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The aim of this study was to analyse the basic mechanisms of the interaction of surfactants anionic rhamnolipids and non-ionic polysorbate-80 on a microbial consortium during the biodegradation of diesel oil under model conditions. The analysed surfactants significantly influenced the metapopulation changes of microorganisms and caused a decrease in metabolic activity; however, they did not decrease the biodiversity of the studied system. Polysorbate-80 was relatively resistant to biological decomposition, whereas rhamnolipids were subjected to biodegradation as well as microbial transformation, as confirmed by the activity of the RhlC gene. Determination of biodegradation kinetics confirmed the positive influence of polysorbate-80 on the degradation efficiency of diesel oil hydrocarbons. The addition of this surfactant in 2-fold and 4-fold critical micelle concentration revealed a positive influence on the total petroleum hydrocarbons biodegradation by 18% and 15% respectively. Rhamnolipids exhibited an inhibiting effect in all fractions, with the exception of n-alkanes. The biodegradation efficiency of total petroleum hydrocarbons was 47% and 40% lower in samples containing biosurfactants in 2-fold and 4-fold critical micelle concentration, compare to that of the control sample. The surfactant-enhanced bioremediation method is a promising alternative to traditional methods; however, the method's efficiency is associated with the proper selection of a surfactant and its concentration and consideration of the occurrence of toxic effects as well as changes in the local soil metapopulation.

Sediment contamination in Taiwan is a critical environmental problem because it threatens human health through food chains and the local ecosystem as well. Er-Ren River (ERR) in southern Taiwan is one of the most polluted and its sediments have been severely contaminated by hydrophobic organic compounds (HOCs). Among all HOCs, polychlorinated biphenyls (PCBs) have been detected at high levels while hexachlorobenzene (HCB) has been most frequently detected. Due to their higher Kow values and lower biodegradability, they can be biomagnified through trophic levels and consequently pose high risks to humans and the ecosystem. This field study is to demonstrate an effective remediation technology on sediments contaminated by Aroclor 1254 and HCB by coupling in situ phase-inversion emulsification and biological reductive dechlorination (ISPIE/BiRD). By using real contaminated sediment with weathered and freshly-added contaminants, a single ISPIE operation can remove about 62% and 60% of weathered Aroclor 1254 and HCB, respectively. For weathered HCB and Aroclor 1254, the total removal could reach as high as 98% in 70 days. Metagenomic results showed that heat selection during ISPIE significantly changed the diversity and species evenness of the microbial community and that the Dehalococcoides were not positively correlated with the PCB removals. Instead, heat-tolerant archaea, Methanosaeta spp., may play much more important roles in the subsequent biological dechlorination. These results strongly support that ISPIE/BiRD is highly feasible on a full-scale field remediation and that this new microbial consortium could be a highly effective tool for bioremediation of HOC-contaminated sediments.

Microbiologically influenced corrosion of carbon steel by a thermophilic microbial consortium was investigated in the presence and absence of sand using surface analysis techniques and 16S rRNA gene sequencing. The activity of the consortium, involving methanogens, fermenting and sulphidogenic microorganisms, significantly increased average and localised corrosion regardless of the presence of sand deposit. Microbial metabolisms and syntrophic relationships of the consortium species contributing to accelerated corrosion were discussed. Electrochemical reactions are proposed based on the layers of corrosion products deposited on the metal surface. Differences in the microbial community composition and corrosion products stratification were identified between steel samples covered and uncovered with sand. This work is closely related to industrial applications highlighting the importance of conducting tests for under deposit corrosion incorporating microbial consortia isolated from the field environment. Otherwise, the severity of localised corrosion could be severely underestimated.

This work mainly aims to develop an efficient method for accelerating degradation of commercial polylactic acid beverage cups (cPLA). Ultraviolet (UV) irradiation was used to reduce the molecular weight of cPLA. The cPLA sheets were buried in soil amended with various sources of microbial consortium, including cow-manure compost, green yard-waste compost, and wastewater sludges from dairy, rice vermicelli and coconut milk factories. Interestingly, a complete degradation of cPLA sheets was found after 15 days of burial in the soil with dairy wastewater sludge, having high total nitrogen content. The dominant bacterial genus in the soil mixture of agricultural soil and dairy wastewater sludge was Actinomadura. In addition, there were the significant increases in the percentages of biodegradation and weight loss of cPLA and neat PLA (nPLA) in the soil with dairy wastewater sludge and Pseudomonas geniculata WS3, compared to the uninoculated control, indicating a synergistic action of the microbial consortium in sludge and P. geniculata WS3 on PLA biodegradability. The cPLA was more difficult to degrade than nPLA. In conclusion, UV-C irradiation of PLA followed by burying in a soil mixture of dairy wastewater sludge with P. geniculata WS3 inoculation is an efficient method for accelerating degradation of PLA waste.

Carbon capture and storage in deep subsurface oil reservoirs followed by subsequent microbial energy reconversion is a potentially new strategy for mitigating global warming and enhanced energy recovery simultaneously. However, our knowledge on the fate of CO2 and microbial community in response to CO2 injection is very limited. In the current study, microcosms containing both NaH13CO3-injected and n-hexadecane amended were established with inoculum of a long-term alkane-degrading microbial consortium. Enhanced and accelerated methane production was observed in the bicarbonate-injected treatments. The isotope data showed that injected bicarbonate was transformed to methane by hydrogenotrophic methanogenesis. The composition of microbial community shifted in response to bicarbonate addition. Competitive Methanoculleus spp. and Methanobacterium spp. became dominant and potentially major contributors to methane production in response to bicarbonate injected and non-injected treatments. At the same time, injection of bicarbonate was associated with a decrease of Anaerolineaceae, but no obvious influence on Thermodesulfovibrio spp. known as the crucial players with potential role in the initial activation and intermediate metabolism, and thus inhibition on initial activation of alkane via fumarate addition mechanism characterized by the existence of assA genes by bicarbonate addition. The results present further promising insights into new technology to enhance microbial energy generation from carbon dioxide capture and storage.

Different molecular tools (PCR-DGGE, 16S rRNA high-throughput sequencing and sequencing of the bamA gene) were used to assess and compare the microbial diversity in a pilot-scale expanded granular sludge bed (EGSB) reactor used for the anaerobic co-digestion of commercial laundry wastewater and domestic sewage and subjected to increasing concentrations of linear alkylbenzene sulfonate (LAS). Using PCR-DGGE, a microbial stratification along the sludge bed of the reactor was observed. When analyzed using 16S rRNA gene sequencing, the samples exhibited high microbial diversity and richness, with the lowest Shannon index obtained for the highest concentration of surfactant. For the Bacteria domain, the genera Bellilinea, Syntrophus, Syntrophobacter, Cytophaga, Bacteroides and Synergistes were the most abundant, whereas for the Archaea domain, the genera Methanosaeta and Methanolinea were predominant. The Pseudomonas genus was the only genus that was predicted to be involved in all steps of surfactant degradation. Additionally, bamA gene sequencing indicated the presence of the species Syntrophorhabdus aromaticivorans, Desulfosarcina cetonica and Syntrophus aciditrophicus, which have genetic potential for the aromatic ring cleavage under anaerobic conditions. Therefore, despite the high toxicity of LAS under anaerobic conditions, the use of different molecular tools revealed the great diversity and richness of the microbial community from the granular biomass of the EGSB pilot reactor, indicating that a microbial consortium is necessary for complete LAS degradation. Additionally, the sequencing analysis of the bamA gene represents a step forward in the understanding of the core microbial community involved in aromatic ring cleavage for anaerobic digestion of real laundry wastewater, which may guide future studies.

Emission of bioaerosols from biofilters during the treatment of toluene vapours was studied. A non-culture-dependent technique, known as epifluorescence microscopy (EM), with several fluorochromes was used to characterize and quantify bioaerosols. The bioaerosol emitted concentrations were between 6.4 × 105 and 1.3 × 108 cells m−3air compared with the bioaerosol concentration in ambient air, which was 3.0 × 107±7 × 106 cells m−3air. EM allowed for a better estimation of bioaerosol concentrations than culture-dependent techniques. Bioaerosol emission was dependent on the packing material. Perlite was a better packing material in terms of removal efficiency (RE; RE of 60%), with a lower bioaerosol emission (7 × 107 cells m−3air) than Tezontle (RE = 40%; 1.3 × 108 cells m−3air). The main drawback of perlite was acidification of the bed. Bioaerosols in biofilters A and B were composed of Gram-negative bacteria (45% and 40%, respectively), a similar percentage of Gram-positive bacteria (28%) and fungi (27% and 32%, respectively). After the shutdown periods, Gram-positive bacteria were predominant (∼60%). The biomass concentrations in leachates were twice those in the air flow and were mainly composed of fungi. Overall, the EM technique is a valuable tool to characterize and quantify bioaerosols in biofilters without under evaluation. This is the first estimation of bioaerosol emissions by biofilters inoculated with a microbial consortium using a noncultivable technique.

Microbial degradation of 1,1,2,2-tetrachloroethane has been rarely analysed under aerobic conditions. In this work, the catabolic potential of a TeCA-degrading aerobic propanotroph consortium (C2) and the optimal bioreactor configuration for an on-site TeCA-bioremediation strategy with C2 were defined. More specifically, the diversity of alkane-oxidizing bacteria in C2 was assessed by means of clone libraries of genes coding for alkane monooxygenases (MOs) of different families (AlkB-like alkane hydroxylase, soluble di-iron MO and cytochromes P450). A large number of alkane MO sequences retrieved in this study showed the highest similarity with reference sequences belonging to Rhodococcus genus, suggesting a key role of this genus in TeCA/propane co-metabolism, while the remaining alkane MO sequences were mainly attributed to other Actinobacteria, to Bradhyrizobiaceae, and Cupriavidus genus. Further, the feasibility of an on-site TeCA bioremediation strategy with C2 was evaluated by simulating a continuous-flow aerobic co-metabolic process with different bioreactor configurations. Our results show that the configuration with a suspended-cell continuous stirred-tank reactor (CSTR) followed by a suspended-cell plug-flow reactor (PFR) was the one giving the best performance with consortium C2.

Sinkholes, also called cenotes , are a common feature in the karst aquifers found along the state Quintana Roo in Mexico. Certain aliphatic and aromatic hydrocarbons have been found in the surface water of these sinkholes resulting in health and environmental hazards. In this study, a mathematical model is evaluated based on its predictive capacity on the biodegradation of oil in an airlift bioreactor (ALB). The model describes the oil uptake at the water-oil interface, whereas the previous modeling approaches focused on oil uptake in emulsified form. Biodegradation of 20 g L −1 diesel in an ALB is achieved by using an oil-degrading microbial consortium isolated from a sinkhole located in the urban zone of Playa del Carmen in Quintana Roo. The diesel degraded 83.6% confirming an effective use of ALB for the bioremediation of oil in water. The model is capable of predicting biomass growth and biodegradation by either integrating Monod or Teissier kinetics depending on the inhibitory effect of high concentration of oil on the microbial growth rate. The model is validated against three experimental campaigns performed in ALBs which indicated that it can serve as a valuable tool in the design and scale-up of bioreactors for the biodegradation of oil.

This work aimed to study the biodegradation of marine fuel MF-380 by selected microbial consortium and to determine the most favorable conditions for this process. Initially, strains isolated from seawater of the port of Suape – PE were subjected to a test to assess the occurrence of microbial interactions and then microbial consortia were mounted and the most promising consortium was selected by redox indicators. The strains of the selected consortium were acclimated to increasing levels of marine fuel MF-380 (1%, 2% and 3%, v v−1) and NaCl (1%, 2% and 3%, w v−1). Subsequently, it was applied a full factorial 23 experimental design to investigate the influence of variables (temperature, pH, C: N ratio) in the biodegradation process and finally an experiment in a bioreactor employing the best conditions found in the experimental design. Consortium named C5 was the most promising and reached as best result a total hydrocarbon biodegradation of 93.5% in the experimental design and reached levels of degradation optimized on trial in the bioreactor for the constituents of the marine fuel MF-380. Therefore, the consortium C5 is capable of degrading marine fuel MF-380 and can be used as a bioremediation agent of environments polluted by this fuel.

A microbial community, able to use 2,4-D (2,4-dichlorophenoxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) as carbon and energy sources, was selected in a continuously operated packed-bed column (PBC). Both active compounds are present in the Banvel herbicide. The predominant cultivable microorganisms isolated belong to the genera Burkholderia, Dyella, Mycobacterium, and Microbacterium. The presence of the catabolic genes tfdACD encoding enzymes involved in the 2,4-D metabolic pathway was evaluated for the bacterial isolates, with positive results for all of them. To evaluate the ability of the entire microbial community to degrade these herbicides in aerobic conditions a horizontal multistage-packed-bed reactor (HMPBR) was constructed. The reactor has four zones packed with fragments of volcanic rock, interspaced with four unpacked aerated zones. The continuous reactor, inoculated with the isolated microbial consortium, was run at increasing Banvel loading rates always operating in an aerobic environment and under steady-state conditions. In no case, 2,4-D or its main aromatic derivatives were detected in reactor's effluent, while dicamba was substantially degraded only at low loading rates. The highest degradation efficiencies of the herbicides were 100% for 2,4-D and 84% for dicamba. COD determinations showed that other components present in the commercial formulation of the herbicide were also removed. To evaluate changes in the diversity of the microbial consortium, massive semiconductor sequencing of 16S rDNA libraries was made. A remarkable variation in the bacterial diversity at phylum level, was observed in biofilm samples obtained from distinct packed bed zones of the reactor, and at different operating conditions.

The possible release of oxyanions, such as nitrate, from radioactive waste repositories may influence redox-conditions of the near field environment and thus promote mobility of some redox sensitive radionuclides. The fate of dissolved oxyanions will be significantly conditioned by microbial activities, if present in the aqueous interstitial phase of a waste cell. This study investigates microbial nitrate reduction in a cementitious environment. A consortium of microorganisms was used, an inoculum prepared with sediments collected from a former lime works site, characterized by a pH of pore water of 11–12. The biomass was acclimated to cement leachate supplemented with nitrate, acetate and yeast extract. According to experiments performed in closed and in dynamic systems, the microbial consortium was adapted to reduce nitrate and nitrite in a cementitious, anaerobic environment (pH 11, with and without hardened cement paste and leachate). Although, nitrite accumulation was observed in close system and temporally in dynamic system. The rate of nitrate reduction was between 0.12 and 0.75 mM/h with incoming nitrate concentrations between 6 and 48 mM, respectively. The microorganism diversity and the biofilm present on the hardened cement paste helped maintain microbial activity in all of the conditions simulating cementitious environments.

The simulated lysimeters of an open waste dump were employed to investigate microbial consortium in relation to the biodegradation of waste plastics (high/low density polyethylene, HDPE/LDPE; polypropylene, PP; polystyrene, PS). A low flow rate of a synthetic biogas was purged continuously to imitate methane oxidation. The plastics were examined periodically for chemical composition and microbial consortium. The PCR-DGGE and FISH techniques revealed bacterial consortium such as heterotrophs, autotrophs and methanotrophs colonizing simultaneously on the waste plastics. Only methanotrophs tended to increase with time throughout the waste bed, particularly for type I/II methanotrophs ( Methylobacter sp./ Methylocella sp.). Some microbes were found only at a 15 cm depth such as Methylococcus capsulatus, Acinetrobacter spp., and Flavobacteria spp. Biodegradation of waste plastics in terms of weight loss, chemical changes and surface deterioration clearly occurred where there was a high density of methanotrophs on the waste plastics. Methanotrophs functioned as the principal decomposer in plastic biodeterioration particularly in the upper zone of the lysimeter. The highest kinetic decay rate was of HDPE ( K , 0.128 y − 1 ) whereas the lowest K (0.048 y − 1 ) was of LDPE. In summary, the waste plastics were biodegraded in the simulated lysimeters which yielded a good correlation between plastic degradation kinetics and rate of methane oxidation.

The present work consisted of evaluating and comparing, at bench scale, the biodeterioration processes of diesel oil, soy biodiesel (B100 soy), beef tallow biodiesel (B100 beef tallow) and the resulting blends containing 5% biodiesel and 95% diesel oil (B5), throughout 42 days storage. Fuels were stored with and without the inoculation of a microbial consortium from a water drainage tank, under conditions that simulated service station storage. Oxygen consumption and carbon dioxide production were more pronounced in the presence of microbial inoculum, especially for B100 and B5 beef tallow. Diesel oil instead was the least subject to chemical and/or biological oxidation. A trend of increase in acid number was also observed and for B100 soy and B5 beef tallow the regulatory limits were exceeded. Residues deposition was observed in all inoculated fuels, especially in B5 beef tallow. Communities' differentiation depended on biodiesel feedstock and occurred during storage time. Among all microcosms, 18 microbial genera (8 fungal and 10 bacterial) were identified by DNA sequencing, being 17 of them directly linked to: fuel microbial contamination and/or biodegradation (74%); biofuel production or related enzymes expression (26%); biofilm formation and/or exopolysaccharide production (26%), emulsifying properties (11%) and nitrogen fixation (5%). Finally, despite the biodeterioration events in all the fuels, such phenomenon had small magnitude, even in inoculated samples.

Cultures were selected to form a consortium, and were submitted to essays in flasks according to a complete factorial design 2³ in order to determine temperature, inoculum concentration and C:N ratio conditions more favorable to biodegradation, which were used later in the experiment conducted in a bioreactor. The micro-organisms with the greatest potentiality to degrade diesel oil, without developing antagonistic activity, were identified as Staphylococcus saprophyticus, Serratia marcescens, Rhodotorula aurantiaca and Candida ernobii , which formed a mixed microbial consortium, consisting of bacteria and yeasts. The C:N ratio and temperature were the factors that displayed significant effect on the bioprocess. The increased C:N ratio and the amount of inoculum yielded a positive effect while the increase of the temperature caused a negative effect on biodegradation. In the seven-day trial in a bioreactor was verified an increase of biomass, decrease in surface tension, reduction of all n-alkanes belonging to the range of C9 to C21 and decreased toxicity for vegetable seeds. The tested mixed microbial consortium present high ability to degrade diesel oil constituents and the maintenance of appropriate conditions leads to transformation of this oily source into less toxic compounds.

Leaks and spillages during the extraction, transport and storage of petroleum and its derivatives may result in environmental contamination. Biodiesel is an alternative energy source that can contribute to a reduction in environmental pollution. The aim of the present work was to evaluate biodegradation of diesel, biodiesel, and a 20% biodiesel-diesel mixture in oxisols from southern Brazil, using two bioremediation strategies: natural attenuation and bioaugmentation/biostimulation. Fuel biodegradation was monitored over 60 days by dehydrogenase activity, CO 2 evolution and gas chromatography. The bacterial inoculum employed for bioaugmentation/biostimulation consisted of Bacillus megaterium , Bacillus pumilus , Pseudomonas aeruginosa , and Stenotrophomonas maltophilia and PCR-DGGE using 16S RNAr primers showed that some members of this consortium survived in the soil after 60 days. The biodegradation of pure biodiesel was higher for bioaugmentation/biostimulation than for natural attenuation, suggesting that the addition of the microbial consortium, together with adjustment of the macronutrient ratio, increased biodiesel degradation. The results of dehydrogenase and respiratory activity, together with GC analysis, suggested that the presence of biodiesel may, by stimulating general microbial degradative metabolism, increase the biodegradation of petroleum diesel. The microbial community was altered by both treatments, with natural attenuation producing a lower diversity index than the amended soil. The bioaugmentation/biostimulation strategy was showed to have a high potential for cleaning up soils contaminated with diesel and biodiesel blends.

Different bioremediation techniques (natural attenuation, biostimulation and bioaugmentation) in contaminated soils with two oily sludge concentrations (1.5% and 6.0%) in open and closed microcosms systems were assessed during 90 days. The results showed that the highest biodegradation rates were obtained in contaminated soils with 6% in closed microcosms. Addition of microbial consortium and nutrients in different concentrations demonstrated higher biodegradation rate of total petroleum hydrocarbons (TPH) than those of the natural attenuation treatment. Soils treated in closed microcosms showed highest removal rate (84.1 ± 0.9%) when contaminated at 6% and bacterial consortium and nutrients in low amounts were added. In open microcosms, the soil contaminated at 6% using biostimulation with the highest amounts of nutrients (C:N:P of 100:10:1) presented the highest degradation rate (78.7 ± 1.3%). These results demonstrate that the application of microbial consortium and nutrients favored biodegradation of TPH present in oily sludge, indicating their potential applications for treatment of the soils impacted with this important hazardous waste.

Ex-Situ Bioremediation has been increasingly viewed as an appropriate remediation technology for hydrocarbon contaminated soils under cold climates conditions in countries like Canada. A response surface methodology (RSM) based on a factorial design was performed to investigate and optimize the effects of the microbial consortia application rate and amount of mature compost amendment on the TPH removal (964 μg g−1 initial concentration). 18 field-scale biopiles (16 m3 each) were constructed, maintained and subjected to different microbial consortium and mature compost application rates under cold climate conditions over a period of 94 days. TPHs removal rates in the range of 74–82% was observed in the treatments setups where mature compost and microbial consortia were used simultaneously, compared to an average 48% of TPHs removal in control setup. The interaction between these two factors were studied and modelled using a statistical regression model, which showed that the microbial consortia application rate, the mature compost amendment and their interactions had a significant effect on TPHs degradation with a coefficient of determination (R2) of 0.88. Furthermore, using a numerical optimization approach, the optimum rates predicted via RSM were estimated at 4.1 ml m−3 and 7% for microbial consortia and compost application rates to obtain a maximum TPH removal of 90.7%.

Sodium Diclofenac and Mefenamic Acid are Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) that contribute to aquatic environmental pollution. The present study illustrates the ability of a microbial consortium comprising of Alcaligenes faecalis, Staphylococcus aureus, Staphylococcus haemolyticus and Proteus mirabilis, to degrade the aforementioned drugs. Up to 89% of degradation of Sodium Diclofenac and 92% of degradation of Mefenamic Acid was observed within 120 h period at a concentration of 150 mg.L−1. The maximum specific growth rate (μmax) of the microorganisms was 0.096 mg.L−1 hr−1 and 0.0943 mg.L−1 hr−1 for Sodium Diclofenac and Mefenamic Acid respectively, while the maximum specific rate of biodegradation (Qmax) for Sodium Diclofenac was 0.89 mg.L−1 hr−1 and 0.95 mg.L−1 hr−1 for Mefenamic Acid. Residual metabolites predicted by spectroscopic analyses were Hydroxy-Sodium Diclofenac, Hydroxy-Mefenamic Acid, Carboxy-Mefenamic Acid and Acyl Glucuronide. The presence of the above metabolic products suggested that Mono-oxygenase and Glucuronidase enzyme activity catalysed the degradation reaction. The study highlights the potential of the microbial consortium in degrading two of the most environment sullying drugs and can possibly be used in the future.

Assessment and development of strategies for ex-situ bioremediation in cold climates, such as in Canada, is of great importance for decontamination of contaminated soils. The purpose of this paper was to evaluate and compare the use of microbial consortia inoculant and mature organic compost as bioaugmentation and biostimulation strategies to enhance ex-situ bioremediation of a soil contaminated with heating oil under cold weather conditions. The soil was impacted as a result of leakage from an above-ground storage tank and had an initial TPH concentration was 940+ 127 μg g −1 (dry weight). Aerobic biopiles of 16 m 3 each were constructed and subjected at a field scale to microbial consortia inoculant and 10:1 ratio of mature organic compost. Two biopiles (S) contained only soil as control, two biopiles (S + C) contained soil and compost to assess the individual effect of compost addition, two biopiles (S + M) contained soil and microbial consortium to assess the individual effect of microbial consortium addition, and three biopiles (S + C + M) contained soil plus compost and microbial consortium to assess the combined effect of compost and microbial consortium addition. Over a 94 days period, composite soil samples for each biopile were collected and analysed for total petroleum hydrocarbons (TPHs), volatiles (F1), semi volatiles (F2) and non-volatiles (F3) fractions, microbial counting, and pH. Additionally, field measurements including soil temperature, moisture content, carbon dioxide (CO 2 ) and oxygen (O 2 ) were carried out. Although the ambient temperature varied from −3.5 °C to −24.1 °C, the internal soil temperatures for the different experimental setups maintained above freezing conditions. Results showed that biocell inoculated with microbial consortia and amended with 10:1 soil to compost ratio under aerobic conditions performed the best, degrading 82% of total petroleum hydrocarbons (TPHs) with a first-order kinetic degradation rate of 0.016 d −1 , in cold weather conditions. The average removal efficiencies for TPHs after 94 days for S, S + M, S + C treatments were 48%, 55%, and 52%, respectively. Statistical analysis indicated significant difference ( p

In the present work was characterized in abiotic and biotic systems, the droplet size of hexadecane (HXD) in emulsified form. Furthermore it was assessed the uptake of HXD in their both form emulsified (microscopic droplets) and free (macroscopic droplets), using a microbial consortium with the capacity of degrading oil. HXD in emulsified form includes microscopic droplets of 0.1 and 0.5 up to 0.7 μm. In the biotic experiments the kinetic parameters values were determined either by fitting to the Contois model the consumed data of HXD emulsified and by considering also the uptake rate of the free forms of HXD as independent of their own concentration. A comparison of the maximum specific HXD uptake rate (qmax) of the oil-degrading consortium when consumes the two forms of HXD, shows to be 53 times greater for the emulsified HXD that for their free form, suggesting that consumption of HXD is realized mostly by the emulsified form. The specific transfer area decreases with the culture time due to that the HXD is emulsified and consumed by the microbial consortium, being the specific transfer area of emulsified forms (microscopic droplets) a parameter that must be considered in the design of biodegradation processes of insoluble organic pollutants.

A co-metabolic degradation of tribenuron methyl bacterial strain NyZ42 was isolated from polluted agricultural soil and classified as genus Pseudomonas by its 16S rRNA gene sequencing. The degradation efficiency of tribenuron methyl was about 80% of the originally supplemented 200 mg l−1 tribenuron methyl in liquid minimal medium within four days, when either glucose or succinate was used as a supplemental carbon source. Three intermediates formed during the degradation of tribenuron methyl mediated by strain NyZ42 were captured by LC-MS, and two alternative pathways were proposed for the microbial mediated tribenuron methyl degradation, via either cleavage of the sulfonylurea bridge or saponification of alkyl-group. Furthermore, inoculation of strain NyZ42 enhanced the degradation of tribenuron methyl in the sterilized soil samples, although the biodegradation/co-metabolism ability of NyZ42 was not obvious in the nonsterilized soil samples when compared with the indigenous microbial consortium under current laboratory conditions.

The aims of this study were to identify the bacteria responsible for the rapid degradation of aromatic hydrocarbons, and to determine the roles of bacterial species in the microbial consortium. The population changes of the four major bacterial groups, namely Burkholderia spp., Achromobacter spp./Alcaligenes spp., Cupriavidus spp., and Rhodanobacter spp. in the Y consortium that preferentially degraded petroleum oil-derived aromatic hydrocarbons were assessed using quantitative real-time polymerase chain reaction (q-PCR). P-xylene was used as a representative aromatic compound, decane as a representative aliphatic compound, p-xylene-decane as a representative hydrocarbon mixture, and kerosene as a representative petroleum-based oil. The results showed that the remarkable increase of Burkholderia spp. coincided with the rapid degradation of aromatic hydrocarbons in kerosene, and p-xylene in single and dual-substrate cultures. Cupriavidus spp. significantly increased when decane was rapidly depleted. Achromobacter spp.,/Alcaligenes spp., and Rhodanobacter spp. were initially inhibited by the presence of aromatic hydrocarbons and seemed not to be active in hydrocarbon degradation, but utilized the metabolic products. This work provided an alternative way to explain the contribution of different microbial species in the degradation of hydrocarbon fractions. The behavior of the consortium is of interest in the context of the bioremediation of the more toxic aromatic hydrocarbons in environments contaminated by petroleum products.

The investigation was carried out to assess the potential of bacterial isolates to degrade phorate in soil and to study the effect of presence of plants, Brassica juncea , on the biodegradation process. The bacterial consortium consisting of three isolates viz. Ralstonia eutropha , Pseudomonas aeruginosa and Enterobacter cloacae obtained by enrichment on phorate could degrade it up to 73 ± 3% in aqueous medium and 55 ± 4% in a sandy loam soil. The degradation of phorate by the consortium in the soil was increased up to 64 ± 5% in the presence of B. juncea . Biodegradation of phorate in soil in presence of plants alone was 38 ± 4% as compared to 15 ± 2% in controls. Additionally, all the three isolates were found to possess plant growth promoting potential. Thus, the isolates can be used for remediation of sites contaminated with phorate and other organophosphates. B. juncea may be a potential plant for phytoremediation and rhizoremediation of such sites.

The evolution of the bacterial community during the bioremediation of diesel-contaminated soil using laboratory scale bioreactors was investigated for 120 days, evaluating the effect of adding individually or together, a mature compost, a bacterial consortium and the biosurfactant (β-cyclodextrin). The dynamics of microbial community was assessed using both a culture-dependent method and denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rDNA gene fragments. Results showed that the addition of compost plus a bacterial consortium caused a progressive increase in both heterotrophic cultivable aerobic bacteria and presumptive Pseudomonas. During the initial stage of the process, biostimulation and bioaugmentation increased species diversity (evaluated by DGGE analysis) and increased biomass-C content. After a transient drop caused by the xenobiotic contaminant, the bacterial community diversity and biomass-C content were restored at the end of the process. The density and activity of the microflora were similar in microcosms with or without β-cyclodextrin, but under the conditions tested, a reduction in total petroleum hydrocarbon (THP) removal was observed in the microcosms containing β-cyclodextrin. The combined use of mature compost and of a selected microbial consortium is a useful strategy for improving TPH removal, achieving a high TPH degradation (96%) at the end of the bioremediation process (120 days).

Microorganisms with high oil-degrading performance are essential for bioremediation of soil contaminated with crude oil. A positive end dilution method was employed for the selection of crude oil-degrading functional consortium from contaminated soil. The selected consortium was consisted of Rhizobiales sp., Pseudomonas sp., Brucella sp., Bacillus sp., Rhodococcus sp., Microbacterium sp. and Roseomonas sp. and removed nearly 52.1% of crude oil at initial concentration of 10,000 mg l−1 at 30 °C within 7 days, with removal of aliphatic hydrocarbons by 71.4% and aromatic hydrocarbons by 36.0%, respectively. The effectiveness of the consortium for bioaugmentation was confirmed with microcosm test by contaminated soil (1.0 kg) from Karemary Oilfield, China. The removal efficiency of crude oil was enhanced to >50% in microcosms with the consortium compared with 8–13% or lower in controls over a 60 day period. The crude oil removal reaction was probably first order reaction and the rate was greatly enhanced by bioaugmentation. Supplementation of nitrogen and phosphate sources had limited effect on the oil removal in the tested soil.

This study is a part of efforts to develop new batch method with the help of prepared consortium GG-BL using two microbial cultures viz. Galactomyces geotrichum MTCC 1360 and Brevibacillus laterosporus NCIM 2298, varying oxidation conditions for the bio-treatment processes to produce reusable water by decolorization of Golden Yellow HER (GYHER) to less toxic metabolites. Consortium was found to be much faster for decolorization and degradation of GYHER as compared to the individual strains. The intensive metabolic activity of these strains led to 100% decolorization of GYHER (50 mg l � 1 ) within 24 h with significant reduction in chemical oxygen demand (84%) and total organic carbon (63%). The presence of veratryl alcohol oxidase, NADH-DCIP reductase and induction in laccase, tyrosinase, azo reductase and riboflavin reductase during decolorization suggests their role in decolorization process. Substrate staining of nondenaturing polyacrylamide electrophoresis gel (PAGE) also confirms induction of oxidative enzymes during GYHER degradation. The degradation of the GYHER into different metabolites by individual organism and in consortium was confirmed using High Performance Thin Layer Chromatography (HPTLC), High Performance Liquid Chromatography (HPLC), Fourier Transform Infra Red Spectroscopy (FTIR), Gas Chromatography Mass Spectroscopy (GCeMS) analysis. Phytotoxicity studies revealed nontoxic nature of the metabolites of GYHER.

Wastewater from textile industry usually undergoes activated sludge biotreatment ahead of refining treatments, final discharge or reuse. To identify the most effective bioreactor typology for the secondary treatment of a wastewater resulting from a textile industry of the Biella district (Italy), four pilot units characterized by a different configuration and fluid dynamics (i.e., Bioflotation®, Fixed Bed Biofilm Reactor (FBBR), flow-jet aeration and standard aerobic sludge reactors) were operated in parallel, inoculated with the same microbial consortium and fed with identical streams of wastewater discharged from wet textile processes of the industy. COD, TC and non-ionic surfactants were monitored in effluents of the compared bioreactors working under continuous mode and the cultivable heterotrophic microorganisms prevailing in each of them were isolated and characterized as the end of the study. The results demonstrated that the air supply system greatly influenced the treatment efficiency which reached the highest value in the case of Bioflotation® and FBBR technology. A highly specialized bacterial biomass mostly composed by strains of the Pseudomonas, Stenotrophomonas and Ochrobactrum genera was isolated in such reactors, thus suggesting that a direct correlation between reactor configuration, decontamination performances and microbial biomass composition exist.

Numerous studies on the biodegradation of petroleum products using total petroleum hydrocarbons (TPH) have been carried out; however, the biodegradation of equivalent carbon number (EC) based hydrocarbon fractions in mineral oil has attracted little attention. This study investigated the ability of a microbial consortium to degrade the EC fractions in kerosene, which was used as a representative mineral oil. Based on the cloning and sequencing of the 16S rRNA gene, the microbial community was predominantly identified as Betaproteobacteria of the genera Achromobacter , Alcaligenes , and Cupriavidus . Degradation experiments in sealed 120-ml vials containing 1% (w v −1 ) kerosene revealed that aromatic fractions were degraded faster than aliphatic fractions. Aromatic fractions EC >7–8 and EC >8–10 were completely degraded after three days while aliphatic fractions EC >6–8 and EC >8–10 were only partially degraded. The aromatic EC >10–12 fraction was the third most degraded, and the aliphatic EC >10–12 and EC >12–16 fractions were the least degraded fractions. The first-order rate constants for the aromatic fractions ranged from 0.12 d −1 to 0.51 d −1 and from 0.06 d −1 to 0.32 d −1 for the aliphatic fractions. The microbial consortium preferentially utilized aromatic fractions, which are more toxic than aliphatic fractions. This finding is useful when considering risk-based bioremediation: A microbial community could potentially degrade the more toxic aromatic hydrocarbon components in petroleum-contaminated environments.

In this study, we evaluated the efficiency of BTEX biodegradation by a consortium acclimatized to unleaded gasoline and bacterial strains isolated from it. The isolates were identified by PCR-amplification of 16S rRNA genes, and BTEX biodegradation was confirmed by the identification of dioxygenase-related proteins. The consortium degraded 95% of total BTEX and the following genera were present in the consortium: Pseudomonas, Shewanella, Burkholderia, Alcanivorax, Rhodococcus, and Bacillus. Strain FMB08, isolated from a consortium, was capable of removing 90% of total BTEX and its 16S rDNA analysis was similar to that of Pseudomonas.

A microbial consortium capable of degrading turbine oil (TuO) consisting mainly of recalcitrant branched and polycyclic alkanes, has been established using a sludge sample collected from an oil-water separation tank of a hydraulic plant, by repeated enrichment cultivation. When this consortium, named the tank-2 consortium, was cultivated in a minimal salts medium containing 0.5% TuO, it degraded approximately 90% of TuO at 30 °C under shaking at 160 rpm in five days. During cultivation, the consortium formed cell aggregates. Fourteen bacterial species were isolated from the consortium. Although the mixtures of all of the isolated strains (IM) and predominant strains selected from the IM (PM) degraded approximately 60% of the TuO maximally in seven days after repeated enrichment, the degradation rate was not maintained. The decreased rate of TuO degradation in the PM was recovered by inoculation with a mixture (AM) consisting of isolates involved in the cell aggregate formation in the tank-2 consortium, suggesting that the formation of bacterial aggregates is an important factor for the degradation of TuO by the bacterial consortia. Interestingly, the formation of bacterial aggregates was only observed when cyclic alkanes were added to the consortium as a source of carbon. The cell surface hydrophobicity of the bacterial aggregates was significantly high (77.6%). These results suggest that the growth of bacteria with high cell hydrophobicity can be induced by the cyclic alkanes fraction of TuO, and that the formation of aggregates facilitates cells to form contact with the recalcitrant components of TuO and uptakes these components.

Superparamagnetic iron oxide nanoparticles (SPION) with size ranging 10.6–37.8 nm were synthesized and characterized through XRD, FT-IR spectra, simultaneous TG-DTG-DTA, vibrational sample magnetometry (VSM) and transmission electron microscopy (TEM). Effect of SPION size variants on the growth-profile of Low-Density Polyethylene (LDPE) degrading microbial consortium consisting of Microbacterium sp., Pseudomonas putida and Bacterium Te68R was monitored in Minimal broth Davis medium lacking iron and dextrose. Besides accelerating the bacterial growth, these nanoparticles also improved the exponential phase durability by 36 h. Further, shifting in lag-phase and the additive effect of sonication was also documented on growth profiling. SPION of size 10.6 nm were selected and were found to significantly increase the biodegradation efficiency of consortium as revealed by λ-max shifts, Fourier transform infrared spectroscopy (FT-IR) and simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA). The study highlights the significance of bacteria–nanoparticle interactions which can dramatically influence key metabolic processes like biodegradation.

At the locality of the former producer of PCBs Chemko Stražske in East Slovakia, a large amount of PCBs (the commercial mixture DELOR 103, an equivalent of AROCLOR 1242) is still persisting in sediments and negatively influences health of the population. The objective of this work was to provide a study of ecotoxicity and genotoxicity of PCBs in contaminated sediments. Toxicity of the PCB-contaminated sediments sampled from Zemplinska sirava and Stražsky canal (surroundings of the former producer of PCBs) was determined applying a standard aquatic plant toxicity test using Lemna minor . The endpoints for the test were frond numbers and frond areas. The sediment sampled from Zemplinska sirava was more toxic to L. minor than the one sampled from Stražsky canal. The results on genotoxicity showed that both sediments were not mutagenic toward the standard strains of the Ames test, Salmonella typhimurium TA98 and TA100. This work deals also with biodegradation of PCBs in two samples of the above mentioned contaminated sediments: a) in the natural sediments by autochthonous microbial consortium and b) in the bioaugmented sediments inoculated by allochthonous bacterial strains, two bacterial isolates from long-term PCB-contaminated soil Pseudomonas stutzeri and Alcaligenes xylosoxidans . Both approaches were applied under the biostimulation conditions, with addition of glucose or biphenyl as co-substrates, as well. The highest PCB degradation was observed in the bioaugmented sediment inoculated with bacterial strain P. stutzeri . Addition of biphenyl, as the co-substrate and the inducer, positively affected degradation of PCBs. The bphA1 gene, encoding enzyme biphenyldioxygenase, responsible for the start of PCB degradation, was identified in genome of P. stutzeri , a potential PCB-degrader isolated from long-term PCB-contaminated soil, but not in genome of A. xylosoxidans .

A microbial consortium consisting of two isolates of Pseudomonas aeruginosa and one of rhodococcal from soil contaminated with oily sludge was able to degrade 90% of hydrocarbons in 6 weeks in liquid culture. The ability of the consortium to degrade sludge hydrocarbons was tested in two separate field trials. In addition, the effect of two additives (a nutrient mixture and a crude biosurfactant preparation) on the efficiency of the process was also assessed. The biosurfactant used was produced by a consortium member and was identified as being a mixture of 11 rhamnolipid congeners. The consortium degraded 91% of the hydrocarbon content of soil contaminated with 1% (v/v) Ratnagiri, India, crude oil sludge in 5 weeks. Separate use of any one additive along with the consortium brought about a 91–95% depletion of the hydrocarbon content in 4 weeks, with the crude biosurfactant preparation being a more effective enhancer of degradation. However, more than 98% hydrocarbon depletion was obtained when both additives were added together with the consortium. Similar results were observed with soil contaminated with sludge from IOCL, Faridabad, India. The data substantiate the use of a crude biosurfactant preparation for hydrocarbon remediation.

A microbial consortium capable of degrading turbine oil (TuO), which consisted mainly of recalcitrant cycloalkanes and isoalkanes, was obtained from a soil sample collected from oil fields using repeated enrichment. When this consortium, named Atsuta A, was cultured in minimal salts medium containing 0.5% (w/v) TuO, it degraded 90% of TuO at 30 °C and pH 7 over 5 days. Although nine bacterial strains were isolated from the Atsuta A consortium, TuO degradation by the individual isolates and by a mixture of them was negligible. The community structure of the consortium, which was investigated by PCR–denaturing gradient gel electrophoresis (DGGE) targeting 16S rRNA genes, changed significantly during the degradation of TuO. Four major bands (F, K, N and T) out of at least 23 DGGE bands significantly increased in intensity over time during incubation. The DGGE bands F, K and N corresponded to those of previously isolated species. However, DGGE band T did not correspond to any isolated strain. The 16S rRNA gene sequence collected from band T was 98% homologous to that of an unculturable strain belonging to the γ-Proteobacteria. The degradation of TuO in the consortium may occur by cooperation between the unculturable species corresponding to band T and other strains in the consortium, including species corresponding to bands F, K and N.

The contribution of bacteria, isolated from sewage sludge, towards the microbial degradation of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was studied. A microbial consortium was inoculated on mineral salt agar plates containing different concentrations of PHBV as a substrate. The PHBV degraders showed optimum depolymerase production at pH 7.0, 37 °C, and 0.4% substrate concentration during 2–5 weeks of incubation. Additional carbon sources like glucose, fructose, sucrose, lactose and nitrogen sources including yeast extract were used as co-metabolites. The highest degree of degradation of PHBV was observed in the presence of glucose. Among the surfactants, Tween 80, was found to be a good inducer for the release of extracellular depolymerase enzyme as compared to Tween 20. When the PHBV depolymerase activity of isolates present in the consortium was determined separately, it was found that the enzyme activity was higher in case of Bacillus sp. AF3. The purification steps included ammonium sulfate fractionation and gel permeation chromatography on Sephadex G-75. The enzyme has been purified to homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and molecular weight was found to be approximately 37 kDa.

The effect of fermented whey on the aerobic degradation of n -alkanes by a microbial consortium was investigated in an aqueous system. Microbial degradation of 100 mg n -alkanes l −1 (C 12 , C 14 , C 16 and C 18 ) in mineral nutrient medium was assessed by measuring the decrease in n -alkanes, production of CO 2 and increase in biomass. The addition of fermented whey at a concentration of 5 mg dry weight l −1 to a nutrient medium receiving a small-sized inoculum (10 3.4 CFU ml −1 ) shortened the lag phase from 8 to 3 days, but the degradation rate during the degradation phase was not enhanced. The shortened lag phase at low initial concentration of microorganisms indicates that the fermented whey stimulates growth in the initial phase, without reducing the consortium's capacity for n -alkane degradation.

Picocyanobacteria floating on the surface of the water body in the Arabian Gulf were found associated with heterotrophic bacteria. Haemocytometer counting of fresh 1-cm surface water revealed 10 7 –10 8 bacterial cells ml −1 , but only 10 2 –10 3 cells ml −1 in 10-cm deep water samples. The heterotrophic bacteria comprised hydrocarbon utilizers that could grow on a mineral medium containing crude oil as sole carbon and energy source. Three-week liquid cultures of the picocyanobacteria Synechococcus , Synechocystis , Pleurocapsa and Dermocarpella were found by dilution plating to contain 10 6 –10 13 oil-utilizing bacteria ml −1 . These were members of the genera Pseudomonas , Bacillus and Acinetobacter and nocardioforms. Growth and hydrocarbon consumption potential of individual types of oil-utilizing bacteria in culture were higher in the presence of the picocyanobacteria than in their absence. Evidence was presented that picocyanobacterial cells may accumulate hydrocarbons from the medium, and subsequently make those compounds available to the associated hydrocarbon-utilizing bacteria. It was concluded that this microbial consortium, which is apparently of cosmopolitan occurrence, could be active in controlling marine oil-pollution.

The bioremediation of hydrocarbon in contaminated soils by mixed cultures of hydrocarbon-degrading bacteria was investigated. The mixtures or consortia of bacteria, denoted as Consortium 1 and Consortium 2 consisted of 3 and 6 bacterial strains, respectively. Bacterial strains used in this study were from the Center for Research in Enzymes and Microbiology (CREAM) collection of strains, at Universiti Putra Malaysia, and were isolated from hydrocarbon-contaminated soil samples by enrichments on either crude oil or individual hydrocarbons as the sole carbon source. The strains were selected based on the criteria that they were able to display good growth in crude oil, individual hydrocarbon compounds or both. Their ability to degrade hydrocarbon contamination in the environment was investigated using soil samples that were contaminated with diesel, crude oil or engine oil. Consortium 2, which consisted of 6 bacterial strains, was more efficient at removing the medium- and long-chain alkanes in the diesel-contaminated soil compared to Consortium 1. Further, Consortium 2 could effectively remove the medium- and long-chain alkanes in the engine oil such that the alkanes were undetectable after a 30-day incubation period. Consortium 2 consisted predominantly of Bacillus and Pseudomonas spp.