Eco-Friendly Water-Processable Polyimide Binders with High Adhesion to Silicon Anodes for Lithium-Ion Batteries

Silicon is an attractive anode material for lithium-ion batteries (LIBs) because of its natural abundance and excellent theoretical energy density. However, Si-based electrodes are difficult to commercialize because of their significant volume changes during lithiation that can result in mechanical damage. To overcome this limitation, we synthesized an eco-friendly water-soluble polyimide (W-PI) precursor, poly(amic acid) salt (W-PAmAS), as a binder for Si anodes via a simple one-step process using water as a solvent. Using the W-PAmAS binder, a composite Si electrode was achieved by low-temperature processing at 150 °C. The adhesion between the electrode components was further enhanced by introducing 3,5-diaminobenzoic acid, which contains free carboxylic acid (-COOH) groups in the W-PAmAS backbone. The -COOH of the W-PI binder chemically interacts with the surface of Si nanoparticles (SiNPs) by forming ester bonds, which efficiently bond the SiNPs, even during severe volume changes. The Si anode with W-PI binder showed improved electrochemical performance with a high capacity of 2061 mAh g^-1 and excellent cyclability of 1883 mAh g^-1 after 200 cycles at 1200 mA g^-1. Therefore, W-PI can be used as a highly effective polymeric binder in Si-based high-capacity LIBs.

Synergistic Effect of a Dual-Salt Liquid Electrolyte with a LiNO3 Functional Additive toward Stabilizing Thin-Film Li Metal Electrodes for Li Secondary Batteries

Li metal thickness has been considered a key factor in determining the electrochemical performance of Li metal anodes. The use of thin Li metal anodes is a prerequisite for increasing the energy density of Li secondary batteries intended for emerging large-scale electrical applications, such as electric vehicles and energy storage systems. To utilize thin (20 μm thick) Li metal anodes in Li metal secondary batteries, we investigated the synergistic effect of a functional additive (Li nitrate, LiNO₃) and a dual-salt electrolyte (DSE) system composed of Li bis(fluorosulfonyl)imide (LiTFSI) and Li bis(oxalate)borate (LiBOB). By controlling the amount of LiNO₃ in DSE, we found that DSE containing 0.05 M LiNO₃ (DSE-0.05 M LiNO₃) significantly improved the electrochemical performance of Li metal anodes. DSE-0.05 M LiNO₃ increased the cycling performance by 146.3% [under the conditions of a 1C rate (2.0 mA cm^-2), DSE alone maintained 80% of the initial discharge capacity up to the 205th cycle, whereas DSE-0.05 M LiNO₃ maintained 80% up to the 300th cycle] and increased the rate capability by 128.2% compared with DSE alone [the rate capability of DSE-0.05 M LiNO₃ = 50.4 mAh g^-1, and DSE = 39.3 mAh g^-1 under 7C rate conditions (14.0 mA cm^-2)]. After analyzing the Li metal surface using scanning electron microscopy and X-ray photoelectron spectroscopy, we were able to infer that the stabilized solid electrolyte interphase layer formed by the combination of LiNO₃ and the dual salt resulted in a uniform Li deposition during repeated Li plating/stripping processes.

Microalgae-Templated Spray Drying for Hierarchical and Porous Fe3O4/C Composite Microspheres as Li-ion Battery Anode Materials

A method of microalgae-templated spray drying to develop hierarchical porous Fe₃O₄/C composite microspheres as anode materials for Li-ion batteries was developed. During the spray-drying process, individual microalgae serve as building blocks of raspberry-like hollow microspheres via self-assembly. In the present study, microalgae-derived carbon matrices, naturally doped heteroatoms, and hierarchical porous structural features synergistically contributed to the high electrochemical performance of the Fe₃O₄/C composite microspheres, enabling a discharge capacity of 1375 mA·h·g^-1 after 700 cycles at a current density of 1 A/g. Notably, the microalgal frameworks of the Fe₃O₄/C composite microspheres were maintained over the course of charge/discharge cycling, thus demonstrating the structural stability of the composite microspheres against pulverization. In contrast, the sample fabricated without microalgal templating showed significant capacity drops (up to ~40% of initial capacity) during the early cycles. Clearly, templating of microalgae endows anode materials with superior cycling stability.

Highly Stable Porous Polyimide Sponge as a Separator for Lithium-metal Secondary Batteries

To inhibit Li-dendrite growth on lithium (Li)-metal electrodes, which causes capacity deterioration and safety issues in Li-ion batteries, we prepared a porous polyimide (PI) sponge using a solution-processable high internal-phase emulsion technique with a water-soluble PI precursor solution; the process is not only simple but also environmentally friendly. The prepared PI sponge was processed into porous PI separators and used for Li-metal electrodes. The physical properties (e.g., thermal stability, liquid electrolyte uptake, and ionic conductivity) of the porous PI separators and their effect on the Li-metal anodes (e.g., self-discharge and open-circuit voltage properties after storage, cycle performance, rate capability, and morphological changes) were investigated. Owing to the thermally stable properties of the PI polymer, the porous PI separators demonstrated no dimensional changes up to 180 °C. In comparison with commercialized polyethylene (PE) separators, the porous PI separators exhibited improved wetting ability for liquid electrolytes; thus, the latter improved not only the physical properties (e.g., improved the electrolyte uptake and ionic conductivity) but also the electrochemical properties of Li-metal electrodes (e.g., maintained stable self-discharge capacity and open-circuit voltage features after storage and improved the cycle performance and rate capability) in comparison with PE separators.

Midkine Promotes Odontoblast-like Differentiation and Tertiary Dentin Formation

Autophagy is an intracellular self-degradation process that is essential for tissue development, cell differentiation, and survival. Nevertheless, the role of autophagy in tooth development has not been definitively identified. The goal of this study was to investigate how autophagy is involved in midkine (MK)-mediated odontoblast-like differentiation, mineralization, and tertiary dentin formation in a mouse tooth pulp exposure model. In vitro studies show that MK and LC3 have similar expression patterns during odontoblast-like cell differentiation. Odontoblast-like cell differentiation is promoted through MK-mediated autophagy, which leads to increased mineralized nodule formation. Subcutaneous transplantation of hydroxyapatite/tricalcium phosphate with rMK-treated human dental pulp cells led to dentin pulp-like tissue formation through MK-mediated autophagy. Furthermore, MK-mediated autophagy induces differentiation of dental pulp cells into odontoblast-like cells that form DSP-positive tertiary dentin in vivo. Our findings may provide 1) novel insight into the role of MK in regulating odontoblast-like differentiation and dentin formation in particular via autophagy and 2) potential application of MK in vital pulp therapy.

PIN1 is a new therapeutic target of craniosynostosis

Gain-of-function mutations in fibroblast growth factor receptors (FGFRs) cause congenital skeletal anomalies, including craniosynostosis (CS), which is characterized by the premature closure of craniofacial sutures. Apert syndrome (AS) is one of the severest forms of CS, and the only treatment is surgical expansion of prematurely fused sutures in infants. Previously, we demonstrated that the prolyl isomerase peptidyl-prolyl cis-trans isomerase interacting 1 (PIN1) plays a critical role in mediating FGFR signaling and that Pin1+/- mice exhibit delayed closure of cranial sutures. In this study, using both genetic and pharmacological approaches, we tested whether PIN1 modulation could be used as a therapeutic regimen against AS. In the genetic approach, we crossbred Fgfr2S252W/+, a mouse model of AS, and Pin1+/- mice. Downregulation of Pin1 gene dosage attenuated premature cranial suture closure and other phenotypes of AS in Fgfr2S252W/+ mutant mice. In the pharmacological approach, we intraperitoneally administered juglone, a PIN1 enzyme inhibitor, to pregnant Fgfr2S252W/+ mutant mice and found that this treatment successfully interrupted fetal development of AS phenotypes. Primary cultured osteoblasts from Fgfr2S252W/+ mutant mice expressed high levels of FGFR2 downstream target genes, but this phenotype was attenuated by PIN1 inhibition. Post-translational stabilization and activation of Runt-related transcription factor 2 (RUNX2) in Fgfr2S252W/+ osteoblasts were also attenuated by PIN1 inhibition. Based on these observations, we conclude that PIN1 enzyme activity is important for FGFR2-induced RUNX2 activation and craniofacial suture morphogenesis. Moreover, these findings highlight that juglone or other PIN1 inhibitors represent viable alternatives to surgical intervention for treatment of CS and other hyperostotic diseases.

Paratubal cancer found at the time of laparoscopic surgery for adnexal torsion: a case report and literature review

INTRODUCTION

Paratubal cysts are common incidental finding, but malignant paratubal cancers have rare occurrence and have not been sufficiently described and discussed in previous studies.

CASE REPORT

This report describes a case of a 70-year-old female who underwent emergent laparoscopy for adnexal torsion. A serous cystadenocarcinoma arising in a paratubal cyst and accompanied by tubal torsion was revealed by frozen section and successfully treated with laparoscopic cytoreductive surgery and adjuvant chemotherapy.

CONCLUSION

This report is the first case of paratubal cancer with bilateral tubal torsion which was diagnosed and treated with laparoscopic surgery, and the third report describing serous cystadenocarcinoma arising in a paratubal cyst. In the laparoscopic surgery for the paratubal cyst clinically presumed as accompanied with tubal torsion, surgeons should not ignore the possibility of malignancy in spite of the rare incidence of paratubal cancers and the preconception that adnexal malignancies are seldom accompanied by tubal torsion.

Demographic and serological characteristics of Asian Americans with hepatitis B infection diagnosed at community screenings

There is limited information regarding follow-up and hepatitis B serological status of Asian Americans diagnosed with chronic hepatitis B (CHB) through community screening. The aims of this study were to evaluate the prevalence and characterize CHB among Asians living in Los Angeles, assess follow-up of individuals with CHB diagnosed at screening and compare with patients with CHB followed by community gastroenterologists. Between October 2007 and May 2010, 7387 Asians were tested for HBV. HBsAg positive individuals (CHB) underwent additional testing for ALT, HBeAg/anti-HBe and HBV DNA. Patients with CHB were contacted 6 months later to determine whether they received follow-up care. We compared serological patterns of these individuals with CHB to patients with CHB who were seen for the first time (treatment naïve) by community gastroenterologists during the study period. Prevalence of CHB was 5.2%. About 99% patients with CHB were foreign-born, and only 27% could read/write English. 297 (77%) patients with CHB could be reached 6 months after diagnosis; 43% did not receive follow-up care, mostly because of lack of medical insurance. Patients with CHB followed by gastroenterologists were more likely to have insurance (69% vs 26%, P < 0.0001). 90% patients with CHB at screening were HBeAg negative/anti-HBe positive with 62% having inactive disease compared to only 30% of patients seen by gastroenterologists (P < 0.0001). Among CHB participants, 13% met criteria for treatment compared to 51% of patients with CHB (P < 0.0001). Only a small number of CHB screening participants require antiviral therapy. Lack of medical insurance is the main reason for most patients with CHB not seeking follow-up care after screening.

Nestin expression as an indicator of cervical cancer initiation

Nestin is an intermediate filament protein expressed in proliferating cells during embryonic development of the central nervous system (CNS) and considered to be a neuronal stem cell/progenitor cell marker. This study investigated the difference of nestin expression between pre-cancer (carcinoma in situ - CIS) and cancer of cervix in 129 tissues (49 normal cervix, 41 CIS, and 39 invasive cervical cancer) through the use of a paraffin-embedded tissue array. Immunostaining was evaluated by intensity, proportion of stained cells, and pattern of expression. The expression of nestin was positive in 63.4% (26/41) for CIS and 43.6% (17/39) for invasive cervical cancer, but only 26.5% (13/49) for normal tissues (p = 0.002). Strong positive staining/large proportion staining were 53.7% (22/41) / 36.6% (15/41), 15.4% (6/39) / 61.5% (24/39) in the CIS and invasive cervical cancer tissues, respectively (p = 0.043, p < 0.001). The diffuse stain with basal layer was positive in 90.2% (37/41) for CIS, but only 24.5% (12/49) of the samples were positive in normal tissues (p < 0.001). Based on these results, the authors suggest that nestin expression seems to participate in the step of cancer initiation and could potentially be a useful marker in the early detection of cervical cancer.

Modulation of natural killer cell activity affected by electroacupuncture through lateral hypothalamic area in rats

Electroacupuncture (EA) has been reported to modulate natural killer cell (NK cell) activities. Also it is well known that hypothalamus directly mediates the effects of EA on analgesia. Especially lateral hypothalamic area (LHA) is related to splenic NK cell activities. In order to investigate the relationship between hypothalamus and effects of EA on NK cell activity, lesions have been made bilaterally at LHA of Spraque-Dawley rats. Subsequently, NK cell cytotoxities of normal and lesioned rats were measured with (51)Cr release immunoassay after EA stimulation for 2 and 14 days. NK cell activity of EA group was significantly higher than sham group. In addition, lesions abolished effects of EA on NK cell activity. These results strongly suggest that LHA is closely related to increase of NK cell activity induced by EA.

Effects of uwhangchungsimwon on cell viability, proliferation, and gene expression of human neuronal cell line IMR32

Uwhangchungsimwon (pill, UC) is one of the traditional Korean medical prescriptions that has been most frequently used for stroke. To characterize the effects of UC on human neuronal cells, the human neuroblastoma cell line IMR32 was treated with UC, and cell viability, cell proliferation, apoptosis, and gene expression were analyzed. The effect of UC on recovery of cell viability was analyzed following stress induction by nutrient depletion or cold shock. Flow cytometric analysis of the cell cycle showed that UC inhibits cell cycle progression of IMR32 in a dose- and time-dependent manner. UC was also identified to increase cell viability and suppress apoptosis induction by a DNA-damaging agent, etoposide. Quantitative RT-PCR analysis revealed that expressions of the p53 tumor suppressor gene and its downstream effect, Waf1, are stimulated whereas expressions of positive cell cycle regulators, c-Myc, c-Fos, and Cyclin D1 were repressed by UC treatment. Moreover, while expression levels of apoptosis inhibitors, Bcl-2 and Bcl-XL were increased following UC treatment, that of an apoptosis promoter, Bax, was decreased. In addition, expression of BMP-7, which has been recently demonstrated to improve the motor neuron recovery from stroke, was induced by UC while it was not detected in untreated cells. Taken together, our data suggest that the pharmacoclinical effects of UC might be derived in part from its negative regulation of cell proliferation and apoptosis through the transcriptional control of related genes.

Developing and sustaining 3-chlorophenol-degrading populations in up-flow anaerobic column reactors under circum-denitrifying conditions

Microbial consortia capable of degrading 3-chlorophenol (3-CP) were enriched in continuous up-flow column reactors under circum-denitrifying conditions. 3-CP degradation capability was developed and sustained when 3-CP was supplied at 16-21 microM, although suppression of the 3-CP degradation capability was observed when 3-CP was supplied at 42 microM. When 3-CP was stably degraded, the ratio of nitrate consumption to 3-CP degradation approached the theoretical stoichiometric value, which was calculated by assuming a 3-CP degradation-dependent nitrate reduction. Batch-incubation experiments demonstrated that the microbial consortium that was enriched in the column reactors required either nitrate or oxygen for degrading 3-CP, while 3-CP was not degraded under sulfate-degrading conditions. Although many attempts were made to sustain the microbial 3-CP degradation capability under denitrifying conditions, mostly in batch cultures, none of them have been successful so far. Therefore, the results obtained in this study may be the first to demonstrate sustainable 3-CP degradation capability under circum-denitrifying conditions.

A controlled clinical study of serosa-invasive gastric carcinoma patients who underwent surgery plus intraperitoneal hyperthermo-chemo-perfusion (IHCP)

BACKGROUND

Despite recent advances in the treatment of advanced gastric carcinomas, no satisfactory outcomes are available because of micrometastases and free-floating carcinoma cells already existing in the peritoneal cavity. From 1990, we started using intraperitoneal hyperthermo-chemo-perfusion (IHCP) to prevent and to treat peritoneal metastasis after surgical resection of stomach cancer.

METHOD

We analyzed 103 serosa-invasive gastric carcinoma patients who underwent surgical resection between 1990 and 1995. Fifty-two patients who received surgery plus IHCP were compared with 51 patients who underwent surgery only, as controls. IHCP was administered for 2 h with an automatic IHCP device (closed-circuit system) just after surgical resection, with the patient under hypothermic general anesthesia (32.4 degrees C-34.0 degrees C). As perfusate, we used 1.5% peritoneal dialysis solution mixed with 10 micrograms/ml of mitomycin-C (MMC), warmed at an inflow temperature of over 44 degrees C.

RESULTS

The overall 5-year survival rate (5-YSR) of the 103 patients was 29.97%. The 5-YSR was higher in the IHCP group than in the control group, at 32.7% and 27.1%, respectively, but this difference was not significant. However, in the 65 serosa-invasive gastric carcinoma patients (excluding those in stage IV) the 5-YSR was significantly higher (P = 0.0379) in the IHCP group than in the control group, at 58.6% and 44.4%, respectively. On multivariate analysis of all 103 patients, depth of tumor invasion and lymph node metastasis were significant factors for survival, whereas significant factors on univariate analysis, such as combined operation, distant metastasis, and peritoneal metastasis, were not significant. The most common recurrence patterns were loco-regional in the IHCP group and peritoneal in the control group.

CONCLUSION

Complete cytoreductive surgery plus IHCP is effective to prevent and to treat peritoneal metastasis, and it should lead to long-term survival for serosa-invasive gastric carcinoma patients. However, there are some limitations for the treatment of peritoneal metastasis in stage IV patients with distant metastases.

A novel denitrifying bacterial isolate that degrades trimethylamine both aerobically and anaerobically via two different pathways

The aerobic and anaerobic degradation of trimethylamine by a newly isolated denitrifying bacterium from an enrichment culture with trimethylamine inoculated with activated sludge was studied. Based on 16S rDNA analysis, this strain was identified as a Paracoccus sp. The isolate, strain T231, aerobically degraded trimethylamine, dimethylamine and methylamine and released a stoichiometric amount of ammonium ion into the culture fluid as a metabolic product, indicating that these methylated amines were completely degraded to formaldehyde and ammonia. The strain degraded trimethylamine also under denitrifying conditions and consumed a stoichiometric amount of nitrate, demonstrating that complete degradation of trimethylamine was coupled with nitrate reduction. Cell-free extract prepared from cells grown aerobically on trimethylamine exhibited activities of trimethylamine mono-oxygenase, trimethylamine N-oxide demethylase, dimethylamine mono-oxygenase, and methylamine mono-oxygenase. Cell-free extract from cells grown anaerobically on trimethylamine and nitrate exhibited activities of trimethylamine dehydrogenase and dimethylamine dehydrogenase. These results indicate that strain T231 had two different pathways for aerobic and anaerobic degradation of trimethylamine. This is a new feature for trimethylamine metabolism in denitrifying bacteria.

Association between TNF-alpha promoter polymorphism and Helicobacter pylori cagA subtype infection

AIMS

To assess the importance of tumour necrosis factor alpha (TNF-alpha) promoter polymorphism in relation to infection with the cytotoxin associated gene A (cagA) subtype of Helicobacter pylori within a dyspeptic Korean population.

METHODS

Eighty three patients with gastric disease and 113 healthy controls were studied. The DNA from gastric biopsy specimens was analysed by H pylori specific and cagA specific polymerase chain reaction (PCR). To characterise TNF-alpha polymorphism at positions -308 and -238, PCR based restriction fragment length polymorphism analysis was performed.

RESULTS

Helicobacter pylori infection was closely correlated with G to A transition at position -308 of the TNF-alpha promoter when compared with healthy controls (odds ratio (OR), 2.912; 95% confidence interval (CI), 1.082 to 7.836; p = 0.034). Although TNF-alpha -308 polymorphism in patients with H pylori was not significantly different from that in patients without H pylori, the -308A polymorphism was strongly associated with H pylori cagA subtype infection when compared with the polymorphism in cagA negative H pylori infection (OR, 8.757; 95% CI, 1.413 to 54.262; p = 0.019) and healthy controls (OR, 3.683; 95% CI, 1.343 to 10.101; p = 0.011). G to A genetic change at position -238 of the TNF-alpha gene was not significantly associated with H pylori cagA subtype infection. In addition, genetic polymorphisms at both sites of the TNF-alpha promoter in patients with H pylori infection did not correlate with the severity of disease.

CONCLUSION

TNF-alpha -308A polymorphism was significantly related to infection with the H pylori cagA subtype in Korean patients with gastric disease.

A phase II study of VP-16-fosfamide-cisplatin combination chemotherapy plus early concurrent thoracic irradiation for previously untreated limited small cell lung cancer

BACKGROUND

At present the addition of thoracic irradiation to combination chemotherapy is a standard treatment for limited staged small cell lung cancer. However, there is still controversy about the optimum timing of chest irradiation. We conducted a phase II study of etoposide (VP-16)-ifosfamide-cisplatin (VIP) combination chemotherapy plus early concurrent thoracic irradiation for the patients with previously untreated limited small cell lung cancer in order to assess if the treatment modality could improve the response rate and the toxicity.

METHODS

Forty-four patients with limited small cell lung cancer were treated with etoposide-ifosfamide-cisplatin and concurrent thoracic irradiation. Combination chemotherapy consisted of etoposide 100 mg/m2 (on days 1-3), ifosfamide 1000 mg/m2 (on days 1 and 2) and cisplatin 100 mg/m2 (on day 1). Concurrent thoracic irradiation consisted of a total of 4000 cGy over 4 weeks starting on the first day of the first chemotherapy. All patients who showed a complete response were given prophylactic cranial irradiation for 2.5 weeks.

RESULTS

Forty-four of the 49 patients who entered the study from May 1994 to August 1998 were evaluable. The median age was 59 years and 40 patients had a performance status of 0 or 1. The median survival time was 22.5 months. Twenty-eight patients (62%) showed a complete response and 16 (38%) a partial response. Twenty-four patients (54%) developed grade 3 or 4 neutropenia; there was a 9% RTOG score 3 or 4 esophagitis.

CONCLUSION

VIP combination chemotherapy and early concurrent thoracic irradiation for patients with limited stage small cell lung cancer revealed excellent antitumor response with tolerable toxicity.

Inhibition of human smooth muscle cell proliferation by gamigeonsim-tang through the transcriptional regulation of cell cycle-controlling genes

The effects of gamigeonsim-tang (GGT) on cellular proliferation and expression of cell cycle-related genes were investigated in human smooth muscle cell HISM. HISM cells were treated with an aqueous extract of GGT. Cellular proliferation was investigated by an immunocytometric analysis of PCNA expression and a flow cytometric analysis of the cell cycle progression. Reduced expression of PCNA and a significant accumulation of G1 phase cells were observed following treatment, indicating that GGT inhibits cellular proliferation of human smooth muscle cells. To explore whether GGT affects the transcription of cell cycle-regulating genes, we evaluated mRNA expression of p53, p21Waf1 PCNA, Cyclin D1, Cdc2, Histone H3, c-Myc, and c-Fos using a quantitative RT-PCR analysis. While increased expressions of two negative cell cycle regulators, p53 and p21Waf1 were found, reduced expressions of cell cycle stimulators, PCNA, c-Fos, and c-Myc, were identified following treatment. Taken together, our study demonstrates that GGT inhibits cellular proliferation of human smooth muscle cell through the up- and down-regulation of growth-inhibiting and growth-promoting genes, respectively.

Anaerobic and aerobic degradation of pyridine by a newly isolated denitrifying bacterium

New denitrifying bacteria that could degrade pyridine under both aerobic and anaerobic conditions were isolated from industrial wastewater. The successful enrichment and isolation of these strains required selenite as a trace element. These isolates appeared to be closely related to Azoarcus species according to the results of 16S rRNA sequence analysis. An isolated strain, pF6, metabolized pyridine through the same pathway under both aerobic and anaerobic conditions. Since pyridine induced NAD-linked glutarate-dialdehyde dehydrogenase and isocitratase activities, it is likely that the mechanism of pyridine degradation in strain pF6 involves N-C-2 ring cleavage. Strain pF6 could degrade pyridine in the presence of nitrate, nitrite, and nitrous oxide as electron acceptors. In a batch culture with 6 mM nitrate, degradation of pyridine and denitrification were not sensitively affected by the redox potential, which gradually decreased from 150 to -200 mV. In a batch culture with the nitrate concentration higher than 6 mM, nitrite transiently accumulated during denitrification significantly inhibited cell growth and pyridine degradation. Growth yield on pyridine decreased slightly under denitrifying conditions from that under aerobic conditions. Furthermore, when the pyridine concentration used was above 12 mM, the specific growth rate under denitrifying conditions was higher than that under aerobic conditions. Considering these characteristics, a newly isolated denitrifying bacterium, strain pF6, has advantages over strictly aerobic bacteria in field applications.

Biodegradation of 4-chlorophenol via a hydroquinone pathway by Arthrobacter ureafaciens CPR706

A newly isolated Arthrobacter ureafaciens, strain CPR706, could degrade 4-chlorophenol via a new pathway, in which the chloro-substituent was eliminated in the first step and hydroquinone was produced as a transient intermediate. Strain CPR706 exhibited much higher substrate tolerance and degradation rate than other strains that degraded 4-chlorophenol by the hydroxylation at the second carbon position to form chlorocatechol. Strain CPR706 could also degrade other para-substituted phenols (4-nitro-, 4-bromo-, 4-iodo-, and 4-fluoro-phenol) via the hydroquinone pathway.

Biodegradation of the mixtures of 4-chlorophenol and phenol by Comamonas testosteroni CPW301

A 4-chlorophenol (4-CP)-degrading bacterium, strain CPW301, was isolated from soil and identified as Comamonas testosteroni. This strain dechlorinated and degraded 4-CP via a meta-cleavage pathway. CPW301 could also utilize phenol as a carbon and energy source without the accumulation of any metabolites via the same meta-cleavage pathway. When phenol was added as an additional substrate, CPW301 could degrade 4-CP and phenol simultaneously. The addition of phenol greatly accelerated the degradation of 4-CP due to the increased cell mass. The simultaneous degradation of the 4-CP and phenol is useful not only for enhanced cell growth but also for the bioremediation of both compounds, which are normally present in hazardous waste sites as a mixture.