Assessment of phytokinetic removal of pollutants of paper mill effluent using water hyacinth (Eichhornia crassipes [Mart.] Solms)

Laboratory experiments were carried out to assess the phytoremediation potential of water hyacinth (Eichhornia crassipes [Mart.] Solms) for the removal of different parameters of the paper mill effluent. The maximum removal efficiency of E. crassipes and phytokinetic removal rate were recorded at 50% concentration of the paper mill effluent followed by 60 days of phytoremediation experiments. The most percent reduction was observed in the contents of electrical conductivity (EC; 62.23%), total dissolved solid (TDS; 72.54%), biochemical oxygen demand (BOD; 79.93%), chemical oxygen demand (COD; 85.66%), total Kjeldhal nitrogen (TKN; 89.27%), P (72.39%), Ca²⁺ (51.79%), Mg²⁺(51.02%), Na⁺ (57.10%) and K⁺(71.47%) and phytokinetic removal rate in the subjects of EC (0.00011 mg l^-1d^-1), TDS (0.045 mg l^-1d^-1), BOD (0.0314 mg l^-1d^-1), COD (0.0461 mg l^-1d^-1), TKN (0.0034 mg l^-1d^-1), P (0.0050 mg l^-1d^-1), Ca²⁺ (0.0045 mg l^-1d^-1), Mg²⁺ (0.003 mg l^-1d^-1), Na⁺ (0.004 mg l^-1d^-1) and K⁺ (0.004 mg l^-1d^-1) after phytoremediation at 60 days. The maximum plant height (120.73 cm), fresh plant biomass (383.54 ± 0.15 gkg^-1) and total chlorophyll content (3.74 ± 0.05 mgg^-1 fwt), crude protein (19.11 mg 100 g^-1 fwt), crude fiber (29.92 mg 100 g^-1 fwt), total carbohydrate (35.22 mg 100 g^-1 fwt) and total ash (26.88 mg 100 g^-1 fwt) of E. crassipes were observed with 50% concentration of the paper mill effluent at 60 days of phytoremediation experiments. The maximum relative growth rate (13.86 gg^-1d^-1) of E. crassipes was detected with 50% concentration of paper mill effluent at 60 days of phytoremediation experiments. Therefore, E. crassipes was recorded to be feasible for the removal of different pollutants of paper mill effluent, responsible for the eutrophication of the aquatic resources.

Assessment of plant growth attributes, bioaccumulation, enrichment, and translocation of heavy metals in water lettuce (Pistia stratiotes L.) grown in sugar mill effluent

This study was conducted to assess the pollutant uptake capability of water lettuce (Pistia stratiotes L.) in terms of bioaccumulation, enrichment, and translocation of heavy metals grown in sugar mill effluent. Results showed that the maximum fresh weight (328.48 ± 2.04 gm kg^-1), total chlorophyll content (2.13 ± 2.03 mg g^-1 fwt), and relative growth rate, RGR (11.89 gg^-1 d^-1) of P. stratiotes were observed at 75% concentration of the sugar mill effluent after 60 days of phytoremediation experiment. The bioaccumulation factor (B_F) of different heavy metals was greater than 1 with 50% and 75% concentrations of sugar mill effluent and this indicated that P. stratiotes was hyperaccumulator or phytoremediator of these metals. The enrichment factor (E_F < 2 for Cu, Fe, Cr, Pb, Zn, and Mn) and (E_F > 2 for Cd) indicated that P. stratiotes mineral enrichment deficient and it moderately enriched the different heavy metals. Moreover, translocation factor (T_F) was less than 1 which indicated the low mobility of metals in different parts (root and leaves) of P. stratiotes after phytoremediation. Therefore, P. stratiotes can be used for phytotreatment of sugar mill effluent up to 50% to 75% concentrations and considered as hyperaccumulator aquatic plant for different heavy metals and other pollutants from the contaminated effluents.

Phytoremediation potential of water caltrop (Trapa natans L.) using municipal wastewater of the activated sludge process-based municipal wastewater treatment plant

Phytoremediation experiments were carried out to assess the phytoremediation potential of water caltrop (Trapa natans L.) using municipal wastewater collected from the activated sludge process- (ASP) based municipal wastewater treatment plant. The results revealed that T. natans significantly (P ≤ .05/P ≤ .01/P ≤ .001) reduced the contents of total dissolved solids (TDS), electrical conductivity (EC), biochemical oxygen demand (BOD₅), chemical oxygen demand, total Kjeldahl nitrogen, phosphate ([Formula: see text]), sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), zinc (Zn), standard plate count, and most probable number of the municipal wastewater after phytoremediation experiments. The maximum removal of these parameters was obtained at 60 days of the phytoremediation experiments, but the removal rate of these parameters was gradually increased from 15 to 45 days and it was slightly decreased at 60 days. Most contents of Cd, Cu, Fe, Mn and Zn were translocated in the leaves of T. natans, whereas most contents of Cr and Pb were accumulated in the root of T. natans after phytoremediation experiments. The contents of different biochemical components were recorded in the order of total sugar > crude protein > total ash > crude fiber > total fat in T. natans after phytoremediation of municipal wastewater. Therefore, T. natans was found to be effective for the removal of different parameters of municipal wastewater and can be used effectively to reduce the pollution load of municipal wastewater drained from the ASP-based treatment plants.

Irrigating okra with secondary treated municipal wastewater: Observations regarding plant growth and soil characteristics

The present study was carried out to probe the agronomic response of hybrid cultivar of okra (Hibiscus esculentus L. var. JK 7315) grown in secondary treated municipal wastewater irrigated soil with field investigations. The concentrations of the municipal wastewater viz., 10%, 20%, 40%, 60%, 80%, and 100% along with the control (groundwater) were used for the irrigation of the H. esculentus. The study revealed that the concentrations of the municipal wastewater showed significant (p < 0.05/p < 0.01) effect on the soil parameters after wastewater fertigation in comparison to groundwater in both the seasons. The maximum agronomic performance of the H. esculentus was recorded with 60% concentration of the municipal wastewater in both the seasons. The contamination factor of heavy metals varied in the H. esculentus plants and soils. In the H. esculentus plants, following fertigation with municipal wastewater, the contamination factor of manganese was the highest, while that of chromium was the lowest. Intermediate contamination factor were observed for zinc, copper, and cadmium. Therefore, secondary treated municipal wastewater can be used as an agro-fertigant after appropriate dilution (up to 60%) to achieve the maximum yield of the H. esculentus.

Experimental and kinetic studies for phycoremediation and dye removal by Chlorella pyrenoidosa from textile wastewater

Potential of Chlorella pyrenoidosa was experimentally investigated for phycoremediation and dye removal from textile wastewater (TWW) in batch cultures. Growth of alga was observed at various concentration of textile wastewater (25%, 50%, 75% and 100%) and was found in a range of 8.1-14 μg ml(-1) day(-1). Growth study revealed that alga potentially grows up to 75% concentrated textile wastewater and reduces phosphate, nitrate and BOD by 87%, 82% and 63% respectively. Methylene blue dye (MB) removal was also observed by using dry and wet algal biomass harvested after phycoremediation. Adsorption isotherms (Langmuir and Freundlich) and kinetic models (pseudo first and second order) were applied on adsorption process. Dry algal biomass (DAB) was found more efficient biosorbent with large surface area and showed high binding affinity for MB dye in compare to wet algal biomass (WAB). The RL value for both biosorbent showed feasible adsorption process as the obtained value was between 0 and 1. Pseudo second order kinetic model with high degree of correlation coefficient and low sum of error squares (SSE %) value was found more suitable for representation of adsorption process in case of both biosorbents, however pseudo first order also showed high degree of correlation for both biosorbents.

Accumulation of heavy metals in the vegetables grown in wastewater irrigated areas of Dehradun, India with reference to human health risk

The present study on accumulation of heavy metals in the vegetables viz. Beta vulgaris, Phaseolus vulgaris, Spinacea oleracea, and Brassica oleracea var. botrytis grown in the wastewater-irrigated soil near the Bindal river, Dehradun, has shown the maximum accumulation of metals for Pb (196.91 ± 8.13 mg/kg), Cu (36.75 ± 6.19 mg/kg), Zn (305.54 ± 14.30 mg/kg), Ni (125.48 ± 5.97 mg/kg), Cd (29.58 ± 4.26 mg/kg), and Cr (93.06 ± 3.25 mg/kg) in agricultural soil irrigated with wastewater. The enrichment factor of soil was maximum for Cr (8.74) and minimum for Cu (0.88). In case of vegetables, the concentrations of heavy metals were maximum for Pb (86.69 ± 6.69) in the flower of B. oleracea var. botrytis, Cu (33.49 ± 2.09) and Zn (161.86 ± 17.79) in the leaves of S. oleracea, Ni (80.72 ± 8.40) and Cd (23.19 ± 2.76), and Cr (57.18 ± 8.16) in the root of B. vulgaris grown in wastewater (WW)-irrigated soil. The bioaccumulation factor (BAF) for Cu (0.911) was maximum in S. oleracea and minimum for Pb (0.440) in B. vulgaris. The maximum daily intake of metals was found for Zn (0.059) in S. oleracea and minimum for Cd (0.008) in B. vulgaris. The human health risk index was found to be more than 1 for Pb and Cd. The long-term wastewater irrigation resulted in accumulation of heavy metals in vegetables which may cause potential health risks to consumers as these vegetables are sold in local markets of Dehradun city.

Phycoremediation of textile wastewater by unicellular microalga Chlorella pyrenoidosa

The potential application of microalga Chlorella pyrenoidosa was investigated for phycoremediation of textile wastewater. Two 15 days batch experiment containing autoclaved and unautoclaved textile wastewater were performed to measure the efficiency of alga to remediate the wastewater. Experiments were set at equivalent external conditions and pollutant load was measured on alternate of 5 days to determine the pollutant removal efficiency of alga. Alga was found to be more efficient in removal of pollutants load in autoclaved wastewater; agents of eutrophication such as nitrate and phosphate are reduced by 62% ±0.5 and 87% ±0.7 respectively while organic load in terms of BOD is reduced by 81% ±0.2 whereas, In unautoclaved wastewater in presence of algal-bacterial consortium, nitrate and phosphate were removed by 81% ±1 and 36% ±2.2 while BOD is reduced by 73% ±1.6 only. Another time dependent experiment of dye removal was also performed to measure the adsorption potential of selected dried algal biomass. An equal amount of dried algal biomass was introduced to various range of textile wastewater simulated with methylene blue (MB) dye. The maximum colour removal was observed afterduration of 30 minutes by dry algal biomass.

Ferti-irrigational impact of sugar mill effluent on agronomical characteristics of Phaseolus vulgaris (L.) in two seasons

Ferti-irrigation response of 5, 10, 25, 50, 75, and 100 % concentrations of the sugar mill effluent (SME) on French bean (Phaseolus vulgaris L., cv. Annapurna) in the rainy and summer seasons was investigated. The fertigant concentrations produced significant (P < 0.01) changes in the soil parameters, viz., electrical conductivity (EC), pH, organic carbon (OC), sodium (Na(+)), potassium (K(+)), calcium (Ca(2+)), magnesium (Mg(2+)), total Kjeldahl nitrogen (TKN), phosphate (PO4 (3-)), sulfate (SO4 (2-)), ferrous (Fe(2+)), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn), in both seasons. The contents of Cr, Cu, Mn, and Zn except Cd were found to be below the maximum levels permitted for soils in India. The agronomic performance of P. vulgaris was gradually increased at lower concentrations, i.e., from 5 to 25 %, and decreased at higher concentrations, i.e., from 50 to 100 %, of the SME in both seasons when compared to controls. The accumulations of heavy metals were increased in the soil and P. vulgaris from 5 to 100 % concentrations of the SME in both seasons. The contents of Cu, Mn, and Zn except Cd and Cr were noted under the permissible limit of Food and Agriculture Organization (FAO)/World Health Organization (WHO) standards. Most contents of biochemical components like crude proteins, crude fiber, and total carbohydrates were found with 25 % concentration of the SME in both seasons. The contamination factor (Cf) of various metals was in the order of Cd > Cr > Zn > Mn > Cu for soil and Mn > Zn > Cu > Cr > Cd for P. vulgaris in both seasons after fertigation with SME. Therefore, the SME can be used to improve the soil fertility and yield of P. vulgaris after appropriate dilution.

Irrigational impact of distillery effluent on Abelmoschus esculentus L. Okra with special reference to heavy metals

The present study was performed under natural environment to assess levels of different heavy metals in soil and Abelmoschus esculentus plants along with soil microbial population irrigated with five rates of distillery effluent (DE) viz. 10, 25, 50, 75 and 100 % concentration in comparison with control (Bore well water). Results revealed that among various concentrations of DE, irrigation with 100 % DE significantly (P < 0.001) increased Zn (+63.46 %), Cu (+292.37 %), Zn (+3763.63 %), Cd (+264.29 %), Ni (+48.39 %) and Cr (+815.74 %), while decreased total bacteria (-45.23 %), fungi (-17.77 %) and actinomycetes (-42.57 %) in the soil. Enrichment factor of various heavy metals for soil was in the order Ni > Cr > Cd > Zn > Cu, and for A. esculentus plants, it was in the order Ni > Cr > Cu > Cd > Zn after irrigation with distillery effluent. The enrichment factor value was found maximum for Ni in comparison to other metals at 100 % DE concentration as compared with BWW. However, the values of these metals were below the recommended permissible limit.

Accumulation and translocation of metals in soil and different parts of French bean (Phaseolus vulgaris L.) amended with sewage sludge

A pot experiment was conducted to study the accumulation and translocation of metals in French bean (Phaseolus vulgaris L.). Plants were grown in soil amended with up to 100 % sewage sludge. Significant (p < 0.01) changes to soil characteristics were observed. The maximum growth of P. vulgaris was noted in the treatment with 40 % of sewage sludge. Metal concentrations were significantly (p < 0.05) higher in P. vulgaris after sewage sludge amendment where Fe > Zn > Cd > Cu > Cr > Pb. The translocation for Fe and Zn was in the order of leaves > shoot > root > fruits, for Cd, shoot > root > leaves > fruits, for Cu and Pb shoot > leaves > root > fruits and for Cr root > shoot > leaves > fruits of P. vulgaris. All accumulated metal concentrations except Cd in the fruit were below the FAO/WHO standard limits. Thus, the amendment of agricultural soil by sewage sludge might be feasible. However, a regular monitoring of metal levels in agricultural products is recommended to prevent their accumulation in the food chain.

Ferti-irrigational effect of paper mill effluent on agronomical characteristics of Abelmoschus esculentus L. (Okra)

The ferti-irrigational effect of an agro-based paper mill effluent on Abelmoschus esculentus (var. IHR-31) was investigated. Different doses of paper mill effluent viz. 5, 10, 25, 50, 75 and 100% were used for fertigation ofA. esculentus along with bore well water (control). The study revealed that paper mill effluent had significant (p < 0.05) effect on EC, pH, OC, Na+, K+, Ca2+, Mg2+, Fe2+, TKN, PO4(3-), SO4(2-), Cd, Cr, Cu, Mn and Zn of the soil in both seasons. Insignificant (p > 0.05) changes in WHC and bulk density of the soil were observed after irrigation with paper mill effluent. The agronomical performance of A. esculentus was increased from 5 to 25% and decreased from 50 to 100% concentration of paper mill effluent as compared to control in both seasons. The heavy metals concentration was increased in A. esculentus from 5 to 100% concentrations of paper mill effluent in both seasons. Biochemical components like crude proteins, crude fiber and crude carbohydrates were found maximum with 25% paper mill effluent in both seasons. The order of Contamination Factor (Cf) of various heavy metals was Cr > Cd > Mn > Zn > Cu for soil and Zn > Mn > Cu > Cr > Cd for A. esculentus plants after fertigation with paper mill effluent. Therefore, paper mill effluent can be used as a biofertigant after appropriate dilution to improve yield of A. esculentus.

Accumulation of heavy metals in Spinacia oleracea irrigated with paper mill effluent and sewage

The present study on heavy metal contamination in soil and their accumulation in edible part (leaves) and roots of Spinacia oleracea (Spinach) on irrigation with paper mill effluent (PME)/sewage revealed that there was significant increase in the nickel (Ni, +227.17 %) content of the soil irrigated with PME, whereas in the soil irrigated with sewage chromium (Cr, +274.84 %), iron (Fe, +149.56 %), and cadmium (Cd, +133.39 %), contents were increased appreciably. The value of enrichment factor (EF) for Ni (3.27) indicated moderate enrichment in PME-irrigated soil. The EF of Fe, zinc (Zn), Cd, and Cr were <2 in PME effluent-irrigated soil which showed deficiency of minimal enrichment. In sewage irrigated soil, EF value for Cr, Fe, and Cd indicated moderate enrichment, while the values for Zn and Ni indicated deficiency of minimal enrichment. Among various metallic concentrations, the maximum concentration of Fe was observed in leaves (400.12 ± 11.47 mg/kg) and root (301.41 ± 13.14 mg/kg) of S. oleracea after irrigation with PME, whereas the maximum concentrations of Fe was found in leaves (400.49 ± 5.97 mg/kg) and root (363.94 ± 11.37 mg/kg) of S. oleracea after irrigation with sewage for 60 days. The bioaccumulation factor value was found maximum for Cd (2.23) in the plants irrigated with PME while that of Fe (0.90) in the plants irrigated with sewage. The undiluted use of PME/sewage for irrigation increased the concentration of Cr, Cd, Zn, Ni, and Fe metals which were accumulated in S. oleracea, posing a potential threat to human health from this practice of irrigation.

Agro-potentiality of distillery effluent on soil and agronomical characteristics of Abelmoschus esculentus L. (okra)

The present study showed that irrigation of soil with different effluent concentrations (10, 25, 50, 75, and 100 %) of distillery effluent (DE) for 60 days resulted in significant (P < 0.001) changes in moisture content; electrical conductivity (EC), pH, chlorides (Cl(-)), total organic carbon (TOC), exchangeable sodium (Na(+)), available potassium (K(+)), calcium (Ca(2+)), magnesium (Mg(2+)), iron (Fe(2+)), total Kjeldahl nitrogen (TKN), available phosphorus (P), and sulfate (SO4 (2-)) of soil. The non-significant (P > 0.05) changes were observed for water-holding capacity and bulk density of the soil. Among various concentrations of DE irrigation, irrigation with 100 % effluent concentration increased moisture content, (24.85 %), EC (77.88 %), Cl(-) (285.95 %), TOC (3,171.42 %), exchangeable Na(+) (241.04 %), available K(+) (52.49 %), Ca(2+) (990.37 %), Mg(2+) (1,751.72 %), TKN (1,417.00 %), available P (305.00 %), and SO4 (2-) (75.32 %) in the soil and decreased pH (-20.22 %). The more stimulation in agronomical parameters such as shoot length, root length, number of leaves, flowers, pods, dry weight, fresh weight, chlorophyll content, leaf area index, and crop yield of A. esculentus were observed to be inversely proportional to the concentration of effluent water, with the best results being obtained at a dilution of 25 % of DE concentration.

Bio-monitoring of persistent organochlorines in human milk and blood samples from sub-Himalayan region of India

In the present study, concentrations of organochlorine pesticide residues viz. Dichlorodiphenyltrichloroethane and its metabolites (DDTs) and Hexachlorocyclohexane isomers (HCHs) in human breast milk and human blood samples, collected from several high altitude regions of Garhwal Himalaya in Uttarakhand, India viz. Devprayag, Chamoli, Uttarkashi, Joshimath, Bhatwari and Gangnani (altitude ranging from 472 to 1,982 m above sea level) were determined. Mean concentrations of HCH and DDT in human milk samples ranged from 4.53 to 34.32 mg/kg and 6.09 to 12.98 mg/kg, respectively. While the human blood showed mean values ranging from 6.64 to 281.7 μg/L and 12.37 to 104.10 μg/L for HCH and DDT, respectively. The study showed much higher concentrations of organochlorine residue contamination in the Garhwal region as compared to other parts of India. Risk assessments for infants were also calculated and were found within WHO limits.

Fertigation effect of distillery effluent on agronomical practices of Trigonella foenum-graecum L. (Fenugreek)

The fertigation effect of distillery effluents concentrations such as 5%, 10%, 25%, 50%, 75% and 100% were studied on Trigonella foenu-graecu (Pusa early bunching) along with control (bore well water). On irrigation of soil with different effluents up to 90 days of harvesting, it was observed that there was a significant effect on moisture content (P < 0.001), EC, pH, Cl(-), total organic carbon (TOC), HCO₃⁻, CO₃⁻², Na(+), K(+), Ca(2+), Mg(2+), Fe(2+), TKN, NO₃²⁻, PO₄³⁻, and SO₄²⁻ (P < 0.0001) and insignificant effect on WHC and bulk density (P > 0.05).There was no significant change in the soil texture of the soil. Among various concentrations of effluent irrigation, the irrigation with 100% effluent concentration decreased pH (16.66%) and increased moisture content (30.82%), EC(84.13%), Cl(-) (292.37%), TOC (4311.61%), HCO₃⁻ (27.76%), CO₃⁻² (32.63%), Na +) (273%), K(+) (31.59%), Ca(2+) (729.76%), Mg(2+) (740.47%), TKN (1723.32%), NO₃²⁻ (98.02%), PO₄³⁻ (337.79%), and SO₄²⁻ (77.78%), Fe(2+) (359.91%), Zn (980.48%), Cu (451.51%), Cd (3033.33%), Pb (2350.00%), and Cr (2375.00%) in the soil. The agronomical parameters such as shoot length, root length, number of leaves, flowers, pods, dry weight, chlorophyll content, LAI, crop yield, and HI of T. foenum-graecum were recorded to be in increasing order at low concentration of the effluent, i.e., from 5% to 50% and in decreasing order at higher effluent concentration, i.e., from 75% to 100% as compared to control. The enrichment factor of various heavy metals was ordered for soil Cd>Cr> Pb>Zn>Cu>Fe and for T. foenum-graecum plants Pb>Cr>Cd>Cu>Zn>Fe after irrigation with distillery effluent.

Fate of coliforms and pathogenic parasite in four full-scale sewage treatment systems in India

The occurrence and removal of fecal indicators (total coliforms (TC), fecal coliforms (FC), fecal streptococci (FS)) and pathogens (helminthes eggs) were studied in various municipal wastewater treatment processes (UASB + FPU, ASP, EA, WSP). The reductions in TC and FC concentrations were usually between 2.0 and 2.5 log units in up-flow anaerobic sludge blanket reactor incorporated with final polishing unit (UASB + FPU). Almost similar reduction was observed in activated sludge process system (ASP) and waste stabilization ponds system (WSP), while it was log 3.0 in extended aeration system (EA). UASB + FPU and WSP systems were observed more efficient to reduce helminthes eggs at almost 100%, whereas only 97% removal was observed in case of ASP and EA system. In addition to monitoring of indicator organisms, turbidity, suspended solids (SS), and biochemical oxygen demand (BOD) were used as indirect measure of the potential presence of microorganisms. Interrelationship of BOD, SS, and turbidity with fecal indicator bacteria concentration in influent and effluent manifest that improvement of the microbiological quality of wastewater is strongly linked to the removal of BOD and SS.

Toxicological properties of several medicinal plants from the Himalayas (India) against vectors of malaria, filariasis and dengue

The leaves of five plants namely Nyctanthes arbortistis (Oleaceae), Catharanthus roseus (Apocynaceae), Boenininghusenia albiflora (Rutaceae), Valeriana hardwickii (Valerianaceae) and Eupatorium odoratum (Asteraceae) were selected for the first time from the Garhwal region of north west Himalaya to investigation its toxicological properties against mosquito vectors of malaria, filariasis and dengue. In a laboratory study, using different polarity solvents (petroleum ether, chloroform and methanol) were tested against important larvae of malaria, filariasis and dengue vectors in India. It was observed that petroleum ether fraction of all selected plant possess good larvicidal properties than other solvent fraction. The LC(50) values of isolates from Nyctanthes arbortistis (HAR-1), C. roseus (CAT-1), B. albiflora (BOA-1), V. hardwickii (SUG-1) and E. odoratum (EUP-1) against Anopheles stephensi were 185 ppm, 150 ppm, 105 ppm, 225 ppm and 135 ppm, respectively. The results therefore suggest that the fraction code BOA-1 has excellent larvicidal properties and could be incorporated as botanical insecticides against mosquito vectors with high safety to nontarget organisms. The same fraction was tested against adult vectors of malaria, filariasis and dengue, but no mortality was observed.

Effect of sewage-water irrigation on physico-chemical parameters with special reference to heavy metals in agricultural soil of Haridwar city

The present study revealed that use of sewage for irrigation of agricultural soil of Haridwar city improved the water holding capacity (+27.98%), electrical conductivity (+196.15%), sulphate (+2.34%), organic carbon (+30.48%), total Kjeldhal nitrogen (+87.5%), available potassium (+25.77%) and available phosphorous (+59.97%) and fertility status of the soil in comparison to natural water irrigated soil. Further sewage irrigation also resulted in a significant build-up of total Pb (+98.95%), Ni (+128.29%), Cu (+253.17%), Fe (+39.74%), Cd (+30.92%), Zn (+696.03%) and Cr (+13.15%) than the natural water irrigated soil. The mean concentrations of these metals were below the permissible limits of Indian standards. The enrichment factor (Ef) for Cu (9.62) was maximum and minimum for Cr (1.13).The Ef for different metals was in the order of Cu> Zn > Ni > Pb > Cd > Cr > Fe. Pollution index (Pi) value of the sewage water irrigated soil ranged from 0.505 to 0.901 which indicated that the soil was not yet polluted.

Bioaccumulation of organochlorine pesticides in aquatic system--an overview

In recent years, various environmental issues have aroused a concern on the pollution of pesticides in rivers and in their various intercompartments. Multiple residues of pesticides discharged from industries or as a result of extensive use of agrochemicals in agriculture have been monitored. These pesticide residues contaminate the river ecosystem and its intercompartments such as sediments, and aquatic biota, and make it harmful to humans when they contaminate food and drinking water. The pesticide contamination in water, sediments, and aquatic biota has been reported to be beyond the acceptable range. The most commonly found pesticides are organochlorine, namely, dichlorodiphenyltrichloroethane, hexachlorocyclohexane, endosulfan, heptachlor, lindane, dieldrin, aldrin, endrin, and others. The paper discusses the general description, classification, and toxicity of pesticides; it also aims to create public awareness among people and appraise them with various alternate methods to combat the problem of pesticide contamination. An attempt has also been made to elucidate the findings of various works on pesticides in aquatic system and to highlight the challenging aspects of pesticide contamination, which have not attracted the attention of investigators yet.

Influence of sugar mill effluent on physico-chemical characteristics of soil at Haridwar (Uttarakhand), India

The influence of seven rates of Sugar mill effluent (viz. 0, 5, 10 25, 50, 75 and 100 ml/kg soil) along with control (Bore-well water, BWW) on the physical and chemical properties of soils revealed that among various concentrations of the effluents, the irrigation with 100% effluent concentration decreased moisture content (20.44%),WHC (13.80%), BD (4.14%) and increased pH (9.56%), EC (64.28%), ECEC (149.25%), Cl- (194.71%), OC (3228.89%), HCO3- (22.34%), CO3-2 (29.38%), Na + (185.48%), K+(53.40%), Ca2+ (1262.24%), Mg2+ (1818.24%), TKN (1206.36%), NO32- (80.87%), PO43- (236.04%), SO42- (72.08%), Fe2+ (234.34%), Zn (317.72%), Cd (404.35%), Cu (374.90%), Pb (645.71%) and Cr (1024.80%) in the soil when compared to control. There was a significant (P<0.001) effect on EC, pH, Cl-, OC, HCO3- , CO32- , Na + , K + , Ca2+, Mg 2+, Fe 2+, TKN, NO3 2- , PO4 3- and SO42- , Zn, Cu, Cd, Cr and Pb and insignificant (P>0.05) effect on moisture content, WHC and bulk density after sugar mill effluent irrigation when compared to control. There was no momentous change in the soil texture of the soil. The enrichment factor (Ef) of various micronutrients in the soil was recorded in order of Cr>Pb>Cd>Cu>Zn after irrigation with sugar mill effluent.

Scenario of heavy metal contamination in agricultural soil and its management

Soil is a complex structure and contains mainly five major components i.e. mineral matter, water, air, organic matter and living organisms. The quantity of these components in the soil does not remain the same but varies with the locality. Soil possesses not only a nucleus position for existence of living being but also ensures their future existence. Therefore, it is essential to make an adequate land management to maintain the quality of soil in both rural and urban soil. The presence of different kinds of heavy metals such as Cd, Cu, Mn, Bi and Zn etc. in trace or in minimum level is a natural phenomenon but their enhanced level is an indicator of the degree of pollution load in that specific area. The precise knowledge of these kinds of heavy metals, their forms and their dependence on soil provides a genuine base for soil management. The heavy metals have potent cumulative properties and toxicity due to which they have a potential hazardous effect not only on crop plants but also on human health. The metal contaminants can be reduced by immobilization of contaminants using macrophytes and also by using genetically engineered microorganisms.

Impact of climate change on biodiversity of India with special reference to Himalayan region-An overview

India possesses a distinct identity, not only because of its geography, history and culture, but also because of the great diversity of its natural ecosystems. The panorama of Indian biological diversity is much wider, as it comes under the twelve mega biodiverse (Hot-spot) centers of the world. It contains a great wealth of biological diversity in its forests, its wetlands and in its marine areas which are distributed all over the country. This richness is shown in absolute numbers of species and the proportion they represent of the world total. The great Himalayan region has peculiar identity in the perspective of its unique biogeography. It supports a large number of glaciers, lakes, rivers, flora and fauna due to its variable climate. It has a profound effect on the climate of the subcontinent. But due to anthropogenic activities the global climate has changed since last few decades. The climate of the subcontinent has also adversely affected the biological resources of the country along with that of the Himalayan region. The present paper discusses the various causes responsible for melting and shrinkage of glaciers, decreasing water flow in the major rivers, increasing pressure of extinction of the ecological wealth of the country. It also talks about the control measures and various management steps which can be taken, with special reference to the Himalayan region.

Removal of fecal indicators and pathogens in a waste stabilization pond system treating municipal wastewater in India

This study assess the removal of fecal indicators (i.e., total coliforms, fecal coliforms, E. coli, fecal streptococci, and pathogens [Salmonella sp. and helminth eggs]) in a full-scale facultative and maturation pond system with primary screening and manual grit removal facility. The capacity of the plant is 6 ML/d. The results showed that the system was able to remove approximately 2.0 to 3.5 log units of fecal indicators and almost 100% of helminth eggs. Meanwhile, Salmonella was not eliminated significantly, as only 1.26 log units removal was found. Removal efficiency of fecal indicator bacteria was reported maximum during summers (3.4 to 4.0 log units) and minimum (1.9 to 2.0 log units) in winters. Further efforts were made to seek the correlation between key physicochemical wastewater quality parameters (biochemical oxygen demand, turbidity, and suspended solids) and indicator microorganisms (total coliforms, fecal coliforms, and fecal streptococci). Among all these parameters, suspended solids showed the highest correlation coefficient (r2) with total coliforms (0.79), fecal coliforms (0.78), and fecal streptococci (0.75). These correlations manifest that the improvement of microbiological quality of wastewater is strongly linked to the removal of suspended solids.

Insecticidal activity of Valeriana jatamansi (Valerianaceae) against mosquitoes

A root extract of Valeriana jatamansi (code BAL-O) exhibited larvicidal and adulticidal activity against different mosquito species. The median lethal concentration (LC50) of BAL-O against larvae of Anopheles stephensi, Anopheles culicifacies, Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus were 68.1, 42.8, 51.2, 53.8, and 80.6 mg/liter, respectively. The LC50 and the 90% lethal concentration against adult An. stephensi, An. culicifacies, Ae. aegypti, Ae. albopictus, and Cx. quinquefasciatus were 0.14, 0.16, 0.09, 0.08, and 0.17 and 0.24, 0.34, 0.25, 0.21, and 0.28 mg/cm2, respectively. The median knock-down time and 90% knock-down time of the fraction were 13, 13, 12, 13, and 18 and 24, 25, 21, 20, and 42 min against An. stephensi, An. culicifacies, Ae. aegypti, An. albopictus and Cx. quinquefasciatus, respectively, using 0.28 mg/cm2 impregnated papers. The median effective time and 90% effective time against An. stephensi at 4 degrees C were 46.6 and 8.7 days, and at 29 degrees C, 25.5 and 5.6 days, respectively. Gas chromatographic-mass spectrometric analysis of BAL-O showed 2-butanone,4-(2,6,6-trimethyl-2-cyclohexen-l-yl) (10.11%), patchouli alcohol (8.55%), cubenol (5.97%), caryophyllene oxide (5.46%), cadinol (5.23%), and aristolene (5.19%).

Further characterization of a type III secretion system (T3SS) and of a new effector protein from a clinical isolate of Aeromonas hydrophila--part I

A type III secretion system (T3SS)-associated cytotoxin, AexT, with ADP-ribosyltransferase activity and homology to Pseudomonas aeruginosa bifuncational toxins ExoT/S, was recently identified from a fish pathogen Aeromonas salmonicida. In this study, we reported the molecular characterization of an aexT-like toxin gene (designated as aexU) from a diarrheal isolate SSU of A. hydrophila. The aexU gene was 1539bp in length and encoded a protein of 512 amino acid (aa) residues. The NH(2)-terminus of AexU (aa residues 1-231) exhibited a 67% homology with the NH(2)-terminus of AexT from A. salmonicida. Importantly, its COOH-terminus (aa residues 232-512) had no homology with any known functional proteins in the database; however, the full-length AexU retained ADP-ribosyltransferase activity. The expression and subsequent secretion of AexU was T3SS dependent, as inactivation of the ascV gene that codes for an inner-membrane component of the T3SS channel from the wild-type (WT) bacterium, blocked translocation of AexU in HT-29 human colonic epithelial cells. We provided evidence that inactivation of acrV and axsE genes (homologs of lcrV and exsE in Yersinia species and P. aeruginosa, respectively) from A. hydrophila SSU, altered expression and/or secretion of AexU. We deleted an aexU gene from the WT, as well as from the DeltaaopB mutant, of A. hydrophila, generating a single knockout (DeltaaexU) and a double knockout mutant, DeltaaopB/DeltaaexU. Increased phagocytosis was observed in RAW264.7 murine macrophages infected with the DeltaaopB/DeltaaexU mutant, as compared to macrophages when infected with the parental DeltaaopB strain. Further, mice infected with the DeltaaexU mutant had a 60% survival rate, compared to animals infected with the WT or the DeltaaexU-complemented strain that caused 90-100% of the animals to die at a 2-3 LD(50s) dose. Immunization of mice with the recombinant AexU protected them from subsequent lethal challenge dose by the WT bacterium. Finally, we detected specific anti-AexU antibodies in the sera of mice that survived challenge by the WT bacterium, which may indicate that AexU plays an important role in the pathogenesis of Aeromonas infections.

Proteomic analyses of murine macrophages treated with Bacillus anthracis lethal toxin

Bacillus anthracis is the etiological agent of anthrax and the bacterium produces a tripartite anthrax toxin composed of protective antigen (PA), lethal factor (LF) and edema factor (EF). PA represents the binding domain of the toxin and acts in concert with either LF, a metalloprotease, or EF, an adenylate cyclase, to form lethal toxin (LeTx) or edema toxin (EdTx), respectively. We analyzed the proteomics response of two murine macrophage cell lines (J774.1A and RAW264.7) following B. anthracis LeTx treatment to detect unique host proteins involved in anthrax infection using difference in-gel electrophoresis (DIGE) followed by nanoLC-MS for identification of the proteins. The comparative proteomics approach identified a set of proteins in each cell line that was consistently upregulated when the two macrophage cell lines were treated with LeTx. The upregulated proteins include those involved in energy metabolism, cytoskeleton structure and stress response. A subset of five proteins (ATP synthase beta subunit, beta-actin, Hsp70, vimentin, and Hsp60 homolog) was identified that were commonly upregulated in both cell lines. The proteomic data suggest the involvement of reactive oxygen species (ROS) in cell lysis as seen by the upregulation of proteins that lead to the production of ROS in both the cell lines used in our study. However, proteins that afford protection against ROS may play an important role in the survival of the macrophage to LeTx infection as shown by the differences in proteomic responses of the two cell lines to the action of LeTx. These identified proteins may have the potential to be used as biomarkers for diagnostics and therapeutics.

Alterations in the virulence potential of enteric pathogens and bacterial-host cell interactions under simulated microgravity conditions

Host immune mechanisms were proposed to decline under microgravity conditions during spaceflights, which might result in severe infections in astronauts. Therefore, it was important to investigate the effects of microgravity on infecting organisms and their interaction with host cells. Data showed that simulated microgravity (SMG) conditions markedly increased production of the enterotoxigenic Escherichia coli (ETEC) heat-labile enterotoxin, which induced fluid secretory responses in a mouse model. SMG also enhanced production of tumor necrosis factor-alpha in murine macrophages infected with enteropathogenic E. coli (EPEC). In a similar fashion, simulated microgravity conditions augmented the invasive potential of Salmonella enterica serovar typhimurium and enhanced production of tumor necrosis-factor alpha in S. typhimurium-infected epithelial cells. Furthermore, coculturing of macrophages and S. typhimurium in a simulated microgravity environment resulted in activation of stress-associated mitogen-activated protein kinase kinase 4. Using the antiorthostatic tail suspension mouse model, which simulates some aspects of microgravity, oral inoculation of S. typhimurium markedly reduced the 50% lethal dose compared to mice infected under normal gravitational conditions. Microarray analysis revealed simulated microgravity-induced alterations in the expression of 22 genes in S. typhimurium, and protein expression profiles were altered in both EPEC and S. typhimurium, based on two-dimensional gel electrophoresis. These studies indicated alterations in the virulence potential of bacteria and in host responses to these pathogens under simulated microgravity conditions, which may represent an important environmental signal. Such studies are essential for better understanding bacterial-host cell interactions, particularly in the context of spaceflights and space habitations of long duration.

Evaluation of the protective effects of quinacrine against Bacillus anthracis Ames

Bacillus anthracis has gained notoriety as a dangerous biological weapon because of its virulence and ability to produce highly resistant spores. In addition, the ability of this organism to produce plasmid-encoded edema toxin (EdTx) and lethal toxin (LeTx) plays a pivotal role in the pathogenesis of anthrax. In this study, the efficacy of quinacrine was evaluated against the effects of anthrax toxins in vitro and its ability to provide protection against challenge with B. anthracis Ames strain spores in an intranasal mouse and guinea pig model. Quinacrine protected murine macrophages in vitro against cytotoxicity and cAMP production induced by LeTx and EdTx, respectively, at concentrations of 40-80 microM, most likely by preventing acidification of the endosomes. However, animals dosed with human equivalent doses of quinacrine were not protected against respiratory spore challenge. The failure of quinacrine to provide protection against inhalation anthrax was attributed to our inability to attain inhibitory concentrations of the drug in the serum or tissues. After daily administration of 43.3 mg quinacrine to guinea pigs (300 g), serum levels after 96 h were only 9.9 microM, a concentration not sufficient to protect macrophages in vitro. Administration of high doses of quinacrine (86.6 mg/kg) was toxic to the animals. These results illustrate some of the difficulties in developing protective therapeutic strategies against inhalation anthrax even when antitoxic drugs appear effective in vitro.

Global gene expression of a murein (Braun) lipoprotein mutant of Salmonella enterica serovar Typhimurium by microarray analysis

Braun/murein lipoprotein (Lpp) is one of the major outer membrane components of gram-negative enteric bacteria involved in inflammatory responses and septic shock. In previous studies, we reported that two copies of the lipoprotein (lpp) gene (designated as lppA and lppB) existed on the chromosome of Salmonella enterica serovar Typhimurium. Deletion of both lppA and lppB genes rendered Salmonella defective in invasion, motility, induction of cytotoxicity, and production of inflammatory cytokines/chemokines. The lppAB double-knockout (DKO) mutant was attenuated in mice, and animals immunized with this mutant were protected against subsequent challenge with lethal doses of wild-type (wt) S. Typhimurium. To better understand how deletion of the lpp gene might affect Salmonella virulence, we performed global transcriptional profiling of the genes in the wt and the lppAB DKO mutant of S. Typhimurium using microarrays. Our data revealed alterations in the expression of flagellar genes, invasion-associated type III secretion system genes, and transcriptional virulence gene regulators in the lppAB DKO mutant compared to wt S. Typhimurium. These data correlated with the lppAB DKO mutant phenotype and provided possible mechanism(s) of Lpp-associated attenuation in S. Typhimurium. Although these studies were performed in in vitro grown bacteria, our future research will be targeted at global transcriptional profiling of the genes in in vivo grown wt S. Typhimurium and its Lpp mutant.

Potential involvement of galectin-3 and SNAP23 in Aeromonas hydrophila cytotoxic enterotoxin-induced host cell apoptosis

We investigated the potential of the cytotoxic enterotoxin (Act) of Aeromonas hydrophila to bind to 1869 human and 4319 yeast proteins, using protein microarray technology. Act was capable of binding nine different human proteins, including the SNARE complex scaffolding protein synaptosomal-associated protein 23 (SNAP23), galectin-3, and guanylate kinase 1 (GUK-1). Act was also able to bind to four of the yeast proteins examined, which included the vesicle tethering protein Vsp52. We verified interaction of Act with murine and human SNAP23, galectin-3, and GUK-1 by sandwich Western blot analysis. In order to determine the physiological relevance of Act binding to these three proteins, we performed small interfering RNA (siRNA) gene knockdown experiments in RAW 264.7 cells, a murine macrophage cell line in which Act-induced signaling and cell death is well characterized. Based on real-time reverse transcriptase-polymerase chain reaction, siRNA transfection of RAW 264.7 cells with specific oligonucleotides reduced the expression of genes encoding SNAP23, galectin-3, and GUK-1 by 62, 63, and 99%, respectively. Knockdown of galectin-3 and SNAP23, but not GUK-1, significantly reduced Act-induced apoptosis of host cells, as determined by TUNEL (TdT-mediated dUTP nick end labeling) assay, lactate dehydrogenase release, Giemsa staining, and reduction in activation of caspase 3, compared to toxin-treated macrophages that were transfected with a random sequence control siRNA. We also performed these assays using a human intestinal epithelial cell line (HT-29) and observed a similar trend of galectin-3 and SNAP23 association with Act-induced apoptosis. This is the first report of putative protein binding partners for this toxin and potential mediators/regulators of Act-induced apoptosis.

Attenuation of Salmonella enterica Serovar Typhimurium by altering biological functions of murein lipoprotein and lipopolysaccharide

We constructed Salmonella enterica serovar Typhimurium double-knockout mutants in which either the lipoprotein A (lppA) or the lipoprotein B (lppB) gene was deleted from an msbB-negative background strain by marker exchange mutagenesis. These mutants were highly attenuated when tested with in vitro and in vivo models of Salmonella pathogenesis.

Microarray and proteomics analyses of human intestinal epithelial cells treated with the Aeromonas hydrophila cytotoxic enterotoxin

We performed microarray analyses on RNA from human intestinal epithelial (HT-29) cells treated with the cytotoxic enterotoxin (Act) of Aeromonas hydrophila to examine global cellular transcriptional responses. Based on three independent experiments, Act upregulated the expression of 34 genes involved in cell growth, adhesion, signaling, immune responses (including interleukin-8 [IL-8] production), and apoptosis. We verified the upregulation of 14 genes by real-time reverse transcriptase-PCR and confirmed Act-induced production of IL-8 by enzyme-linked immunosorbent assay on supernatants from nonpolarized and polarized HT-29 cells. Maximal production of IL-8 in response to Act required the presence of intracellular calcium, since chelation of calcium with BAPTA-AM significantly reduced Act-induced IL-8 production in HT-29 cells. We also examined activation of mitogen-activated protein kinases and, as demonstrated by Western blot analysis of apical side-treated polarized HT-29 cells, Act induced phosphorylation of p38, c-Jun NH(2)-terminal kinase, and extracellular signal-regulated kinase 1/2. In addition, KinetWorks proteomics screening of whole-cell lysates revealed Act-induced phosphorylation of cyclic AMP-response element binding protein (CREB), c-Jun, adducin, protein kinase C, and signal transducer and activator of transcription 3 (STAT3) and decreased phosphorylation of protein kinase Balpha, v-raf-1 murine leukemia viral oncogene homolog 1 (i.e., Raf1), and STAT1. We verified activation of CREB and activator protein 1 in polarized cells by gel shift assay. This is the first description of human intestinal epithelial cell transcriptional alterations, phosphorylation or activation of signaling molecules, cytokine production, and calcium mobilization in response to this toxin.

Murein lipoprotein is a critical outer membrane component involved in Salmonella enterica serovar typhimurium systemic infection

Lipopolysaccharide (LPS) and Braun (murein) lipoprotein (Lpp) are major components of the outer membrane of gram-negative enteric bacteria that function as potent stimulators of inflammatory and immune responses. In a previous paper, we provided evidence that two functional copies of the lipoprotein gene (lppA and lppB) located on the chromosome of Salmonella enterica serovar Typhimurium contributed to bacterial virulence. In this study, we characterized lppA and lppB single-knockout (SKO) mutants and compared them with an lpp double-knockout (DKO) mutant using in vitro and in vivo models. Compared to the lpp DKO mutant, which was nonmotile, the motility of the lpp SKO mutants was significantly increased (73 to 77%), although the level of motility did not reach the level of wild-type (WT) S. enterica serovar Typhimurium. Likewise, the cytotoxicity was also significantly increased when T84 human intestinal epithelial cells and RAW264.7 murine macrophages were infected with the lpp SKO mutants compared to the cytotoxicity when cells were infected with the lpp DKO mutant. The level of interleukin-8 (IL-8) in polarized T84 cells infected with the lppB SKO mutant was significantly higher (two- to threefold higher), reaching the level in cells infected with WT S. enterica serovar Typhimurium, than the level in host cells infected with the lppA SKO mutant. The lpp DKO mutant induced minimal levels of IL-8. Similarly, sera from mice infected with the lppB SKO mutant contained 4.5- to 10-fold-higher levels of tumor necrosis factor-alpha and IL-6; the levels of these cytokines were 1.7- to 3.0-fold greater in the lppA SKO mutant-infected mice than in animals challenged with the lpp DKO mutant. The increased cytokine levels observed with the lppB SKO mutant in mice correlated with greater tissue damage in the livers and spleens of these mice than in the organs of animals infected with the lppA SKO and lpp DKO mutants. Moreover, the lppB SKO mutant-infected mice had increased susceptibility to death. Since the lpp DKO mutant retained intact LPS, we constructed an S. enterica serovar Typhimurium triple-knockout (TKO) mutant in which the lppA and lppB genes were deleted from an existing msbB mutant (msbB encodes an enzyme required for the acylation of lipid A). Compared to the lpp DKO and msbB SKO mutants, the lpp-msbB TKO mutant was unable to induce cytotoxicity and to produce cytokines and chemokines in vitro and in vivo. These studies provided the first evidence of the relative contributions of Lpp and lipid A acylation to Salmonella pathogenesis.

Microarray analysis of Aeromonas hydrophila cytotoxic enterotoxin-treated murine primary macrophages

We performed microarray analyses of murine peritoneal macrophages to examine cellular transcriptional responses to a cytotoxic enterotoxin of Aeromonas hydrophila. While 66% of altered genes were common to both primary macrophages and the murine macrophage cell line RAW 264.7, Act caused expression changes of 28 genes specifically in murine peritoneal macrophages.

Biological characterization of Aeromonas spp. isolated from the environment

Cytotoxic enterotoxin (Act) is a key virulence factor in the pathogenesis of infections caused by Aeromonas spp. The cytotoxic enterotoxin gene (act) was detected in 32 out of 69 environmental isolates of Aeromonas spp. by hybridization with the act gene probe. To evaluate the pathogenic potential of the act gene probe-positive isolates, 32 act gene probe-positive and 31 randomly selected act gene probe-negative isolates were tested for enterotoxicity in a suckling mice assay (SMA), for haemolytic activity on sheep blood agar plates, for the presence of CAMP-like factors, and for cytotoxicity in a Vero cell line. The act gene probe-positive isolates significantly differed from the toxin gene probe-negative ones with respect to enterotoxicity in the SMA (P=0.009) and haemolytic activity (P=0.005). The CAMP-haemolysin phenotype was significantly associated with the rabbit ileal loop assay (P= 0.08), Vero cell assay (P= 0.064), and haemolysin production under the microaerophilic conditions (P= 0.056) of the act gene probe-positive isolates of Aeromonas spp. These data indicated the role of Act in the pathogenesis of Aeromonas infections and that the enterotoxic potential of Aeromonas spp. could be assessed by simply performing a CAMP-haemolysin assay.

The two murein lipoproteins of Salmonella enterica serovar Typhimurium contribute to the virulence of the organism

Septic shock due to Salmonella and other gram-negative enteric pathogens is a leading cause of death worldwide. The role of lipopolysaccharide in sepsis is well studied; however, the contribution of other bacterial outer membrane components, such as Braun (murein) lipoprotein (Lpp), is not well defined. The genome of Salmonella enterica serovar Typhimurium harbors two copies of the lipoprotein (lpp) gene. We constructed a serovar Typhimurium strain with deletions in both copies of the lpp gene (lpp1 and lpp2) by marker exchange mutagenesis. The integrity of the cell membrane and the secretion of the effector proteins through the type III secretion system were not affected in the lpp double-knockout mutant. Subsequently, the virulence potential of this mutant was examined in a cell culture system using T84 intestinal epithelial and RAW264.7 macrophage cell lines and a mouse model of salmonellosis. The lpp double-knockout mutant was defective in invading and inducing cytotoxic effects in T84 and RAW264.7 cells, although binding of the mutant to the host cell was not affected when compared to the wild-type (WT) serovar Typhimurium. The motility of the mutant was impaired, despite the finding that the number of flagella was similar in the lpp double knockout mutant and the WT serovar Typhimurium. Deletion in the lpp genes did not affect the intracellular survival and replication of Salmonella in macrophages and T84 cells. Induction of the proinflammatory cytokines tumor necrosis factor alpha and interleukin-8 (IL-8) was significantly reduced in macrophages and T84 cells infected with the lpp double-knockout mutant. The levels of IL-8 remained unaffected in T84 cells when infected with either live or heat-killed WT and lpp mutant, indicating that invasion was not required for IL-8 production and that Toll-like receptor 2 signaling might be affected in the Lpp double-knockout mutant. These effects of the Lpp protein could be restored by complementation of the isogenic mutant. The lpp double-knockout mutant was avirulent in mice, and animals infected with this mutant were protected from a lethal challenge dose of WT serovar Typhimurium. The severe combined immunodeficient mice, on the other hand, were susceptible to infection by the lpp double-knockout mutant. The serovar Typhimurium mutants from which only one of the lpp (lpp1 or lpp2) genes was deleted were also avirulent in mice. Taken together, our data indicated that Lpp specifically contributed to the virulence of the organism.

Molecular characterization of a glucose-inhibited division gene, gidA, that regulates cytotoxic enterotoxin of Aeromonas hydrophila

By using a mini-transposon, we obtained two mutated strains of a diarrheal isolate, SSU, of Aeromonas hydrophila that exhibited a 50 to 53% reduction in the hemolytic activity and 83 to 87% less cytotoxic activity associated with the cytotoxic enterotoxin (Act). Act is a potent virulence factor of A. hydrophila and has been shown to contribute significantly to the development of both diarrhea and septicemia in animal models. Subsequent cloning and DNA sequence analysis revealed that transposon insertion occurred at different locations in these two mutants within the same 1,890-bp open reading frame for the glucose-inhibited division gene (gidA). A similar reduction in hemolytic (46%) and cytotoxic (81%) activity of Act was noted in the gidA isogenic mutant of A. hydrophila that was generated by marker exchange mutagenesis. Northern blot analysis revealed that the transcription of the cytotoxic enterotoxin gene (act) was not altered in the gidA transposon and isogenic mutants. However, by generating a chromosomal act::alkaline phosphatase gene (phoA) reporter construct, we demonstrated significantly reduced phosphatase activity in these mutants, indicating the effect of glucose-inhibited division (GidA) protein in modulating act gene expression at the translational level. The biological effects of Act in the gidA mutants were restored by complementation. The virulence of the gidA mutants in mice was dramatically reduced compared to the those of the wild-type (WT) and complemented strains of A. hydrophila. The histopathological examination of lungs, in particular, indicated severe congestion, alveolar hemorrhage, and acute inflammatory infiltrate in the interstitial compartment and the alveolar spaces when mice were infected with the WT and complemented strains. Minimal-to-mild changes were noted in the lungs with the gidA mutants. Taken together, our data indicate for the first time that GidA regulates the most-potent virulence factor of A. hydrophila, Act.

Differential expression of the enolase gene under in vivo versus in vitro growth conditions of Aeromonas hydrophila

Aeromonas hydrophila is an emerging human pathogen that leads to gastroenteritis and other invasive diseases. By using a murine peritoneal culture (MPC) model, we identified via restriction fragment differential display PCR (RFDDPCR) five genes of A. hydrophila that were differentially expressed under in vivo versus in vitro growth conditions. The gene encoding enolase was among those five genes that were differentially up regulated. Enolase is a glycolytic enzyme and its surface expression was recently shown to be important in the pathogenesis of a gram-positive bacterium Streptococcus pyogenes. By Western blot analysis and Immunogold staining, we demonstrated secretion and surface expression of enolase in A. hydrophila. We also showed that the whole cells of A. hydrophila had strong enolase activity. Using an enzyme-linked immunosorbant assay and sandwich Western blot analysis, we demonstrated binding of enolase to human plasminogen, which is involved in the fibrinolytic system of the host. We cloned the A. hydrophila enolase gene, which exhibited 62% homology at the DNA level and 57% homology at the amino acid level when compared to S. pyogenes enolase. This is a first report describing the increased expression of enolase gene in vivo that could potentially contribute to the pathogenesis of A. hydrophila infections.

Role of various enterotoxins in Aeromonas hydrophila-induced gastroenteritis: generation of enterotoxin gene-deficient mutants and evaluation of their enterotoxic activity

Three enterotoxins from the Aeromonas hydrophila diarrheal isolate SSU have been molecularly characterized in our laboratory. One of these enterotoxins is cytotoxic in nature, whereas the other two are cytotonic enterotoxins, one of them heat labile and the other heat stable. Earlier, by developing an isogenic mutant, we demonstrated the role of a cytotoxic enterotoxin in causing systemic infection in mice. In the present study, we evaluated the role of these three enterotoxins in evoking diarrhea in a murine model by developing various combinations of enterotoxin gene-deficient mutants by marker-exchange mutagenesis. A total of six isogenic mutants were prepared in a cytotoxic enterotoxin gene (act)-positive or -negative background strain of A. hydrophila. We developed two single knockouts with truncation in either the heat-labile (alt) or the heat-stable (ast) cytotonic enterotoxin gene; three double knockouts with truncations of genes encoding (i) alt and ast, (ii) act and alt, and (iii) act and ast genes; and a triple-knockout mutant with truncation in all three genes, act, alt, and ast. The identity of these isogenic mutants developed by double-crossover homologous recombination was confirmed by Southern blot analysis. Northern and Western blot analyses revealed that the expression of different enterotoxin genes in the mutants was correspondingly abrogated. We tested the biological activity of these mutants in a diet-restricted and antibiotic-treated mouse model with a ligated ileal loop assay. Our data indicated that all of these mutants had significantly reduced capacity to evoke fluid secretion compared to that of wild-type A. hydrophila; the triple-knockout mutant failed to induce any detectable level of fluid secretion. The biological activity of selected A. hydrophila mutants was restored after complementation. Taken together, we have established a role for three enterotoxins in A. hydrophila-induced gastroenteritis in a mouse model with the greatest contribution from the cytotoxic enterotoxin Act, followed by the Alt and Ast cytotonic enterotoxins.

Early cell signaling by the cytotoxic enterotoxin of Aeromonas hydrophila in macrophages

A cytotoxic enterotoxin (Act) of Aeromonas hydrophila is an important virulence factor with hemolytic, cytotoxic and enterotoxic activities. In this report, we demonstrated Act rapidly mobilized calcium from intracellular stores and evoked influx of calcium from the extracellular milieu in macrophages. A direct role of calcium in Act-induced prostaglandin (e.g. PGE(2)) and tumor necrosis factor alpha (TNF alpha) production was demonstrated in macrophages using a cell-permeable calcium chelator BAPTA-AM, which also down-regulated activation of transcription factor NF-kappa B. We showed that Act's capacity to increase PGE(2) and TNF alpha production could be blocked by inhibitors of tyrosine kinases and protein kinase A. In addition, Act caused up-regulation of the DNA repair enzyme redox factor-1 (Ref-1), which potentially could promote DNA binding of the transcription factors allowing modulation of various genes involved in the inflammatory response. Taken together, a link between Act-induced calcium release, regulation of downstream kinase cascades and Ref-1, and activation of NF-kappa B leading to PGE(2) and TNF alpha production was established. Since Act also caused extensive tissue damage, we showed that Act increased reactive oxygen species, and the antioxidant N-acetyl cysteine, blocked Act-induced PGE(2) and TNF alpha production, as well as NF-kappa B nuclear translocation in macrophages. We have demonstrated for the first time early cell signaling initiated in eukaryotic cells by Act, which leads to various biological effects associated with this toxin.

Regulation of the cytotoxic enterotoxin gene in Aeromonas hydrophila: characterization of an iron uptake regulator

The cytotoxic enterotoxin Act from a diarrheal isolate, SSU, of Aeromonas hydrophila is aerolysin related and crucial to the pathogenesis of Aeromonas infections. To elucidate the role of environmental signals which influence the expression of the cytotoxic enterotoxin gene (act), a portion of the act gene, including the putative promoter region, was fused in frame to a truncated alkaline phosphatase gene (phoA) of Escherichia coli. The act::phoA reporter gene was then introduced into the chromosome of A. hydrophila by using the suicide vector pJQ200SK, allowing the fusion protein to be secreted out into the culture medium. Western blot analysis demonstrated the presence of a correctly size 110-kDa fusion protein in the culture supernatant, which reacted with both anti-Act and anti-alkaline phosphatase antibodies. Based on alkaline phosphatase (PhoA) activity in the culture supernatant, we demonstrated that calcium significantly increased the activity of the act promoter but that glucose and iron repressed its activity in a dose-dependent fashion. The act promoter exhibited optimal activity at pH 7.0 and at 37 degrees C, and maximal PhoA activity was noted when the culture was aerated. Using a Vibrio cholerae iron uptake regulator gene (fur) as a probe, a 2.6-kb SalI/HindIII DNA fragment from an A. hydrophila chromosome was cloned and sequenced. The DNA sequence revealed a 429-bp open reading frame that exhibited 69% homology at the DNA level with the fur gene and 79% homology at the amino acid level with the iron uptake regulator (Fur) protein of V. cholerae. Complementation experiments demonstrated that the A. hydrophila fur gene could restore iron regulation in an E. coli fur-minus mutant. Using the suicide vector pDMS197, we generated a fur isogenic mutant of wild-type A. hydrophila SSU. Northern blot analysis data indicated that the repression in the transcription of the act gene by iron was relieved in the fur isogenic mutant. Further, iron regulation in the fur isogenic mutant of A. hydrophila could be restored by complementation. These results are important in understanding the regulation of the act gene under in vivo conditions.

Effects of extracellular pH on tumour necrosis factor-alpha production by resident alveolar macrophages

Cellular acid-base status has been found to exert selective actions on the effector functions of activated macrophages (mphi). We examined the effects of extracellular pH (pH(o)) on the production of tumour necrosis factor-alpha (TNF-alpha) induced by lipopolysaccharide (LPS) in resident alveolar mphi. Cells were obtained by bronchoalveolar lavage of rabbits, activated in vitro with LPS, and cultured at pH(o) 5.5, 6.5 or 7.4 for up to 18 h. The relative abundance of TNF-alpha mRNA peaked at approximately 2 h. The peak transcript abundance was increased at lower pH(o) values. This finding probably reflected pre-transcription/transcription effects of pH, in as much as the stability of TNF-alpha mRNA induced with phorbol ester was unaffected by the experimental pH(o) values. TNF-alpha secretion by LPS-treated mphi decreased at lower pH(o) values. The TNF-alpha content of mphi-conditioned media decreased progressively with decrements in pH(o). The reduced TNF-alpha secretion at pH(o) 5.5 was accompanied by an increase in the cytosolic TNF-alpha content (compared with that at pH(o) 7.4), indicating that pH(o) altered TNF-alpha secretion due, in part, to the intracellular retention of synthesized cytokine (i.e. a post-translation effect). The data show that pH(o) has multiple effects (pre-transcription/transcription and post-translation) on TNF-alpha production induced by LPS in resident alveolar mphi. These results suggest that the role of alveolar mphi in inflammatory responses is modulated by pH(o), which may be important in tumours/abscesses and sites of infection where the external milieu is acidic.

Cholera toxin-induced PGE(2) activity is reduced by chemical reaction with L-histidine

Mediators of cholera toxin (CT)-induced fluid secretion include 3',5'-adenosine monophosphate (cAMP), prostaglandin E(2) (PGE(2)), and 5-hydroxytryptamine (5-HT). Administration of L-histidine significantly reduced the net secretory response of the small intestine of mice challenged with CT and reduced the capacity of PGE(2) to stimulate Na+ transport in Ussing chambers. We demonstrated that L-histidine chemically modified the structure of PGE(2) but had no direct effect on cAMP or 5-HT. L-Histidine and imidazole reacted with PGE(2) in vitro in cell-free mixtures incubated at 37 degrees C and pH 7.0 under an atmosphere of N(2) with the formation of PGE(2)-imidazole and PGE(2)-histidine covalent adducts. Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) analysis of the purified adduct showed that imidazole catalyzed the dehydration of PGE(2). A Michael adduct then was formed between C11 of 11-deoxy-Delta(10) PGE(2) (PGA(2)) and the tau nitrogen in the imidazole ring of L-histidine. Importantly, the isolated PGE(2)-imidazole and PGE(2)-histidine adducts inhibited CT-induced fluid loss and cAMP accumulation in mouse intestinal loops. The protection provided by PGE(2)-imidazole, PGE(2)-histidine, and L-histidine against intestinal fluid loss could provide a basis for future therapy against cholera.

Cholera toxin induces prostaglandin synthesis via post-transcriptional activation of cyclooxygenase-2 in the rat jejunum

The mechanisms of diarrhea in Asiatic cholera have been studied extensively. Cyclic AMP, 5-hydroxytryptamine, prostaglandins, and the function of neuronal structures have been implicated in the pathogenesis of cholera. To elucidate the role of the different isoforms (COX-1 and COX-2) of cyclooxygenase in cholera toxin (CT)-induced fluid secretion and intraluminal prostaglandin E(2) (PGE(2)) release in the rat jejunum in vivo, the effects of the COX-2 inhibitors NS-398 ([N-(2-cyclohexaloxy-4-nitrophenyl)methanesulfonamide]) and DFU [5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulfonyl)phenyl-2(5H)-furanone], and of the COX-1 inhibitor SC-560, were studied. Net fluid transport was measured gravimetrically and PGE(2) by radioimmunoassay. COX-1 and COX-2 mRNA expression were determined by reverse transcription-polymerase chain reaction (RT-PCR) and COX-2 protein by Western blot analysis in mucosal scrapings. CT caused profuse net fluid secretion in all control rats. The COX-2 inhibitors NS-398 and DFU, but not the COX-1 inhibitor SC-560 or dexamethasone, dose-dependently inhibited CT-induced fluid secretion and PGE(2) release. RT-PCR showed expression of COX-1 and of COX-2 mRNA in control rats. CT did not induce an increase and dexamethasone did not reduce COX-2 mRNA, whereas lipopolysaccharide caused a marked induction of COX-2 mRNA, which was inhibited by dexamethasone. A weak band of COX-2 protein was observed in controls; however, CT enhanced COX-2 levels, which remained unaffected by dexamethasone. It can be assumed that post-transcriptional modulation is responsible for CT-induced increase in COX-2 protein. COX-1 does not seem to be involved. Therefore, PGE(2) produced by COX-2 seems to be responsible for the profuse fluid secretion induced by CT, and COX-2 appears to be a specific target for the treatment of Asiatic cholera.

Post-transcriptional effects of extracellular pH on tumour necrosis factor-alpha production in RAW 246.7 and J774 A.1 cells

The present studies determined the effects of extracellular pH (pH(o)) on the production of tumour necrosis factor-alpha (TNF-alpha) in the macrophage-like cell lines RAW 246.7 and J774 A.1. The cells were activated with lipopolysaccharide (LPS) at pH(o) 5.5, 6.5 or 7.4. TNF-alpha gene transcription was monitored by Northern blot analysis. Synthesis of the cytokine was monitored by ELISA measurements of the TNF-alpha content of cell-conditioned media (extracellularly released TNF-alpha) and cell lysates (cytosolic TNF-alpha). The magnitude of the TNF-alpha response differed markedly between the two cell lines. RAW cells were more responsive to LPS than were J774 cells. However, the effects of pH(o) on TNF-alpha production were similar in the two cell lines. TNF-alpha gene transcription was insensitive to experimental pH(o). The pH(o) had no effect on the abundance of TNF-alpha mRNA at 2, 4 or 18 h. Nonetheless, synthesis of TNF-alpha was affected significantly by pH(o). The TNF-alpha contents of cell-conditioned medium and cell lysate at 18 h were reduced progressively at lower pH(o) values. The data indicate that pH(o) alters TNF-alpha production in RAW and J774 cells at a post-transcriptional level. These findings suggest that pH(o) influences the phenotypic responses of macrophages to activating stimuli and modifies the role that macrophages play in inflammatory and immune actions.

Prostaglandin levels in stimulated macrophages are controlled by phospholipase A2-activating protein and by activation of phospholipase C and D

Prostaglandins (PG), which are responsible for a large array of biological functions in eukaryotic cells, are produced from arachidonic acid by phospholipases and cyclooxygenase enzymes COX-1 and COX-2. We demonstrated that PG levels in cells were partly controlled by a regulatory protein, phospholipase A2 (PLA2)-activating protein (PLAA). Treatment of murine macrophages with lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha increased PLAA levels at early time points (2-30 min), which correlated with an up-regulation in cytosolic PLA2 and PGE2 levels. Both COX-2 and secretory PLA2 were also increased in lipopolysaccharide-stimulated macrophages, however, at later time points of 4-24 h. The role of PLAA in eicosanoid formation in macrophages was confirmed by the use of an antisense plaa oligonucleotide. Within amino acid residues 503-538, PLAA exhibited homology with melittin, and increased PGE(2) production was noted in macrophages stimulated with melittin. In addition to PLA2, we demonstrated that activation of phospholipase C and D significantly controlled PGE2 production. Finally, increased antigen levels of PLAA, COX-2, and phospholipases were demonstrated in biopsy specimens from patients with varying amounts of intestinal mucosal inflammation, which corresponded to increased levels of phospholipase activity. These results could provide a basis for the development of new therapeutic tools to control inflammation.