scanning electron microscopy (SEM) images clearly show that the prepared particles are flake like in structure. Fourier transform infrared (FTIR) spectra exhibits three different bands that correspond to the A u and B u modes. Antibacterial studies were performed on Shigella flexneri, Staphylococcus aureus, Staphylococcus epidermidis, Salmonella typhimurium, Bacillus subtilis, Escherichia coli, Vibrio cholera, Pseudomonas aeruginosa and Aeromonas liquefaciens bacterial strains. Among these bacterial strains, S. flexneri and B. subtilis are most sensitive to copper oxide nanoparticles than the positive control (Penicillin G) and S. typhimurium strain shows the less sensitive. Results show that sensitivity is highly dependent on the concentrations of CuO nanoflakes.