A method for detecting perfluorooctanoic acid and perfluorooctane sulfonate in water samples using genetically engineered bacterial biosensor.

A simple, reagent and pre-treatment (i.e. dilution, sample purification and pH adjustment) free approach based genetically engineered bacterial biosensor is developed and demonstrated for the detection of perfluorinated compounds in water samples. The bacterial biosensor was developed by integrating two genes called regulatory (defluorinase gene) and reporter gene (green fluorescence gene) through genetic engineering techniques. The as-developed bacterial biosensor was employed to detect perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in water samples upon induction of regulatory gene and expression of green fluorescence protein. The induced fluorescence emission by the biosensor was visualized using fluorescence microscopic images. The specificity of biosensor was evaluated with different types of organic pollutants such as chlorinated compounds, polyaromatic hydrocarbons and pesticides etc., in both presence and absence of PFOA and PFOS. The biosensor was employed to detect the perfluorinated compounds at nano gram level in both standard solutions and natural water samples like river water, wastewater and drinking water with an analysis time of 24 h. The detection of PFOA and PFOS by the developed-bacterial sensor is validated by liquid chromatography coupled with mass spectrometer. The developed biosensor has demonstrated a rapid and sensitive detection of PFOA and PFOS in various water samples.

Detection of phthalate esters in PET bottled drinks and lake water using esterase/PANI/CNT/CuNP based electrochemical biosensor.

Phthalate esters (PEs) are the most common plasticizers that tends to exhibit endocrine disruption. Since, these PEs are used in the manufacture of PET bottles and PVC products: point of exposure magnifies up on consumption of PET bottle and plastic container stored drinking water and beverages. Apart from human exposure to PEs, bioaccumulation of PEs and toxic effects among wildlife also seems to be divergent. In the present study, an enzyme-based biosensor for the detection of PEs was developed to overcome the tedious extraction procedures involving PE extraction and sophisticated instruments for the detection. Linear Sweep voltammetry analysis of Nafion (NF) surface modified glassy carbon electrode with esterase (EST) and nano-components was carried-out. Peak potential of individual PEs were in the range of -1.72 to -1.82 V at the concentration of 1 × 10-5 mmol L-1. Sensitivity of EST/PANI/CNT/CuNP-NF modified GCE was determined in terms of detection limit and was calibrated to be 0.03-0.08 nmol L-1. Thus, the developed enzyme based electrochemical sensor could be successfully employed in determining PE exposure in humans and bioaccumulation among aquatic flora and fauna via., consumption of PET bottle stored drinks and industrial effluents discharged into the lakes.

Bacteria amended clay biochar composite biobed system to treat agriculture runoff.

An efficient adsorbent which can resolve the existing limitations of a biobed is of concern. In the present study, a composite is prepared by mixing and pyrolyzing clay and plant parts. This is finally converted to clay biochar composite with enhanced porosity and adsorption capacity. Composite consists of clay with sawdust or clay with powdered dry fruit of Acacia concinna. Among the different composites employed, clay/Acacia concinna (7.6/0.4) with higher structural stability was used as the biomix for biobed. The clay biochar composite (20%) bioaugmented with biosurfactant producing bacterial consortium was then mixed with sandy clay loam soil in a laboratory-scale biobed system. The study showed a COD removal of 95% and cypermethrin removal of 98%. Biodegradation of cypermethrin isomers in soil and clay biochar composite was observed. The study revealed that clay biochar composite amended with biosurfactant producing bacterial consortium is an efficient biomix for the biobed system.

Enhanced biodegradation of an endocrine disrupting micro-pollutant: Di (2-ethylhexyl) phthalate using biogenic self-assembled monolayer of silver nanoparticles.

Di (2-ethylhexyl) phthalate (DEHP) is one of the predominant plasticizer and an endocrine disrupting chemical occurring almost in all partitions of the environment. Though DEHP occur at lower concentration, reluctance arises due to their ability to disrupt endocrine system even lower concentration. In the present study, DEHP was assessed for degradation at minimal level (1-100 µg L-1) by a novel bacterial strain, Rhodococcus jostii PEVJ9. In the experimental design, significant variables were concentration of silver nitrate and DEHP, pH, temperature, time and agitation. Degradation without SAM-silver nanoparticles was 30-66% (predicted value = 30.8-66.8%, R2 = 99.7%) while, degradation in the presence of SAM-silver nanoparticles onto bacterial cells was 100% (predicted value = 98.4-102.1%, R2 = 99.6%) within 72 h. In short, this is the first report illustrating the experimental designs in biogenic synthesis of SAM-silver nanoparticles and enhanced degradation of DEHP at minimal level. The study overcomes poor bioavailability and assimilation of DEHP at lower concentration by the microbial population present in the environment. Thus, an efficient clean-up would prevent or minimize DEHP exposure at all trophic levels ranging from feminization of fishes to reproductive disorders in humans.

Performance evaluation of ETP from pesticide manufacturing industry by using WWQI and multivariate statistical analysis.

The appropriate operation of wastewater treatment plants is essential to maintain the quality of treated water. The aim of the present study is to monitor the effluent quality by applying the Wastewater Quality Index (WWQI) and statistical method. The influent and effluent wastewater samples were collected from an Effluent Treatment Plant (ETP) of pesticide manufacturing industry in Tamil Nadu, India. The study was carried out during the period 2014-2018. The physicochemical parameters were analyzed to determine the biodegradable and non-biodegradable contaminants in the wastewater. The organic removal in ETP for high Total Dissolved Solids (TDS) wastewater treatment was 97-100% and low TDS wastewater treatment was 96-99%. The overall quality of the wastewater was determined by WWQI using irrigation standards. The quality of all the influent samples was poor. The WWQI of high TDS effluent samples varied from marginal to good. The low TDS effluent quality varied from fair to excellent. The interdependencies between the variables were observed using Principal Component Analysis (PCA). From the influent and effluent variables, five and two PCA components were extracted with 92 and 85% of the total dataset information, respectively. The correlation analysis was carried out to observe the interrelationship between the wastewater quality parameters. The regression model achieved 99% of accuracy for fitting the model with the calculated WWQI. The final effluent showed a higher removal efficiency and better quality to reuse for irrigation. It was concluded that the ETP of the PMI is maintained properly and can be also applied to other industrial wastewater. Graphical abstract.

Intracellular toxicity exerted by PCBs and role of VBNC bacterial strains in biodegradation.

Polychlorinated biphenyls (PCBs) are xenobiotic compounds that persists in the environment for long-term, though its productivity is banned. Abatement of the pollutants have become laborious due to it's recalcitrant nature in the environment leading to toxic effects in humans and other living beings. Biphenyl degrading bacteria co-metabolically degrade low chlorinated PCBs using the active metabolic pathway. bph operon possess different genetic arrangements in gram positive and gram negative bacteria. The binding ability of the genes and the active sites were determined by PCB docking studies. The active site of bphA gene with conserved amino acid residues determines the substrate specificity and biodegradability. Accumulation of toxic intermediates alters cellular behaviour, biomass production and downturn the metabolic activity. Several bacteria in the environment attain unculturable state which is viable and metabolically active but not cultivable (VBNC). Resuscitation-promoting factor (Rpf) and Rpf homologous protein retrieve the culturability of the so far uncultured bacteria. Recovery of this adaptive mechanism against various physical and chemical stressors make a headway in understanding the functionality of both environmental and medically important unculturable bacteria. Thus, this paper review about the general aspects of PCBs, cellular toxicity exerted by PCBs, role of unculturable bacterial strains in biodegradation, genes involved and degradation pathways. It is suggested to extrapolate the research findings on extracellular organic matters produced in culture supernatant of VBNC thus transforming VBNC to culturable state.

Removal of phosphate by Staphylococcus aureus under aerobic and alternating anaerobic-aerobic conditions.

Eutrophication of water bodies due to phosphate enrichment is an ecological problem. Phosphate is removed from wastewaters by enhanced biological phosphate removal worldwide by phosphate accumulating organism. In order to understand the process of treatment, the existing microbial community and its metabolism of phosphate removal are studied widely. This study focuses on the isolation of polyphosphate-accumulating bacteria from different environments and studying their phosphate removal capacity with different carbon supplements under varying culture conditions. The total heterotrophic bacterial population from the diverse environments showed the existence of phosphate-accumulating bacteria. Among them, Staphylococcus aureus removed 81% of phosphate in a polyphosphate-accumulating medium with storage of 93 mM polyphosphate internally. Among the different carbon sources provided, glucose induced a net specific growth rate of 0.816/d. S. aureus removed 70% of phosphate with a phosphate uptake rate of 6.29 mg PO4/g cells and a growth yield of 0.2 g cells/g glucose consumed when 1 g/L glucose was provided. Furthermore, when 2 g/L glucose was provided, 78% of phosphate was removed with a phosphate uptake rate of 13.24 mg PO4/g cells and a growth yield of 0.4 g cells/g glucose consumed under aerobic condition. S. aureus showed enhanced phosphate removal under aerobic condition in the presence of glucose.

Spatial variance of POPs and heavy metals in transformer oil-contaminated soil around Tamil Nadu.

The persistent organic pollutants in the environment are one of the global issues to their unregulated disposal and informal recycling. This study investigates the contamination of soil with polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), phenolic compounds and heavy metals via spillage of transformer oil (TO). Fresh TO (FTO), used TO (UTO) and soil samples were analysed using GC-MS to confirm the presence of 8 PCB congeners, 16 PAHs and 24 types of phenolic compounds and using inductively coupled plasma optical emission spectrometry to confirm the presence of 7 heavy metals. The chromatographic analysis revealed the levels of mono-, di-, tri-, tetra-, penta-, hexa-, hepta- and octachlorobiphenyls in FTO to be 5.63, 25.24, 0.195, 0.185, 2.169, 1.023 and 5.28 mg/L and the level of mono-, di-, tri-, tetra-, penta- and hexachlorobiphenyls in UTO to be 0.27, 1.21, 1.31, 0.80, 1.77 and 3.90 mg/L. Analysis of soil from 10 different TO-contaminated sites showed the presence of PCBs, PAHs, phenolic compounds and heavy metals in the concentration range of 0.53-42.87 mg/kg, 3.19-246.6 µg/kg, 0.01-4086.45 µg/kg and 1.0-401.3 mg/kg, respectively. The variation in the concentration of these compounds and heavy metals among different sampling sites was determined using principal component analysis (PCA), metric multi-dimensional scaling (MDS) and Bray-Curtis cluster analysis (Bu-CA). The toxicity equivalence factor and the mechanism involved in the disruption of endocrine system are discussed. Thus, this study exemplifies the need for complete ban of PCB-containing TOs in developing countries and urges the need for technology for the disposal of TO.

Root Exudates of Cyperus alternifolius in Partial Hydroponic Condition under Heavy Metal Stress.

Secondary metabolites play a vital role in the treatment of various ailments as well as in phytoremediation. The link between secondary metabolites and phytoremediation needs exploration. Hitherto, no information is available regarding the phytochemical components that exist in the root exudates of Cyperus alternifolius. This study was designed to determine the phytocomponents in the root exudates of C. alternifolius under heavy metal stress. C. alternifolius was grown by a novel technique in partial hydroponic conditions and imperiled to a mixture of heavy metals (Cd, Cu, Cr, Ni, Zn, Pb, and Fe) at different concentrations. The root exudates were collected, freeze-dried, redissolved and reconstituted in hexane and analyzed in gas chromatography-mass spectrometry using JEOL GCMATE II in SAIF IIT-Madras. The analysis revealed that the profile of phytochemicals in root exudates is diverse with biological properties. Few phytochemicals found in the root exudates are not cited earlier in any literature. The composition and percentage of phytochemicals could not be correlated to heavy metal concentration. Phytochemical composition decreased with an increase in heavy metal concentration. Control plant released more phytochemicals than the plants under heavy metal stress. From the results, it is evident that root exudates of C. alternifolius contain various bioactive components. Further research can be extended to evaluate the pharmaceutical importance of the species and explore its role in phytoremediation of heavy metals. SUMMARY: The control and test plants are grown under partial hydroponic condition. Test plants are subjected to heavy metal stress, root exudates were collected from control and test plants, freeze dried, constituted in hexane and subjected to GC-MS analysis. Abbreviations Used: GC-MS: Gas chromatography-Mass spectrometry.

Assessment of perfluorooctanoic acid and perfluorooctane sulfonate in surface water - Tamil Nadu, India.

As an emerging class of environmentally persistent organic pollutants, perfluorinated compounds (PFCs), particularly perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS); have been universally found in the environment. Wastewater and untreated effluents are likely the major causes for the accumulation of PFCs in surface water. There are very few reports on the contamination of PFCs in the developing countries, particularly in India. This study reports the quantitative analysis of PFOA and PFOS in Noyyal, Cauvery, and also lakes in and around Chennai, using Ultra-Fast liquid chromatograph. The concentration of PFOA and PFOS ranged from 4 to 93ng/L and 3 to 29ng/L, respectively. The concentration of PFOS was below detectable limit in Cauvery River. A reliable concentration of PFOA was recorded at all sites of River Cauvery (5ng/L). The present study could be useful for the assessment of future monitoring programs of PFOA and PFOS in the surface water.

Residues of endosulfan in surface and subsurface agricultural soil and its bioremediation.

The persistence of many hydrophobic pesticides has been reported by various workers in various soil environments and its bioremediation is a major concern due to less bioavailability. In the present study, the pesticide residues in the surface and subsurface soil in an area of intense agricultural activity in Pakkam Village of Thiruvallur District, Tamilnadu, India, and its bioremediation using a novel bacterial consortium was investigated. Surface (0-15 cm) and subsurface soils (15-30 cm and 30-40 cm) were sampled, and pesticides in different layers of the soil were analyzed. Alpha endosulfan and beta endosulfan concentrations ranged from 1.42 to 3.4 mg/g and 1.28-3.1 mg/g in the surface soil, 0.6-1.4 mg/g and 0.3-0.6 mg/g in the subsurface soil (15-30 cm), and 0.9-1.5 mg/g and 0.34-1.3 mg/g in the subsurface soil (30-40 cm) respectively. Residues of other persistent pesticides were also detected in minor concentrations. These soil layers were subjected to bioremediation using a novel bacterial consortium under a simulated soil profile condition in a soil reactor. The complete removal of alpha and beta endosulfan was observed over 25 days. Residues of endosulfate were also detected during bioremediation, which was subsequently degraded on the 30th day. This study revealed the existence of endosulfan in the surface and subsurface soils and also proved that the removal of such a ubiquitous pesticide in the surface and subsurface environment can be achieved in the field by bioaugumenting a biosurfactant-producing bacterial consortium that degrades pesticides.

Biodegradation of endosulfan isomers and its metabolite endosulfate by two biosurfactant producing bacterial strains of Bordetella petrii.

The main objective of the investigation was to study the biodegradation of endosulfan isomers and its major metabolite endosulfate by two biosurfactant producing bacterial strains of Bordetella petrii. The significance of the study is to evaluate the capability of biosurfactant producing bacterial strains in enhancing the bioavailability of endosulfan. Sixty bacterial strains were isolated from the endosulfan degrading bacterial consortium and were screened for endosulfan degradation and biosurfactant production. Among those, two strains Bordetella petrii I GV 34 (Gene bank Accession No KJ02262) and Bordetella petrii II GV 36 (Gene bank Accession No KJ022625) were capable of degrading endosulfan with simultaneous biosurfactant production. Bordetella petrii I degraded 89% of α and 84% of ß isomers of endosulfan whereas Bordetella petrii II degraded 82% of both the isomers. Both the strains were able to reduce the surface tension up to 19.6% and 21.4% with a minimum observed surface tension of 45 Dynes/cm and 44 Dynes/cm, respectively. The study revealed that the strains have the potential to enhance the degradation endosulfan residues in contaminated sites and water by biosurfactant production.

Enhanced biodegradation of endosulfan and its major metabolite endosulfate by a biosurfactant producing bacterium.

The present study was carried out to isolate bacteria capable of producing biosurfactant that solublize endosulfan (6,7,8,9,10,10-Hexachloro-1,5,5a,6,9,9a-hexahydro- 6,9-methano-2,4,3-benzodioxathiepine-3-oxide) and for enhanced degradation of endosulfan and its major metabolite endosulfate. The significance of the study is to enhance the bioavailability of soil-bound endosulfan residues as its degradation is limited due to its low solubility. A mixed bacterial culture capable of degrading endosulfan was enriched from pesticide-contaminated soil and was able to degrade about 80% of α-endosulfan and 75% of ß-endosulfan in five days. Bacterial isolates were screened for biosurfactant production and endosulfan degradation. Among the isolates screened, four strains produced biosurfactant on endosulfan. ES-47 showed better emulsification of endosulfan and degraded 99% of endosulfan and 94% of endosulfate formed during endosulfan degradation. The strain reduced the surface tension up to 37 dynes/cm. The study reveals that the strain was capable of degrading endosulfan and endosulfate with simultaneous biosurfactant production.

Removal of nutrients in denitrification system using coconut coir fibre for the biological treatment of aquaculture wastewater.

Ideal bacterial support medium for fixed film denitrification processes/bioreactors must be inexpensive, durable and possess large surface area with sufficient porosity. The present study has been focussed on removing nitrate nitrogen at two different nitrate nitrogen loading rates (60 (NLR I) and 120 (NLR II) mg l(-1)) from simulated aquaculture wastewater. Coconut coir fibre and a commercially available synthetic reticulated plastic media (Fujino Spirals) were used as packing medium in two independent upflow anaerobic packed bed column reactors. Removal of nitrate nitrogen was studied in correlation with other nutrients (COD, TKN, dissolved orthophosphate). Maximum removal of 97% at NLR-I and 99% at NLR - II of nitrate nitrogen was observed in with either media. Greater consistency in the case of COD removal of upto 81% was observed at NLR II where coconut coir was used as support medium compared to 72% COD removal by Fujino Spirals. The results observed indicate that the organic support medium is just as efficient in nitrate nitrogen removal as conventionally used synthetic support medium. The study is important as it specifically focuses on denitrification of aquaculture wastewater using cheaper organic support medium in anoxic bioreactors for the removal of nitrate nitrogen; which is seldom addressed as a significant problem.

Studies on adsorption of nickel on sand from constructed wetland and effect of leaching agents.

The present study chronicles experiments done on the feasibility of exploiting sand's natural capacity as an adsorbant for the removal of nickel laden wastewater. Batch adsorbtion studies were carried out. Leaching agents such as 0.01 M EDTA (disodium salt), 0.1 N HCI and acetic acid alongwith water as control showed 0.01 M EDTA-Na and 0.1 N HCl as suitable leaching agents to enhance metal removal from sand. Pot experiments were successively carried out with Arundo donax plants to determine the effectiveness of treatment on the sand. It was found that sand could continue as a good substrate for plant growth and the amount of leaching agent required for a pilot scale constructed wetland was estimated. The maximum amount of nickel adsorbed was 5 mg/L at a pH of 6. EDTA was selected as the chelating agent and the pot experiments showed no immediate effects on plant growth.