Aerobic Degradation

Efecto de la inmovilización celular sobre el tratamiento del alpechín con una bacteria que degrada polifenoles y los ácidos acéticos y fórmico. El alpechín (OMW) es un residuo puro de la extracción del aceite de oliva, que contiene una elevada carga orgánica y de polifenoles por lo que es resistente a la degradación. Su descarga produce graves problemas de contaminación medioambiental en toda el área mediterránea. Se ha aislado una bacteria anaerobia del OMW, que , durante tres ciclos consecutivos de tratamiento del OMW diluido y suplementado, produjo una disminución significativa de las sustancias fitotóxicas del residuo. De hecho, la concentración en fenoles totales, ácido acético y ácido fórmico se redujeron entre 33 y 64% cuando las células no estaban inmovilizadas y entre el 62 y 78% cuando las células bacterianas se inmovilizaron en una esponja de poliuretano. Estos resultados indican que el cultiva de la nueva bacteria aislada puede disminuir la fototoxicidad el alpechín. Análisis filogenético del ribosoma 16S de DNA demostró que todas las secuencias eran miembros de la familia Enterobacteriaceae y que la bacteria aislada podía identi- ficarse como una cepa de Klebsiella oxytoca. PALABRAS-CLAVE: Alpechín -Degradación anaeróbica -Fenoles totales -Inmovilización -Klebsiella oxytoca. Olive mill wastewater (OMW) is a pure vegetative by-product, containing a high organic and polyphenol content and is resistant to biodegradation. Its disposal lead to major environmental pollution problems in the Mediterranean basin. An aerobic bacterium was isolated from OMW. During three consecutive diluted and supplemented OMW treatment cycles, significant abatement of its phytotoxic substances was observed. In fact, total phenols, acetic and formic acids were reduced between 33 and 64% when cells of the isolated bacterium were grown free; and between 62 and 78% when cells of the same isolated bacterium were grown immobilized in a polyurethane sponge. These results suggest that the bacterium culture of the new isolate would decrease the OMW phytotoxicity. Phylogenetic analysis of 16S ribosomal DNA showed that all the related sequences are members of the Enterobacteriaceae family and revealed that the isolated bacterium was characterized as a Klebsiella oxytoca strain

The segment from positions 280 to 283 in BphAEs is located at the entrance of the catalytic pocket, and it shows variation in conformation. In previous works, results have suggested but never proved that residue Ser283 of BphAE LB400 might play a role in substrate specificity. In the present paper, we found that the Ser283Met substitution significantly increased the specificity of the reaction of BphAE toward biphenyl, 2,3′,4,4′-CB, 2,2′,6,6′-CB, and 2,3′,4,4′,5-CB. Meanwhile, the Ser283Met substitution altered the regiospecificity of BphAE toward 2,2′-dichlorobiphenyl and 2,6-dichlorobiphenyl. Additionally, this substitution extended the range of PCBs metabolized by the mutated BphAE. BphAE S283M and BphAE p4-S283M were clearly improved in oxidizing some of the more highly chlorinated biphenyls (3 to 6 chlorines), which are generally very poorly oxidized by most dioxygenases. We used modeled and docked enzymes to identify some of the structural features that explain the new propert...

 Composting, digestion and CH 4 oxidation rates were measured in the top 1.6m of two soil capped landfill profiles.  Anaerobic and aerobic activity observed simultaneously in a lift of waste for 18 months after placement of interim cover.  Composting accounts for 30% of waste degradation for an extended period.  Carbon mass balance is improved with stable isotopes (δ 13 C-CO 2 , δ 13 C-CH 4).

The segment from positions 280 to 283 in BphAEs is located at the entrance of the catalytic pocket, and it shows variation in conformation. In previous works, results have suggested but never proved that residue Ser283 of BphAE LB400 might play a role in substrate specificity. In the present paper, we found that the Ser283Met substitution significantly increased the specificity of the reaction of BphAE toward biphenyl, 2,3′,4,4′-CB, 2,2′,6,6′-CB, and 2,3′,4,4′,5-CB. Meanwhile, the Ser283Met substitution altered the regiospecificity of BphAE toward 2,2′-dichlorobiphenyl and 2,6-dichlorobiphenyl. Additionally, this substitution extended the range of PCBs metabolized by the mutated BphAE. BphAE S283M and BphAE p4-S283M were clearly improved in oxidizing some of the more highly chlorinated biphenyls (3 to 6 chlorines), which are generally very poorly oxidized by most dioxygenases. We used modeled and docked enzymes to identify some of the structural features that explain the new propert...

The organochlorine insecticide c-hexachlorocyclohexane (c-HCH, lindane) and its non-insecticidal aand b-isomers continue to pose serious environmental and health concerns, although their use has been restricted or completely banned for decades. In this study we report the first evidence of the growth ability of a Streptomyces strain in a mineral salt medium containing high doses of aand b-HCH (16.6 mg l-1) as a carbon source. Degradation of HCH isomers by Streptomyces sp. M7 was investigated after 1, 4, and 7 days of incubation, determining chloride ion release, and residues in the supernatants by GC with lECD detection. The results show that both the aand b-HCH isomers were effectively metabolized by Streptomyces sp. M7, with 80 and 78 % degradation respectively, after 7 days of incubation. Moreover, pentachlorocyclohexenes and tetrachlorocyclohexenes were detected as metabolites. In addition, the formation of possible persistent compounds such as chlorobenzenes and chlorophenols were studied by GC-MS, while no phenolic compounds were detected. In conclusion, we have demonstrated for the first time that Streptomyces sp. M7 can degrade aand b-isomers individually or combined with c-HCH and could be considered as a potential agent for bioremediation of environments contaminated by organochlorine isomers.

Twin mathematical models were developed for substrate reduction and biomass increase respectively. The analytical solution of the twin models gave a sigmoidal substrate decline curve and a sigmoidal biomass increase curve respectively. The developed models aided the monitoring and prediction of crude oil sludge degradation in soil by the activities of stimulated biomass. The solution of the twin models when subjected to turning points was useful in determining the biomass daily rate and the biomass peak time.

The slurry bioreactor system is an effective means for treating highly saline food wastes, which may not be recycled as composts. The effect of aeration rate was investigated in a slurry bioreactor as a major factor affecting the slurryphase decomposition of food wastes. The aeration rate affected significantly the decomposition performance and the composition profiles of the liquid and solid phases. The decomposed carbon was almost linear with oxygen consumption, indicating that the slurry-phase decomposition of food wastes was limited by oxygen transfer. The oxygen requirement for decomposing 1 g organic carbon in food wastes was estimated to be 61.5 g O 2 .

An observation term was carried on in an MBT plant owned and run by a public Company to treat MSW left by separate collection. All observations and measurements were made without interfering with the ordinary operation rules, in order to assess the efficiency of one process cycle for a given batch of waste. Analytical data came from both a) process instruments and b) physical analysis of a batch of waste entering / exiting from a selected bio-cell. From the process mass losses (about 37% – including moisture evaporation – in that single process cycle) the theoretical amounts of water and carbon dioxide produced by biodegradation were calculated. A verification of the results was tried through a thermal balance, comparing the energy released by degradation with the energy losses from the bio-cell. The results showed a fair agreement, within 80%; what appeared critical is the knowledge of the chemical composition of fermentable waste (taken as cellulose as first attempt) and the actua...

The segment from positions 280 to 283 in BphAEs is located at the entrance of the catalytic pocket, and it shows variation in conformation. In previous works, results have suggested but never proved that residue Ser283 of BphAE LB400 might play a role in substrate specificity. In the present paper, we found that the Ser283Met substitution significantly increased the specificity of the reaction of BphAE toward biphenyl, 2,3′,4,4′-CB, 2,2′,6,6′-CB, and 2,3′,4,4′,5-CB. Meanwhile, the Ser283Met substitution altered the regiospecificity of BphAE toward 2,2′-dichlorobiphenyl and 2,6-dichlorobiphenyl. Additionally, this substitution extended the range of PCBs metabolized by the mutated BphAE. BphAE S283M and BphAE p4-S283M were clearly improved in oxidizing some of the more highly chlorinated biphenyls (3 to 6 chlorines), which are generally very poorly oxidized by most dioxygenases. We used modeled and docked enzymes to identify some of the structural features that explain the new propert...

The molecular and kinetic characterization of a microorganism able to aerobically degrade 4-nitrophenol (4NP) is presented. The microorganism was isolated from a mixed culture operating in a laboratory-scale sequencing batch reactor with an aerobic anoxic cycle. It was identified as a member of Ralstonia genus within Betaproteobacteria. It is a gram negative coccobacillum (cell length of 2-3 lm) able to aerobically store lipid inclusions when grown aerobically on nitrophenol as the sole carbon source in the range of tested concentrations (80-320 mg l À1). Batch kinetic tests were performed with the pure culture, while the kinetics of the mixed biomass was directly investigated in the reactor. For pure cultures exponential growth was observed, with growth rate values in the range of 2-6 d À1 ; in experiments with the mixed cultures 4NP concentrations were correlated with growth using the Haldane equation (k max = 0.30 mg 4NP mg À1 VSS h À1 ; K s = 55 mg 4NP l À1 and K I = 15 mg 4NP l À1). Observed pure culture growth rates were higher than those of mixed cultures. This result can be explained by considering that in mixed culture the biomass is evaluated as volatile suspended solids, including both specialized biomass for 4NP removal and denitrifying bacteria.

This work was undertaken to investígate the effect of variations of the feed rate on a fed-batch setup used to degrade xenobiotics. The mixture of substrates was composed of PCP, 2,4,6 TCP and 2,3,5,6 TeCP (pentachlorophenol, 2,4,6 trichlorophenol and 2,3,5,6 tetrachlorophenol respectively). Two acclimated bacteria isolated from soil were used: Pseudomonas aeruginosa and Achromobacter sp. nov. The different flow rates tested were: I: 0.5 mf-min'1, II: 1.67 mf-min'1 and III: 2.00 mf-min'1. Our results show that during fed-batch operation the 2,4,6 TCP exhibits an earlier degradation than the other compounds, for all of the flow rates tested. This indicates that in this case the degradation of the most recalcitrant compounds (PCP and 2,3,5,6 TeCP) is benefited by the increase in biomass ofbacteria, due to the metabolisation of a less recalcitrant compound (2,4,6 TCP). The defined parameter, specific degradation rate (SDR), was demonstrated to be very useful for comparing the degradation abilities at different flow rates of a fed-batch system. The degradation efficiencies were shown to be higher than 90% for all of the cases and to decrease as the feed rate increases. However, the SDR, a parameter that involves the rate of degradation and the biomass, increases as the flow rate increases. At a feed flow rate of 2 mf-min'1 SDR reaches a maximum of 12.476 x 10'10 mgCP-M-CFU'1. Finally, among the feed flows tested, taking into account both the degradation efficiency and the SDR, 2 mf-min'1 is the most convenient flow rate for chlorophenol degradation in fed-batch Systems. An even higher degradation efficiency (97%) can be achieved by using the feed rate of 2 mf-min'1 followed by an additional batch post-treatment of2 h, with a SDR of 13.136 x 10'10 mg CP-h'1-CFU'1.

The biodrying process was studied as an alternative technology to reduce the mass and volume of horticultural waste. Four static piles were prepared inside a greenhouse: two containing whole waste and two consisting of shredded waste. All the piles were compared with a test pile containing whole waste and placed outside the greenhouse. In two cases, ventilation ducts were installed to improve aeration. Each greenhouse was 2.0 m wide, 3.5 m long and 1.16 m high. The air temperature and relative humidity were monitored both inside and outside the greenhouse. Mass, humidity, organic matter and total nitrogen in the waste were measured. Piles inside the greenhouse showed decreases of 80% and 75% in weight and volume, respectively, during the first 16 days. The data obtained in this work suggest that biodrying could improve the handling and transport of horticultural waste while also minimizing the impact of pollutants.

Microbial degradation of phthalate and dimethyl phthalate esters was investigated using an enrichment culture obtained from sewage sludge. Optimal degradation conditions were determined by an orthogonal test for environmental factors. More than 99% PA at a concentration of 4 000 mg/L was degraded within 5 days under the optimized conditions at an initial pH 6.0, m(C)m(N)m(P)=10051, and NaCl concentration 10 g/L. As the sole source of carbon and energy, dimethyl phthalate (DMP) can be degraded by a culture derived from an acclimated activated-sludge under aerobic conditions and two degradation intermediates were identified as mono-methyl phthalate (MMP) and PA. The addition of PA, one of DMP biodegradation intermediates, resulted in acceleration of DMP degradation rate in the culture. Fig 2, Tab 3, Ref 1

The study is aimed to monitor bioremediation of hydrocarbon-polluted soils by measuring geophysical electromagnetic parameters. A previous study at lab scale showed that biostimulated indigenous microorganisms can remove diesel oil from soil successfully. Herein, we focused on the result of a laboratory test using Time Domain Reflectometry (TDR) probes to measure electrical conductivity and dielectric permittivity in a column of sandy soil artificially contaminated with diesel oil. To simulate aerobic degradation of hydrocarbons, mesocosms were set-up in two Plexiglas columns (inner diameter = 13.8 cm) with 3.4 kg of soil (layer height = 14 cm) spiked with 0.24 kg of diesel oil and hydrated with 0.4 kg of Mineral Salt Medium for Bacteria. One mesocosm was aerated by air injection from the bottom of the column, while the other had only natural aeration due to air diffusion through the soil itself. In each column, electrical conductivity and dielectric permittivity were monitored by TDR probes for 105 days. TDR measurements were supported by microbiological and gas chromatographic analyses, along with SEM images. The findings showed that air injection heavily influenced the TDR monitoring, probably due to generation of air bubbles around the probe that interfered with probe-soil coupling. Therefore, the measurement accuracy was reduced in an irreversible way. In the non-aerated system, a slight (2%) and linear decreas