Citrobacter Freundii Bacteria Research Articles

Synthesis of water-soluble CdS quantum dots for the fluorescence detection of tetracycline

An effective strategy for combating antibiotic-resistant bacteria (ARB) entails the early detection of antibiotics during the initial stages of water treatment facilities. In this context, cadmium sulfide quantum dots (CdS QDs) were employed for the precise detection of tetracycline (TET), an emerging contaminant, in water. CdS QDs with fluorescence properties were synthesized by culturing Citrobacter freundii bacteria. The CdS QDs were characterized by spectroscopy techniques, and the quantum efficiency was estimated to be 55.8% which is ∼2-fold high compared to the standard rhodamine-B solution. The fluorescence of CdS QDs was quenched at 440 nm in the presence of TET. The linear range of TET was varied from 10 to 100 μM with a lower limit of detection of ∼23 nM. The CdS QDs were used to detect TET in river water, tap water, and milk which showed an excellent recovery rate. Therefore, the novel biosynthesis CdS QDs can be a significant fluorescence probe for the detection of TET that shows exceptional sensitivity and selectivity.

Coal mine wastes: Effective mitigation of coal waste slurry and acid mine drainage through bioflocculation using mixotrophic bacteria as bioflocculants

Acid mine drainage (AMD) and coal waste slurry, byproducts of global mining and coal processing activities, represent significant environmental pollution concerns due to their acidic nature and high total suspended solids (TSS) content. The exploration of microbial treatment methods, specifically the utilization of microorganisms and their metabolic byproducts as bioflocculants, is underway to mitigate the adverse effects of these byproducts. This investigation assessed the effectiveness of 54 mixotrophic bacterial strains in treating coal waste slurry and AMD from coal mines located in Kalimantan, Indonesia. The bacterium Citrobacter freundii (strain SKC-4), cultured in SKC1 medium (comprising 225 mL of seawater from the Java Sea and 15 g/L molasses), demonstrated superior performance, reducing the TSS value from 4998.20 ppm to 16 ppm within an hour. Fourier Transform Infrared (FTIR) analysis revealed an increase in the intensity of the CO and CN groups from protein amides and CH2 from carbohydrates, suggesting an interaction between bacteria and clay minerals in the coal waste slurry. The bacteria also played a crucial role in adjusting the pH of AMD, elevating it from 3.82 to 6.07 after one hour of conditioning with a bacterial culture to AMD ratio of 1:9. The interaction between bacteria and their metabolic products was further substantiated by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, which detected the presence of an extracellular polymeric substance (EPS). To our knowledge, this study represents the first exploration of the potential of mixotrophic bacteria as bioflocculants in the biotreatment of coal waste slurry and AMD from coal mining operations.

Synthesis, Cu(II) Schiff base complexation and structural annalysis of the ligand 4-{[2-(methoxycarbonyl) pyrrolidin-1-yl] methyl} benzoic acid

A new proline based ligand was syn thesized by a convenient procedure. The ligand was characterized by 1 H NMR, 13 C NMR and IR spectroscopies. Copper (II) Schiff base complexes of 4 --{[2 --(methoxycarbonyl) pyrrolidin 1 yl] methyl} benzoic acid of this ligand were synthesized and characterized by the aforementioned spectroscopy techniques, i.e. 1 H NMR, 13 C NMR and IR. Moreover, its bactericidal activity was assessed through the determination of the minimum inhibitory concentration (MIC) values as well as the i nhibition zone diameter for gram po sitive bacteria, such as Staphylococcus aureus , and gram negative bacteria like Klebsiella pneumoniae, Citrobacter freundii, Salmonella typhi, Enterobacter cloacae (the two bacteria Citrobacter freundii and Salmonella typhi are very sensitive against this molecule unlike Enterobacter cloac ae bacteria which is resistant).

Effect of Vitamin C on Cadmium Depending Growth and Vitamin C Contents of Citrobacter Freundii

Citrobacter freundii bacteria were grown in LB medium containing cadmium ion. In order to reduce adverse effect caused by cadmium, different concentrations of vitamin C, were added to the growth medium. While the concentration of bacteria grown was determined by spectrophotometer, the amounts of water and fat-soluble vitamins were also determined by HPLC. The cadmium concentration varied from 0 (control), to 10, 20, 40, 60, 75, 100, 125 ppm in LB growth medium. The effect of cadmium has not been observed on the growth of bacteria, up to 40 ppm, on the other hand no significant microorganism growth was observed over 150 ppm cadmium. Significant change of bacteria concentration was observed in the medium containing 75, 100 and 125 ppm Cd. Microorganism concentrations decreased 18.8, 40.5 and 45.5 percent in the growth medium containing 75, 100 and 125 ppm Cadmium respectively. With the addition of 75 ppm vitamin C to the same growth medium, microorganism concentration was decreased about 2.0, 28.0 and 31.0 percent, respectively compared to the control. In addition, fat and water-soluble vitamins in bacteria grown in cadmium-containing medium was decreased in comparison to the control (p<0.05). With the addition of 25, 50 and 75 ppm vitamin C to cadmium-containing medium, fat and water soluble vitamin concentrations were increased. As a result, it can be said that the negative effects of cadmium on bacterial growth and vitamin content can be reversed by the addition of vitamin C in to the growth medium of bacteria.

A fungus–bacterium co-culture synergistically promoted nitrogen removal by enhancing enzyme activity and electron transfer

The fungus Penicillium citrinum WXP-2 and the bacterium Citrobacter freundii WXP-9 were isolated and found to have poor denitrification performance. Surprisingly, co-culture of the two strains which formed fungus–bacterium pellets (FBPs) promoted the removal efficiency of nitrate (NO3−-N; 95.78%) and total nitrogen (TN; 81.73%). Nitrogen balance analysis showed that excess degraded NO3−-N was primarily converted to N2 (77.53%). Moreover, co-culture increased the dry weight to 0.74 g/L. The diameter of pellets and cell viability also increased by 1.49 and 1.78 times, respectively, indicating that the co-culture exerted a synergistic effect to promote growth. The increase in electron-transmission system activity [99.01 mg iodonitrotetrazolium formazan/(g·L)] and nitrate reductase activity [8.65 mg N/(min·mg protein)] were responsible for denitrification promotion. The FBPs also exhibited the highest degradation rate at 2:1 inoculation ratio and 36 h delayed inoculation of strain WXP-9. Finally, recycling experiments of FBP demonstrated that the high steady TN removal rate could be maintained for five cycles.

Bioelectricity and bioactive compound productionin an algal-assisted microbial fuel cell with immobilized bioanode

This study investigates the influence of immobilized bacterial anode on the performance of algal-assisted microbial fuel cell (AAMFC) that treats dairy wastewater with concurrent bioelectricity and bioactive compound production. Immobilized exoelectrogenic bacterium—Enterobacter aerogenes—was used in the anode region, and Nostoc sp. was used in the cathode region. The investigation on the influence of sodium alginate (SA) concentration indicated that E. aerogenes immobilized using 20 g/L SA produced highest power density of 168 ± 3.5 mW/m2, whereas free cells showed 75 ± 5.32 mW/m2. The coulombic efficiency, chemical oxygen demand (COD) removal, and volatile fatty acid (VFA) recovery obtained for cells immobilized using 20 g/L SA were 12.54, 83.15, and 92%, respectively. This system gave a CO2 supply of 4.2 mM, which increased the productivity of Nostoc sp. to 64.3 ± 3.8 mg/L d. Algal cathode produced a maximum dissolved oxygen content of 12.8 mg/L. The constituents of Nostoc sp. were extracted using ethanol, and the antimicrobial activity of the extract was tested against aquatic bacterial pathogens. The extract at a dosage of 500 μg showed highest zone of inhibition of 11 mm for the gram-negative bacteria Citrobacter freundii and least inhibition of 2 mm for Escherichia coli. FTIR analysis of the extract confirmed the presence of bioactive compounds. This study substantiated that the immobilized anodic exoelectrogens with microalgal biocathode in an AAMFC will find a promising application in energy harvesting from wastewater and bioactive compound synthesis.

Genomic and Phenotypic Characterization of a Lytic Bacteriophage CF1 Infecting the Multi-drug Resistant Bacterium Citrobacter freundii

Citrobacter freundii is a facultative anaerobic and Gram-negative bacterium belonging to the Enterobacteriaceae family. Citrobacter spp. are opportunistic pathogens that are commonly found in water, soil, food, animals, or intestines in humans and warm-blooded animals and are a major concern for antibiotic resistance, especially C. freundii that exists in the farms, medical environment, and is difficult to eradicate. In this study, genomic and phenotypic characterization of a newly isolated bacteriophage CF1 capable of specifically infecting C. freundii is presented. The bacteriophage CF1 was isolated from sewage water sample near a livestock farm. The bacteriophage was morphologically and microbiologically characterized including one stage growth curve, and host range, on top of which the genome sequence of bacteriophage CF1 was determined. Microbiological characterization demonstrated that bacteriophage CF1 is stable in a range of pH4-9, and at the temperature below 70°C for 60 min. Genomic analysis revealed that bacteriophage CF1 is a new one with a double-stranded DNA of 50,339 bp, GC content of 42.65% that encodes 89 predicted open reading frames. Comparative analysis showed that bacteriophage CF1 is similar to C. freundii bacteriophage Stevie. Thus, this study provides genomic and phenotypic characteristics of a newly isolated bacteriophage, which can serve as a knowledge-base to use bacteriophage CF1 in the treatment of pathogenic C. freundii particularly with antimicrobial resistance in livestock industry.

Cross-Flow Microfiltration of Glycerol Fermentation Broths with Citrobacter freundii.

This paper reports the study of the cross-flow microfiltration (MF) of glycerol fermentation broths with Citrobacter freundii bacteria. A single channel tubular ceramic membrane with a nominal pore size of 0.14 µm was used. It has been demonstrated that the MF ceramic membrane has been successfully applied to bacteria cell removal and to effectively eliminate colloidal particles from glycerol fermentation broths. However, due to fouling, the significant reduction of the MF performance has been demonstrated. In order to investigate the impact of transmembrane pressure (TMP) and feed flow rate (Q) on MF performance, 24 experiments have been performed. The highest steady state permeate flux (138.97 dm3/m2h) was achieved for 0.12 MPa and 1000 dm3/h. Fouling analysis has been studied based on the resistance-in series model. It has been found that the percentage of irreversible fouling resistance during the MF increases with increasing TMP and Q. The permeate flux regeneration has been achieved by membrane cleaning with 3 wt % NaOH and 3 wt % H3PO4 at 45 °C. The results of this study are expected to be useful in industrially employing the MF process as the first step of glycerol fermentation broth purification.

Bio-Precipitation of Carbonate and Phosphate Minerals Induced by the Bacterium Citrobacter freundii ZW123 in an Anaerobic Environment

In this study, a facultative anaerobic strain isolated from marine sediments and identified as Citrobacter freundii, was used to induce the precipitation of carbonate and phosphate minerals in the laboratory under anaerobic conditions. This is the first time that the ability of C. freundii ZW123 to precipitate carbonate and phosphate minerals has been demonstrated. During the experiments, carbonic anhydrase, alkaline phosphatase and ammonium released by the bacteria not only promoted an increase in pH, but also drove the supersaturation and precipitation of carbonate and phosphate minerals. The predominant bio-mediated minerals precipitated at various Mg/Ca molar ratios were calcite, vaterite, Mg-rich calcite, monohydrocalcite and struvite. A preferred orientation towards struvite was observed. Scanning transmission electron microscopy (STEM) and elemental mapping showed the distribution of magnesium and calcium elements within Mg-rich calcite. Many organic functional groups, including C=O, C–O–C and C–O, were detected within the biominerals, and these functional groups were also identified in the associated extracellular polymeric substances (EPS). Fifteen kinds of amino acid were detected in the biotic minerals, almost identical to those of the EPS, indicating a close relationship between EPS and biominerals. Most amino acids are negatively charged and able to adsorb cations, providing an oversaturated microenvironment to facilitate mineral nucleation. The X-ray photoelectron spectroscopy (XPS) spectrum of struvite shows the presence of organic functional groups on the mineral surface, suggesting a role of the microorganism in struvite precipitation. The ZW123 bacteria provided carbon and nitrogen for the formation of the biotic minerals through their metabolism, which further emphasizes the close relationship between biominerals and the microorganisms. Thermal studies showed the enhanced thermal stability of biotic minerals, perhaps due to the participation of the bacteria ZW123. The presence of amino acids such as Asp and Glu may explain the high magnesium content of some calcites. Molecular dynamics simulations demonstrated that the morphological change and preferred orientation were likely caused by selective adsorption of EPS onto the various struvite crystal surfaces. Thus, this study shows the significant role played by C. freundii ZW123 in the bioprecipitation of carbonate and phosphate minerals and provides some insights into the processes involved.

Identifikasi Bakteri Patogen Pada Ikan Nila (Oreochromis niloticus) di Danau Batur, Bali

This research aims to determine types of pathogen bacteria presented in body parts (liver and kidneys) of Tilapia (Oreochromis nilotics), types of bacteria attacks wild Tilapia and fish in Floating Culture Net (FCN) of Batur Lake as well as its prevalence bacteria found in Tilapia on Batur lake. Method used in this research is descriptive method, with a sampling method based on purposive sampling technique. According to identification’s result obtained, types of bacteria that infect liver were including to Aeromonas hydrophila, Plesiomonas shigelloides and Citrobacter freundii bacteria. Meanwhile, bacteria that infect kidneys are Aeromonas hydrophila, Aeromonas caviae, Plesiomonas shigelloides and Citrobacter freundii. Bacteria that infect wild fish are Aeromonas hydrophila, Aeromonas caviae and Plesiomonas shigelloides , while fishes in FCN are infected by Aeromonas hydrophila, Aeromonas caviae, Plesiomonas shigelloides and Citrobacter freundii bacteria. Infection prevalence of pathogen bacteria in Tilapia in Batur Lake is Aeromonas hydrophila at 55,5%, Plesiomonas shigelloides for 27,7%, Aeromonas caviae and Citrobacter freundii at 11,1%. According to sampling location, prevalence of bacteria that attacks wild fish are Aeromonas hydrophila and Plesiomonas shigelloides at 44,4%, Aeromonas caviae for 11,1%. Prevalence of bacteria that attacks fish in FCN is Aeromonas hydrophila for 66,6%, Citrobacter freundii infection at 22,2%, Aeromonas caviae and Citrobacter freundii at 11,1%.

Coupling heavy metal resistance and oxygen flexibility for bioremoval of copper ions by newly isolated Citrobacter freundii JPG1

The potential for bioremoval of copper ions was investigated by a novel strain of bacterium Citrobacter freundii JPG1, which was newly isolated from gold mining tailing in China and grew either aerobically or anaerobically. The strain cross-tolerated heavy metals of Ag+, Cd2+, Co2+, Cr6+, Cu2+ and Ni2+ and removed copper under both aerobic and anaerobic conditions with the stress of copper. Under aerobic conditions, the cells grew rapidly and exhibited higher biomass at low copper concentrations (<1 mmol L−1), while the growth of cells was almost completely inhibited at high copper concentrations (2 mmol L−1). However, the cell growths were less affected by copper under anaerobic conditions. Similarly, the copper-removal efficiency was affected by oxygen and the capability of copper removal by anaerobic cells was significantly higher than that of aerobic cells (P < 0.05). The quantitative measurement of extracellular biosorption and intercellular bioaccumulation of copper indicated that biosorption efficiencies for aerobic cells (37%) and anaerobic cells (38%) were similar but the bioaccumulation by anaerobic cells was almost ten-fold higher than that by aerobic cells, indicating bioaccumulation contributed most in copper reduction under anaerobic conditions. Overall, the results suggested the facultative strain C. freundii JPG1 had great potential in the treatment of copper-laden industrial wastewater under both aerobic and anaerobic conditions.

Drug Management Policies and Measures to Protect Consumer's Right -Improvement in Management System for Injectable Drugs-

이대목동병원 신생아 중환자실 환아 4명이 인큐베이터 안에서 치료를 받고 있던 중 숨지는 사고가 발생했다. 이에 대해 국립과학수사연구원은 사인을 시트로박터 프룬디균 감염에 의한 패혈증으로 추정하면서 주사제 및 취급 과정 중 오염에 의한 감염가능성이 있다고 했다. 이대목동병원 신생아 중환자실 사망사고 원인이라고 추정되는 문제는 병원 내 감염관리 문제, 의료인력 부족으로 인한 문제, 주사제 분주문제 등이 있다. 국민의 건강을 보호하기 위해서는 의약품을 제조하는 단계에서부터 이력추적을 통해 해당 의약품의 안전관리가 보장될 필요가 있다. 본고에서는 의약품 안전관리 현황과 주사제 안전관리에 대해서 검토한 후 주사제 분주문제에 관한 문제점과 해결방안을 검토해 보았다. 연구결과 다음과 같은 개선방안을 마련하게 되었다. 첫째, 미흡한 주사제 소량포장을 의무화해야 한다. 이를 위해서는 「의약품 소량포장단위 공급에 관한 규정」에서 주사제의 소량포장을 의무화할 필요가 있다. 둘째, 주사제를 1병 1환자로 의무화 하더라도 주사제에 대한 관리체계가 병원자율에 맡겨져 있어, 원천적으로 예방하는 데 한계가 있다. 따라서 「의약품 바코드와 RFID tag의 사용 및 관리요령」[별표 1의 2]에서 수액류 관련 예외 사항을 삭제하는 것이 필요하다.Four premature babies died while treated in the neonatal intensive care unit at Ewha Womans University Mokdong Hospital. The National Forensic Service suspected that the consecutive deaths were caused by blood poisoning brought about by the bacteria Citrobacter freundii, raising the possibility that the injectable drugs had already been contaminated or become contaminated in the preparation process before administered to the babies. The possible causes of this unfortunate incident lie in such problems as inadequate infection control, lack of medical personnel and divided use of injection solution at hospital. Public health necessitates safety management of drugs by ensuring traceability from the manufacturing stage. This study examined the current status of safety management of drugs including injectable ones and explored problems associated with divided use of injectable drugs and solutions to the problems. The study suggests the following ways for improvement. First, the duty to produce small packaged drugs needs to be performed more strictly. To this end, the Regulations on Small Volume Packaging Supply of Drugs have to prescribe a mandatory obligation concerning small volume packaging of injectable drugs. Next, even though the “one bottle of injection solution for one patient” duty becomes mandatory, managing injectable drugs is still left to the discretion of hospitals, which will make the duty less workable. It is, therefore, required to delete the provisions on exceptive cases of injections in the attached Table 1-2 to the Guidelines on the Use and Management of Barcodes and RFID Tags for Drugs.

The Application of Membrane Distillation for Broth Separation in Membrane Bioreactors

The possibility of applying membrane distillation to support the fermentation process was investigated. The capillary polypropylene membranes were assembled in the membrane modules. The studies were carried out using the standard solutions containing the compounds frequently occurring in the broths such as ethanol, citric, acetic and lactic acids, glycerol and 1,3-propanediol. The performance of membrane bioreactor, in which glycerol was fermented by the use of Citrobacter freundii bacteria was also examined. The separation of particular components of broths was investigated in a long-term application of membrane distillation and a good resistance to wetting of the used polypropylene membrane was demonstrated during the two year period.

Application of nanofiltration for production of 1,3-propanediol in membrane bioreactor

Biodiesel production from rapeseed oil generates various by-products, for example crude glycerol. Glycerol can be utilized by microbial conversion to 1,3-propanediol (1,3-PD), which can be used as a raw material for the synthesis of polyesters and polyurethanes. The results of studies on the synthesis of 1,3-PD from glycerol by use of Citrobacter freundii bacteria were presented. A biosynthesis cost is generally determined based on the costs of nutrients used for culture medium preparation and the costs of broth separation by integrated downstream processes. In this work nanofiltration (NF) was used as a pre-treatment stage for 1,3-PD separation from the broth. Additionally, the NF retentate was reused for the preparation of culture medium, resulting in a change of the initial composition of broth. The catalytic activity of enzymes is strongly affected by broth composition. However, the efficiency of batch fermentations based on the commercial media and NF retentate was similar. Thus, the application of NF process enables a cheaper production of 1,3-PD by biosynthesis. The influence of some broth ingredients, such as carboxylic acids, on variations of biocatalytic properties of used bacteria was discussed.

Studies of polypropylene membrane fouling during microfiltration of broth with Citrobacter freundii bacteria

Abstract In this work a fouling study of polypropylene membranes used for microfiltration of glycerol solutions fermented by Citrobacter freundii bacteria was presented. The permeate free of C. freundii bacteria and having a turbidity in the range of 0.72–1.46 NTU was obtained. However, the initial permeate flux (100–110 L/m2h at 30 kPa of transmembrane pressure) was decreased 3–5 fold during 2–3 h of process duration. The performed scanning electron microscope observations confirmed that the filtered bacteria and suspensions present in the broth formed a cake layer on the membrane surface. A method of periodical module rinsing was used for restriction of the fouling influence on a flux decline. Rinsing with water removed most of the bacteria from the membrane surface, but did not permit to restore the initial permeate flux. It was confirmed that the irreversible fouling was dominated during broth filtration. The formed deposit was removed using a 1 wt% solution of sodium hydroxide as a rinsing solution.

The ultrafiltration ceramic membrane used for broth separation in membrane bioreactor

In this work the studies of glycerol fermentation in a bioreactor connected with separation of broth by ultrafiltration process were presented. The study was carried out with broths, which were prepared using Citrobacter freundii bacteria. A tubular tight ultrafiltration ceramic membrane (8kD) was applied and the complete rejection of bacterial and other suspended solids was achieved. The produced permeate was clear, with a turbidity at a level of 0.1NTU. Although a tight ultrafiltration membrane was used, the ions retention was at a low level – below 10%. In a comparison with a classical method of fermentation with broth bleeding, the yield of fermentation was increased by the application of ultrafiltration for treatment of broth from the bioreactor. However, a significant (over 70%) permeate flux decrease was observed due to a fouling, which is an essential limitation in the application of the membrane separation. A periodical module rinsing with 1% NaOH solutions was used for limitation of the fouling influence on a flux decline.

In Vitro Assessment for Antimicrobial Activity of Lactobacillus Helveticus and its Natural Glycopeptides Against Mastitis Causing Pathogens in Dairy Cat

Probiotic lactic acid bacteria have a great potential to control bovine mastitis as well as they are favourable choice to treat many infectious diseases of human. These bacteria are well known as having many properties which make them beneficial to control pathogenic microorganisms. These include, the ability to adhere to cell, the reduction of pathogenic bacteria adherents, the co–aggregation, the production of organic acids, hydrogen peroxide, bacteriocin and etc., to be safe and non–pathogenic, which antagonize pathogenic microorganisms. However, each strain must be well identified and characterized in vitro before using for disease treatment. The aim of the present study was to screen three kind of test suspensions: TS1, TS2 and TS3, which contains probiotic lactic acid bacterium Lactobacillus helveticus or its natural glycopeptides, and other natural immunomodulators, in order to investigate which content were the most effective in inhibiting several mastitis causing bacteria in dairy cattle: coagulase–positive Staphylococcus aureus, coagulase–negative staphylococci S. haemolyticus, S. saprophyticus, S. simulans, S. vitulinus, and Gram–negative bacteria Citrobacter freundii and Serratia liquefaciens. Test suspensions TS1, TS2 and TS3 were adjusted by pH 6.3, then tested in vitro by well diffusion assay to determine their antimicrobial effect against bacteria. Furthermore haemolytic activity of applied test suspensions were determined. In results TS1 (9-13 mm) and TS2 (10-15 mm) showed the inhibition effect on four of eight tested bacterial strains, whereas TS3 did not displayed any antimicrobial effect. TS2 have a greatest antimicrobial activity as they resulted in the largest inhibition zones.

Comparative bacterial degradation and detoxification of model and kraft lignin from pulp paper wastewater and its metabolites

Continuous discharge of lignin containing colored wastewater from pulp paper mill into the environment has resulted in building up their high level in various aquatic systems. In this study, the chemical texture of kraft lignin in terms of pollution parameters (COD, TOC, BOD, etc.) was quite different and approximately twofold higher as compared to model lignin at same optical density (OD 3.7 at 465 nm) and lignin content (2000 mg/L). For comparative bacterial degradation and detoxification of model and kraft lignin two bacteria Citrobacter freundii and Serratia marcescens were isolated, screened and applied in axenic and mixed condition. Bacterial mixed culture was found to decolorize 87 and 70 % model and kraft lignin (2000 mg/L), respectively; whereas, axenic culture Citrobacter freundii and Serratia marcescens decolorized 64, 60 % model and 50, 55 % kraft lignin, respectively, at optimized condition (34 °C, pH 8.2, 140 rpm). In addition, the mixed bacterial culture also showed the removal of 76, 61 % TOC; 80, 67 % COD and 87, 65 % lignin from model and kraft lignin, respectively. High pollution parameters (like TOC, COD, BOD, sulphate) and toxic chemicals slow down the degradation of kraft lignin as compared to model lignin. The comparative GC–MS analysis has suggested that the interspecies collaboration, i.e., each bacterial strain in culture medium has cumulative enhancing effect on growth, and degradation of lignin rather than inhibition. Furthermore, toxicity evaluation on human keratinocyte cell line after bacterial treatment has supported the degradation and detoxification of model and kraft lignin.

The study of glycerol-based fermentation and broth downstream by nanofiltration

Abstract In this work, the glycerol fermentation was carried out using Citrobacter freundii bacteria. The influence of glycerol and metabolites concentrations, and the pH changes on the efficiency of 1,3-propanediol production, during batch and fed-batch processes, was presented. The nanofiltration was used for the separation of obtained post-fermentation solutions. The resulted 1,3-PD solutions were significantly desalted, which may facilitate further downstream processes during 1,3-PD production.

Separation of post-fermentation glycerol solution by nanofiltration membrane distillation system

The fermentation process generates a broth containing the metabolites, residual substrates and mineral salts. Various unit operations are required for the separation, purification and concentration of organic compounds from the fermentation broth. In this work, nanofiltration (NF) and membrane distillation (MD) were proposed as a method for the preparation of preliminary separated concentrates for a further separation by other processes, such as rectification. The study was carried out using the real broths obtained from the fermentation of glycerol solutions with the Leuconostoc mesenteroides and Citrobacter freundii bacteria. The obtained broths were subjected to the pretreatment by microfiltration, followed by a further separation with NF. The NF270 membrane was used for NF process, and the rejection of citric acid and multivalent ions close to 100% was achieved. The permeate and retentate from NF process were subsequently concentrated about four to five times using membrane distillation. The membrane fouling during the NF and MD processes was observed.