Biodegradation Data Research Articles

Compositional Analysis and Environmental Performance of LAS Produced from GTL Normal Paraffin and Different Alkylation Routes

Abstract The production of normal paraffin from Gas to Liquids (GTL) plants provides LAB producers with a more cost-effective feedstock than normal paraffin extracted from kerosene. Test results to date demonstrate that the performance of GTL Normal Paraffin, and LAB and LAS derived from it, however, is equal to that of kerosene derived normal paraffin. Recent work has particularly focussed on the environmental performance of LAS produced from GTL Normal Paraffin. Detailed GC and NMR analyses confirm that there is little, if any, significant difference in the analytical “profiles” of the kerosene and GTL Normal Paraffin derived LAS samples. It is therefore not surprising that there is no difference in the biodegradability of kerosene and GTL Normal Paraffin derived LAS samples. All samples achieved > 60% mineralisation after 28 days (OECD 301B); all these data were consistent with previous biodegradability data for LAS from European Chemical Bureau (ECB) and Human & Environmental Risk Assessment (HERA) databases. Similarly, there is no difference in the ecotoxicity of kerosene and GTL Normal Paraffin derived LAS samples. Test results to fish (LC50), invertebrates (EC50) and algae (EC50) lay in the range 1–10 mg/l, 1–10 mg/l and 10–100 mg/l respectively; again these data are entirely consistent with previous ecotoxicity data for LAS from ECB and HERA databases.

Biodegradation of methyl tert-butyl ether as a sole carbon source by aerobic granules cultivated in a sequencing batch reactor

Aerobic granules efficient at degrading methyl tert-butyl ether (MTBE) were successfully developed in a well-mixed sequencing batch reactor (SBR). Treatment efficiency of MTBE in the reactor during the stable operations exceeded 99.8%, and effluent MTBE was consistently below 800 microg/L. The specific MTBE degradation rate was observed to increase with increasing MTBE initial concentrations from 25 to 400 mg/L, peaked at 18.2 mg-MTBE/g-VSS h, and declined with further increases in MTBE concentration as substrate inhibition effects became significant. There was a good fit between these biodegradation data and the Haldane equation (R (2) = 0.976). Microbial community DNA profiling was carried out using denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction amplified 16S rDNA. The aerobic granule was found to contain a wide diversity of microorganisms. More than 70% similarity among the samples in the time period examined indicated a highly stable microbial community as the reactor reached the stable operation.

A Processing, Characterization and Marine Biodegradation Study of Melt-Extruded Polyhydroxyalkanoate (PHA) Films

A series of polyhydroxyalkanoates (PHA), all containing 1% nucleating agent but varying in structure, were melt-processed into films through single screw extrusion techniques. This series consisted of three polyhydroxybutyrate (PHB) and three polyhydroxybutyrate-valerate (PHBV) resins with varying valerate content. Processing parameters of temperature in the barrel (165–173 °C) and chill rolls (60 °C) were optimized to obtain cast films. The gel-permeation chromatography (GPC) results showed a loss of 8–19% of the polymer’s initial molecular weight due to extrusion processing. Modulated differential scanning calorimetry (MDSC) displayed glass transition temperatures of the films ranging from −4.6 to 6.7 °C depending on the amount of crystallinity in the film. DSC data were also used to calculate the percent crystallinity of each sample and slightly higher crystallinity was observed in the PHBV series of samples. X-ray diffraction patterns did not vary significantly for any of the samples and crystallinity was confirmed with X-ray data. Dynamic mechanical analysis (DMA) verified the glass transition trends for the films from DSC while loss modulus (E′) reported at 20 °C showed that the PHBV (3,950–3,600 MPa) had the higher E′ values than the PHB (3,500–2,698 MPa) samples. The Young’s modulus values of the PHB and PHBV samples ranged from 700 to 900 MPa and 900 to 1,500 MPa, respectively. Polarized light microscopy images revealed gel particles in the films processed through single-screw extrusion, which may have caused diminished Young’s modulus and tensile strength of these films. The PHBV film samples exhibited the greatest barrier properties to oxygen and water vapor when compared to the PHB film samples. The average oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) for the PHBV samples was 247 (cc-mil/m2-day) and 118 (g-mil/m2-day), respectively; while the average OTR and WVTR for the PHB samples was 350 (cc-mil/m2-day) and 178 (g-mil/m2-day), respectively. Biodegradation data of the films in the marine environment demonstrated that all PHA film samples achieved a minimum of 70% mineralization in 40 days when run in accordance with ASTM 6691. For static and dynamic incubation experiments in seawater, microbial action resulting in weight loss as a function of time showed all samples to be highly biodegradable and correlated with the ASTM 6691 biodegradation data.

Environmentally friendly biocomposites based on waste of the dairy industry and poly(vinyl alcohol)

AbstractEnvironmentally friendly polymeric biocomposites based on whey powder, a waste material of the dairy industry, and fully or partially hydrolyzed poly (vinyl alcohol) were prepared and characterized with optical microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and stress–strain analysis, and their biodegradation was evaluated with the modified Zahn–Wellens method and the spectrophotometric determination of poly(vinyl alcohol). In addition, the ability of the biocomposites to absorb moisture and its consequent influence on the mechanical properties were investigated under different storage conditions. The structural differences of the two types of poly(vinyl alcohol) matrices had a significant effect on all the mentioned characteristics. Possible molecular interactions between the polymer matrix and modifier, due to hydrogen bonding, were also examined. First‐order kinetics were applied for the biodegradation data. The two‐phase character of the biodegradation was shown. The results indicated that whey powder is suitable for the modification of polymers, and this is important for the production of biodegradable polymer materials and the consequent reduction of the environmental load. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Development of Chitosan Dermal Scaffold and its Characterization

We have developed tensile and porous neutralized chitosan scaffold (NCS) whose pore size was controlled by freezing temperatures. At -70 oC, mean pore size of 112 μm was obtained. At -196 oC, mean pore size was approximately 70 μm at surface. The scaffold processed at -196 oC showed homogeneous small pores with structural integrity, which may be more useful as a guidance dermal scaffold for inward cell migration. The scaffold processed at –70 oC may be more useful for cell loading scaffold requiring wider pore. Since biodegradability and biocompatibility are crucial parameters for the development of dermal scaffold, we evaluated the rate of NCS degradation in the culture medium containing lysozyme by measuring weight loss as well as mean molecular weight of the scaffold. Approximately 40% weight loss at one week and 70% weight loss at 30 days was observed, which means that 70% of the scaffold will be degraded and releasable if the wound microenvironment is similar to the test condition. Again, mean molecular weight of the scaffold based on gel permeation chromatography was less than 1x105 after 10 day incubation. This result suggests that degradation of the NCS begins earlier than the observation of gross weight loss. We also evaluated whether degradation product of NCS are toxic to the human dermal fibroblast or not. Chitosan oligomer up to 1.0 mg/ml, which corresponds to 10% of the total degradation derivatives of the NCS, did not affect the viability of the dermal fibroblast based on MTT assay. This result along with the biodegradation data suggests that the NCS can be developed as suitable dermal scaffold.

Measurement of biodegradability parameters for single unsubstituted and methylated polycyclic aromatic hydrocarbons in liquid bacterial suspensions

Substrate depletion experiments were conducted to characterize aerobic biodegradation of 20 single polycyclic aromatic hydrocarbons (PAHs) by induced Sphingomonas paucimobilis strain EPA505 in liquid suspensions. PAHs consisted of low molecular weight, unsubstituted, and methyl-substituted homologs. A material balance equation containing the Andrews kinetic model, an extension of the Monod model accounting for substrate inhibition, was numerically fitted to batch depletion data to estimate extant kinetic parameters including the maximal specific uptake rates, q(max), the affinity coefficients, K(S), and the substrate inhibition coefficients, K(I). Strain EPA505 degraded all PAHs tested. Applied kinetic models adequately simulated experimental data. A cell proliferation assay involving reduction of the tetrazolium dye WST-1 was used to evaluate the ability of strain EPA505 to utilize individual PAHs as sole energy and carbon sources. Of the 22 PAHs tested, 9 supported bacterial growth. Evaluation of the biokinetic data showed that q(max) correlated highly with transmembrane flux as theoretically estimated by a diffusion model, pointing to transmembrane transport as a potential rate-determining process. The biodegradability data generated in this study is essential for the development of quantitative structure-activity relationships (QSARs) for biodegradability and for modeling biodegradation of simple PAH mixtures.

Biodegradation of phenol by Pseudomonas pictorum on immobilized with chitin

Biodegradation of phenol using Pseudomonas pictorum (ATCC 23328) a potential biodegradant of phenol was investigated under different operating conditions. Chitin was chosen as a support material and then partially characterized physically and chemically. The pH of the solution was varied over a range of 7 – 9. The maximum adsorption and degradation capacity of bacteria immobilized with chitin at 30oC when the phenol concentration was 0.200 mg/L is at pH 7.0. The results showed that the equilibrium data for all phenol-degradation sorbent systems fitted the Langmuir, Freundlich and Redlich-Peterson model best. Kinetic modeling of phenol degradation was done using the pseudo-first order and pseudo-second order rate expression. The biodegradation data generally fit the intraparticle diffusion rate equation from which biodegradation rate constant, diffusion rate constant were determined.

Biochemical Interpretation of Quantitative Structure−Activity Relationships (QSAR) for Biodegradation of N-Heterocycles: A Complementary Approach to Predict Biodegradability

Prediction of the biodegradability of organic compounds is an ecologically desirable and economically feasible tool for estimating the environmental fate of chemicals. We combined quantitative structure-activity relationships (QSAR) with the systematic collection of biochemical knowledge to establish rules for the prediction of aerobic biodegradation of N-heterocycles. Validated biodegradation data of 194 N-heterocyclic compounds were analyzed using the MULTICASE-method which delivered two QSAR models based on 17 activating (OSAR 1) and on 16 inactivating molecular fragments (GSAR 2), which were statistically significantly linked to efficient or poor biodegradability, respectively. The percentages of correct classifications were over 99% for both models, and cross-validation resulted in 67.9% (GSAR 1) and 70.4% (OSAR 2) correct predictions. Biochemical interpretation of the activating and inactivating characteristics of the molecular fragments delivered plausible mechanistic interpretations and enabled us to establish the following biodegradation rules: (1) Target sites for amidohydrolases and for cytochrome P450 monooxygenases enhance biodegradation of nonaromatic N-heterocycles. (2) Target sites for molybdenum hydroxylases enhance biodegradation of aromatic N-heterocycles. (3) Target sites for hydratation by an urocanase-like mechanism enhance biodegradation of imidazoles. Our complementary approach represents a feasible strategy for generating concrete rules for the prediction of biodegradability of organic compounds.

Efficient microbial degradation of Toluidine Blue dye by Brevibacillus sp.

Economical and bio-friendly approaches are needed to degrade dye-contaminated wastewater from various industries. In this study, we report on the isolation and characterization of a strain of Brevibacillus that can efficiently degrade Toluidine Blue dye (TB). Eight different bacterial strains which were initially isolated from soil contaminated with Coomassie Brilliant Blue dye (CBB) showed varying degradation rates for CBB. The most efficient isolate was further tested on 7 other dyes; surprisingly, we found this isolate to be much more efficient in degrading TB. Morphological and enzymatic analyses, as well as 16S rRNA sequencing were used to identify this isolate as a species of Brevibacillus. We have characterized the efficiency of TB degradation by this isolate as a function of dye concentration, pH, aeration, as well as nitrogen source. Under optimum conditions, most of the TB could be degraded within 24 h. The biodegradation data for TB were fitted to first-order equation with good correlation.

Sulfolane Attenuation by Surface and Subsurface Soil Matrices

This study was undertaken to evaluate sulfolane (tetrahydrothiophene-1, 1-dioxide) attenuation by soil and subsurface materials collected from a sour gas plant site using batch equilibration systems. The analyzed sample materials used in this study showed a wide range in terms of their selected physical and chemical properties. The reaction of sulfolane with the sample materials was fast initially and followed by slower rates at longer times. There was not much increase in the amount of sulfolane sorbed after about 5 hours of equilibration time irrespective of the temperature of the system. The rate of sorption of sulfolane followed a first-order reaction at both 25 and 8°C temperature conditions and not affected by the temperatures range considered in this study. It appears that the sorption data of sulfolane on the various sorbents could be best described mathematically by the Freundlich equation. Kd values derived at 25°C ranged from 0.05 to 0.88 L/kg and from 0.30 to 1.23 L/kg at 8°C. Furthermore, increasing the ionic strength of the solution didn't affect sulfolane sorption by the various sorbents, which indicates that sulfolane sorption is not consistent with an ion-exchange mechanism but rather occurs through dipole-dipole interactions. Desorption of sulfolane was relative high in all systems. Multiple regression analysis shows a high level of correlation between Kd and several soil parameters. No sulfolane biodegradation was detected under anerobic conditions in any of the microcosms systems after 45 days of incubation at 25 and 8°C, respectively. Sulfolane biodegradation data could be all fitted to zero-order kinetics. Biodegradation rates of sulfolane in the microcosms was the highest in sample depth 0–0.20 m, decreased with sample depth but significantly increased with the addition of nitrogen, and markedly decreased with temperature. At 25°C and no supplement of N, biodegradation rate ranged from 4.26 to 12.70 mg/kg/day but with addition of N, the range was from 9.41 to 16.50 mg/kg/day.

Modelagem empírica do processo de biodegradação de efluentes protéicos por enzimas de Carica papaya sp.

O objetivo deste trabalho foi modelar empiricamente a biodegradação de efluentes protéicos por enzimas papaínas do látex de Carica papaya sp. num biorreator agitado, para facilitar a otimização do processo por metodologia de análise de superfície de resposta (RSM) e aplicar em tratamento de efluentes provenientes de indústrias de processamento de carne. As análises das curvas de biodegradação mostraram que o tempo de residência para os biorreatores está entre 28 e 30 h. O modelo empírico que mais se ajustou aos dados de biodegradação sob influência dos fatores (pH e temperatura) foi o de um hiperplano e a região de operação otimizada para a degradação de proteínas pelas papaínas foi aquela que apresentou os maiores valores de temperatura e menores valores de pH.

Effect of river sediment on the biodegradation kinetics of surfactant and non-surfactant compounds

The half-time of biodegradation of the surfactant sodium dodecylsulfate (SDS) by Pseudomonas species C12B, was reduced two fold by the presence of a riverine sediment. The sediment alone gave comparatively negligible biodegradation of SDS under otherwise equivalent conditions. The sediment had no effect on the kinetics of biodegradation of the non-surfactant pyruvate by Pseudomonas strain C12B. In the light of (i) the known strong adsorption of the surfactant SDS, but not pyruvate, to river sediment and (ii) the SDS-stimulated attachment of Pseudomonas C12B and other SDS-degraders to the sediment, the above observations indicate that acceleration of biodegradation was the result of simultaneous attachment of both SDS and biodegradation competent bacteria to the sediment. This interpretation was strengthened by analysis of the biodegradation kinetics. The data obtained for biodegradation in the absence of sediment, were fitted best by a model involving logistic growth on the added surfactant. The biodegradation data in the presence of sediment were fitted to variants of this model, including one allowing growth on material endogenous to the sediment. Of the several models tested, the data were fitted best by one which is consistent with accumulation of both bacterial cells and substrate at the sediment surface. The enhancement of surfactant biodegradation by sediment is discussed in the context of the design of biodegradability tests and environmental acceptability.

Enhanced Biodegradation of Azo Dyes Using an Integrated Elemental Iron‐Activated Sludge System: I. Evaluation of System Performance

The objective of this research is to evaluate an integrated system coupling zero-valent iron (Fe(0)) and aerobic biological oxidation for the treatment of azo dye wastewater. Zero-valent (elemental) iron can reduce the azo bond, cleaving dye molecules into products that are more amenable to aerobic biological treatment processes. Azo dye reduction products, including aniline and sulfanilic acid, were shown to be readily biodegradable at concentrations up to approximately 25 mg/L. Batch reduction and biodegradation data support the proposed integrated iron pretreatment and activated sludge process for the degradation of the azo dyes orange G and orange I. The integrated system was able to decolorize dye solutions and yield effluents with lower total organic carbon concentrations than control systems without iron pretreatment. The success of the bench-scale integrated system suggests that iron pretreatment may be a feasible approach to treat azo dye containing wastewaters.

Biodegradability of 14C-Labeled Antibiotics in a Modified Laboratory Scale Sewage Treatment Plant at Environmentally Relevant Concentrations

For all new pharmaceuticals, an environmental risk assessment (ERA) has to be performed according to guidelines developed by the European Medicines Evaluation Agency. An important factor of this procedure is the assessment of the predicted environmental concentration in the aquatic environment, which is significantly influenced by the biodegradability of pharmaceuticals in sewage treatment plants. Established standardized methods for determining biodegradation under laboratory conditions apply to substance concentrations, which are much higherthan those expected in reality. Against this background, the laboratory scale sewage treatment plant (LSSTP), as described by the Organisation for Economic Cooperation and Development (OECD) Guideline No. 303A, was modified to construct a lossless system, which allows laboratory testing at realistic concentrations. To verify the experimental setup, the antibiotics benzylpenicillin, ceftriaxone, and trimethoprim were tested at low concentrations (microg/L) using 14C-labeled compounds. The results show that approximately 25% of benzylpenicillin was mineralized, whereas ceftriaxone and trimethoprim were not mineralized at all. Due to the high total recoveries of added radioactivity (> or =95%) and the fact that the findings comply with available literature data, the lossless operation of the test system could be proved. Consequently, the modified LSSTP is a suitable tool to determine more realistic biodegradation data required for the exposure assessment within the scope of an ERA for pharmaceuticals.

External validation of EPIWIN biodegradation models*

The BIOWIN biodegradation models were evaluated for their suitability for regulatory purposes. BIOWIN includes the linear and non-linear BIODEG and MITI models for estimating the probability of rapid aerobic biodegradation and an expert survey model for primary and ultimate biodegradation estimation. Experimental biodegradation data for 110 newly notified substances were compared with the estimations of the different models. The models were applied separately and in combinations to determine which model(s) showed the best performance. The results of this study were compared with the results of other validation studies and other biodegradation models. The BIOWIN models predict not-readily biodegradable substances with high accuracy in contrast to ready biodegradability. In view of the high environmental concern of persistent chemicals and in view of the large number of not-readily biodegradable chemicals compared to the readily ones, a model is preferred that gives a minimum of false positives without a corresponding high percentage false negatives. A combination of the BIOWIN models (BIOWIN2 or BIOWIN6) showed the highest predictive value for not-readily biodegradability. However, the highest score for overall predictivity with lowest percentage false predictions was achieved by applying BIOWIN3 (pass level 2.75) and BIOWIN6.

New Evaluation Scheme for Two-Dimensional Isotope Analysis to Decipher Biodegradation Processes: Application to Groundwater Contamination by MTBE

Compound-specific analysis of stable carbon and hydrogen isotopes was used to assess the fate of the gasoline additive methyl tert-butyl ether (MTBE) and its major degradation product tert-butyl alcohol (TBA) in a groundwater plume at an industrial disposal site. We present a novel approach to evaluate two-dimensional compound-specific isotope data with the potential to identify reaction mechanisms and to quantify the extent of biodegradation at complex field sites. Due to the widespread contaminant plume, multiple MTBE sources, the presence of numerous other organic pollutants, and the complex biogeochemical and hydrological regime atthe site, a traditional mass balance approach was not applicable. The isotopic composition of MTBE steadily changed from the source regions along the major contaminant plume (-26.4% to +40.0% (carbon); -73.1% to +60.3% (hydrogen)) indicating substantial biodegradation. Constant carbon isotopic signatures of TBA suggest the absence of TBA degradation at the site. Published carbon and hydrogen isotope fractionation data for biodegradation of MTBE under oxic and anoxic conditions, respectively, were examined and used to determine both the nature and the extent of in-situ biodegradation along the plume(s). The coupled evaluation of two-dimensional compound-specific isotope data explained both carbon and hydrogen fractionation data in a consistent way and indicate anaerobic biodegradation of MTBE along the entire plume. A novel scheme to reevaluate empiric isotopic enrichment factors (epsilon) in terms of theoretically based intrinsic carbon (12k/13k) and hydrogen (1k/2k) kinetic isotope effects (KIE) is presented. Carbon and hydrogen KIE values, calculated for different potential reaction mechanisms, imply that anaerobic biodegradation of MTBE follows a SN2-type reaction mechanism. Furthermore, our data suggest that additional removal process(es) such as evaporation contributed to the overall MTBE removal along the plume, a phenomenon that might be significant also for other field sites at tropic or subtropic climates with elevated groundwater temperatures (25 degrees C).

Cleavable Ortho Ester Type Surfactants

Abstract With the focus on quaternary ammonium compounds, this paper describes how the ortho ester chemistry can be used as a versatile tool for synthesis of cleavable surfactants of various types. This class of chemodegradable surfactants hydrolyzes rapidly under mild acidic conditions at the same time as they are long-term stable in alkaline aqueous solutions. Further, the rate of cleavage can be modified by varying the structure of the surfactant. An additional feature is the possibility to design surface active compounds that release a daughter surfactant with different properties upon cleavage. Ortho ester-based surfactants could be of use in a large number of applications as exemplified in the paper. Good biodegradation data are of importance for virtually all types of surfactants nowadays. However, there actually seem to exist very few, if any, investigations regarding the biodegradation of cleavable surfactants under both hydrolytical and non-hydrolytical conditions. Data from the initial part of such a study on cationic ortho ester surfactants are presented and discussed in this paper. The results strongly indicate rapid biodegradation for this class of compounds under varying conditions.

04/02100 Measuring reporting and verifying greenhouse gas emissions from aluminum reduction operations: Martcheck, K. J. Light Metals, 2003, 227–231

Two new screening-test systems for biodegradation in water–sediment systems (WSST; Water–Sediment Screening Tool) and soil (SST; Soil Screening Tool) were developed in analogy with the water-only test system OECD 301C (MITI-test).The test systems could be applied successfully to determine reproducible experimental mineralization rates and kinetics on the screening-test level for fifteen organic chemicals in water (MITI), water-sediment (WSST) and soil (SST). Substance-specific differences were observed for mineralization compared among the three test systems. Based on mineralization rate and mineralization half-life, the fifteen compounds could be grouped into four biodegradation categories: substances with high mineralization and a half-life < 28 days in (1) all three test systems, (2) only in the MITI test and in the WSST, (3) only in the SST, and (4) none of the test systems. The observed differences between the MITI results and the WSST and SST biodegradation rates of the compounds do not reflect their (reversible) sorption into organic matter in terms of experimental Koc values and log D values for the relevant pH range. Regarding mineralization kinetics we recommend to determine the lag-phase, mineralization half-life and mineralization rate using a 5-parameter logistic regression for degradation curves with and without lag-phase. Experimental data obtained with the WSST and the SST could be verified by showing good agreement with biodegradation data from databases and literature for the majority of compounds tested. Thus, these new screening-tools for water–sediment and soil are considered suitable to determine sound and reliable quantitative mineralization data including mineralization kinetics in addition to the water-only ready biodegradability tests according to OECD 301.

Using Biowin, Bayes, and batteries to predict ready biodegradability.

Whether or not a given chemical substance is readily biodegradable is an important piece of information in risk screening for both new and existing chemicals. Despite the relatively low cost of Organization for Economic Cooperation and Development tests, data are often unavailable and biodegradability must be estimated. In this paper, we focus on the predictive value of selected Biowin models and model batteries using Bayesian analysis. Posterior probabilities, calculated based on performance with the model training sets using Bayes' theorem, were closely matched by actual performance with an expanded set of 374 premanufacture notice (PMN) substances. Further analysis suggested that a simple battery consisting of Biowin3 (survey ultimate biodegradation model) and Biowin5 (Ministry of International Trade and Industry [MITI] linear model) would have enhanced predictive power in comparison to individual models. Application of the battery to PMN substances showed that performance matched expectation. This approach significantly reduced both false positives for ready biodegradability and the overall misclassification rate. Similar results were obtained for a set of 63 pharmaceuticals using a battery consisting of Biowin3 and Biowin6 (MITI nonlinear model). Biodegradation data for PMNs tested in multiple ready tests or both inherent and ready biodegradation tests yielded additional insights that may be useful in risk screening.

In vitro enzymatic biodegradation of amino acid based poly(ester amide)s biomaterials.

A systematic in vitro biodegradation study of regular poly(ester amide)s (PEAs) composed of naturally occurring hydrophobic alpha-amino acids, fatty diols and dicarboxylic acids was carried out in the presence of hydrolases like trypsin, alpha-chymotrypsin, and lipase. An automatic potentiometric titration method was used to examine the biodegradation property of the PEAs. Spontaneous immobilization (absorption) of the enzymes onto the PEAs films surfaces was observed. The surface immobilized enzyme not only accelerated the erosion of the PEAs but also was able to catalyze the hydrolysis of both low-molecular-weight (ATEE) and high-molecular-weight (protein) external substrates. It was found that the enzyme surface absorption process is reversible by nature. A kinetic method for a quantitative determination of the enzyme desorbed from the film surface was developed. The enzymes could also be impregnated into the PEAs to make them "self-destructive" at a target rate. A comparison of the PEAs' in vitro biodegradation data with polylactide (PDLLA) showed that PEAs exhibited a far more tendency toward enzyme catalyzed biodegradation than PDLLA.