28 research outputs found
Seasonal changes in the abundance of biological agents killing Microcystis aeruginosa in a hypereutrophic pond
No full textSeasonal changes in abundance of the heterotrophic flagellates Polytomella sp., rotifersCephalodella sp., Brachionus caliciflorous and the testate amoeba Penardochlamyssp. as grazers, cyanophages and algicidal bacteria as infectious agents on mortality ofcyanobacterium, Microcysis aeruginosa was intensively studied in a hypereutrophic pond fromSeptember to November 2000. Abundance of the rotifers Cephalodella sp., B. caliciflorousand the Penardochlamys sp. were relatively high with large fluctuations. The cell density of M.aeruginosa ranged between 3.0 x 105 to 1.9 x 107 cells ml-1, whereas those of algicidal bacteriawere between 0.3 x 12 to 3.7 x 102 PFU ml-1 and cyanophages were between 0.9 x 103 to7.1x 103 PFU ml-1. Algicidal bacteria were relatively high with fluctuation between0.3 x 104 to3.7 x 104 PFU ml-1 and bacterial peaks were followed with M. aeruginosa peaks. Occationalcyanophages peaks on 2 and 20 October were followed by sudden collapse of M.aeruginosabloom. Percentages of M. aeruginosa cells in food vacuole of Penardochlamys sp.was high(77%) during September following increase of the M. aeruginosa cell density. The flagellatePolytomella sp. was increased to a peak (2.5 x 105 indi. M-1) from 10 to 17 November withdecrease of M. aeruginosa cell density. The percentage of B. caliciflorous individuals ingestingcolonies of M. aeruginosa during the bloom period was significantly high (t-test, P Percentageof testate amoebae Penardochlamys sp. ingesting M. aeruginosa cells was very high (?77%)during the bloom period. The food vacuoles of Penardochlamys sp. contained only Microcysisindicating its specific preference of Microcysis. The overall results of the study suggest thegrazers’ protozoa; Polytomella sp., and the testate amoeba Penardochlamys sp., zooplankton;Cephalodella sp. and Brachionus caliciflorous, cyanophages and algicidal bacteria successivelyinvolved in suppressing M. aeruginosa bloom in a freshwater environment.Key words : Microcysis aeruginosa, cyanophages, algicidal bacteria, Penardochlamys sp.,Cephalodella sp. and Brachionus caliciflorou
Accumulation of Microcystin-LR in Grains of Two Rice Varieties (Oryza sativa L.) and a Leafy Vegetable, Ipomoea aquatica
No full textThe potential transfer of microcystin-LR (MC-LR) to humans via crop plants irrigated with MC-contaminated water is causing serious concern. In this study, two Oryza sativa variants, a hybrid (BG358), a traditional (Suwandel) variety, and a leafy green vegetable crop, Ipomoea aquatica, were exposed under laboratory conditions to natural blooms of Microcystis aeruginosa sampled from a hypereutrophic lake contaminated with MC-LR (3,197.37 ± 1.04 µg/L). Field samples of O. sativa and I. aquatica were collected from farmlands that had been irrigated from a reservoir, containing MC-LR (180 µg/L). MC-LR was quantified by high performance liquid chromatography followed by photodiode-array detection (HPLC-PDA). From the laboratory study, we calculated the potential human health exposure from BG358, Suwandel and I. aquatica as 2.84 ± 0.01, 0.22 ± 0.01, and 0.06 ± 0.01 µg/kg of body weight/day, respectively, whereas the potential health exposures from BG358, Suwandel and I. aquatica collected from the field were 0.10 ± 0.01, 0.009 ± 0.005, and 0.03 ± 0.01 µg/kg of body weight/day, respectively. In certain instances, the results exceeded the World Health Organization’s (WHO) tolerable daily intake of MC-LR, posing a potential health risk to humans. Thus, our results emphasize the importance of continuous screening programs for cyanotoxins in edible plants in the future to prevent the consumption of contaminated crops
Decolorization of CI Direct Blue 201 Textile Dye by Native Bacteria
No full textWater pollution from untreated or partially treated textile dye effluents is one of the major problem concerns globally. Synthetic dyes extensively are used for textile dyeing process. They are highly recalcitrant to natural decolorization and degradation processes and will create drastic negative impacts on natural environment. Remediation of synthetic textile dyes through biological agents has been recorded as low cost and environmental friendly alternative for expensive chemical and physical treatment methods. Therefore the present study was aimed on the determination of CI Direct Blue 201 textile dye decolorizing ability by isolated bacteria strains. Among the 35 bacteria strains isolated from effluents of textile industries, five bacteria strains have shown remarkable decolorizing abilities on CI Direct Blue textile dye. The isolated bacteria were tentatively identified as Pseudomonas sp.1, Pseudomonas sp.2, Bacillus sp.1, Bacillus sp.2 and Micrococcus sp. by morphological features and biochemical tests. Decolorization kinetics of bacteria was recorded after 14 days of incubation with CI Direct Blue 201 dye treated at 75 ppm. Descending order of dye decolorization was resulted by Pseudomonas sp.2 (58.15 ± 0.92%), Bacillus sp.2 (55.02 ± 0.70%), Pseudomonas sp.1 (54.73 ± 1.99%), Micrococcus sp. (51.86 ± 0.49%) and Bacillus sp. 1 (51.55 ± 0.74%) at 280C respectively. Descending decolorization potential was shown by all bacteria as a response for the ascending initial concentration of dye. The highest decolorization of dye was recorded by Pseudomonas sp.2 as 67.93 ± 1.23% at 50 ppm. High decolorization percentages were obtained when bacteria were incubated at 320C compared to 280C and 240C. Results of the present study revealed that isolated bacteria will be successful aspirants for remediation of synthetic textile dyes as an ecofriendly bioremediators to consider for green application approaches. However further studies are needed to understand their dye degradation mechanism in natural environment.KEYWORDS: Bioremediation; dye decolorizing bacteria; CI Direct blue 201; Azo dy
Heavy use of antibiotics in aquaculture: Emerging human and animal health problems – A review
No full textRemoval of Ciprofloxacin (CIP) by bacteria isolated from hospital effluent water and identification of degradation pathways
No full textWater quality and microbial contamination status of groundwater in Jaffna Peninsula, Sri Lanka
No full textIn Sri Lanka, among 2588 Salmonella positive cases, the highest incidences were recorded from Jaffna peninsula during 2005 to 2013. Therefore, the present study aimed to identify the microbiological and chemical contamination status of groundwater (40 well water) sources in Jaffna during November 2016. The total coliform, E. coli, Salmonella spp. and Shigella spp. along with some physico-chemical parameters of groundwater were studied. The results revealed that entire peninsula was contaminated with total coliform and E. coli bacteria and the parameters recorded were not within the WHO and SLS (Sri Lanka Standards) drinking water quality standards. 38% of sampling locations were positive for Salmonella spp. and among them six sampling locations were being used for drinking purposes. The results of the study correlates with the statistics of typhoid cases recorded in Jaffna. Results of the study also revealed that around 80% of wells were not within the values specified in guidelines of the SLS for drinking water quality on electrical conductivity. Further, 15% of wells recorded greater than 10 mgꞏdm–3 nitrate, which is still below the SLS drinking water standards (45 mgꞏdm–3). According to the water quality data, PCA analysis showed that Jaffna town, Nallur, Tellippalai and Kopay DS divisions has similar characteristics for water quality
Contamination Status of Salmonella spp., Shigella spp. and Campylobacter spp. in Surface and Groundwater of the Kelani River Basin, Sri Lanka
No full textWaterborne diseases are a global problem that causes more than 2.2 million deaths annually. Therefore, the present study was focused on microbiological contamination of both ground and surface water by means of total coliform, Escherichia coli (E. coli), Salmonella spp., Shigella spp. and Campylobacter spp. Seventy two groundwater and 45 surface water sampling locations were selected to collect water from the head, transitional and meandering regions of the Kelani River Basin for a period of one year (both dry and wet seasons). The results of the study revealed that the entire Kelani River basin was contaminated with total coliform and E. coli bacteria and almost all the sampling locations exceed Sri Lanka Standards Institute (SLSI) guideline value given for drinking water (0 CFU/100 mL). Further, in groundwater, 17 locations were positive for Salmonella spp., whereas only 2 locations were positive for Campylobacter spp. In surface water, 26 and three sampling locations were positive for Salmonella spp. and Campylobacter spp., respectively. In this study, 23 different human pathogenic serovars were isolated and the Salmonella enterica serovar Kentucky was identified as the commonest type. Thus, the result of the study revealed that the consumption of raw water from the Kelani River Basin is unsafe and possible to cause gastrointestinal diseases
Isolation and characterisation of oil degrading bacteria from coastal waters and sediments from three locations in Sri Lanka
No full textToxicological Effects of Tributyltin in Zebrafish (Danio rerio) Embryos
No full textTributyltin (TBT) is known as an endocrine-disrupting chemical abundant in the aquatic environment. In the present study, zebrafish fish embryos were used to observe the chronic toxicity of TBT. Fish embryo toxicity analysis was carried out for different TBT concentrations (100, 50, 25, 12.5, 6.2, and 3.1 ng/L) and fertilized eggs were used to test each concentration effect. Fertilized eggs in 24-well plates (20 eggs in each well) were incubated at 26°C for four days and embryo coagulation, heartbeat of the embryo and mortality lethal endpoints (LC50 values) were recorded after 8, 24, 48, and 96 h. The results revealed that 100% coagulations of the embryos occurred at TBT doses of 50 and 100 ng/L. The coagulation significantly increased in a dose-dependent manner and TBT might induce coagulation of zebrafish embryos. Heartbeat changes were significantly decreased (p<0.05) in a dose-dependent manner at different TBT doses. LC50 values of TBT for zebrafish embryos were 19.9, 11.7, 7.3, and 5.2 ng/L at 8, 24, 48, and 96 h, respectively. The percentage of mortality was higher in embryos for the trace level of TBT, indicating that embryos are more sensitive to TBT toxicity. Hence, TBT is highly toxic and leads to a lethal effect on the zebrafish embryo, resulting in species extinction and declining biodiversity in the aquatic environment
Seasonal occurrence of Microcystin-LR with respect to physico-chemical aspects of Beira lake water
No full textCyanobacteria are well known for their ability to produce a group of cyanotoxins referred as microcystins(MCs). MCs show both acute and chronic hepatotoxic effects on animals and humans. Microcystin-LR(MCLR) is the dominant type of MCs prevailing in Sri Lankan water bodies. The present study records theseasonal variation of MCLR, in the Beira lake waters from January 2013 to January 2014 with respect tosome physico-chemical parameters of the lake. Quantification of MCLR was done using photodiode array -High Pressure Liquid Chromatography method (PDA-HPLC). The physico-chemical parameters of the waterbody were measured using standard methods. Microcystis aeruginosa, Microcystis wesenbergii andMicrocystis incerta, were the toxic cyanobacterial species present in the Beiralake while Microcystisaeruginosa (49.63%) was the dominant species. MCLR concentration of the lake varied between 11.45±0.73to 17.57±0.13 μg/ml throughout the dry season of the sampling period while varied between 13.21 ±0.73 to25.23±0.42 μg/ml during the rainy season. The Pearsons correlation coefficient analysis done for total toxinconcentration and the water quality parameters suggested that the water temperature (r=0.914, pvalue=0.000), and the total phosphate concentration (r=0.988, p-value=0.000) have a strong positivecorrelation with the total MCLR concentration, while pH (r=0.766, p-value=0.002) has a moderatecorrelation for the production of total MCLR.KYWORDS: Cyanobacteria, Microcystin-LR (MCLR), Microcystis aeruginosa, Physico-chemicalparameters, High Pressure Liquid Chromatography method (PDA-HPLC)
