Comprehensive Study on Solomonamides: Total Synthesis, Stereochemical Revision, and SAR Studies toward Identification of Simplified Lead

Solomonamides, a pair of macrocyclic peptide natural products originating from marine sources, have garnered significant attention within the synthetic community owing to their marked anti-inflammatory efficacy and intricate molecular architectures. In this paper, we present a very detailed investigation into solomonamides, including the challenges associated with the total synthesis, the evolution of our synthetic strategies, structural reassignment, synthesis of all possible stereoisomeric macrocycles, biological assessment, structure-activity relationship (SAR) studies, etc. Within the ambit of this total synthesis, diverse strategies for macrocyclization were rigorously explored, encompassing the Friedel-Crafts acylation, cyclization involving the aniline NH2 moiety, macrolactamization utilizing Gly-NH2, and Heck macrocyclization methodologies. In addition, an array of intriguing chemical transformations were devised, including but not limited to photo-Fries rearrangement, Wacker oxidation, ligand-free Heck macrocyclization, oxidative cleavage of indole, synthesis of contiguous stereocenters via substrate/reagent-controlled protocols, and simultaneous making and breaking of olefinic moieties. The findings of this investigation revealed a structurally simplified lead compound. Remarkably, the lead compound, while possessing structural simplification in comparison to the intricate solomonamide counterparts, demonstrates equipotent in vivo anti-inflammatory efficacy.

Synthesis, biological evaluation and docking studies of silicon incorporated diarylpyrroles as MmpL3 inhibitors: An effective strategy towards development of potent anti-tubercular agents

Growing global demand for new molecules to treat tuberculosis has created an urgent need to develop novel strategies to combat the menace. BM212 related compounds were found to be potent anti-TB agents and they inhibit mycolic acid transporter, MmpL3, a known potent drug target from Mycobacterium tuberculosis. In order to enhance their inhibitory potency, several silicon analogues of diarylpyrroles related to BM212 were designed, synthesized, and evaluated for anti-tubercular activities. In Alamar blue assay, most of the silicon-incorporated compounds were found to be more potent than the parent compound (BM212), against Mycobacterium tuberculosis (MIC = 1.7 μM, H37Rv). Docking results from the crystal structure of MmpL3 and silicon analogues as pharmacophore model also strongly correlate with the biological assays and suggest that the incorporation of silicon in the inhibitor scaffold could enhance their potency by stabilizing the hydrophobic residues at the binding pocket. The best docking hit, compound 12 showed an MIC of 0.1 μM against H37Rv with an acceptable in vitro ADME profile and excellent selectivity index. Overall, the present study indicates that, the designed silicon analogues, especially compound 12 could be a good inhibitor for an intrinsically flexible drug-binding pocket of MmpL3 and has potential for further development as anti-tubercular agents.

Sewage Treatment through Constructed Wetland System Tailed by Nanocomposite Clay Filter: A Clean Green Initiative

Sewage treatment through constructed wetland is an ecofriendly and sustainable approach proven effective worldwide. Constructed wetland with appropriate species is capable of eliminating all pollutants in sewage, except pathogen removal. An additional polishing treatment is required to eliminate pathogen. Optimization of HLR in CWS was executed by applying first order kinetics. Nanocomposite clay filter with economically viable materials was synthesized and disinfection ability was evaluated. A novel approach integrating constructed wetland system tailed by nanocomposite clay filter was designed. Control was setup with constructed wetland system devoid of plants integrated with clay filter devoid of nanoparticles. The constructed wetland system devoid of plants was used as plants play a vital role in the removal of pollutants. The quality of the influent for (n=20) BOD, COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron were 248, 345, 26, 4.8, 350, 450, 50, 48, 0.2, 5 mg/L respectively. The quality of effluent in the control was 145, 225, 18, 3.8, 185, 345, 31, 30, 0.6, 2 mg/L for BOD,COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron respectively. While in the test, 10, 30, 2, 1, 30, 128, 13, 12, BDL, BDL mg/L for BOD, COD, TKN, TP,TSS, TDS, SO4, Cl, lead and iron respectively. The inlet concentration of T.C, F.C and E.coli were 42.1x106-6.3x108, 4.9x105-14.4x106 and 7.8x103-3.8x105 respectively. The pathogen reduction in log removal for test and control units were 5.4 and 1.1 for T.C, 4.4 and 1.2 for F.C and 3 and 1 for E.coli.  Thus it is a clean green initiative combating the limitations of disinfection surpassing the existing barriers.

Sewage Treatment through Constructed Wetland System Tailed by Nanocomposite Clay Filter: A Clean Green Initiative

Sewage treatment through constructed wetland is an ecofriendly and sustainable approach proven effective worldwide. Constructed wetland with appropriate species is capable of eliminating all pollutants in sewage, except pathogen removal. An additional polishing treatment is required to eliminate pathogen. Optimization of HLR in CWS was executed by applying first order kinetics. Nanocomposite clay filter with economically viable materials was synthesized and disinfection ability was evaluated. A novel approach integrating constructed wetland system tailed by nanocomposite clay filter was designed. Control was setup with constructed wetland system devoid of plants integrated with clay filter devoid of nanoparticles. The constructed wetland system devoid of plants was used as plants play a vital role in the removal of pollutants. The quality of the influent for (n=20) BOD, COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron were 248, 345, 26, 4.8, 350, 450, 50, 48, 0.2, 5 mg/L respectively. The quality of effluent in the control was 145, 225, 18, 3.8, 185, 345, 31, 30, 0.6, 2 mg/L for BOD,COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron respectively. While in the test, 10, 30, 2, 1, 30, 128, 13, 12, BDL, BDL mg/L for BOD, COD, TKN, TP,TSS, TDS, SO4, Cl, lead and iron respectively. The inlet concentration of T.C, F.C and E.coli were 42.1x106-6.3x108, 4.9x105-14.4x106 and 7.8x103-3.8x105 respectively. The pathogen reduction in log removal for test and control units were 5.4 and 1.1 for T.C, 4.4 and 1.2 for F.C and 3 and 1 for E.coli.  Thus it is a clean green initiative combating the limitations of disinfection surpassing the existing barriers.

Application of Vinamidinium Salt Chemistry for a Palladium Free Synthesis of Anti-Malarial MMV048: A "Bottom-Up" Approach

MMV390048 (1) is a clinical compound under investigation for antimalarial activity. A new synthetic route was developed which couples two aromatic fragments while forming the central pyridine ring over two steps. This sequence takes advantage of raw materials used in the existing etoricoxib supply chain and eliminates the need for palladium catalysts, which were projected to be major cost-drivers.

Pollutant Removal from Sewage in Tropical Climate by Constructed Wetland System: An Asset for Irrigation

In the global outlook, letting of untreated sewage in existing river bodies deteriorates the water quality. The seepage likely depreciates the quality of ground water too. The quality of groundwater with special reference to India has tremendously gone down in the past twenty years leading to sour taste. On the other hand, agriculture sector is deprived of water in many places of India. A solution can be arrived concurrently by treating sewage and consuming the effluent in agricultural sector. First order kinetics was applied in constructed wetland system at different flow rates and optimised. At optimised HLR, effluent met the standards of discharge that can be utilized for agricultural/ irrigational purpose. The emanating major pollutants can be effectively treated using constructed wetland system under tropical climate. A few clippings at the onsite treatment illustrated the diversity of species thus adjoining sustainable biodiversity and treatment. Thus in tropical countries like India, constructed wetland system might pave solution not only for the treatment of sewage but in deploying the effluent in agricultural sector. A clean ecosystem can be achieved with sustainability.

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.

Development of a continuous flow synthesis of FGIN-1-27 enabled by in-line 19F NMR analyses and optimization algorithms

A continuous flow synthesis of FGIN-1-27 has been developed using enabling technologies such as real-time in-line benchtop 19F NMR analysis and an optimization algorithm.

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.

Development of foam mat dried soursop powder using arabic gum and fish gelatin as foaming agent

Soursop is also known as Annona muricata from Annonaceae family. Soursop flavour has been described as a combination of strawberry and pineapple, with sour citrus flavor. The foam mat drying is a process in which the transformation of products from liquid to stable foam followed by air drying. The foam mat drying process is reported to be considerably cheaper than vacuum, freeze and spray drying methods. Foam mat drying was done using different foaming agents at various concentration: fish gelatin (FG: 5, 10, 15, 20%) and arabic gum (AG: 2, 4, 6, 8%). Foam properties and physicochemical properties such as bulk density, tap density, pH, moisture content, water activity, total phenolic content, color and flowability of powder were analyzed. Increasing the concentration of foaming agents showed a decreasing trend of the total phenolic contents and the value ranges from 222 to 453 mg GAE/100 g. Soursop powder with fish gelatin has higher total phenolic content compared to sample with Arabic gum. Soursop powder with both foaming agents showed an excellent flowability.

A concise route to MK-4482 (EIDD-2801) from cytidine

A two-step route to MK-4482 (EIDD-2801, 1) was developed consisting of an esterification and hydroxamination of cytidine.

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.

A multi-step continuous flow synthesis of the cystic fibrosis medicine ivacaftor

A continuous flow ozonolysis method combined with a multi-step flow sequence is developed for the synthesis of the drug ivacaftor for the first time.

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.

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 β 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.

Impact of heavy metal toxicity and constructed wetland system as a tool in remediation

The objective of this review is to throw light upon the global concern of heavy metal-contaminated sites and their remediation through an ecofriendly approach. Accumulated heavy metals in soil and water bodies gain entry through the food chain and pose serious threat to all forms of life. This has engendered interest in phytoremediation techniques where hyperaccumulators are used. Constructed wetland has a pivotal role and is a cost-effective technique in the remediation of heavy metals. Metal availability and mobility are influenced by the addition of chelating agents, which enhance the availability of metal uptake. This review helps in identifying the critical knowledge gaps and areas to enhance research in the future to develop strategies such as genetically engineered hyperaccumulators to attain an environment devoid of heavy metal contamination.

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 β-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.

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.

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.

Decolourisation of azo dye, Acid Red-18 by Phanerochaete chrysosporium

The ability of wood rotting fungus, Phanerochaete chrysosporium to decolourise azo dye, Acid Red -18 was investigated. The optimal parameters (pH and cell load) required for effective decolourisation were determined. The strain was capable of decolourising dye over a pH range of 4-6 and decolourisation was rather fast, more than 90% in all cases. The optimal pH 5 and cell load of 2.4 x 10(6) spores/mL is required for complete decolourisation of 100 micromol of azo dye Acid Red-18 at a temperature of 37 degrees C. The fungus proved to be capable of both biodegradation and biosorption, and biosorption was found to be the major dye removal mechanism.

Biodegradation of polycyclic aromatic hydrocarbons by a halotolerant bacterial strain Ochrobactrum sp. VA1

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in the environment and are derived from both man-made and natural resources. The present study is focused on the degradation of PAHs by a halotolerant bacterial strain under saline conditions. The bacterial strain VA1 was isolated from a PAH-degrading consortium that was enriched from marine water samples that were collected from different sites at Chennai, India. In the present study, a clearing zone formed on PAH-amended mineral salt agar media confirmed the utilization of PAH by the bacterial strain VA1. The results show that the strain VA1 was able to degrade anthracene (88%), phenanthrene (98%), naphthalene (90%), fluorene (97%), pyrene (84%), benzo(k)fluoranthene (57%) and benzo(e)pyrene (50%) at a 30 g/L NaCl concentration. The present study reveals that the VA1 strain was able to degrade PAHs in petroleum wastewater under saline conditions. The promising PAH-degrading halotolerant bacterial strain, VA1, was identified as Ochrobactrum sp. using biochemical and molecular techniques.

Role of a moderately halophilic bacterial consortium in the biodegradation of polyaromatic hydrocarbons

Polycyclic aromatic hydrocarbons are ubiquitous pollutants in the environment, and most high molecular weight PAHs cause mutagenic, teratogenic and potentially carcinogenic effects. While several strains have been identified that degrade PAHs, the present study is focused on the degradation of PAHs in a marine environment by a moderately halophilic bacterial consortium. The bacterial consortium was isolated from a mixture of marine water samples collected from seven different sites in Chennai, India. The low molecular weight (LMW) PAHs phenanthrene and fluorine, and the high molecular weight (HMW) PAHs pyrene and benzo(e)pyrene were selected for the degradation study. The consortium metabolized both LMW and HMW PAHs. The consortium was also able to degrade PAHs present in crude oil-contaminated saline wastewater. The bacterial consortium was able to degrade 80% of HMW PAHs and 100% of LMW PAHs in the saline wastewater. The strains present in the consortium were identified as Ochrobactrum sp., Enterobacter cloacae and Stenotrophomonas maltophilia. This study reveals that these bacteria have the potential to degrade different PAHs in saline wastewater.

Persistence and distribution of endosulfan under field condition

Rapid increase in industrialization and agricultural activities to meet the population need has led to environmental pollution. The major revolution in agricultural production is mainly due to increased use of pesticides and fertilizers. Soil act as a major sink for majority of pesticides applied on agricultural crops. Among the organochlorines, endosulfan is the most commonly used pesticide, hence this study concentrates on the persistence and distribution behaviour of endosulfan under field conditions. The result showed that the alpha endosulfan concentrations were very minimum (0.98 mg/kg of soil) in all the four fields under study (Nazarath, Othikadu, Ekkadu and Ekkadukandigai of Thiruvallur district, Tamil Nadu). Where as beta endosulfan concentration at the time of application was 6.39 mg/kg and declined to 0.8 mg/kg on soil at 150th day. The endosulfan sulfate concentration was 11.8 mg/kg in soil at 15th day and then concentration declined to 2.2 mg/kg at 150th day. Field run-off samples showed maximum residue levels (0.024 mg/l) at the early irrigation period. While plant foliar parts showed maximum concentrations of alpha-endosulfan (43.4 mg/kg), beta-endosulfan (40.6 mg/kg) and endosulfan sulfate (20.1 mg/kg). At harvest stage, rice grain and husk also had lower concentrations of endosulfan sulfate (2.2 and 0.09 mg/kg), respectively.

Microbial diversity in hypersaline wastewater: the example of tanneries

In contrast to conventional wastewater treatment plants and saline environments, little is known regarding the microbial diversity of hypersaline wastewater. In this study, the microbial communities of a hypersaline tannery effluent, and those of three treatment systems operating with the tannery effluent, were investigated using 16S rDNA phylogenetic markers. The comparative analysis of 377 bacterial sequences revealed the high diversity of this type of hypersaline environment, clustering within 193 phylotypes (> or = 97% similarity) and covering 14 of the 52 divisions of the bacterial domain, i.e. Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Chlorobi, Planctomycetes, Spirochaetes, Synergistes, Chloroflexi, Thermotogae, Verrucomicrobia, OP3, OP11 and TM7. Most of the phylotypes were related to halophilic and pollutant-degrading bacteria. Using statistical analysis, the diversity of this type of environment was compared to that of other environmental samples selected on the basis of their salinity, oxygen content and organic load.

Role of plasmid in the degradation of petroleum hydrocarbon by Pseudomonas fluorescens NS1

In this study the role of plasmid in Pseudomonas fluorescens, isolated from petroleum contaminated soil on hexadecane degradation was assessed. The organism was able to utilize hexadecane as sole carbon source and also reduce surface tension up to 27 mN/m. The organism harboured a plasmid of approximately 1.8 kb. Plasmid curing and transformation of plasmid DNA into E. coli revealed that the plasmid was involved in hexadecane degradation. When compared to P. fluorescens, no significant growth was observed with wild-type E. coli strain. P. fluorescens degraded 95% of hexadecane (0.4% (v/v)) whereas the transformed strain degraded 92% of hexadecane in 120 h, which was almost equivalent to the degradation by P. fluorescens. The wild-type E. coli showed no significant degradation of hexadecane whereas, the plasmid transformed E. coli was able to degrade hexadecane, which indicates the expression of the catabolic genes in the transformed E. coli strain.

Organochlorine pesticide residues in ground water of Thiruvallur district, India

Modern agriculture practices reveal an increase in use of pesticides and fertilizers to meet the food demand of increasing population which results in contamination of the environment. In India crop production increased to 100% but the cropping area has increased marginally by 20%. Pesticides have played a major role in achieving the maximum crop production, but maximum usage and accumulation of pesticide residues was highly detrimental to aquatic and other ecosystem. The present study was chosen to know the level of organochlorines contamination in ground water of Thiruvallur district, Tamil Nadu, India. The samples were highly contaminated with DDT, HCH, endosulfan and their derivatives. Among the HCH derivatives, Gamma HCH residues was found maximum of 9.8 microg/l in Arumbakkam open wells. Concentrations of pp-DDT and op-DDT were 14.3 microg/l and 0.8 microg/l. The maximum residue (15.9 microg/l) of endosulfan sulfate was recorded in Kandigai village bore well. The study showed that the ground water samples were highly contaminated with organochlorine residues.

Anaerobic digestion of tannery soak liquor with an aerobic post-treatment

The leather industry occupies a place of prominence in the Indian economy due to its massive potential for employment, growth and exports. The potential environmental impact of tanning is significant. This study focuses on tannery soak liquor, generated by the soaking of hides and skins, which is characterised by high organic load and high salinity. For these reasons, the soak liquor should be segregated and pre-treated separately before being mixed with the composite wastewater, made of all other streams mixed together. The anaerobic digestion of tannery soak liquor was studied using a UASB. COD removal reached 78% at an OLR of 0.5 kg COD m(-3) d(-1), a HRT of 5 days and a TDS concentration of 71 gl(-1). The combination of the UASB with an aerobic post-treatment enhanced the performance of the overall wastewater treatment process and the COD removal efficiency of the combined anaerobic/aerobic treatment system reached 96%. However, for effective operation, the system had to be operated at very low OLRs, which affects the economic viability of such a process.

Halophilic biological treatment of tannery soak liquor in a sequencing batch reactor

Hypersaline wastewater (i.e. wastewater containing more than 35 gl(-1) total dissolved solids (TDS)) is generated by various industrial activities. This wastewater, rich in both organic matter and TDS, is difficult to treat using conventional biological wastewater treatment processes. Among the industries generating hypersaline effluents, tanneries are prominent in India. In this study, tannery wastewater from soak pit was treated in a lab-scale SBR for the removal of organic matter. The characterisation of the soak liquor showed that this effluent is biodegradable, though not easily, and highly variable, depending on the origin and the nature of the hides. TDS was in the range of 21-57 gl(-1) and COD was in the range of 1.5-3.6 gl(-1). This soak liquor was biologically treated in an aerobic sequencing batch reactor seeded with halophilic bacteria, and the performance of the system was evaluated under different operating conditions with changes in hydraulic retention time, organic loading rate and salt concentration. The changes in salinity appeared to affect the removal of organic matter more than the changes in hydraulic retention time or organic loading rate. Despite the variations in the characteristics of the soak liquor, the reactor achieved proper removal of organic matter, once the acclimation of the microorganisms was achieved. Optimum removal efficiencies of 95%, 93%, 96% and 92% on COD, PO4 3-, TKN and SS, respectively, could be reached with 5 days hydraulic retention time (HRT), an organic loading rate (OLR) of 0.6 kg COD m(-3)d(-1) and 34 g NaCl l(-1). The organisms responsible for nitrogen removal appeared to be the most sensitive to the modifications of these parameters.

Degradation of anthracene and pyrene supplied by microcrystals and non-aqueous-phase liquids

Polycyclic aromatic hydrocarbons (PAHs) are worldwide environmental pollutants. Their bioavailability is limited by a low aqueous solubility, which causes specific adaptations in degrading bacteria. To compare bacterial degrading behavior, a study was conducted on the mineralization, metabolization and formation of biomass from (14)C-anthracene by Sphingomonas sp. BA2 compared with those from (14)C-pyrene by Gordonia-like strain BP9 and Mycobacterium gilvum VF1. Different conditions of PAH supply were used in the medium: crystals <0.5 mm, microcrystals <<0.1 mm formed by sonication, or PAH solubilized in 2,2,4,4,6,8,8-heptamethylnonane (HMN) or silicone oil. Anthracene supply by crystals and silicone oil led to similar maximum mineralization rates 33 ng ml(-1) h(-1) and the same amount of mineralization (24%) after 168 h. Microcrystals increased the rates and amounts only slightly. HMN decreased the values to less than one-third. In comparison with crystals, microcrystals increased overall pyrene mineralization by strain BP9 from 53% to 58%, with maximum mineralization rates of 160 ng ml(-1) h(-1) and 166 ng ml(-1) h(-1). Silicone oil heavily increased the rate to 292 ng ml(-1) h(-1) and the amount mineralized to 71%, whereas HMN inhibited the degradation by one order of magnitude. A similar degradation behavior showing lower mineralization rates and extent was observed with strain VF1. However, inhibition by HMN was less pronounced. Sonication, leading to decreased PAH crystal size, increased the mass transfer and mineralization rates. PAH supply by silicone oil led to a much higher mass transfer, which may be due to emulsification of the oil, whereas such effects were not observed with HMN.

Changes in fatty acid composition of Chromohalobacter israelensis with varying salt concentrations

The adaptation of fatty acid composition of Chromohalobacter israelensis, a euryhalophilic bacterium, grown at different salt concentrations was studied. C. israelensis tolerated NaCl up to concentrations of 20% (w/v) and showed optimal growth at 7% (w/v). Major fatty acids of this bacterium were palmitic acid (16:0), stearic acid (18:0), palmetoleic acid (16:1cisDelta9), and cis-vaccenic acid (18:1Delta11). The salt concentration strongly influenced the fatty acid composition. In the presence of sub-optimal salt concentrations, the degree of saturation decreased, suggesting the importance of salt in maintaining the osmotic balance of the cell with its environment.

Bioremediation of crude oil contaminated soil by bioaugmentation of Pseudomonas fluorescens NS1

A feasibility study was conducted to evaluate the efficiency of Pseudomonas fluorescens NS1 bioaugmented to stimulate in situ bioremediation of crude oil-contaminated soil with different amendments in treatment units. Pure culture of P. fluorescens NS1 was isolated from a petroleum-contaminated soil. The rate of degradation of petroleum hydrocarbons by the indigenous soil microflora and in the presence of P. fluorescens NS1 was assessed with the addition of nutrients and bulking agents for a period of about 35 days. The study showed that addition of wheat bran as bulking agent rapidly enhanced bioremediation of crude oil-contaminated soil compared to amendments in other treatment units.

Isoform specificity for oestrogen receptor and thyroid hormone receptor genes and their interactions on the NR2D gene promoter

Oestrogens are critical for the display of lordosis behaviour and, in recent years, have also been shown to be involved in synaptic plasticity. In the brain, the regulation of ionotropic glutamate receptors has consequences for excitatory neurotransmission. Oestrogen regulation of the N-methyl-d-aspartate receptor subunit 2D (NR2D) has generated considerable interest as a possible molecular mechanism by which synaptic plasticity can be modulated. Since more than one isoform of the oestrogen receptor (ER) exists in mammals, it is possible that oestrogen regulation via the ERalpha and ERbeta isoforms on the NR2D oestrogen response element (ERE) is not equivalent. In the kidney fibroblast (CV1) cell line, we show that in response to 17beta-oestradiol, only ERalpha, not ERbeta, could upregulate transcription from the ERE which is in the 3' untranslated region of the NR2D gene. When this ERE is in the 5' position, neither ERalpha nor ERbeta showed transactivation capacity. Thyroid hormone receptor (TR) modulation of ER mediated induction has been shown for other ER target genes, such as the preproenkephalin and oxytocin receptor genes. Since the various TR isoforms exhibit distinct roles, we hypothesized that TR modulation of ER induction may also be isoform specific. This is indeed the case. The TRalpha1 isoform stimulated ERalpha mediated induction from the 3'-ERE whereas the TRbeta1 isoform inhibited this induction. This study shows that isoforms of both the ER and TR have different transactivation properties. Such flexible regulation and crosstalk by nuclear receptor isoforms leads to different transcriptional outcomes and the combinatorial logic may aid neuroendocrine integration.