Semi-specific Microbacterium phyllosphaerae-based microbial sensor for biochemical oxygen demand measurements in dairy wastewater

Although the long incubation time of biochemical oxygen demand (BOD₇) measurements has been addressed by the use of microbial biosensors, the resulting sensor-BOD values gained from the measurements with specific industrial wastewaters still underestimates the BOD value of such samples. This research aims to provide fast and more accurate BOD measurements in the dairy wastewater samples. Unlike municipal wastewater, wastewater from the dairy industry contains many substrates that are not easily accessible to a majority of microorganisms. Therefore, a bacterial culture, Microbacterium phyllosphaerae, isolated from dairy wastewater was used to construct a semi-specific microbial biosensor. A universal microbial biosensor based on Pseudomonas fluorescens, which has a wide substrate spectrum but is nonspecific to dairy wastewater, was used as a comparison. BOD biosensors were calibrated with OECD synthetic wastewater, and experiments with different synthetic and actual wastewater samples were carried out. Results show that the semi-specific M. phyllosphaerae-based microbial biosensor is more sensitive towards wastewaters that contain milk derivates and butter whey than the P. fluorescens-based biosensor. Although the M. phyllosphaerae biosensor underestimates the BOD₇ value of actual dairy wastewaters by 25–32 %, this bacterial culture is more suitable for BOD monitoring in dairy wastewater than P. fluorescens, which underestimated the same samples by 46–61 %.     

Highly efficient decolorization of Malachite Green by a novel Micrococcus sp. strain BD15

Purpose

Malachite Green (MG) is used for a variety of applications but is also known to be carcinogenic and mutagenic. In this study, a novel Micrococcus sp. (strain BD15) was observed to efficiently decolorize MG. The purposes of this study were to explore the optimal conditions for decolorization and to evaluate the potential use of this strain for MG decolorization.

Methods

Optical microscope and UV?Cvisible analyses were carried out to determine whether the decolorization was due to biosorption or biodegradation. A Plackett?CBurman design was employed to investigate the effect of various parameters on decolorization, and response surface methodology was then used to explore the optimal decolorization conditions. Kinetics analysis and antimicrobial activity tests were also performed.

Results

The results indicated that the decolorization by the strain was mainly due to biodegradation. Concentrations of MG, urea, and yeast extract and inoculum size had significantly positive effects on MG decolorization, while concentrations of CuCl₂ and MgCl₂, and temperature had significantly negative effects. The interaction between different parameters could significantly affect decolorization, and the optimal conditions for decolorization were 1.0 g/L urea, 0.9 g/L yeast extract, 100 mg/L MG, 0.1 g/L inoculums (dry weight), and incubation at 25.2°C. Under the optimal conditions, 96.9% of MG was removed by the strain within 1 h, which represents highly efficient microbial decolorization. Moreover, the kinetic data for decolorization fit a second-order model well, and the strain showed a good MG detoxification capability.

Conclusion

Based on the results of this study, we propose Micrococcus sp. strain BD15 as an excellent candidate strain for MG removal from wastewater.     

Isolation and characterization of a Rhodococcus strain with phenol-degrading ability and its potential use for tannery effluent biotreatment

Introduction

Wastewater derived from leather production may contain phenols, which are highly toxic, and their degradation could be possible through bioremediation technologies.

Materials, methods and results

In the present work, microbial degradation of phenol was studied using a tolerant bacterial strain, named CS1, isolated from tannery sediments. This strain was able to survive in the presence of phenol at concentrations of up to 1,000?mg/L. On the basis of morphological and biochemical properties, 16S rRNA gene sequencing, and phylogenetic analysis, the isolated strain was identified as Rhodococcus sp. Phenol removal was evaluated at a lab-scale in Erlenmeyer flasks and at a bioreactor scale in a stirred tank reactor. Rhodococcus sp. CS1 was able to completely remove phenol in a range of 200 to 1,000?mg/L in mineral medium at 30 ± 2?°C and pH 7 as optimal conditions. In the stirred tank bioreactor, we studied the effect of some parameters, such as agitation (200?C600 rpm) and aeration (1?C3?vvm), on growth and phenol removal efficiency. Faster phenol biodegradation was obtained in the bioreactor than in Erlenmeyer flasks, and maximum phenol removal was achieved at 400?rpm and 1 vvm in only 12?h. Furthermore, Rhodococcus sp. CS1 strain was able to grow and completely degrade phenols from tannery effluents after 9?h of incubation.

Conclusion

Based on these results, Rhodococcus sp. CS1 could be an appropriate microorganism for bioremediation of tannery effluents or other phenol-containing wastewaters.     

Synthetic olive mill wastewater treatment by Fenton’s process in batch and continuous reactors operation

Degradation of total phenol (TPh) and organic matter, (expressed as total organic carbon TOC), of a simulated olive mill wastewater was evaluated by the Fenton oxidation process under batch and continuous mode conditions. A mixture of six phenolic acids usually found in these agro-industrial wastewaters was used for this purpose. The study focused on the optimization of key operational parameters of the Fenton process in a batch reactor, namely Fe²⁺ dosage, hydrogen peroxide concentration, pH, and reaction temperature. On the assessment of the process efficiency, > 99% of TPh and > 56% of TOC removal were attained when [Fe²⁺] = 100 ppm, [H₂O₂] = 2.0 g/L, T = 30 °C, and initial pH = 5.0, after 300 min of reaction. Under those operational conditions, experiments on a continuous stirred-tank reactor (CSTR) were performed for different space-time values (τ). TOC and TPh removals of 47.5 and 96.9%, respectively, were reached at steady-state (for τ = 120 min). High removal of COD (> 75%) and BOD₅ (> 70%) was achieved for both batch and CSTR optimum conditions; analysis of the BOD₅/COD ratio also revealed an increase in the effluent’s biodegradability. Despite the high removal of lumped parameters, the treated effluent did not met the Portuguese legal limits for direct discharge of wastewaters into water bodies, which indicates that coupled chemical-biological process may be the best solution for real olive mill wastewater treatment.     

Synthesis of α-Fe2O3 nanofibers for applications in removal and recovery of Cr(VI) from wastewater

Purpose

Nanomaterials such as iron oxides and ferrites have been intensively investigated for water treatment and environmental remediation applications. The purpose of this work is to synthesize α-Fe₂O₃ nanofibers for potential applications in removal and recovery of noxious Cr(VI) from wastewater.

Methods

α-Fe₂O₃ nanofibers were synthesized via a simple hydrothermal route followed by calcination. The crystallographic structure and the morphology of the as-prepared α-Fe₂O₃ nanofibers were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Batch adsorption experiments were conducted, and Fourier transform infrared spectra were recorded before and after adsorption to investigate the Cr(VI) removal performance and adsorption mechanism. Langmuir and Freundlich modes were employed to analyze the adsorption behavior of Cr(VI) on the α-Fe₂O₃ nanofibers.

Results

Very thin and porous α-Fe₂O₃ nanofibers have been successfully synthesized for investigation of Cr(VI) removal capability from synthetic wastewater. Batch experiments revealed that the as-prepared α-Fe₂O₃ nanofibers exhibited excellent Cr(VI) removal performance with a maximum adsorption capacity of 16.17 mg g^?1. Furthermore, the adsorption capacity almost kept unchanged after recycling and reusing. The Cr(VI) adsorption process was found to follow the pseudo-second-order kinetics model, and the corresponding thermodynamic parameters ΔG°, ΔH°, and ΔS° at 298 K were calculated to be ?26.60 kJ?mol^?1, ?3.32 kJ?mol^?1, and 78.12 J?mol^?1 K^?1, respectively.

Conclusions

The as-prepared α-Fe₂O₃ nanofibers can be utilized as efficient low-cost nano-absorbents for removal and recovery of Cr(VI) from wastewater.     

Temporal variations of atmospheric aerosol in four European urban areas

Purpose

The concentrations of PM₁₀ mass, PM_2.5 mass and particle number were continuously measured for 18 months in urban background locations across Europe to determine the spatial and temporal variability of particulate matter.

Methods

Daily PM₁₀ and PM_2.5 samples were continuously collected from October 2002 to April 2004 in background areas in Helsinki, Athens, Amsterdam and Birmingham. Particle mass was determined using analytical microbalances with precision of 1 ??g. Pre- and post-reflectance measurements were taken using smoke-stain reflectometers. One-minute measurements of particle number were obtained using condensation particle counters.

Results

The 18-month mean PM₁₀ and PM_2.5 mass concentrations ranged from 15.4 ??g/m³ in Helsinki to 56.7 ??g/m³ in Athens and from 9.0 ??g/m³ in Helsinki to 25.0 ??g/m³ in Athens, respectively. Particle number concentrations ranged from 10,091 part/cm³ in Helsinki to 24,180 part/cm³ in Athens with highest levels being measured in winter. Fine particles accounted for more than 60% of PM₁₀ with the exception of Athens where PM_2.5 comprised 43% of PM₁₀. Higher PM mass and number concentrations were measured in winter as compared to summer in all urban areas at a significance level p?Conclusions Significant quantitative and qualitative differences for particle mass across the four urban areas in Europe were observed. These were due to strong local and regional characteristics of particulate pollution sources which contribute to the heterogeneity of health responses. In addition, these findings also bear on the ability of different countries to comply with existing directives and the effectiveness of mitigation policies.     

Removal of Pb(II) and Cd(II) ions from water by Fe and Ag nanoparticles prepared using electro-exploding wire technique

Purpose

This work aimed at investigating the adsorption of lead and cadmium onto Fe and Ag nanoparticles for use as a water contaminant removal agent as a function of particle type, sorbent concentration, and contact time.

Methods

Fe and Ag spherical nanoparticles were prepared in water by the lab-made electro-exploding wire (EEW) system and were investigated for their structure properties. Adsorption experiments were carried out at room temperature and pH 8.3 water solutions.

Results

The removal/adsorption of both Pb(II) and Cd(II) ions was found to be dependent on adsorbent dosage and contact time. Pb(II) adsorption onto Fe and Ag nanoparticles showed more or less similar efficiency and behavior. The kinetic data for the adsorption process obeyed pseudo second-order rate equations. The calculated equilibrium adsorption capacities (q _e) were 813 and 800 mg/g for Pb sorption onto Fe and Ag nanoparticles, respectively. Cd(II) ion adsorption onto Fe nanoparticles obeyed pseudo second-order rate equations with q _e equal to 242 mg/g, while their adsorption onto Ag nanoparticles obeyed pseudo first-order rate equations with q _e of 794 mg/g. The calculated q _es are in quite agreement with the experimental values. The removal/uptake mechanisms of metal ions involved interaction between the metal ion and the oxide/hydroxyl layer around the spherical metallic core of the nanoparticle in water medium.

Conclusion

Fe and Ag nanoparticles prepared using the EEW technique exhibited high potentials for the removal of metal ions from water with very high adsorption capacities, suggesting that the EEW technique can be enlarged to generate nanoparticles with large quantities for field or site water purification.     

Cr(VI) and COD removal from landfill leachate by polyculture constructed wetland at a pilot scale

Four subsurface horizontal-flow constructed wetlands (CWs) at a pilot scale planted with a polyculture of the tropical plants Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He) were evaluated for 7 months. The CW cells with an area of 17.94 m² and 0.60 m (h) each and 0.5 m of gravel were operated at continuous gravity flow (Q?=?0.5 m³ day^?1) and a theoretical HRT of 7 days each and treating landfill leachate for the removal of filtered chemical oxygen demand (COD_f), BOD₅, TKN, NH₄ ⁺, NO₃ ^?, PO₄ ^3?–P and Cr(VI). Three CWs were divided into three sections, and each section (5.98 m²) was seeded with 36 cuttings of each species (plant density of six cuttings per square metre). The other unit was planted randomly. The final distributions of plants in the bioreactors were as follows: CW I (He-Ce-Gs), CW II (randomly), CW III (Ce-Gs-He) and CW IV (Gs-He-Ce). The units received effluent from a high-rate anaerobic pond (BLAAT®). The results show a slightly alkaline and anoxic environment in the solid-liquid matrix (pH?=?8.0; 0.5–2 mg L^?1 dissolved oxygen (DO)). COD_f removal was 67 %, BOD₅ 80 %, and TKN and NH₄ ⁺ 50–57 %; NO₃ ^? effluents were slightly higher than the influent, PO₄ ^3?–P (38 %) and Cr(VI) between 50 and 58 %. CW IV gave the best performance, indicating that plant distribution may affect the removal capacity of the bioreactors. He and Gs were the plants exhibiting a translocation factor (TF) of Cr(VI) >1. The evaluated plants demonstrated their suitability for phytoremediation of landfill leachate, and all of them can be categorized as Cr(VI) accumulators. The CWs also showed that they could be a low-cost operation as a secondary system for treatment of intermediated landfill leachate (LL).     

Enhanced reduction of phenol content and toxicity in olive mill wastewaters by a newly isolated strain of Coriolopsis gallica

The search for novel microorganisms able to degrade olive mill wastewaters (OMW) and withstand the toxic effects of the initially high phenolic concentrations is of great scientific and industrial interest. In this work, the possibility of reducing the phenolic content of OMW using new isolates of fungal strains (Coriolopsis gallica, Bjerkandera adusta, Trametes versicolor, Trichoderma citrinoviride, Phanerochaete chrysosporium, Gloeophyllum trabeum, Trametes trogii, and Fusarium solani) was investigated. In vitro, all fungal isolates tested caused an outstanding decolorization of OMW. However, C. gallica gave the highest decolorization and dephenolization rates at 30 % v/v OMW dilution in water. Fungal growth in OMW medium was affected by several parameters including phenolic compound concentration, nitrogen source, and inoculum size. The optimal OMW medium for the removal of phenolics and color was with the OMW concentration (in percent)/[(NH₄)₂SO₄]/inoculum ratio of 30:6:3. Under these conditions, 90 and 85 % of the initial phenolic compounds and color were removed, respectively. High-pressure liquid chromatography analysis of extracts from treated and untreated OMW showed a clear and substantial reduction in phenolic compound concentrations. Phytotoxicity, assessed using radish (Raphanus sativus) seeds, indicated an increase in germination index of 23–92 % when a 30 % OMW concentration was treated with C. gallica in different dilutions (1/2, 1/4, and 1/8).

The effects of elevated carbon dioxide levels on a Vibrio sp. isolated from the deep-sea

Introduction

The effect of oceanic CO₂ sequestration was examined exposing a deep-sea bacterium identified as Vibrio alginolyticus (9NA) to elevated levels of carbon dioxide and monitoring its growth at 2,750 psi (1,846 m depth).

Findings

The wild-type strain of 9NA could not grow in acidified marine broth below a pH of 5. The pH of marine broth did not drop below this level until at least 20.8 mM of CO₂ was injected into the medium. 9NA did not grow at this CO₂ concentration or higher concentrations (31.2 and 41.6 mM) for at least 72 h. Carbon dioxide at 10.4 mM also inhibited growth, but the bacterium was able to recover and grow. Exposure to CO₂ caused the cell to undergo a morphological change and form a dimple-like structure. The membrane was also damaged but with no protein leakage.     

Binding of triclosan to human serum albumin: insight into the molecular toxicity of emerging contaminant

Purpose

The interaction between triclosan (TCS) and human serum albumin (HSA) was investigated in order to obtain the binding mechanism, binding constant, the type of binding force, the binding distance between the donor and acceptor, and the effect of TCS on the conformation change of HSA.

Methods

A HSA solution was added to the quartz cell and then titrated by successive addition of TCS. The fluorescence quenching spectra and synchronous spectra were recorded with the excitation and emission slits of the passage of band set at 10 and 20 nm. Three-dimensional fluorescence spectra of HSA were recorded before and after the addition of TCS. The capillary electrophoresis was conducted with the pressure injection mode at 0.5 psi for 5 s, separation under 25 kV, and detection at 214 nm.

Results

Fluorescence data indicated the fluorescence quenching of HSA by TCS was static quenching, and the quenching constants (K _a ) were 1.14?×?10⁵, 8.75?×?10⁴, 6.67?×?10⁴, and 5.00?×?10⁴ at 293, 298, 303, and 309 K, respectively. The thermodynamic parameters, enthalpy change (??H) and entropy change (??S) for the interaction were calculated to be ?37.9 kJ mol^?1 and 32.6 J?mol^?1 K^?1. The binding distance between TCS and tryptophan residues of HSA was obtained to be 1.81 nm according to F??rster nonradioactive energy transfer theory. The UV-Vis absorption spectroscopy, the synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, and circular dichroism spectroscopy revealed the alterations of HSA secondary structure in the presence of TCS. Finally, the interaction between TCS and HSA was further confirmed by capillary electrophoresis.

Conclusions

TCS was bound to HSA to form the TCS-HSA complex, with the binding distance of 1.81 nm. Hydrophobic interaction and hydrogen bond were dominated in the binding. TCS could change the secondary conformation of HSA. This work provides an insight into noncovalent interaction between emerging pollutants and protein, helping to elucidate the toxic mechanism of such pollutants.     

The adsorption process during inorganic phosphorus removal by cultured periphyton

To explain the detailed process involved in phosphorus removal by periphyton, the periphyton dominated by photoautotrophic microorganisms was employed in this study to remove inorganic phosphorus (P _i ) from wastewater, and the removal kinetics and isotherms were then evaluated for the P _i removal process. Results showed that the periphyton was capable of effectively removing P _i that could completely remove the P _i in 24 h at an initial P _i concentration of 13 mg P L^?1. Furthermore, the P _i removal process by the periphyton was dominated by adsorption at initial stage (~24 h), which involved physical mechanistic process. However, this P _i adsorption process was significantly influenced by environmental conditions. This work provides an insight into the understanding of phosphorus adsorption by periphyton or similar microbial aggregates.

Thermophilic desulfurization of dibenzothiophene and different petroleum oils by Klebsiella sp. 13T

Purpose

Biodesulfurization (BDS) has the potential to desulfurize dibenzothiophene (DBT) and its alkylated derivatives, the compounds that are otherwise refractory to hydrodesulfurization (HDS). Thermophilic microorganisms are more appropriate to be used for BDS applications following HDS. The aim of the present study was to isolate a thermophilic microorganism and to explore its commercial relevance for BDS process.

Methods

The desulfurizing thermophilic strain was isolated and enriched from various soil and water samples using sulfur free medium (SFM) supplemented with DBT. Microbiological and genomic approach was used to characterize the strain. Desulfurization reactions were carried out using DBT and petroleum oils at 45°C followed by different analytical procedures.

Results

We report the isolation of a thermophilic bacterium Klebsiella sp. 13T from contaminated soils collected from petroleum refinery. HPLC analysis revealed that Klebsiella sp. 13T could desulfurize DBT to 2-hydroxybiphenyl (2-HBP) at 45°C through 4S pathway. In addition, adapted cells of Klebsiella sp. 13T were found to remove 22?C53% of sulfur from different petroleum oils with highest sulfur removal from light crude oil.

Conclusion

Klebsiella sp. 13T is a potential candidate for BDS because of its thermophilic nature and capability to desulfurize petroleum oils.     

Evaluation of substrate removal kinetics for UASB reactors treating chlorinated ethanes

Purpose

Lack of focus on the treatment of wastewaters bearing potentially hazardous pollutants like 1,1,2 trichloroethane and 1,1,2,2 tetrachloroethane in anaerobic reactors has provided an impetus to undertake this study. The objective of this exercise was to quantify the behavior of upflow anaerobic sludge blanket reactors and predict their performance based on the overall organic substrate removal.

Methods

The reactors (wastewater-bearing TCA (R2), and wastewater-bearing TeCA (R3)) were operated at different hydraulic retention times (HRTs), i.e., 36, 30, 24, 18, and 12?h corresponding to food-to-mass ratios varying in the range of 0.2?C0.7?mg chemical oxygen demand (COD) mg^?1 volatile suspended solids day^?1. The process kinetics of substrate utilization was evaluated on the basis of experimental results, by applying three mathematical models namely first order, Grau second order, and Michaelis-Menten type kinetics.

Results

The results showed that the lowering of HRT below 24?h resulted in reduced COD removal efficiencies and higher effluent pollutant concentrations in the reactors. The Grau second-order model was successfully applied to obtain the substrate utilization kinetics with high value of R ² (>0.95). The Grau second-order substrate removal constant (K ₂) was calculated as 1.12 and 7.53?day^?1 for reactors R2 and R3, respectively.

Conclusion

This study demonstrated the suitability of Grau second-order kinetic model over other models, for predicting the performance of reactors R2 and R3, in treating wastewaters containing chlorinated ethanes under different organic and hydraulic loading conditions.     

Modelling the adsorption of mercury onto natural and aluminium pillared clays

Introduction

The removal of heavy metals by natural adsorbent has become one of the most attractive solutions for environmental remediation. Natural clay collected from the Late Cretaceous Aleg formation, Tunisia was used as a natural adsorbent for the removal of Hg(II) in aqueous system.

Methods

Physicochemical characterization of the adsorbent was carried out with the aid of various techniques, including chemical analysis, X-ray diffraction, Fourier transform infrared and scanning electron micrograph. Batch sorption technique was selected as an appropriate technique in the current study. Method parameters, including pH, temperature, initial metal concentration and contact time, were varied in order to quantitatively evaluate their effects on Hg(II) adsorption onto the original and pillared clay samples. Adsorption kinetic was studied by fitting the experimental results to the pseudo-first-order and pseudo-second-order kinetic models. The adsorption data were also simulated with Langmuir, Freundlich and Temkin isotherms.

Results

Results showed that the natural clay samples are mainly composed of silica, alumina, iron, calcium and magnesium oxides. The sorbents are mainly mesoporous materials with specific surface area of <250 m² g^?1. From the adsorption of Hg(II) studies, experimental data demonstrated a high degree of fitness to the pseudo-second-order kinetics with an equilibration time of 240 min. The equilibrium data showed the best model fit to Langmuir model with the maximum adsorption capacities of 9.70 and 49.75 mg g^?1 for the original and aluminium pillared clays, respectively. The maximum adsorption of Hg(II) on the aluminium pillared clay was observed to occur at pH 3.2. The calculated thermodynamic parameters (?G°, ?H° and ?S°) showed an exothermic adsorption process. The entropy values varied between 60.77 and 117.59 J?mol^?1 K^?1, and those of enthalpy ranged from 16.31 to 30.77 kJ mol^?1. The equilibrium parameter (R _L) indicated that the adsorption of Hg(II) on Tunisian smectitic clays was favourable under the experimental conditions of this study.

Conclusion

The clay of the Aleg formation, Tunisia was found to be an efficient adsorbent for Hg(II) removal in aqueous systems.     

Pilot project at Hazira,India, for capture of carbon dioxide and its biofixation using microalgae

The objective of the present study was to set up a small-scale pilot reactor at ONGC Hazira, Surat, for capturing CO₂ from vent gas. The studies were carried out for CO₂ capture by either using microalgae Chlorella sp. or a consortium of microalgae (Scenedesmus quadricauda, Chlorella vulgaris and Chlorococcum humicola). The biomass harvested was used for anaerobic digestion to produce biogas. The carbonation column was able to decrease the average 34 vol.% of CO₂ in vent gas to 15 vol.% of CO₂ in the outlet gas of the carbonation column. The yield of Chlorella sp. was found to be 18 g/m²/day. The methane yield was 386 l CH₄/kg VS_fed of Chlorella sp. whereas 228 l CH₄/kg VS_fed of the consortium of algae.     

Chemotaxis to atrazine and detection of a xenobiotic catabolic plasmid in Arthrobacter sp. DNS10

Introduction

A plasmid named pDNS10 was detected from an atrazine-degrading strain Arthrobacter sp. DNS10 which has been isolated previously in our laboratory.

Materials and methods

In this paper, a special plasmid-detecting method and drop assays experiments were mainly used to achieve research goals.

Results and discussion

pDNS10 exhibited an excellent stability because it also could be detected even when the strain DNS10 has been subcultured under nonselective conditions for eight times. Over a 48-h incubation period, the OD₆₀₀ of samples inoculated with strain DNS10 and strain DNS10-ST (both of them contained pDNS10) were 0.31 ± 0.042 and 0.305 ± 0.034, respectively ,whereas the OD₆₀₀ of samples inoculated strain without pDNS10 (strain DNS10-PE) was only 0.138 ± 0.018. No atrazine was detected in the inoculated strain DNS10 and strain DNS10-ST samples at this period. Contrarily, the atrazine-degrading rate of strain DNS10-PE was only 5.23 ± 0.71%. Furthermore, both the two types of strains containing pDNS10 confirmed the presence of known degrading genes such as trzN, atzB, and atzC. It suggests that pDNS10 is an atrazine catabolic plasmid. In drop assays experiments, the wild-type strain DNS10 cells were chemotactically attracted to atrazine, whereas strain DNS10-PE showed no chemotaxis to atrazine and hydroxyatrazine. There was some relationship between atrazine degradation and the chemotactic response towards atrazine in strain DNS10.

Conclusions

The biochemical characteristics of pDNS10 and the chemotaxis characteristics of strain DNS10 could help us in better understanding of the mechanism of atrazine degradation by strain DNS10.     

Composition analysis and application of degradation products of whole feathers through a large scale of fermentation

Purpose

Feathers are one of the most abundant bioresources. They are discarded as waste in most cases and could cause environmental pollution. On the other hand, keratin constituted by amino acids is the main component of feathers. In this article, we reported on biorefined feathers and integrants and application of degraded products.

Materials and methods

The fermentation of whole chicken feathers with Stenotrophomonas maltophilia DHHJ in a scale-up of a 5-L bioreactor was investigated in this article. The fermentation process was controlled at 0.08 MPa pressure, 2.5 L/min airflow, and 300 rpm as 100% oxygen saturation level, 40°C, and pH 7.8.

Results

Feathers were almost completely degraded in the tested fermentation reaction with the following conditions: 80 g of whole feathers in 3 L fermentation broth for 72 h, seed age of 16 h, 100 mL inoculation amount, and 50% oxygen saturation level. The degraded products contain 397.1 mg/L soluble protein that has mass weight ranging from 10 to 160 kD, 336.9 mg/L amino acids, and many kinds of metal ions. The fermentation broth was evaluated as leaf fertilizer and found to increase plant growth to 82% or 66% for two- or fourfold dilutions, respectively. In addition, in a hair care assay, the broth showed a hair protective function by increasing weight, flexibility, and strength of the treated hair.

Conclusions

The whole feathers were degraded completely by S. maltophilia DHHJ. The degraded product includes many factors to life, such as peptides, amino acids, and mineral elements. It could be applied as leaf fertilizer and hair care product.     

Monitoring heavy metal pollution by aquatic plants

Introduction

The copper bioaccumulation by the floating Lemna minor and by the completely submerged Ranunculus tricophyllus as a function of exposure time and copper concentration was studied, with the aim of proposing these species as environmental biosensors of the water pollution.

Results

The results show that both these aquatic angiosperms are good indicators of copper pollution because the copper uptake is the only function of metal concentration (water pollution).

Conclusion

Uptake behavior is reported as a function of the time and concentration, based on the results of a 3-year study. Kinetic evaluations are proposed.