Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 144-145). Also available via the Internet.

Made available in DSpace on 2016-02-05T18:29:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-04-14. Added 1 bitstream(s) on 2016-02-05T18:33:31Z : No. of bitstreams: 1 000856560.pdf: 7026334 bytes, checksum: 187d889cf3bbf7e7012a8050b181befe (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Dos poços e plataformas de petróleo ao transporte e distribuição de petroquímicos, sempre há o risco de acidentes que resultam em incêndios. Nesses casos são muitas vezes utilizadas espumas formadoras de filme aquoso (AFFF), pois compostos fluorados em grandes quantidades nas misturas das AFFFs contribuem com a capacidade extintora de incêndio. Em situações de emergência, toneladas de AFFF são liberadas no ambiente e, portanto, podem afetar em longo prazo o ambiente mesmo depois do incêndio ser apagado, pois contém substâncias que escoam para corpos d'água. Os flúor-carbonados são altamente resistentes à biodegradação e, por isso, têm prolongada persistência ambiental. As vias de biodegradação dos organo-halogenados são bastante específicas e lentas. Nesse estudo foi determinado o potencial de biodegradação de diferentes microbiotas sobre misturas da AFFF em hidrocarbonetos, e estudado o processo de biotransformação dos compostos presentes na formulação da AFFF. Pela combinação de metodologias foi possível conhecer melhor sobre o impacto dos compostos flúor-carbonados no ambiente. Foram realizados estudos com a técnica de espectrometria de massa, para determinar as vias de biotransformação dos componentes perfluorcarbonados; técnicas respirométricas, para estudar a biodegradabilidade da AFFF em associação com hidrocarbonetos de petróleo; bioensaios com plantas, para determinar a toxicidade da AFFF; e técnicas de biologia molecular, para análise metagenômica de alteração no perfil da comunidade microbiana de solo após a introdução da AFFF ao meio. Os hidrocarbonetos de petróleo influenciaram, durante a aplicação de espumas de incêndio, o processo de transformação de fluorcarbonados, alterando o metabolismo de comunidades microbianas. Em geral, a biotransformação de fluorcarbonados foi mais lenta por uma interferência mútua entre BTEX e AFFF, mas a produção de CO2 foi maior pelo... / From oilrigs extraction to transport and distribution of petrochemicals, there is always the risk of accidents resulting in fires. In such cases, the release of aqueous film forming foams (AFFF) are a usual practice. These compounds are comprised of compounds containing fluorine-carbon, which contribute to their fire extinguishing capabilities when released in large amounts. Tons of AFFF are released into the environment during emergencies and thus causing long term harnessing of the environment even long after the fire is extinguished, since such substances end up in water bodies. Fluorine and carbon bonds are highly resistant to degradation and therefore have long environmental persistence. Biodegradation pathways of organic halogens are quite specific and slow. In this study, we determined the potential microbiota in different biodegradation AFFF mixtures of hydrocarbons, and studied the biotransformation of compounds in the formulation of AFFF. Thus, it was possible to better understand the impact of fluorinated compounds into the environment. A wide variety of techniques was applied, involving a combination of mass spectrometry techniques to determine the biotransformation pathways of perfluorcarbonados components; respirometric techniques to study the biodegradability of AFFF in association with petroleum hydrocarbons; bio-assays to determine the phyto-toxicity of AFFF; and molecular biology techniques for metagenomic analyzes evaluating changes in the profile of soil microbial communities after AFFF was introduced in the medium. It was observed that petroleum hydrocarbons during application of fire foams fluorocarbon influenced the overall biotransformation process, altering the metabolism of the microbial communities. In general, the fluorocarbon biotransformation is slower by a mutual interference between AFFF and BTEX, but the CO2 production is increased by the effect of the perfluorinated surfactant combined with the ...

Orientador: Ederio Dino Bidoia / Banca: Marcelo Henrique Otenio / Banca: Edson Aparecido Abdul Nour / Banca: Dejanira de Franceschi de Angelis / Banca: Maria Aparecida Marin Morales / Resumo: Dos poços e plataformas de petróleo ao transporte e distribuição de petroquímicos, sempre há o risco de acidentes que resultam em incêndios. Nesses casos são muitas vezes utilizadas espumas formadoras de filme aquoso (AFFF), pois compostos fluorados em grandes quantidades nas misturas das AFFFs contribuem com a capacidade extintora de incêndio. Em situações de emergência, toneladas de AFFF são liberadas no ambiente e, portanto, podem afetar em longo prazo o ambiente mesmo depois do incêndio ser apagado, pois contém substâncias que escoam para corpos d'água. Os flúor-carbonados são altamente resistentes à biodegradação e, por isso, têm prolongada persistência ambiental. As vias de biodegradação dos organo-halogenados são bastante específicas e lentas. Nesse estudo foi determinado o potencial de biodegradação de diferentes microbiotas sobre misturas da AFFF em hidrocarbonetos, e estudado o processo de biotransformação dos compostos presentes na formulação da AFFF. Pela combinação de metodologias foi possível conhecer melhor sobre o impacto dos compostos flúor-carbonados no ambiente. Foram realizados estudos com a técnica de espectrometria de massa, para determinar as vias de biotransformação dos componentes perfluorcarbonados; técnicas respirométricas, para estudar a biodegradabilidade da AFFF em associação com hidrocarbonetos de petróleo; bioensaios com plantas, para determinar a toxicidade da AFFF; e técnicas de biologia molecular, para análise metagenômica de alteração no perfil da comunidade microbiana de solo após a introdução da AFFF ao meio. Os hidrocarbonetos de petróleo influenciaram, durante a aplicação de espumas de incêndio, o processo de transformação de fluorcarbonados, alterando o metabolismo de comunidades microbianas. Em geral, a biotransformação de fluorcarbonados foi mais lenta por uma interferência mútua entre BTEX e AFFF, mas a produção de CO2 foi maior pelo... / Abstract: From oilrigs extraction to transport and distribution of petrochemicals, there is always the risk of accidents resulting in fires. In such cases, the release of aqueous film forming foams (AFFF) are a usual practice. These compounds are comprised of compounds containing fluorine-carbon, which contribute to their fire extinguishing capabilities when released in large amounts. Tons of AFFF are released into the environment during emergencies and thus causing long term harnessing of the environment even long after the fire is extinguished, since such substances end up in water bodies. Fluorine and carbon bonds are highly resistant to degradation and therefore have long environmental persistence. Biodegradation pathways of organic halogens are quite specific and slow. In this study, we determined the potential microbiota in different biodegradation AFFF mixtures of hydrocarbons, and studied the biotransformation of compounds in the formulation of AFFF. Thus, it was possible to better understand the impact of fluorinated compounds into the environment. A wide variety of techniques was applied, involving a combination of mass spectrometry techniques to determine the biotransformation pathways of perfluorcarbonados components; respirometric techniques to study the biodegradability of AFFF in association with petroleum hydrocarbons; bio-assays to determine the phyto-toxicity of AFFF; and molecular biology techniques for metagenomic analyzes evaluating changes in the profile of soil microbial communities after AFFF was introduced in the medium. It was observed that petroleum hydrocarbons during application of fire foams fluorocarbon influenced the overall biotransformation process, altering the metabolism of the microbial communities. In general, the fluorocarbon biotransformation is slower by a mutual interference between AFFF and BTEX, but the CO2 production is increased by the effect of the perfluorinated surfactant combined with the ... / Doutor

The potential application of sulphate reducing bacteria for the bioremediation of acid mine drainage has already been recognised, and offers significant financial advantages over conventional chemical treatment approaches. Although the technology has been demonstrated successfully on both small- and large-scale, it’s extensive implementation has been constrained by the provision of suitable and cost effective electron donor and carbon sources. Primary sewage sludge is readily available in large quantities, but the slow rate of solubilization and low yield of soluble products do not apparently favour its use for this application. A number of pre-treatment steps have been introduced in an attempt to improve the yield and rates under methanogenic conditions. However, although early work suggested that degradation of lignocellulose and proteins may be more rapid under sulphate reducing conditions, the fate of primary sewage sludge under these conditions has been ignored. It was proposed that by combining the hydrolysis of primary sewage sludge and biological sulphate reduction, in a settling sludge bed, both processes would be enhanced. The aim of this study was to test this hypothesis on laboratory- and pilot-scale, and attempt to elucidate the underlying mechanism involved. The solubilization of primary sewage sludge was enhanced in the presence of sulphate reduction in continuous laboratory-scale reactors. Particulate matter accumulated in the bed of non-sulphidogenic systems, but not in sulphidogenic ones. This was attributed to increased solubilization and the smaller average floc size in the latter. Solubilization occurred within the settling sludge bed of the reactors, and offered a possible explanation for the better performance of the multiple- over single-stage reactor. A pilot-scale Falling Sludge Bed Reactor was constructed at Grootvlei Gold Mine, Springs, South Africa, and resulted in the solubilization of more than 70% of the influent primary sewage sludge. The system was also found to be highly resilient to severe perturbations, and returned rapidly to steady-state. Flask studies revealed that the hydrolysis of both proteins and complex carbohydrates was accelerated in the presence of biological sulphate reduction or sulphide. A study of the enzymology of sludge digestion revealed that sulphate reduction had little direct effect on the activity of the hydrolytic enzymes, but that reactor design was critical in the prevention of washout of these enzymes. Finally, a descriptive model was developed to explain the enhanced hydrolysis of primary sewage sludge. The model incorporated the effect of sulphidogenesis on floc fracture and reflocculation, and likely implications for mass transfer limitations.

Heavy metal contamination from mining and other industrial operations is becoming an increasing problem with regards to the depleting water resources in South Africa. This study involved the investigation of the use of an algal biomass as a possible alternative to the traditional chemical means of removing these metals. When the toxic effects of metals were investigated, Spirulina was found to have a threshold level of about 30 μM for copper, zinc and lead. Copper and zinc appeared to have a direct effect on the photosynthetic pathway, thereby causing a rapid decline in cell growth. Lead on the other hand seemed to affect surface properties and hence took longer to cause deterioration in growth. Although relatively low concentrations of metal may have a toxic effect on the cyanobacterium, Spirulina may have potential as a precipitation agent. The role of Spirulina in the precipitation of heavy metals appears to be through its ability to maintain a high pH in the surrounding medium, possibly through the enzyme carbonic anhydrase. Subsequent studies therefore focused on the assay and isolation of this enzyme. Two different radiotracer assays, in which carbonic anhydrase converts radiolabelled bicarbonate to carbon dioxide, were investigated, but were found to have several problems. Results were insensitive and could not be reproduced. The standard Wilbur-Anderson method subsequently investigated also proved to be insensitive with a tremendous degree of variability. Although not quantitative, SDS-PAGE proved to be the most reliable method of detection, and was therefore used in subsequent procedures. Chlamydomonas reinhardtii was the subject of initial enzyme isolation studies as these procedures are well documented. Although the published protocols proved unsuccessful, affinity chromatography of a membrane stock solution from Chlamydomonas reinhardtii yielded two relatively pure protein bands. These bands were presumed to represent two subunits of carbonic anhydrase, although Western blot analysis would be required to confirm their identity. Purification of carbonic anhydrase from Spirulina, however, proved unsuccessful and results obtained were very inconclusive. Hence, further analysis of Spirulina is required. The possibility of cloning CA from a genomic library was also considered, but suitable primers could not be designed from the aligned sequences.

Plant mechanisms regulating environmental heavy metal interactions are vital for plant survival. Plants must maintain adequate metal levels while preventing excesses. Several mechanisms involved in heavy metal uptake and sequestration have been identified and studied in hyperaccumulating plants such as Thlaspi caerulescens. These plants accumulate large quantities of metals, but their use in remediation is limited by their small size. On the other hand, mechanisms in high-biomass, non-hyperaccumulating perennial species such as poplar (Populus spp.) are unknown. The central goal of this project is to delineate specific mechanisms in poplar regulating the heavy metal zinc (Zn) for potential use in bioremediation and real-time monitoring. Specifically, project aims are: 1) Determine the role of HMA4 and PCS1 genes in poplar; 2) Delineate the ZIP gene family including ZIP1 and ZNT1 activity; and 3) Harness fluorescent energy transfer to engineer a poplar tree that monitors Zn-soil contamination. These are addressed using current technologies including phylogenetic analysis, gene transformation, expression assays, promoter-GUS assays, fluorescent-gene imaging, and metal assays. Through these experiments, mechanisms controlling heavy metal interaction are identified and characterized in poplar. Poplar contains a large number of genes in both the ZIP and HMA4 families, but only two members in the PCS family. Poplar also contains several genes that share close sequence and structural homology to those in hyperaccumulators. However, there is an overall divergence from hyperaccumulators in regards to expression across an environmental Zn gradient. Poplar tightly regulates Zn intake by suppressing absorption avenues under Zn excess. Over-expression of HMA4 and PCS1 resulted in more tolerance and more accumulation, respectively, in poplar lines. These findings support a regulatory system used in poplar to limit Zn under excess and promote Zn under deficiency. Using ZNT1 and its natural expression gradient, a chimeric protein was created that served as a biosensor in both poplar and Arabidopsis thaliana host plants and was able to discriminate between 1μM and 10mM Zn concentrations. These findings add to current knowledge of heavy metal regulation and help fill the gap of knowledge currently existing on the regulatory mechanisms that perennial trees use to control heavy metals.

Pentachlorophenol (PCP) is widely used as a wood preservative for wood products. It has been proposed that a modified PCP carrier system based on a diesel/biodiesel mixture should be used in place of the conventional diesel/KB3 carrier, but there is some question as to whether or not this modified carrier system can provide the same service life for wood products treated with PCP. The main objectives of this research were to evaluate: 1) the comparative biodegradability of PCP in soil containing either diesel/KB3 or diesel/biodiesel, and 2) the comparative decay resistance of wood treated with formulations containing either diesel/KB3 or diesel/biodiesel. For the biodegradability test a six month study was conducted to evaluate the remediation of PCP in the presence of either biodiesel or diesel in soil. Different percentages of biodiesel, diesel and PCP were mixed with clean soil and samples were taken and analyzed. The results showed significant reductions over time in oil and grease concentration, PCP concentration and toxicity for soils amended with both of these preservatives. The addition of biodiesel and PCP to the soil resulted in a significant increase in the Toxicity Characteristic Leaching Potential (TCLP) levels of PCP, suggesting that the co-metabolic effect of biodiesel on microorganisms could accelerate the degradation of PCP in soil. Also, a two year efficacy study using an accelerated soil contact decay test was initiated to compare the performance of treated wood with diesel/KB3 carrier and diesel/biodiesel carrier both with and without PCP. The residual hydrocarbon levels, PCP reduction, toxicity and leaching of PCP of the samples remained at the same level for treatments with similar PCP retention values for both of these carriers. Wood treated with PCP in two different carriers, the rate of decay was generally greater—particularly for the highest PCP retention level—for the biodiesel/diesel formulation, but this difference was not statistically significant. This study suggests that PCP formulated in a biodiesel/diesel carrier is not as effective as the conventional diesel/KB3 formulation against wood decay fungi. However, additional long term field stake tests will be required to determine the practical significance of this determination.

The nitroaromatic explosive 2,4,6-trinitrotoluene is a widespread, toxic groundwater contaminant. The objective of this work was to describe TNT fate in contaminated aquifer sediments. A series of bench scale experiments and model simulations were performed to evaluate the fate of TNT in historically contaminated aquifer sediments. A TNT contaminated site on the National Priorities List, Former Nansemond Ordnance Depot (FNOD), Suffolk, VA, served as the model site for this work. To describe desorption rate in contaminated sediments, two approaches for a first order single-site desorption were evaluated. In Model 1, the driving force for desorption is mathematically related to the sorbed phase concentrations, whereas in Model 2 the rate is based on aqueous phase concentrations. Two data sets were used to evaluate the models: (1) batch draw-and-fill experiments using FNOD sediment and (2) results from a previously published report from the Louisiana Army Ammunition Plant. Both models provided adequate fit, but Model 2 was better behaved and first order parameters fell within a smaller confidence interval. Draw-and-fill experiments were observed to yield first-order mass transfer coefficients well aligned with those derived from column experiments. The effect of organic amendments on anaerobic TNT degradation rate and microbial community structure in culture enriched from the FNOD site was studied in batch anaerobic microcosms. TNT readily degraded under all experimental conditions. A reductive pathway of TNT degradation was observed across all conditions, however, denaturing gradient gel electrophoresis (DGGE) analysis revealed distinct bacterial community compositions. In all microcosms, Gram-negative γ- or β-Proteobacteria and Gram-positive Negativicutes or Clostridia were observed. According to non-metric multidimensional scaling analysis of DGGE profiles, the microcosm communities were most similar to field site sediment corresponding to the highest TNT concentration, relative to moderately and uncontaminated sediments, suggesting that TNT contamination itself is a major driver of microbial community structure. Candidate degraders were identified and a Pseudomonas sp. was observed to be stimulated under all conditions, which was confirmed to rapidly degrade TNT in pure culture. Mathematical modeling of the batch microcosm results revealed that TNT degraded 1.7 times faster in lactate amended microcosms than in ethanol amended microcosms, which degraded 3.0 times faster than natural organic matter amended microcosms. Simulation of the TNT degradation pathway included determination of branching coefficients representing whether the first reduction of nitro group occurred in the ortho or para position or whether TNT was removed from the aqueous phase (i.e. bound to dissolved organic matter). Branching coefficients were greater for initial reduction of para (17-27% initial TNT concentration) over ortho (3-9% initial TNT concentration) for all test conditions. However, a greater degradate recovery and a different (lower para/ortho) ratio was observed for ethanol compared to lactate and un-amended conditions. Given the difference in sorption parameters between degradate isomers, these results suggest that differences in pathway branching stimulated by different electron donors are potentially relevant to long term site models. This work provides parameter values and model simulations of desorption relevant to other TNT contaminated sites, qualitative observations of how TNT-reducing bacterial community structure changes in response to electron donor addition, and quantitative comparison of the effect of electron donor addition on biodegradation rate with cultures relevant to field conditions; in addition, this work serves as a feasibility study demonstrating biodegradation as well as biostimulation potential at FNOD. / Ph. D.

Enhanced Reductive Bioremediation (ERB) is a sustainable remediation technology for the in situ treatment of chlorinated solvent contamination in aquifers. However, monitoring efforts employed to measure performance metrics rely on inferences of the subsurface environment from water samples collected at monitoring wells, ignoring the microbial activity that occurs at the granular level of aquifer sediment. This study compared potential bioavailable organic carbon (PBOC) and microbial diversity of two ERB sites. A two-sample t-test and a one-way ANOVA test with Tukey's HSD were performed to show differences between ERB and non-ERB samples and their degree of variability at selected geospatial locations downgradient of ERB treatment. Non-parametric multidimensional scaling (MDS) with similarity analysis was performed along with other data visualization plots to show microbial diversity. At Tinker AFB, results from the t-test showed that the PBOC concentrations from the ERB samples were statistically significantly greater than the samples without treatment (95% confidence; p-value = 0.018). For Dover AFB, results from the ANOVA with Tukey's HSD showed that there is a significant difference between the sample (DV3) collected in the ERB treatment zone to all other samples upgradient and downgradient of the ERB treatment. MDS and similarity analysis performed on relative abundance results from the Illumina MiSeq Sequencing of 16S rRNA genes showed large similarities among the samples within each site and the only observed differences occurred when comparing any sample to DV3, nearest to treatment. / Master of Science

The rivers, lakes and seas are the major water sources for the animal and plant kingdom in this earth. In recent times, the usage and wastage of water have been increasing due to the uncontrolled population growth. In addition to that, the rapid industrialization over the years has led to the gradual depletion of the natural resources like water, soil and air. Some of these industries discharge contaminants like organic products and inorganic (or) toxic heavy metals without treatment into the environment, leading to its degradation. Zinc is the 24th most abundant element present in the earth crust, amounting 75 ppm (0.0075%). The concentration of zinc present in the soil and seawater is about 64 ppm and 30 ppb respectively (Emsley, 2001). Generally, the zinc is found with the base metals such as copper and lead and it has less affinity with oxides and strong affinity with sulphides. Sphalerite, a zinc sulphide ore, is majorly containing 60-62% of zinc. The other sources of zinc from the minerals are smithsonite, hemimorphite, quartzite, and hydro zincate. The major sources of zinc contamination arise from several industrial activities such as mining, coal, waste combustion and steel and iron processing. Drinking water also contains certain amounts of Zn, which may be higher when it is stored in metal tanks. The acute toxicity arises from the ingestion of excessive amounts of zinc salts, either accidentally or as dietary supplement. Vomiting, nausea and stomach cramps usually occur after the consumption of more than 500 mg of zinc sulfate. In addition to that, the higher amounts of zinc affect gastrointestinal tract, liver, bone and prostate glands. Finally, Zn can interrupt the activity in soils, as it negatively influences the activity of microorganisms and earthworms, thus retarding the breakdown of organic matter. To combat this problem, techniques such as chemical precipitation, ion exchange, reverse osmosis, etc. are adopted, but these processes result in a huge amount of secondary sludge formation, inefficient removal of metals and are not cost effective. In recent times, an innovative, eco-friendly, cost-effective method has been introduced to treat the toxic heavy metals namely bioremediation. ―Bioremediation‖ is a process of removal of organic or inorganic contaminants by using bacteria, fungi, algae and its metabolites In this research work, the potential of four bacterial strains of the Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens and the extracellular proteins secreted by these four species for the bio-sorption of zinc has been investigated through batch experiments. The mechanisms of interaction between the zinc ion and the bacterial biomass as well as with the extracellular proteins have been elucidated. Additionally, a carbon paste electrode has been modified by using Pseudomonas sp. and its metabolites to develop biosensors for zinc and the lower limit of detection of zinc in aqueous solution has been determined. The major objectives of this research work are specified below: • To study the potential of Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens for the bio sorption of zinc, in batch systems. • To determine the speciation of zinc with respect to pH in the growth medium and the maximum inhibitory effect of zinc on the growth of the four chosen Pseudomonas sp. • To isolate and characterize the extracellular proteins from the four Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens. • To study the biosorption of zinc by extracellular proteins secreted by the Pseudomonas sp. • To elucidate the mechanisms involved in the biosorption of zinc at the microbe- metal interface and protein-metal ion interface for all the four systems by different characterization studies such as zeta potential, FTIR analysis and EDAX analysis. • To develop a biomass modified CPE using bacterial cells and extracellular protein to detect the concentration of zinc in aqueous solutions adopting voltammetric techniques. The significant results obtained from this research work are summarized as follows: The initial studies were concentrated on the bio sorption of zinc by using four Pseudomonas species such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens. The various factors affecting the bio sorption of zinc by these species were investigated by varying the contact time (10-80 min), pH (2-5±0.2), biomass concentration of the four species in the range of 108- 1011 cells / mL, and the initial zinc concentration from 5 mg/L to 80 mg/L respectively, keeping other parameters such as temperature and agitation speed constant in all the experiments. From the results obtained, the maximum percentage of biosorption achieved by the P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens was found to be 60%, 93%, 70% and 65% respectively for 25 mg/L at pH 5±0.2. The equilibrium time taken by the four species to achieve maximum biosorption was about 10 min and the biosorption kinetics adhered to pseudo-second order reaction and the rate constants were determined for different concentrations of zinc. The biosorption isotherm followed both the Langmuir and Freundlich isotherm models. The Gibbs free energy (ΔG) values determined from the Langmuir isotherm model for all the four systems were found to be -26, -32, -30 and -28 kJ /mole respectively. The Gibbs free energy values indicate that the biosorption of zinc ions onto the bacterial surface is a chemi-sorption process involving co-ordination, complexation or chelation. The characterization studies, namely zeta potential, FTIR analysis and SEM-EDX were also carried out on the bacterial cells before and after interaction with zinc. These studies also provide evidence in support of the complexation of zinc with the functional groups on the bacterial cell surface apart from electrostatic interaction. In the second part of the investigation, the inhibitory effect of zinc on the growth of four Pseudomonas sp. was investigated by varying the concentration of zinc from 50 mg/L to 1000 mg/L and the stability of zinc was analysed with respect to pH (2-12) with different concentrations from 50 - 1700 mg/L. It was found that in the absence of zinc the time taken to reach the exponential phase and the specific growth were almost the same for all the four systems. However, in the presence of zinc ions, the growth of the four Pseudomonas sp. was suppressed beyond 50mg/L of zinc. A control study on the stability of zinc in Luria broth medium showed that zinc was highly stable up to 200 mg/L from pH 2-8. However, the stability of zinc in the growth medium decreased beyond that concentration Additionally, studies on the biosorption of zinc were performed using extracellular proteins isolated from the four Pseudomonas sp. The amount of protein was estimated by the Bradford protein assay method at 594 nm. The biosorption experiments were carried out by varying the protein concentration from 50 to 1000µg/mL and the zinc concentration from 50-1000 mg/L and keeping other parameters fixed, namely such as pH at 5±0.2, reaction time of 20 min, temperature at 30±0.2 and the speed of rotation of 200 rpm. It was found that the maximum percentage of zinc biosorbed by the proteins isolated from P.putida was found to be 91% at 500µg/mL of protein concentration and from the other three species, it was found to be about 60% of biosorption at the same protein concentration. The biosorption isotherms of zinc for extracellular protein adhered to the Giles H1 type for all the four systems. The maximum amount of zinc biosorbed by the protein isolated from P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens was found to be 35.6, 19,18.3 and 10 mg/µg respectively and the Gibbs free energy values were found to be -32, -22,-22 and -23 kJ/mole. The mechanisms involved in protein-zinc interaction were elucidated using FTIR analysis and EDX analysis. The FTIR analysis revealed, that the zinc ions were complexed with carboxylic and amine functional groups. Further, the potential of P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens and their extracellular proteins of P.putida as biosensors for detecting zinc ions in aqueous solutions, using electrochemical methods such as, Cyclic Voltammetry and Differential pulse anodic stripping voltammetry, was assessed. The developed carbon paste electrode coated by the biomass showed an approximately 3-fold increase in the sensing of Zn2+ ion in comparison with the bare electrode. The lower limit of detection of the biosensor for zinc ions by Cyclic voltammetry was found to be 10-6 M, and in case of DPASV the lower limit of detection was about 10-7M. The lower limit of detection of the protein modified biosensor for zinc ions by cyclic voltammetry was found to be 10-7M and in the case of DPASV method the lower limit of detection was found to be 10-9 M.