Decoding microbial community intelligence through metagenomics for efficient wastewater treatment.

Activated sludge, a microbial ecosystem at industrial wastewater treatment plants, is an active collection of diverse gene pool that creates the intelligence required for coexistence at the cost of pollutants. This study has analyzed one such ecosystem from a site treating wastewater pooled from over 200 different industries. The metagenomics approach used could predict the degradative pathways of more than 30 dominating molecules commonly found in wastewater. Results were extended to design a bioremediation strategy using 4-methylphenol, 2-chlorobenzoate, and 4-chlorobenzoate as target compounds. Catabolic potential required to degrade four aromatic families, namely benzoate family, PAH family, phenol family, and PCB family, was mapped. Results demonstrated a network of diverse genera, where a few phylotypes were seen to contain diverse catabolic capacities and were seen to be present in multiple networks. The study highlights the importance of looking more closely at the microbial community of activated sludge to harness its latent potential. Conventionally treated as a black box, the activated biomass does not perform at its full potential. Metagenomics allows a clearer insight into the complex pathways operating at the site and the detailed documentation of genes allows the activated biomass to be used as a bioresource.

Liquid chromatography/isotope ratio mass spectrometry analysis of halogenated benzoates for characterization of the underlying degradation reaction in Thauera chlorobenzoica CB-1T.

RATIONALE: Halogenated benzoic acids occur in the environment due to their widespread agricultural and pharmaceutical use. Compound-specific stable isotope analysis (CSIA) has developed over the last decades for investigation of in situ transformation and reaction mechanisms of environmental pollutants amenable by gas chromatography (GC). As polar compounds are unsuitable for GC analysis we developed a method to perform liquid chromatography (LC)/CSIA for halogenated benzoates. METHODS: LC/isotope ratio mass spectrometry (IRMS) utilizing a LC-Surveyor pump coupled to a MAT 253 isotope ratio mass spectrometer via a LC-Isolink interface was applied. For chromatographic separation a YMC-Triart C18 column and a potassium hydrogen phosphate buffer (150 mM, pH 7.0, 40°C, 200 µL mL-1 ) were used, followed by wet oxidation deploying 1.5 mol L-1 ortho-phosphoric acid and 200 g L-1 sodium peroxodisulfate at 75 µL mL-1 . RESULTS: Separation of benzoate and halogenated benzoates could be achieved in less than 40 min over a concentration range of 2 orders of magnitude. Under these conditions the dehalogenation reaction of Thauera chlorobenzoica 3CB-1T using 3-chloro-, 3-bromo- and 4-chlorobenzoic acid was investigated resulting in inverse carbon isotope fractionation for meta-substituted benzoic acids and minor normal fractionation for para-substituted benzoic acids. Together with the respective growth rates this led to the assumption that dehalogenation of para-halobenzoic acids follows a different mechanism from that of meta-halobenzoic acids. CONCLUSIONS: A new LC/IRMS method for the quantitative determination of halogenated benzoates was developed and used to investigate the in vivo transformation pathways of these compounds, providing some insights into degradation and removal of these widespread compounds by T. chlorobenzoica 3CB-1T .

Conversion of benzoic acid into phenol in an ITMS under CI-MSn conditions. Recognition of ortho-chlorobenzoyl derivatives.

Isomeric chlorobenzoyl cations (m/z 139), under collision-induced experiments, fragment identically. Chlorobenzoyl cations can be efficiently converted into cholorophenol radical cations by the reaction with methanol in the ion trap analyzer under CI-MSn conditions. The substitution of the carbonyl group with a hydroxyl moiety is able to induce an ortho effect, which is absent in the startingortho-chlorobenzoyl cation. This transformation could be useful to recognize ortho-chlorinated benzoyl derivatives without the need of MS spectrum comparison of the whole set of isomers. The method reported in this study could be applicable to biologically active molecules that dissociate to form the chlorobenzoyl cations under CI or CI collision-induced dissociation conditions, such as indomethacin, the degradation products from the insect growth regulator 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea, and lorazepam.

Quantitative analysis of anti-inflammatory drugs using FTIR-ATR spectrometry.

Four simple, accurate, sensitive and economic Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopic (ATR-FTIR) methods have been developed for the quantitative estimation of some non-steroidal anti-inflammatory drugs. The first method involves the determination of Etodolac by direct measurement of the absorbance at 1716cm-1. In the second method, the second derivative of the IR spectra of Tolfenamic acid and its reported degradation product (2-chlorobenzoic acid) was used and the amplitudes were measured at 1084.27cm-1 and 1056.02cm-1 for Tolfenamic acid and 2-chlorobenzoic acid, respectively. The third method used the first derivative of the IR spectra of Bumadizone and its reported degradation product, N,N-diphenylhydrazine and the amplitudes were measured at 2874.98cm-1 and 2160.32cm-1 for Bumadizone and N,N-diphenylhydrazine, respectively. The fourth method depends on measuring the amplitude of Diacerein at 1059.18cm-1 and of rhein, its reported degradation product, at 1079.32cm-1 in their first derivative spectra. The four methods were successfully applied on the pharmaceutical formulations by extracting the active constituent in chloroform and the extract was directly measured in liquid phase mode using a specific cell. Moreover, validation of these methods was carried out following International Conference of Harmonisation (ICH) guidelines.

Efficient transformation of DDT by peroxymonosulfate activated with cobalt in aqueous systems: Kinetics, products, and reactive species identification.

Recently, sulfate radical ( [Formula: see text] ) based-advanced oxidation technologies (AOTs) have been attracted great attention in the remediation of contaminated soil and groundwater. In the present study, Co(2+) ions activated peroxymonosulfate (PMS) system was used to degrade 1, 1, 1-trichloro-2, 2'bis(p-chlorophenyl) ethane (DDT) in aqueous solutions. It was found that DDT was efficiently degraded in the PMS/Co(II) solutions within several hours, and the degradation efficiency of DDT was dependent on the concentrations of PMS and Co(II), and the optimum molar ratio of PMS and Co(II) was 50:1. The degradation kinetics of DDT were well described with pseudo-first-order equations over a range of temperature (10-40 °C), and the activation energy that was calculated with Arrhenius equation was 72.3 ± 2.6 kJ/mol. Electron paramagnetic resonance (EPR) and GC-MS techniques were applied to identify the intermediates and reactive species for DDT degradation. The results indicated that [Formula: see text] and OH were the main reactive species accounting for DDT degradation. Dichlorobenzophenone, 4-chlorobenzoic acid and benzylalcohol were the dominant intermediates for DDT degradation, and the likely degradation pathway of DDT was proposed on the basis of these identified products. Increasing pH inhibited the formation of [Formula: see text] and OH, and thus decreased the catalytic degradation of DDT. Cl(-) ion was found to significantly inhibit, while [Formula: see text] and dissolved oxygen had limited effects on DDT degradation.

Novel Chryseobacterium sp. PYR2 degrades various organochlorine pesticides (OCPs) and achieves enhancing removal and complete degradation of DDT in highly contaminated soil.

Long term residues of organochlorine pesticides (OCPs) in soils are of great concerning because they seriously threaten food security and human health. This article focuses on isolation of OCP-degrading strains and their performance in bioremediation of contaminated soil under ex situ conditions. A bacterium, Chryseobacterium sp. PYR2, capable of degrading various OCPs and utilizing them as a sole carbon and energy source for growth, was isolated from OCP-contaminated soil. In culture experiments, PYR2 degraded 80-98% of hexachlorocyclohexane (HCH) or 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) isomers (50 mg L(-1)) in 30 days. A pilot-scale ex situ bioremediation study of highly OCP-contaminated soil augmented with PYR2 was performed. During the 45-day experimental period, DDT concentration was reduced by 80.3% in PYR2-augmented soils (35.37 mg kg(-1) to 6.97 mg kg(-1)) but by only 57.6% in control soils. Seven DDT degradation intermediates (metabolites) were detected and identified in PYR2-augmented soils: five by GC/MS: 1,1-dichloro-2,2-bis (4-chlorophenyl) ethane (DDD), 1,1-dichloro-2,2-bis (4-chlorophenyl) ethylene (DDE), 1-chloro-2,2-bis (4-chlorophenyl) ethylene (DDMU), 1-chloro-2,2-bis (4-chlorophenyl) ethane (DDMS), and dichlorobenzophenone (DBP); and two by LC/MS: 4-chlorobenzoic acid (PCBA) and 4-chlorophenylacetic acid (PCPA). Levels of metabolites were fairly stable in control soils but varied greatly with time in PYR2-augmented soils. Levels of DDD, DDMU, and DDE in PYR2-augmented soils increased from day 0 to day 30 and then decreased by day 45. A DDT biodegradation pathway is proposed based on our identification of DDT metabolites in PYR2-augmented systems. PYR2 will be useful in future studies of OCP biodegradation and in bioremediation of OCP-contaminated soils.

Hydroxyl radical formation during ozonation of multiwalled carbon nanotubes: performance optimization and demonstration of a reactive CNT filter.

We explored factors influencing hydroxyl radical (•OH) formation during ozonation of multiwalled carbon nanotubes (MWCNTs) and assessed this system's viability as a next-generation advanced oxidation process (AOP). Using standard reactivity metrics for ozone-based AOPs (RCT values), MWCNTs promoted •OH formation during ozonation to levels exceeding ozone (both alone and with activated carbon) and equivalent to ozone with hydrogen peroxide. MWCNTs oxidized with nitric acid exhibited vastly greater rates of ozone consumption and •OH formation relative to as-received MWCNTs. While some of this enhancement reflects their greater suspension stability, a strong correlation between RCT values and surface oxygen concentrations from X-ray photoelectron spectroscopy suggests that surface sites generated during MWCNT oxidation promote •OH exposure. Removal of several ozone-recalcitrant species [para-chlorobenzoic acid (p-CBA), atrazine, DEET, and ibuprofen] was not significantly inhibited in the presence of radical scavengers (humic acid, carbonate), in complex aquatic matrices (Iowa River water) and after 12 h of continuous exposure of MWCNTs to concentrated ozone solutions. As a proof-of-concept, oxidized MWCNTs deposited on a ceramic membrane chemically oxidized p-CBA in a flow through system, with removal increasing with influent ozone concentration and mass of deposited MWCNTs (in mg/cm2). This hybrid membrane platform, which integrates adsorption, oxidation, and filtration via an immobilized MWCNT layer, may serve as the basis for future novel nanomaterial-enabled technologies, although long-term performance trials under representative treatment scenarios remain necessary.

High lateral resolution vs molecular preservation in near-IR fs-laser desorption postionization mass spectrometry.

Ultrashort pulse length lasers operating in the near-infrared region show promise for submicrometer lateral resolution by laser desorption-based mass spectrometry (MS) imaging. However, these experiments must balance lateral resolution and molecular fragmentation since abundant atomic ions are observed at the high laser irradiances that can be generated by tightly focused ultrashort pulse laser beams. It is shown here that combining ultrashort pulse laser desorption with laser postionization (fs-LDPI) allows for a considerable increase of molecular ion signal while operating with lower laser irradiances, yielding the added benefit of reduced molecular fragmentation. This Letter presents several experimental results in support of the fs-LDPI approach for MS imaging. First, the lateral resolution for MS imaging of molecular species desorbed by ∼75 fs, 800 nm laser pulses was determined to be <2 µm for a simulated organic electronic device under vacuum. Next, the dependence of precursor ion survival on both desorption laser fluence and delay between desorption and photoionization laser pulses was observed for a small molecule desorbed from an organic multilayer that was originally devised as a model of a bacterial biofilm. When considered in light of recent results in the literature (Milasinovic et al. J. Phys. Chem. C 2014, DOI: 10.1021/jp504062u), these experiments demonstrate the potential for submicrometer spatial resolution MS imaging by fs-LDPI.

Influence of organic carbon and metal oxide phases on sorption of 2,4,6-trichlorobenzoic acid under oxic and anoxic conditions.

Chlorobenzoic acids represent crucial recalcitrant metabolites in the environment; thus, the influence of soil components on the sorption of 2,4,6-trichlorobenzoic acid (TCB) under oxic and anoxic conditions was studied. The surficial physiognomies of untreated and isolated soil samples were studied using FTIR, XRD, specific surface area, and PZC determination. The roles of redox potential, dissolved organic carbon (DOC), and pH, particularly under anoxic condition, were appraised. Batch equilibrium adsorption studies on soils of variable Fe/Mn oxides and organic carbon showed that adsorption was low across all components (log Koc = 0.82-3.10 Lg(-1)). The sorption of 2,4,6-TCB was well described by the pseudo second-order kinetic model. The fluctuation of both redox potential and pH during anoxic experiment had a negative impact on the sorption, partitioning, and the oxidation of organic matter. Linear relationships were observed for Kd with both soil total organic carbon (TOC) and surface area (SA). The results showed the existence of DOC-mediated sorption of 2,4,6-TCB which seems to be enhanced at lower pH. The reductive dissolution, particularly of iron compounds, possibly impeded sorption of 2,4,6-TCB under anoxic condition. It could be inferred that habitats dominated by fluctuating oxygen concentrations are best suited for the development of environmental conditions capable of mineralizing 2,4,6-TCB and similar xenobiotics.

Validated chromatographic methods for simultaneous determination of tolfenamic acid and its major impurities.

Two accurate, selective and precise chromatographic methods, namely thin-layer chromatography (TLC)-densitometric method and reversed phase high-performance liquid chromatography (RP-HPLC) method, were developed and validated for the simultaneous determination of tolfenamic acid (TOL) and its two major impurities, 2-chlorobenzoic acid (CBA) and 3-chloro-2-methylaniline (CMA), which are also reported to be its related substances. The developed TLC-densitometric method depended on separation and quantitation of the studied drugs on silica gel 60F254 TLC plates. Hexane:chloroform:acetone:acetic acid (75:25:20:0.1, v/v/v/v) was used as a developing system and the separated bands were UV-scanned at 240 nm. Linear relationships were obtained in the range of 10-100 µg band(-1) for the drug and in the range of 0.1-1 µg band(-1) for the studied impurities. The developed RP-HPLC depended on chromatographic separation of the studied drugs on a C18 column using 0.05 M KH2PO4 buffer (pH 3):acetonitrile (45:55, v/v) as a mobile phase delivered at constant flow rate of 1 mL min(-1) with UV detection at 230 nm. Calibration curves for TOL and the two impurities were constructed over the concentration ranges of 10-100 µg mL(-1) for TOL and 0.01-0.1 µg mL(-1) for both CBA and CMA. Factors affecting the developed methods have been studied and optimized. Further, methods validation has been carried out according to International Conference on Harmonization guidelines. The proposed methods were successfully applied for determination of the studied drug in its bulk powder and in pharmaceutical formulation. The methods showed no significant difference when compared with the reported RP-HPLC one. The developed methods have advantages of being more sensitive and specific than the published methods.

Probing the functional diversity of global pristine soil communities with 3-chlorobenzoate reveals that communities of generalists dominate catabolic transformation.

Understanding of functional diversity of microbial populations has lagged description of their molecular diversity. Differences in substrate specificity, kinetics, products, and regulation can dramatically influence phenotypic variation among closely related strains, features that are missed when the strains studied are the fastest-growing and most easily isolated from serial enrichments. To investigate the broader bacterial diversity underlying degradation of anthropogenic chemicals in nature, we studied the 3-chlorobenzoate (3-CBA) degradation rate in a collection of aerobic 3-CBA degraders previously isolated from undisturbed soils in two representative ecosystems: (i) Mediterranean sclerophyllous woodlands in California, Chile, South Africa, and Australia and (ii) boreal forests in Canada and Russia. The majority of isolates degraded 3-CBA slowly and did not completely mineralize 1.0 mM 3-CBA within 1 week. Those with intermediate degradation rates had incomplete degradation pathways and produced colored intermediates indicative of chlorocatechol, a product likely metabolized by other members of the community. About 10% of the isolates grew rapidly and mineralized greater than 90% of the 3-CBA, but because of population heterogeneity in soil, they are likely not large contributors to a soil's total transformation capacity. This suggests that xenobiotic degradation in nature is carried out by a community of cometabolic generalists and not by the efficient specialists that have been traditionally studied in the laboratory. A subset of 58 genotypically distinct strains able to degrade >80% of the 3-CBA was examined for their catabolic versatility using 45 different compounds: mono- and dichlorinated benzoates, phenols, anilines, toluenes, nitrobenzenes, chlorobenzenes, and 2,4-dichlorophenoxyacetic acid. The isolates degraded from 2 to more than 30 compounds with a median of 7, but there was no correlation to habitat of isolation or 3-CBA activity. However, these findings were indicative of finer-scale functional diversity.

Chlorobenzoic acid degradation by Lentinus (Panus) tigrinus: in vivo and in vitro mechanistic study-evidence for P-450 involvement in the transformation.

Aim of this work was to investigate the ability of Lentinus (Panus) tigrinus to degrade and detoxify a chlorobenzoate (CBA) mixture composed of mono-, di- and tri-chlorinated isomers. The degradation process was investigated as a function of both the growing medium (i.e. low N Kirk's and malt extract-glucose medium) and cultivation conditions (i.e. stationary and shaken cultures). The majority of CBAs were quantitatively degraded within the early 15 d from spiking with the notable exception of the double ortho-chlorinated compounds, 2,6-di-, 2,3,6-tri- and 2,4,6-tri-CBA. Analysis of the degradation intermediates indicated the occurrence of side chain reduction, hydroxylation and methylation reactions. Although CBAs stimulated laccase production, in vitro experiments with a purified L. tigrinus laccase isoenzyme demonstrated its inability to participate in the initial attack on CBAs even in the presence of redox mediators; similar results were found with a Mn-peroxidase isoenzyme. Conversely, prompt degradation was observed upon 1h incubation of CBAs with a purified microsomal fraction containing cytochrome P-450 monooxygenase. The nature of some reaction products (i.e. hydroxylated derivatives), the dependency of the reaction on NADPH and its susceptibility to either CO or piperonyl butoxide inhibition confirmed the involvement of L. tigrinus cytochrome P-450 in the early steps of CBA degradation.

A validated LC method for determination of 2,3-dichlorobenzoic acid and its associated regio isomers.

A simple, selective and sensitive gradient reversed-phase liquid chromatography method has been developed for the separation and determination of 2,3-dichlorobenzoic acid, which is an intermediate of the lamotrizine drug substance, and its regio isomers. The separation was achieved on a reversed-phase United States Pharmacopeia L1 (C-18) column using 0.01 M ammonium acetate buffer at pH 2.5 and methanol (50:50 v/v) mixture as mobile phase A and a methanol and water mixture (80:20 v/v) as mobile phase B in a gradient elution at flow rate 1.2 mL/min with ultraviolet detection at 210 nm. The method is found to be selective, precise, linear, accurate and robust. It was used for quality assurance and monitoring the synthetic reactions involved in the process development of lamotrizine. The method is found to be simple, rapid, specific and reliable for the determination of unreacted levels of raw materials and isomers in reaction mixtures and finished product lamotrizine. The method was fully validated as per International Conference of Harmonization guidelines and results from validation confirm that the method is highly suitable for its intended purpose.

Biodegradation of chlorobenzoic acids by ligninolytic fungi.

We investigated the abilities of several perspective ligninolytic fungal strains to degrade 12 mono-, di- and trichloro representatives of chlorobenzoic acids (CBAs) under model liquid conditions and in contaminated soil. Attention was also paid to toxicity changes during the degradation, estimated using two luminescent assay variations with Vibrio fischeri. The results show that almost all the fungi were able to efficiently degrade CBAs in liquid media, where Irpex lacteus, Pycnoporus cinnabarinus and Dichomitus squalens appeared to be the most effective in the main factors: degradation and toxicity removal. Analysis of the degradation products revealed that methoxy and hydroxy derivatives were produced together with reduced forms of the original acids. The findings suggest that probably more than one mechanism is involved in the process. Generally, the tested fungal strains were able to degrade CBAs in soil in the 85-99% range within 60 days. Analysis of ergosterol showed that active colonization is an important factor for degradation of CBAs by fungi. The most efficient strains in terms of degradation were I. lacteus, Pleurotus ostreatus, Bjerkandera adusta in soil, which were also able to actively colonize the soil. However, in contrast to P. ostreatus and I. lacteus, B. adusta was not able to significantly reduce the measured toxicity.

Induced nanoelectrospray ionization for matrix-tolerant and high-throughput mass spectrometry.

No-contact rule: the title method is ultra-sensitive, high-throughput (4 samples per second), easily multiplexed, and is compatible with serum, urine, and concentrated salt solutions. Other features of this method, which avoids physical contact between the electrode and the solvent, include sample economy and the ability to produce both positive and negative-ion spectra in one cycle.

Determination of 15 isomers of chlorobenzoic acid in soil samples using accelerated sample extraction followed by liquid chromatography.

A study was conducted to elaborate a fast, simple and efficient method for determination of 15 isomers chlorobenzoic acids (CBAs) in soil using HPLC-UV. Artificially contaminated soil samples were extracted using accelerated solvent extraction (ASE) with 1% acetic acid in a mixture of hexane and acetone (1:1, V/V) under a pressure of 10.34 MPa and temperature of 150°C. The recovery of the ASE method was above 82%. The extracts were concentrated; dimethyl sulfoxide was used to prevent CBA volatilization and the final analysis was performed with a C18 XBridge HPLC column employing a mobile phase consisting of acetonitrile and 0.1% trifluoracetic acid in water. A HPLC procedure with gradient elution and UV detection was developed and validated. The method exhibited a linear range for 2-CBA; 2,6-CBA; 3-CBA; 4-CBA; 2,3-CBA; 2,3,6-CBA; 2,5-CBA; and 2,4-CBA from 5 to 120 µg/mL with a limit of quantification (LOQ) of 5 µg/mL, RSD from 2.42 to 9.42% and accuracy from 82 ± 2 to 103 ± 3%. The linear range of determination of 2,4,6-CBA, 3,4-CBA, 2,3,5,6-CBA, 3,5-CBA, 2,3,5-CBA, 2,3,4,5,6-CBA and 2,3,4,5-CBA was 10-120 µg/mL with LOQ 10 µg/mL, RSD from 0.74 to 5.84% and accuracy from 94 ± 1 to 114 ± 1%. The optimized analytical procedure was finally applied on two historically PCB contaminated soils and 9 CBAs were quantified in the samples.

Removal of 4-chlorobenzoic acid from spiked hydroponic solution by willow trees (Salix viminalis).

BACKGROUND: Chlorobenzoic acids (CBA) are intermediate products of the aerobic microbial degradation of PCB and several pesticides. This study explores the feasibility of using basket willows, Salix viminalis, to remove 4-CBA from polluted sites, which also might stimulate PCB degradation. METHODS: The removal of 4-CBA by willow trees was investigated with intact, septic willow trees growing in hydroponic solution and with sterile cell suspensions at concentrations of 5 mg/L and 50 mg/L 4-CBA. Nutrient solutions with different levels of ammonium and nitrate were prepared to achieve different pH levels. The concentration of 4-CBA was tracked over time and quantified by HPLC. RESULTS AND DISCUSSION: At the low level of 4-CBA (5 mg/L), willows removed 70% (pH 4.2) to 90% (pH 6.8), while 48% (pH 4.2) to 52% (pH 6.8) of the water was transpired. At the high 4-CBA level (50 mg/L), the pH varied between 4.4 and 4.6, and 10% to 30% of 4-CBA was removed, but only 5% to 9% of the water. In sterile cell suspensions, removal of 4-CBA by fresh biomass was much higher than removal by dead biomass. CONCLUSIONS: The results indicate that 4-CBA is toxic to willow trees at 50 mg/L. The removal of 4-CBA from solution is by both passive processes (uptake with water, sorption to plant tissue) and metabolic processes of the plants. RECOMMENDATIONS AND OUTLOOK: Plants, such as willow trees, might assist in the degradation of PCB and their degradation products CBA.

Genetically modified Pseudomonas biosensing biodegraders to detect PCB and chlorobenzoate bioavailability and biodegradation in contaminated soils.

Whole cell microbial biosensors offer excellent possibilities for assaying the complex nature of the bioavailable and bioaccessible fraction of pollutants in contaminated soils, which currently cannot be easily addressed. This paper describes the application and evaluation of three microbial biosensor strains designed to detect the bioavailability and biodegradation of PCBs (and end-products) in contaminated soils and sediments. Polychlorinated biphenyls (PCBs) are considered to be one of the most wide spread, hazardous and persistent pollutants. Herein we describe that there was a positive correlation between the PCB levels within the samples and the percentage of biosensor cells that were expressing their reporter gene; gfp. Immobilisation of the biosensors in calcium alginate beads allowed easy and accurate detection of the biosensor strains in contaminated soil and sludge samples. The biosensors also showed that PCB degradation activity was occurring at a much greater level in Pea inoculated planted soil compared to inoculated unplanted soil indicating rhizoremediation (the removal of pollutants by plant root associated microbes) shows considerable promise as a solution for removing organic xenobiotics from the environment.

Spectroscopic (FT-IR, FT-Raman, UV) and microbiological studies of di-substituted benzoates of alkali metals.

The FT-IR, FT-Raman and UV spectra of 3,5-dihydroxybenzoic and 3,5-dichlorobenzoic acids as well as lithium, sodium, potassium, rubidium, caesium 3,5-dihydroxy- and 3,5-dichlorobenzoates were recorded, assigned and compared. The theoretical geometries, Mulliken atomic charges, IR wavenumbers were obtained in B3LYP/6-311++G** level. On the basis of the gathered experimental and theoretical data the effect of metals and substituents on the electronic system of studied compounds were investigated. Moreover, the antimicrobiological activity of studied compounds against two species of bacteria: Bacillus subtilis, Staphylococus aureus and one species of yeast: Candida albicans were studied after 24 and 48 h of incubation. The attempt was made, to find out whether there is any correlation between the first principal component and the degree of growth inhibition exhibited by studied compounds in relation to selected microorganisms.

Analysis of p-chlorobenzoic acid in water by liquid chromatography-tandem mass spectrometry.

para-Chlorobenzoic acid (p-CBA) is typically used as a probe compound to indirectly quantify hydroxyl radicals formed during advanced oxidation processes used in drinking water and wastewater treatment. A method has been developed for the sensitive analysis of p-CBA in water using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A reporting limit in water of 100 ng/L was determined for the method, which is 40-fold lower than the 4.0 microg/L reporting limit of the widely used liquid chromatography with UV detection (LC-UV) method. The method was found to be robust in difficult matrices such as wastewater and highly selective, unlike LC-UV which relies on non-specific detection at 234 nm. The detection of p-CBA below 1 microg/L during bench-scale ozonation of wastewater after hydrogen peroxide addition was demonstrated. Duplicate samples were analyzed by LC-MS/MS and LC-UV and results were found to be comparable at concentrations quantifiable by both methods.