Kinetics of styrene biodegradation by Pseudomonas sp. E-93486

The research into kinetics of styrene biodegradation by bacterial strain Pseudomonas sp. E-93486 coming from VTT Culture Collection (Finland) was presented in this work. Microbial growth tests in the presence of styrene as the sole carbon and energy source were performed both in batch and continuous cultures. Batch experiments were conducted for initial concentration of styrene in the liquid phase changed in the range of 5–90 gm−3. The Haldane model was found to be the best to fit the kinetic data, and the estimated constants of the equation were: μm= 0.1188 h−1, KS=5.984 mg l−1, and Ki=156.6 mg l−1. The yield coefficient mean value Yapp xs for the batch culture was 0.72 gdry cells weight(gsubstrate)−1. The experiments conducted in a chemostat at various dilution rates (D=0.035–0.1 h−1) made it possible to determine the value of the coefficient for maintenance metabolism md=0.0165 h−1 and the maximum yield coefficient value YM xs ¼ 0:913. Chemostatexperiments confirmed the high value of yield coefficient Yapp xs observed in the batch culture. The conducted experiments showed high activity of the examined strain in the styrene biodegradation process and a relatively low sensitivity to inhibition of its growth at higher concentrations of styrene in the solution. Such exceptional features of Pseudomonas sp. E-93486 make this bacterial strain the perfect candidate for technical applications

Influence of additional carbon sources on chlorophenols degradation by strain Pseudomonas sp

Szczep Pseudomonas sp. wykazywał zdolność do rozkładu wybranych chlorofenoli, jednak nie obserwowano wzrostu hodowli bakteryjnej w trakcie prowadzenia badań. W podjętych badaniach sprawdzono wpływ obecności dodatkowego źródła węgla na proces degradacji dichlorofenoli i pentachlorofenolu przez szczep Pseudomonas sp. Wykazano wzrost szybkości degradacji dichlorofenoli w obecności glukozy lub ekstraktu drożdżowego w porównaniu z hodowlami bez dodatkowego źródła węgla. Odmienne wyniki uzyskano w badaniach nad szybkością degradacji PCP w obecności dodatkowego źródła węgla. Dodanie ekstraktu drożdżowego nie zmieniło szybkości degradacji pentachlorofenolu w porównaniu z hodowlą bez dodatkowego źródła węgla. Obecność glukozy lub cytrynianu sodu do pożywki hamowało rozkład pentachlorofenolu. Abstrac

Changes in fatty acid composition of Stenotrophomonas maltophilia KB2 during co-metabolic degradation of monochlorophenols

The changes in the cellular fatty acid composition of Stenotrophomonas maltophilia KB2 during cometabolic degradation of monochlorophenols in the presence of phenol as well as its adaptive mechanisms to these compounds were studied. It was found that bacteria were capable of degrading 4-chlorophenol (4-CP) completely in the presence of phenol, while 2-chlorophenol (2-CP) and 3-chlorophenol (3-CP) they degraded partially. The analysis of the fatty acid profiles indicated that adaptive mechanisms of bacteria depended on earlier exposure to phenol, which isomer they degraded, and on incubation time. In bacteria unexposed to phenol the permeability and structure of their membranes could be modified through the increase of hydroxylated and cyclopropane fatty acids, and straight-chain and hydroxylated fatty acids under 2-CP, 3-CP and 4-CP exposure, respectively. In the exposed cells, regardless of the isomer they degraded, the most important changes were connected with the increase of the contribution of branched fatty acid on day 4 and the content of hydroxylated fatty acids on day 7. The changes, particularly in the proportion of branched fatty acids, could be a good indicator for assessing the progress of the degradation of monochlorophenols by S. maltophilia KB2. In comparison, in phenol-degrading cells the increase of cyclopropane and straight-chain fatty acid content was established. These findings indicated the degradative potential of the tested strain towards the co-metabolic degradation of persistent chlorophenols, and extended the current knowledge about the adaptive mechanisms of these bacteria to such chemicals

Enzymes involved in vinyl acetate decomposition by Pseudomonas fluorescens PCM 2123 strain

Esterases are widely used in food processing industry, but there is little information concerning enzymes involved in decompositions of esters contributing to pollution of environment. Vinyl acetate (an ester of vinyl alcohol and acetic acid) is a representative of volatile organic compounds (VOCs) in decomposition, of which hydrolyses and oxidoreductases are mainly involved. Their activities under periodically changing conditions of environment are essential for the removal of dangerous VOCs. Esterase and alcohol/aldehyde dehydrogenase activities were determined in crude cell extract from Pseudomonas fluorescens PMC 2123 after vinyl acetate induction. All examined enzymes exhibit their highest activity at 30–35 °C and pH 7.0–7.5. Esterase preferably hydrolyzed ester bonds with short fatty chains without plain differences for C2 or C4. Comparison of Km values for alcohol and aldehyde dehydrogenases for acetaldehyde suggested that this metabolite was preferentially oxidized than reduced. Activity of alcohol dehydrogenase reducing acetaldehyde to ethanol suggested that one mechanism of defense against the elevated concentration of toxic acetaldehyde could be its temporary reduction to ethanol. Esterase activity was inhibited by phenylmethanesulfonyl fluoride, while β-mercaptoethanol, dithiothreitol, and ethylenediaminetetraacetic acid had no inhibitor effect. From among metal ions, only Mg2+ and Fe2+ stimulated the cleavage of ester bond

Isolation and characterization of a novel strain of stenotrophomonas maltophilia possessing various dioxygenases for monocyclic hydrocarbon degradation

A Gram-negative bacterium, designated as strain KB2, was isolated from activated sludge and was found to utilize different aromatic substrates as sole carbon and energy source. On the basis of morphological and physiochemical characteristics and 16S rRNA gene sequence analysis, the isolated strain KB2 was identified as Stenotrophomonas maltophilia. Strain KB2 is from among different Stenotrophomonas maltophilia strains the first one described as exhibiting the activities of three types of dioxygenases depending on the structure of the inducer. The cells grown on benzoate and catechol showed mainly catechol 1,2- dioxygenase activity. The activity of 2,3-dioxygenase was detected after phenol induction. Protocatechuate 3,4-dioxygenase was found in crude cell extracts of this strain after incubation with 4-hydroxybenzoic acid, protocatechuic acid and vanillic acid. Because of broad spectrum of dioxygenases' types that Stenotrophomonas maltophilia KB2 can exhibit, this strain appears to be very powerful and useful tool in the biotreatment of wastewaters and in soil decontamination

Kinetics of vinyl acetate biodegradation by Pseudomonas fluorescens PCM 2123

The microbial degradation of vinyl acetate (VA) by Pseudomonas fluorescens PCM 2123 strain was studied in both batch and continuous modes. The purpose of the experiments was to determine the kinetic model of the cell growth and biodegradation rate of vinyl acetate (VA), which was the sole carbon and energy source for tested microorganisms. The experiments, carried out in a batch reactor for several initial concentrations of growth substrate in the liquid phase ranging from 18.6 to 373 gsubstrate·m–3 (gs·m–3) made it possible to choose the kinetic model and to estimate its constants. The Haldane inhibitory model with the values of constants: μm = 0.1202 h–1, KS = 17.195 gs·m–3, Ki = 166.88 gs·m–3 predicted the experimental data with the best accuracy. To set the parameters of maintenance metabolism it was necessary to carry out a series of continuous cultures at different dilution rates (0.05 to 0.072 h–1) and concentrations of VA in the liquid supplied to the chemostat ranging from 30.9 to 123.6 gs·m–3. The obtained data-base enabled to determine the coefficient for maintenance metabolism (me = 0.0251 gsubstrate·gcell dry weight –1·h–1 (gs·gcdw –1·h–1)) as well as the maximal and observed values of yield coefficients, Yxs M = 0.463 gcdw·gs –1 and (Yxs)obs = 0.411 gcdw·gs –1, respectively. The developed kinetics was verified by comparison of the computed and obtained in batch experiments profiles of changes in biomass and growth substrate concentrations

Effect of Nickel as Stress Factor on Phenol Biodegradation by Stenotrophomonas maltophilia KB2

This study focuses on the phenol biodegradation kinetics by Stenotrophomonas maltophilia KB2 in a nickel-contaminated medium. Initial tests proved that a nickel concentration of 33.3 mg L1 caused a cessation of bacterial growth. The experiments were conducted in a batch bioreactor in several series: without nickel, at constant nickel concentration and at varying metal concentrations (1.67–13.33 g m3). For a constant Ni2+ concentration (1.67 or 3.33 g m3), a comparable bacterial growth rate was obtained regardless of the initial phenol concentration (50–300 g m3). The dependence m = f (S0) at constant Ni2+ concentration was very well described by the Monod equations. The created varying nickel concentrations experimental database was used to estimate the parameters of selected mathematical models, and the analysis included different methods of determining metal inhibition constant KIM. Each model showed a very good fit with the experimental data (R2 values were higher than 0.9). The best agreement (R2 = 0.995) was achieved using a modified Andrews equation, which considers the metal influence and substrate inhibition. Therefore, kinetic equation parameters were estimated: mmax = 1.584 h1, KS = 185.367 g m3, KIS = 106.137 g m3, KIM = 1.249 g m3 and n = 1.0706

Molekularne podstawy rozkładu ksenobiotycznych związków aromatycznych

Aromatic compounds in the environment can be of natural or anthropological origins. Xenobiotic arenes are found to be weakly degraded because of the presence of stable aromatic ring (due to the delocalization of their orbitals) and different constituents which can impede biodegradation rate. That’s why the cleavage of aromatic ring by dioxygenases of bacterial origin is the critical step in removing of theses xenobiotics from environment. Also, monooxygenases play important role in biotransformation of the initial structure to one of the central intermediates: catechol, hydroquinone, protocatechuate or gentisate. In biodegradation of haloaromatics, dehalogenases are the essential enzymes in removing these xenobiotics

Impact of the Biological Cotreatment of the Kalina Pond Leachate on Laboratory Sequencing Batch Reactor Operation and Activated Sludge Quality

Hauling landfill leachate to o site urban wastewater treatment plants is a way to achieve pollutant removal. However, the implementation of biological methods for the treatment of landfill leachate can be extremely challenging. This study aims to investigate the e ect of blending wastewater with 3.5% and 5.5% of the industrial leachate from the Kalina pond (KPL) on the performance of sequencing batch reactor (SBR) and capacity of activated sludge microorganisms. The results showed that the removal e ciency of the chemical oxygen demand declined in the contaminated SBR from 100% to 69% and, subsequently, to 41% after the cotreatment with 3.5% and 5.5% of the pollutant. In parallel, the activities of the dehydrogenases and nonspecific esterases declined by 58% and 39%, and 79% and 81% after 32 days of the exposure of the SBR to 3.5% and 5.5% of the leachate, respectively. Furthermore, the presence of the KPL in the sewage a ected the sludge microorganisms through a reduction in their functional capacity as well as a decrease in the percentages of the marker fatty acids for di erent microbial groups. A multifactorial analysis of the parameters relevant for the wastewater treatment process confirmed unambiguously the negative impact of the leachate on the operation, activity, and structure of the activated sludge