Biodegradation of benzene, toluene, ethylbenzene, and o-xylene by a coculture of Pseudomonas putida and Pseudomonas fluorescens immobilized in a fibrous-bed bioreactor

A fibrous-bed bioreactor containing the coculture of Pseudomonas putida and P. fluorescens immobilized in a fibrous matrix was developed to degrade benzene (B), toluene (T), ethylbenzene (E), and o-xylene (X) in synthetic waste streams. The kinetics of BTEX biodegradation by immobilized cells adapted in the fibrous-bed bioreactor and free cells grown in serum bottles were studied. In general, the BTEX biodegradation rate increased with increasing substrate concentration and then decreased after reaching a maximum, showing substrate-inhibition kinetics. However, for immobilized cells, the degradation rate was much higher than that of free cells. Compared to free cells, immobilized cells in the bioreactor tolerated higher concentrations (> 1000 mg l-1) of benzene and toluene, and gave at least 16-fold higher degradation rates for benzene, ethylbenzene, and o-xylene, and a 9-fold higher degradation rate for toluene. Complete and simultaneous degradation of BTEX mixture was achieved in the bioreactor under hypoxic conditions. Cells in the bioreactor were relatively insensitive to benzene toxicity; this insensitivity was attributed to adaptation of the cells in the bioreactor. Compared to the original seeding culture, the adapted cells from the fibrous-bed bioreactor had higher specific growth rate, benzene degradation rate, and cell yield when the benzene concentration was higher than 100 mg l-1. Cells in the fibrous bed had a long, slim morphology, which is different from the normal short-rod shape found for suspended cells in solution.     

Enhancement of Aromatic Hydrocarbon Biodegradation by Toluene and Naphthalene Degrading Bacteria Obtained from Lake Sediment: The Effects of Cosubstrates and Cocultures

Toluene and naphthalene degrading (ND) bacteria, obtained from contaminated lake sediment, were used to degrade both monoaromatics and polycyclic aromatic hydrocarbons (PAHs) and the effects of cosubstrates and cocultures were examined. When toluene and naphthalene enrichments were used, the effect of the substrate interaction on their metabolism was found to be inhibitory and yet the cocultures were stimulatory, especially for toluene enrichment degradation of naphthalene (with toluene). Pseudomonas putida M2T14, a toluene degrading isolate, could efficiently degrade benzene and toluene but not naphthalene. Nonetheless, when toluene was present, this monoaromatic degrader became capable of degrading PAHs, among which the methyl substituted PAHs (mPAHs) were preferred to their corresponding unsubstituted PAHs (uPAHs). Pseudomonas azelaica ND isolate could degrade benzene, toluene, and all test PAHs. Although the uPAHs were preferred, the degradation rates of mPAHs were greatly increased via substrate interactions with naphthalene. The interaction modes of dual aromatic hydrocarbons (AHs) degraded by P. putida M2T14 and P. azelaica ND were cometabolism, synergism, no effect, inhibition, and antagonism. However, when a negative effect of biodegradation from the interaction of these AHs was found on one isolate, a positive effect would be found on the other. When benzene was present, it exhibited inhibitory effects on aromatic hydrocarbon biodegradation by M2T14 and ND isolates. A study of the biodegradation of the ternary mixture of benzene, toluene, and naphthalene by both isolates together illustrated that not only was inhibition relieved but that degradation of each compound was also greatly enhanced. Degradation by the toluene and the ND bacteria could be facilitated by complementary substrate interactions between monoaromatics and PAHs and by bacterial association. These model organisms may be very useful for the study of complex aromatic hydrocarbon degradation and for bioremediation purposes.     

A chromosomally based tod-luxCDABE whole-cell reporter for benzene, toluene, ethybenzene, and xylene (BTEX) sensing

A tod-luxCDABE fusion was constructed and introduced into the chromosome of Pseudomonas putida F1, yielding the strain TVA8. This strain was used to examine the induction of the tod operon when exposed to benzene, toluene, ethylbenzene, and xylene (BTEX) compounds and aqueous solutions of JP-4 jet fuel constituents. Since this system contained the complete lux cassette (luxCDABE), bacterial bioluminescence in response to putative chemical inducers of the tod operon was measured on-line in whole cells without added aldehyde substrate. There was an increasing response to toluene concentrations from 30 micrograms/liter to 50 mg/liter, which began to saturate at higher concentrations. The detection limit was 30 micrograms/liter. There was a significant light response to benzene, m- and p-xylenes, phenol, and water-soluble JP-4 jet fuel components, but there was no bioluminescence response upon exposure to o-xylene. The transposon insertion was stable and had no negative effect on cell growth.     

The broad substrate chlorobenzene dioxygenase and cis-chlorobenzene dihydrodiol dehydrogenase of Pseudomonas sp. strain P51 are linked evolutionarily to the enzymes for benzene and toluene degradation

The chlorobenzene degradation pathway of Pseudomonas sp. strain P51 is an evolutionary novelty. The first enzymes of the pathway, the chlorobenzene dioxygenase and the cis-chlorobenzene dihydrodiol dehydrogenase, are encoded on a plasmid-located transposon Tn5280. Chlorobenzene dioxygenase is a four-protein complex, formed by the gene products of tcbAa for the large subunit of the terminal oxygenase, tcbAb for the small subunit, tcbAc for the ferredoxin, and tcbAd for the NADH reductase. Directly downstream of tcbAd is the gene for the cis-chlorobenzene dihydrodiol dehydrogenase, tcbB. Homology comparisons indicated that these genes and gene products are most closely related to those for toluene (todC1C2BAD) and benzene degradation (bedC1C2BA and bnzABCD) and distantly to those for biphenyl, naphthalene, and benzoate degradation. Similar to the tod-encoded enzymes, chlorobenzene dioxygenase and cis-chlorobenzene dihydrodiol dehydrogenase were capable of oxidizing 1,2-dichlorobenzene, toluene, naphthalene, and biphenyl, but not benzoate, to the corresponding dihydrodiol and dihydroxy intermediates. These data strongly suggest that the chlorobenzene dioxygenase and dehydrogenase originated from a toluene or benzene degradation pathway, probably by horizontal gene transfer. This evolutionary event left its traces as short gene fragments directly outside the tcbAB coding regions.     

Analysis and evaluation of trans,trans-muconic acid as a biomarker for benzene exposure

Benzene is an important industrial chemical and, due to its occurrence in mineral oil and its formation in many combustion processes, a widespread environmental pollutant. Since benzene is hematoxic and has been classified as a human carcinogen, monitoring and control of benzene exposure is of importance. Although trans,trans-muconic acid (ttMA) was identified as a urinary metabolite of benzene at the beginning of this century, only recently has its application as a biomarker for occupational and environmental benzene exposure been investigated. The range of metabolic conversion of benzene to ttMA is about 2-25% and dependent on the benzene exposure level, simultaneous exposure to toluene, and probably also to genetic factors. For the quantitation of ttMA in urine, HPLC methods using UV and diode array detection as well as GC methods combined with MS or FID detection have been described. Sample pretreatment for both HPLC and GC analysis comprises centrifugation and enrichment by solid-phase extraction on anion-exchange sorbents. Described derivatization procedures prior to GC analysis include reaction with N,O-bis(trimethysilyl)acetamide, N,O-bis(trimethylsilyl)trifluoroacetamide, pentafluorobenzyl bromide and borontrifluoride-methanol. Reported limits of detection for HPLC methods range from 0.1 to 0.003 mg l(-1), whereas those reported for GC methods are 0.03-0.01 mg l(-1). Due to its higher specificity, GC methods appear to be more suitable for determination of low urinary ttMA levels caused by environmental exposure to benzene. In studies with occupational exposure to benzene (>0.1 ppm), good correlations between urinary ttMA excretion and benzene levels in breathing air are observed. From the reported regressions for these variables, mean excretion rates of ttMA of 1.9 mg g(-1) creatinine or 2.5 mg l(-1) at an exposure dose of 1 ppm over 8 h can be calculated. The smoking-related increase in urinary ttMA excretion reported in twelve studies ranged from 0.022 to 0.2 mg g(-1) creatinine. Only a few studies have investigated the effect of exposure to environmental levels of benzene (<0.01 ppm) on urinary ttMA excretion. A trend for slightly increased ttMA levels in subjects living in areas with high automobile traffic density was observed, whereas exposure to environmental tobacco smoke did not significantly increase the urinary ttMA excretion. It is concluded that urinary ttMA is a suitable biomarker for benzene exposure at occupational levels as low as 0.1 ppm. Biomonitoring of exposure to environmental benzene levels (<0.01 ppm) using urinary ttMA appears to be possible only if the ingestion of dietary sorbic acid, another precursor to urinary ttMA, is taken into account.     

钨掺杂磷酸银对水体中双酚A的光催化降解行为研究

双酚A是典型的生物毒害性污染物，已严重威胁到人类及其他生物体的健康和安全。钨掺杂磷酸银（W-AP）光催化剂在可见光驱动下可有效去除水体中的双酚A。系统地研究了W-AP对双酚A的降解行为，包括操作条件影响、攻击位点计算、降解路径推断和生态毒性评估。通过响应面优化实验得到二阶回归方程及优化操作条件：催化剂用量为350 mg/L，污染物浓度为10 mg/L，污染物pH为5.60，光照强度为100 mW/cm2，此时双酚A的降解率高达90.61%；采用密度泛函理论（DFT）计算得到双酚A分子的自由基物质攻击位点，并结合实验推测出三条具体的降解路径，其降解位点主要位于苯环以及连接两个苯环的C sp3-C sp2桥键上；生态毒性评估表明W-AP降解双酚A所得中间体的生态毒性显著降低。本文为高效去除水体中的双酚A提供策略，可实现水环境的有益修复。     

Effects of Ethanol versus MTBE on Benzene, Toluene, Ethylbenzene, and Xylene Natural Attenuation in Aquifer Columns

The increased use of ethanol as a replacement for the gasoline oxygenate, methyl tert-butyl ether (MTBE), may lead to indirect impacts related to natural attenuation of benzene, toluene, ethylbenzene, and the three isomers of xylene (BTEX compounds). Ethanol could enhance dissolved BTEX mobility by exerting a cosolvent effect that decreases sorption-related retardation. This effect, however, is concentration dependent and was not observed when ethanol was added continuously (at 1%) with BTEX to sterile aquifer columns. Nevertheless, a significant decrease in BTEX retardation was observed with 50% ethanol, suggesting that neat ethanol spills in bulk terminals could facilitate the migration of pre-existing contamination. MTBE (25 mg/L influent) was not degraded in biologically active columns, and it did not affect BTEX degradation. Ethanol (2 g/L influent), on the other hand, was degraded rapidly and exerted a high demand for nutrients and electron acceptors that could otherwise have been used for BTEX degradation. Ethanol also increased the microbial concentration near the column inlet by one order of magnitude relative to columns fed BTEX alone or with MTBE. However, 16S-ribosomal ribonucleic acid sequence analyses of dominant denaturing gradient gel electrophoresis bands identified fewer species that are known to degrade BTEX when ethanol was present. Overall, the preferential degradation of ethanol and the accompanying depletion of oxygen and other electron acceptors hindered BTEX biodegradation, which suggests that ethanol could increase the length of BTEX plumes.     

Bactericide activity of sulbactam before bacteria belonging to the Acinetobacter calcoaceticus-Acinetobacter baumannii complex

BACKGROUND: To evaluate the bactericidal activity of colistin, imipenem and sulbactam against 24 Acinetobacter calcoaceticus-Acinetobacter baumannii complex isolations. METHODS: Bactericidal activity was estimated by using killing curves method. The concentrations employed were: colistin 4 mg/l, imipenem 8 mg/l and sulbactam 8 and 32 mg/l. RESULTS: Colistin was bactericidal in 24 isolations after 6 hours of incubation. When we used 8 mg/l of imipenem we detected bactericidal activity at the susceptible strains (MIC < or = 4 mg/l). We found bactericidal effect in 15 of 18 strains susceptible to sulbactam when we used 8 mg/l in killing curves after 24 hours of incubation. Using 32 mg/l we detected the same effect in 18 strains with MIC < or = 8 mg/l. CONCLUSIONS: Considering the high incidence of resistance in Acinetobacter spp. to several antibiotics including imipenem, we consider that sulbactam could be an excellent therapeutic alternative because it presents bactericidal activity in susceptible strains.     

Aerobic mineralization of 2,6-dichlorophenol by Ralstonia sp. strain RK1

A new aerobic bacterium was isolated from the sediment of a freshwater pond close to a contaminated site at Amponville (France). It was enriched in a fixed-bed reactor fed with 2,6-dichlorophenol (2,6-DCP)as the sole carbon and energy source at pH 7.5 and room temperature. The degradation of 2,6-DCP followed Monod kinetics at low initial concentrations. At concentrations above 300 microM (50 mg.liter-1), 2,6-DCP increasingly inhibited its own degradation. The base sequence of the 16S ribosomal DNA allowed us to assign the bacterium to the genus Ralstonia (formerly Alcaligenes). The substrate spectrum of the bacterium includes toluene, benzene, chlorobenzene, phenol, and all four ortho- and para-substituted mono- and dichlorophenol isomers. Substituents other than chlorine prevented degradation. The capacity to degrade 2,6-DCP was examined in two fixed-bed reactors. The microbial population grew on and completely mineralized 2,6-DCP at 2,6-DCP concentrations up to 740 microM in continuous reactor culture supplied with H2O2 as an oxygen source. Lack of peroxide completely stopped further degradation of 2,6-DCP. Lowering the acid-neutralizing capacity of the medium to 1/10th the original capacity led to a decrease in the pH of the effluent from 7 to 6 and to a significant reduction in the degradation activity. A second fixed-bed reactor successfully removed low chlorophenol concentrations (20 to 26 microM) with hydraulic residence times of 8 to 30 min.     

Biodegradation of the gasoline oxygenates methyl tert-butyl ether, ethyl tert-butyl ether, and tert-amyl methyl ether by propane-oxidizing bacteria

Several propane-oxidizing bacteria were tested for their ability to degrade gasoline oxygenates, including methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). Both a laboratory strain and natural isolates were able to degrade each compound after growth on propane. When propane-grown strain ENV425 was incubated with 20 mg of uniformly labeled [14C]MTBE per liter, the strain converted > 60% of the added MTBE to 14CO2 in < 30 h. The initial oxidation of MTBE and ETBE resulted in the production of nearly stoichiometric amounts of tert-butyl alcohol (TBA), while the initial oxidation of TAME resulted in the production of tert-amyl alcohol. The methoxy methyl group of MTBE was oxidized to formaldehyde and ultimately to CO2. TBA was further oxidized to 2-methyl-2-hydroxy-1-propanol and then 2-hydroxy isobutyric acid; however, neither of these degradation products was an effective growth substrate for the propane oxidizers. Analysis of cell extracts of ENV425 and experiments with enzyme inhibitors implicated a soluble P-450 enzyme in the oxidation of both MTBE and TBA. MTBE was oxidized to TBA by camphor-grown Pseudomonas putida CAM, which produces the well-characterized P-450cam, but not by Rhodococcus rhodochrous 116, which produces two P-450 enzymes. Rates of MTBE degradation by propane-oxidizing strains ranged from 3.9 to 9.2 nmol/min/mg of cell protein at 28 degrees C, whereas TBA was oxidized at a rate of only 1.8 to 2.4 nmol/min/mg of cell protein at the same temperature.     

Degradation of cyanide in agroindustrial or industrial wastewater in an acidification reactor or in a single-step methane reactor by bacteria enriched from soil and peels of cassava

During cassava starch production, large amounts of cyanoglycosides were released and hydrolysed by plant-borne enzymes, leading to cyanide concentrations in the wastewater as high as 200 mg/l. For anaerobic degradation of the cyanide during pre-acidification or single-step methane fermentation, anaerobic cultures were enriched from soil residues of cassava roots and sewage sludge. In a pre-acidification reactor this culture was able to remove up to 4 g potassium cyanide/l of wastewater at a hydraulic retention time (tHR) of 4 days, equivalent to a maximal cyanide space loading of 400 mg CN- 1(-1) day-1. The residual cyanide concentration was 0.2-0.5 mg/l. Concentrated cell suspensions of the mixed culture formed ammonia and formate in almost equimolar amounts from cyanide. Little formamide was generated by chemical decay. A concentration of up to 100 mmol ammonia/l had no inhibitory effect on cyanide degradation. The optimal pH for cyanide degradation was 6-7.5, the optimal temperature 25-37 degrees C. At a pH of 5 or lower, cyanide accumulated in the reactor and pre-acidification failed. The minimal tHR for continuous cyanide removal was 1.5 days. The enriched mixed culture was also able to degrade cyanide in purely mineralic wastewater from metal deburring, either in a pre-acidification reactor with a two-step process or in a one-step methanogenic reactor. It was necessary to supplement the wastewater with a carbon source (e.g. starch) to keep the population active enough to cope with any possible inhibiting effect of cyanide.     

Pyrene degradation by Mycobacterium sp. strain KR2

A Mycobacterium sp., strain KR2 which was able to utilise pyrene as sole source of carbon and energy was isolated from a polycyclic aromatic hydrocarbon (PAH) contaminated soil originating from the area of a former gaswork plant. The isolate metabolised up to 60% of the pyrene added (0.5 mg/mL) within 8 days at 20 degrees C. Cis-4,5-pyrene dihydrodiol, 4,5-phenanthrene dicarboxylic acid, 1-hydroxy-2-naphthoic acid, 2-carboxybenzaldehyde, phthalic acid, and protocatechuic acid were identified as degradation products. Based on these findings a degradation pathway for pyrene is suggested which is in good accordance with the data published so far on bacterial pyrene metabolism.     

Dose-dependent suppression of toluene metabolism by isopropyl alcohol and methyl ethyl ketone after experimental exposure of rats

In order to examine possible suppression of toluene metabolism due to coexposure to other solvents, female Wistar rats were exposed for 8 h to toluene alone (at 50 or 100 ppm), or in combination with either methyl ethyl ketone (at 50, 100, 200 or 400 ppm) or isopropyl alcohol (at 50, 100, 200, 400, 800 or 1600 ppm). Urine samples were collected for 24 h after initiation of each exposure, and subjected to analysis for two toluene metabolites, hippuric acid and o-cresol, both by HPLC. The excretion of hippuric acid, a major metabolite, was not modified when the concentrations of methyl ethyl ketone or isopropyl alcohol were low, i.e. 100 ppm or below, whereas it was reduced when methyl ethyl ketone or isopropyl alcohol concentrations were twice or more times higher than that of toluene. There were no changes in any cases in excretion of o-cresol, a minor metabolite. The observation after coexposure to methyl ethyl ketone or isopropyl alcohol at low concentration is in line with the negative interaction between toluene and methyl ethyl ketone as well as between toluene and isopropyl alcohol after occupational exposures at low concentrations. Metabolic interaction may take place when the exposure intensity is high, as observed in the present study and also after experimental exposure of volunteers to toluene and m-xylene, or occupational exposure to benzene and toluene.     

Clinical, laboratory, phototest and phototherapy findings in polymorphic light eruptions: a retrospective study of 133 patients

OBJECTIVE: To study the blood benzene levels resulting from environmental and occupational benzene exposure. METHODS: Benzene in venous blood was measured in 243 nonoccupationally exposed subjects ("normal" people) and in 167 workers occupationally exposed to benzene. All exposed workers gave blood samples at the end of the work shift and on the following morning before resuming work. Blood benzene was assayed by gas chromatography (GC)-mass spectrometry. Occupational benzene exposure was monitored by environmental personal samplers and measured by GC analysis. RESULTS: The mean occupational benzene exposure for all 167 workers studied was 186 ng/l (58 ppb; range 5 1535 ng/l, 2-500 ppb). Overall, the mean blood benzene level of all workers was 420 ng/1 at the end of the shift and 287 ng/l on the morning thereafter. The blood benzene levels measured the morning after turned out to be significantly lower (t=3.6; P < 0.0001) than those measured at the end of the shift. The mean blood benzene level of the 243 "normal" subjects was 165 ng/l, which was significantly lower than that measured in the workers on the morning thereafter (t=5.8: P < 0.0000001). The mean blood benzene concentration was significantly higher in smokers than in nonsmokers in both the general population (264 versus 123 ng/l) and in the exposed workers. In the group of nonsmoking workers, whose workplace exposure to benzene was lower than 100 ng/l, blood benzene levels were similar (210-202 ng/l) to those measured in the nonsmoking general population (165 ng/l). End-of-shift blood benzene correlated significantly with environmental exposure (y=0.91x + 251; r=0.581; n=162; P < 0.00001). Finally, there was also a significant correlation between blood benzene measured at the end of the shift and that determined on the morning thereafter (y=0.45x + 109; r=0.572; n=156; P < 0.00001). Conclusion: Nonsmoking workers occupationally exposed to benzene at environmental levels lower than 100 ng/l (mean 35 ng/l) and the nonsmoking general population exposed to ubiquitous benzene pollution have similar blood benzene concentrations. This suggests that it is impossible to distinguish between occupational and environmental exposure when the benzene level in the workplace is less than 100 ng/l.     

Paracetamol poisoning in infancy

An eight-week old infant with alcohol embryopathy, weighing 3,700 g, was found to have abnormal liver functions (GPT 312 U/l, Quick value 25%) after surgical repair of a stenosis of the left ureter at its origin. The hospital notes indicated that the infant had been given a total of 1.6 g paracetamol over 60 hours for postoperative restlessness and pain. The serum paracetamol level was 60 mg/l 8 hours after the last dose of the drug. Blood exchange transfusion lowered the paracetamol level to 11 mg/l within 14 hours. After the exchange transfusion further signs of poisoning, namely renal impairment and a severe encephalopathy were noted, and Candida was demonstrated in urine, tracheal secretion and ascites. The renal and hepatic damage proved reversible under symptomatic treatment. But the child, now 1 year old, is severely retarded mentally and in its motor functions. These sequelae may be a residue of the paracetamol poisoning, complications of the clinical course or a combination of the two.     

Pharmacokinetic profiles of ceftazidime in cochlear perilymph, cerebrospinal fluid and plasma: a high-performance liquid chromatographic study

A pharmacokinetic profile of the antibiotic ceftazidime was established for perilymph, cerbrospinal fluid (CSF) and plasma in 12 guinea pigs using the technique of high-performance liquid chromatography. The mean peak levels of 13.35 mg/l in perilymph and 140.54 mg/l in plasma were reached within the first hour after a single intravenous dose of 100 mg/kg. The CSF mean peak level of 5.36 mg/l, however, was not attained until 3 h after injection. The half-life was about 4 h in perilymph, more than 6 h in CSF and less than 2 h in plasma. Six hours following administration, the perilymph drug concentration remained higher than the plasma level. The study indicates that ceftazidime has excellent penetration into perilymph. It is concluded that ceftazidime should be a very useful agent in the treatment of bacterial labyrinthitis caused by susceptible organisms.     

Isolation and characterization of a marine bacterium capable of utilizing 2-methylphenanthrene

A marine bacterium isolated from a coastal hydrocarbon-polluted sediment has been described and attributed on the basis of its phenotypic and genotypic characteristics to the genus Sphingomonas sp. This strain was capable of using an alkylated phenanthrene 2-methylphenanthrene, as sole source of carbon and energy. In experiments, 2-methylphenanthrene (0.2 g/l) was added as crystals to the culture medium. After 5 days of aerobic growth at 30 degrees C, 70% was degraded and the complete dissipation occurred after 20 days. Furthermore, the strain could degrade various kinds of polyaromatic compounds, but failed to grow on aliphatic hydrocarbons.     

The catabolism of infused maltose in man

The use of intravenously administered maltose was tested in 9 healthy human subjects and 3 insulin-dependent diabetic patients. The concentration of the blood sugar has not been influenced by the administered maltose. The concentration of maltose in the blood increases up to 170 mg/100 ml blood depending on the rate of the maltose infusion. The excretion of maltose in the urinis correlated with the applied dosis and with the blood maltose concentration. Under our experimental conditions 20 to 30% of the administered maltose have been excreted and 7.5 to 23.4% have been oxidized within 8 hours. The highest rate of degradation was about 40 mg maltose/min/human subject and is reached 2 hours later than the peak concentration of maltose in the blood. The metabolism of maltose is reduced in insulin-dependent diabetic patients. In these patients only 3% of the applied maltose have been oxidized and 51% excreted in the urin within 8 hours. Therefore, this disaccharide cannot be recommended as carbohydrate source of parenteral nutrition in insulin-dependent diabetic patients. The balance of intravenously administered maltose is not satisfactory in healthy adult humans, too. Infusion of maltose solutions have no real advantages over the infusions of oligosaccharide solutions.     

Degradation of a sodium acrylate oligomer by an Arthrobacter sp

Arthrobacter sp. strain NO-18 was first isolated from soil as a bacterium which could degrade the sodium acrylate oligomer and utilize it as the sole source of carbon. When 0.2% (wt/wt) oligomer was added to the culture medium, the acrylate oligomer was found to be degraded by 70 to 80% in 2 weeks, using gel permeation chromatography. To determine the maximum molecular weight for biodegradation, the degradation test was done with the hexamer, heptamer, and octamer, which were separated from the oligomer mixture by fractional gel permeation chromatography. The hexamer and heptamer were consumed to the extents of 58 and 36%, respectively, in 2 weeks, but the octamer was not degraded. Oligomers with three different terminal groups were synthesized to examine the effect of the different terminal groups on biodegradation, but few differences were found. Arthrobacter sp. NO-18 assimilated acrylic acid, propionic acid, glutaric acid, 2-methylglutaric acid, and 1,3,5-pentanetricarboxylic acid. Degradation of the acrylic unit structure by this strain is discussed.