Reverse lactate threshold test accurately predicts maximal lactate steady state and 5 km performance in running

This study evaluated the accuracy of the reverse lactate threshold (RLT) and the onset of blood lactate accumulation (OBLA; 4 mmol·L^-1) to determine the running speed at the maximal lactate steady state (MLSS) and 5 km running performance in a field test approach. Study 1: 16 participants performed an RLT test, and 2 or more constant-speed tests, lasting 30 minutes each, to determine running speed at the MLSS. Study 2: 23 participants performed an RLT test and a 5000 m all-out run as an indicator of performance. The RLT test consisted of an initial lactate-priming segment, in which running speed was increased stepwise up to ~5% above the estimated MLSS, followed by a reverse segment in which speed was decreased by 0.1 m·s^-1 every 180 s. RLT was determined using the highest lactate equivalent ([La^-]/running speed) during the reverse segment. OBLA was determined during the priming segment and was set at a value of 4 mmol∙L¹. The mean difference in MLSS was +0.06 ± 0.05 m·s^-1 for RLT, and +0.13 ± 0.23 m·s^-1 for OBLA. OBLA showed a good concordance with the MLSS (ICC = 0.83), whereas RLT revealed excellent concordance with the MLSS with an ICC = 0.98. RLT showed a very high correlation with 5000 m speed (r = 0.97). The RLT exhibited exceptional agreement to MLSS and 5000 m running performance. Due to this high accuracy, especially concerning the small intraindividual differences, the RLT test may be superior to common threshold concepts. Further research is needed to evaluate its sensitivity during the training process.     

Adaptive response of microbial communities to soluble microbial products

We carried out two experiments to study the influence of soluble microbial products (SMP) on biomass concentration [defined as mixed liquor suspended solids (MLSS)] and removal of soluble biological and chemical oxygen demands (sBOD₅ and sCOD): (1) SMP were allowed to accumulate, and (2) SMP content was artificially reduced by washing the biomass. The daily initial sCOD in both experiments was kept constant at 859±6 mg/l for 16 days. In experiment 1, the highest sCOD removal (80%) occurred during the first day. Thereafter, it decreased successively to 40% [sludge retention time (SRT), 12 days], after which it increased steadily to 50±4%. Variations in residual sCOD were accompanied by variations in sBOD₅, showing that the biodegradability of the accumulated SMP components was changing. MLSS fluctuated within the range 1,200±25–1,993±58 mg/l. We attributed the irregular accumulation of the biomass to variations in the biodegradability of SMP components. The initial sBOD₅/MLSS ratio varied according to variations in initial sBOD₅ and MLSS, whereas the residual ratio was constant at 0.025±0.008. This indicated a direct relationship between the concentrations of biomass and SMP produced. In experiment 2, MLSS increased from 1,200±25 to a constant value (2,810±16 mg/l; SRT, 12 days). After this time, no decrease or increase in MLSS was observed. Correspondingly, sCOD and sBOD₅ removal increased from 80–97 to 84–99%. A stable microbial community that could consume organic matter efficiently was developed under these conditions.     

Effect of caffeine concentration on biomass production, caffeine degradation, and morphology of Aspergillus tamarii

The aim of the present study was to evaluate the effect of the initial caffeine concentration (1–8 g/L) on growth and caffeine consumption by Aspergillus tamarii as well as pellet morphology, in submerged fermentation. Caffeine was used as sole nitrogen source. At 1 g/L of initial caffeine concentration, caffeine degradation was not affected, resulting in a production of 8.7 g/L of biomass. The highest biomass production (12.4–14.8 g/L) was observed within a range of 2 to 4 g/L of initial caffeine concentration. At these initial caffeine concentrations, after 96 h of fermentation, 41–51 % of the initial caffeine was degraded. Using an initial caffeine concentration of 2–3 g/L, the highest specific growth rate was observed (μ?=?0.069 1/h). Biomass production decreased at 8 g/L of initial caffeine concentration. A. tamarii formed mainly pellets at all concentrations tested. The size of the pellet decreased at a caffeine concentration of 8 g/L.     

Control of ubiquitination of proteins in rat tissues by ubiquitin conjugating enzymes and isopeptidases

The activity of the ubiquitin-dependent proteolytic system in differentiated tissues under basal conditions remains poorly explored. We measured rates of ubiquitination in rat tissue extracts. Accumulation of ubiquitinated proteins increased in the presence of ubiquitin aldehyde, indicating that deubiquitinating enzymes can regulate ubiquitination. Rates of ubiquitination varied fourfold, with the highest rate in the testis. We tested whether ubiquitin-activating enzyme (E1) or ubiquitin-conjugating enzymes (E2s) could be limiting for conjugation. Immunodepletion of the E2s UBC2 or UBC4 lowered rates of conjugation similarly. Supplementation of extracts with excess UBC2 or UBC4, but not E1, stimulated conjugation. However, UBC2-stimulated rates of ubiquitination still differed among tissues, indicating that tissue differences in E3s or substrate availability may also be rate controlling. UBC2 and UBC4 stimulated conjugation half-maximally at concentrations of 10-50 and 28-44 nM, respectively. Endogenous tissue levels of UBC2, but not UBC4, appeared saturating for conjugation, suggesting that in vivo modulation of UBC4 levels can likely control ubiquitin conjugation. Thus the pool of ubiquitin conjugates and therefore the rate of degradation of proteins by this system may be controlled by E2s, E3s, and isopeptidases. The regulation of the ubiquitin pathway appears complex, but precise.     

Behavior of natural estrogens in semicontinuous activated sludge biodegradation reactors

Biological degradation of natural estrogens was investigated by separately spiking 17 beta-estradiol (E2) and estrone (E1) into activated sludge reactors operated in a semi-continuous flow mode under aerobic conditions. By conducting runs for simultaneous addition of glucose over the designated initial concentrations of 0, 10, 30, 50 and 100 mg l(-1), respectively, the likely effect of the easily biodegradable organic constituent on the degradation rate of the natural estrogens was also studied. The spiked E2 disappeared in a manner much faster than E1; and its disappearance occurred through elimination of its metabolic byproduct of E1. The apparent first-order disappearance rate of E2 and E1 fell in the ranges of 0.84-4.31h(-1) and 0.15-0.84 h(-1), respectively when spiked separately into respective reactors. A general trend of decreases in the disappearance rate with increases of the initial glucose concentration was revealed. The presence of glucose was also found capable of lowering the conversion ratio from E2 to E1.     

S5a promotes protein degradation by blocking synthesis of nondegradable forked ubiquitin chains

Ubiquitin (Ub)–protein conjugates formed by purified ring‐finger or U‐box E3s with the E2, UbcH5, resist degradation and disassembly by 26S proteasomes. These chains contain multiple types of Ub forks in which two Ub's are linked to adjacent lysines on the proximal Ub. We tested whether cells contain factors that prevent formation of nondegradable conjugates and whether the forked chains prevent proteasomal degradation. S5a is a ubiquitin interacting motif (UIM) protein present in the cytosol and in the 26S proteasome. Addition of S5a or a GST‐fusion of S5a's UIM domains to a ubiquitination reaction containing 26S proteasomes, UbcH5, an E3 (MuRF1 or CHIP), and a protein substrate, dramatically stimulated its degradation, provided S5a was present during ubiquitination. Mass spectrometry showed that S5a and GST–UIM prevented the formation of Ub forks without affecting synthesis of standard isopeptide linkages. The forked Ub chains bind poorly to 26S proteasomes unlike those synthesized with S5a present or linked to Lys63 or Lys48 chains. Thus, S5a (and presumably certain other UIM proteins) function with certain E3/E2 pairs to ensure synthesis of efficiently degraded non‐forked Ub conjugates.     

Occurrence and Fate of Estrone, 17β-estradiol and 17α-ethynylestradiol in STPs for Domestic Wastewater

Estrone (E1), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) discharged from sewage treatment plants (STPs) into surface waters, are seen as a threat effecting aquatic life by its estrogenic character. Therefore, much research is conducted on the fate and removal of these compounds. Since these compounds are present in influents and effluents in the ng/l range, methods for detection deserve special attention. Most important processes that play a role in the removal of estrogens are: adsorption, aerobic degradation, anaerobic degradation, anoxic biodegradation and photolytic degradation. Halflifes tend to vary and are remarkably shorter when low initial concentrations are applied. In general anaerobic conditions result in longer halflifes then aerobic conditions. EE2 shows far most persistence of the compounds, thereby also the estrogenic effect in vitro is about 2–3-fold higher compared to E2. The three compounds show a higher affinity to sorb to sludge compared to other tested adsorption materials like sediment. Aerobic degradation is far the most efficient in removing these compounds, but adsorption seems to play a significant role in retaining the estrogens inside full-scale STPs. Removal rates in full scale plants depend on the HRT, SRT and loading rates, but lack of information on the exact dependency so far prevents an optimal design able to fully eliminate estrogens from wastewater.     

施用磷对王桉 (Eucalyptus regnans F. Muell.)幼苗生长及其氨基酸组

王桉 (Eucalyptus regnans F. Muell.) 是澳大利亚桉树中最重要的商业用材和人工造林树种之一.研究王桉的施肥与其体内氨基酸的积累和转化及与食叶虫害之间的相关性具有重要的经济和生态意义.在温室内利用2种不同来源的土壤对王桉幼苗进行了不同磷施用量(100 kg hm~(-2)和 200 kg hm~(-2))处理.结果显示,不同土壤和不同磷施用量对苗木生长影响显著,但均未显著影响苗木各部分的氮和磷含量水平.苗木木质部渗出液中的氨基酸含量以谷氨酰胺为主,并与苗木生长和磷施用量呈反相关.不同土壤和磷施用量对苗木组织中游离氨基酸组分和含量的影响不显著,但游离氨基酸的组分和相对水平随叶龄变化明显,尤其是精氨酸在嫩叶氨基酸总量中只占2%～3%,但在老叶中占到20%多;精氨酸在老叶中的积累极有可能是某些蛋白质降解而精氨酸即时合成所致,因为精氨酸一般不在韧皮部转运.谷氨酰胺在树液中含量最高并与苗木生长呈反相关或许可以作为预测桉树发生食叶昆虫危害的一个有用指标.     

Degradation and Mineralization of the Polycyclic Aromatic Hydrocarbons Anthracene and Naphthalene in Intertidal Marine Sediments

The degradation of the polynuclear aromatic hydrocarbons (PAHs) anthracene and naphthalene by the microbiota of intertidal sediments was investigated in laboratory studies. No mineralization of either PAH was observed in the absence of oxygen. Both rates and total amounts of PAH mineralization were strongly controlled by oxygen content and temperature of the incubations. Inorganic nitrogen and glucose amendments had minimal effects on PAH mineralization. The rates and total amounts of PAH mineralized were directly related to compound concentration, pre-exposure time, and concentration. Maximum mineralization was observed at the higher concentrations (5 to 100 μg/g [ppm]) of both PAHs. Optimal acclimation to anthracene and naphthalene (through pre-exposures to the compounds) occurred at the highest acclimation concentration (1,000 ppm). However, acclimation to a single concentration (100 ppm) resulted in initial relative mineralization rates over a range of re-exposure concentrations (1 to 1,000 ppm) being nearly identical. Maximum mineralization of both PAHs occurred after intermediate periods (1 to 2 weeks) of pre-exposure. The fraction of the total heterotrophic population capable of utilizing anthracene or naphthalene as sole carbon source was also greatest after 2 weeks.     

Ammonia concentration determines differential growth of ammonia-oxidising archaea and bacteria in soil microcosms

The first step of nitrification, oxidation of ammonia to nitrite, is performed by both ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soil, but their relative contributions to ammonia oxidation and existence in distinct ecological niches remain to be determined. To determine whether available ammonia concentration has a differential effect on AOA and AOB growth, soil microcosms were incubated for 28 days with ammonium at three concentrations: native (control), intermediate (20 μg NH₄⁺-N per gram of soil) and high (200 μg NH₄⁺-N per gram of soil). Quantitative PCR demonstrated growth of AOA at all concentrations, whereas AOB growth was prominent only at the highest concentration. Similarly, denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in AOA communities at all ammonium concentrations, whereas AOB communities changed significantly only at the highest ammonium concentration. These results provide evidence that ammonia concentration contributes to the definition of distinct ecological niches of AOA and AOB in soil.     

Genotypic variation in silicon concentration of barley grain

Soluble silicon (Si) in foods and drinks has been suggested to have a protective effect against neurotoxicity of Al. We investigated the genotypic variation in Si concentration of barley grain, which has many uses including in livestock feeds, malts for beer and whisky, and some foods for human consumption. Two collections of barley, grown in the same field, were subjected to analysis; 274 standard varieties selected at the Barley Germplasm Center of the Research Institute for Bioresources, Okayama University (SV), and 135 varieties from the Barley Core Collection of Americans (BCCAM). The Si concentration of barley grain showed large variation, ranging from 0 (under detection) to 3600 mg kg^–1 in SV and from 0 to 3800 mg kg^–1 in BCCAM barleys. The Si concentration was much lower in hull-less barley than in hulled barley. The Si concentration of two-row barley was similar to that of six-row barley, suggesting that Si concentration is not affected by the number of spike rows. Si concentration also did not differ with the origin of the barley variety. More than 80% of total Si was localized in the hull. The Si concentration of the hull was between 15343 and 27089 mg kg^–1 in the varieties tested. A close correlation was obtained between the Si concentrations of barley grains harvested in different years, suggesting that the variation in Si concentration of barley grain is controlled genetically. These results provide fundamental data for breeding Si-rich cultivars.     

Quantitative analysis of protein synthesis inhibition and recovery in CRM107 immunotoxin-treated HeLa cells

Previously a mathematical model was proposed that quantitatively related protein synthesis inhibition kinetics of antitransferrin receptor-gelonin immunotoxins to the cellular trafficking of the targeting agent. That work is here extended to describe protein synthesis inhibition kinetics of immunotoxins containing the diphtheria toxin mutant CRM107. CRM107 differs from gelonin in both translocation and ribosomal inactivation mechanisms. Targeting agents used were antitransferrin monoclonal antibodies 5E9 and OKT9, OKT9Fab, and transferrin. CRM107 conjugates inhibited protein synthesis at substantially lower concentrations than gelonin conjugates; this effect was attributed to substantially higher translocation rates for CRM107. However, under certain conditions, CRM107 immunotoxin-treated cells were able to recover completely; this behavior was never observed with gelonin immunotoxins. To quantitatively capture this phenomenon, extracellular and cytosolic degradation of the toxin as well as growth-related recovery from toxin-induced damage were incorporated into the mathematical model. Translocation and cytosolic degradation rate constants were determined for each immunotoxin. Unlike the gelonin conjugates, the translocation rate of CRM107 conjugates depended on the targeting molecule. This provided indirect evidence that CRM107 remains disulfide linked to the targeting agent for at least part of the translocation process. Although the CRM107 conjugates all had higher translocation rates and inhibited protein synthesis at lower concentrations than the gelonin conjugates, the cells' ability to recover from protein synthesis inhibition at low immunotoxin concentrations limits the utility of CRM107 conjugates for targeted cell killing.     

Degradation kinetics of phenol by immobilized cells of Candida tropicalis in a fluidized bed reactor

Degradation kinetics of phenol by free and agar-entrapped cells of Candida tropicalis was studied in batch cultures. The initial phenol degradation rate achieved with free cells was higher than that obtained with immobilized cells, when phenol concentrations up to 1000 mg l^–1 were used. However, at higher phenol concentrations, the behaviour was quite different. The initial degradation rate of the immobilized yeast cells was about 10 times higher than that of the free cells, at a phenol concentration of 3500 mg l^–1. The semicontinuous and continuous degradation of phenol by immobilized yeast cells was also investigated in a multi-stage fluidized bed reactor. The highest phenol removal efficiencies and degradation rates as well as the lowest values of residual phenol and chemical oxygen demand were obtained in the semicontinuous culture when phenol concentrations up to 1560 mg l^–1 were used.     

Neurite outgrowth in PC12 cells. Distinguishing the roles of ubiquitylation and ubiquitin-dependent proteolysis

Nerve growth factor (NGF)-induced neurite outgrowth from rat PC12 cells was coincident with elevated (>/=2-fold) levels of endogenous ubiquitin (Ub) protein conjugates, elevated rates of formation of 125I-labeled Ub approximately E1 (Ub-activating enzyme) thiol esters and 125I-labeled Ub approximately E2 (Ub carrier protein) thiol esters in vitro, and enhanced capacity to synthesize 125I-labeled Ub-protein conjugates de novo. Activities of at least four E2s were increased in NGF-treated cells, including E2(14K), a component of the N-end rule pathway. Ubiquitylation of 125 I-labeled beta-lactoglobulin was up to 4-fold greater in supernatants from NGF-treated cells versus untreated cells and was selectively inhibited by the dipeptide Leu-Ala, an inhibitor of Ub isopeptide ligase (E3). However, Ub-dependent proteolysis of 125I-labeled beta-lactoglobulin was not increased in supernatants from NGF-treated cells, suggesting that neurite outgrowth is promoted by enhanced rates of synthesis (rather than degradation) of Ub-protein conjugates. Consistent with this observation, neurite outgrowth was induced by proteasome inhibitors (lactacystin and clasto-lactacystin beta-lactone) and was associated with elevated levels of ubiquitylated protein and stabilization of the Ub-dependent substrate, p53. Lactacystin-induced neurite outgrowth was blocked by the dipeptide Leu-Ala (2 mM) but not by His-Ala. These data 1) demonstrate that the enhanced pool of ubiquitylated protein observed during neuritogenesis in PC12 cells reflects coordinated up-regulation of Ub-conjugating activity, 2) suggest that Ub-dependent proteolysis is a negative regulator of neurite outgrowth in vitro, and 3) support a role for E2(14K)/E3-mediated protein ubiquitylation in PC12 cell neurite outgrowth.     

Inverse relationship of protein concentration and binding activity of alpha-galactoside receptors from sugarcane membranes

1. 1. The binding activity of purified α-galactoside receptor proteins from a number of plant species decreases when the protein concentration is increased from 2 ng/ml to 100 μg/ml.

2. 2. The apparent loss of binding activity at high protein concentrations corresponds to the formation of high molecular weight multimers.

3. 3. Raffinose and melibiose cause a ligand-dependent increase in binding activity and a corresponding decrease in the relative abundance of multimers at any given protein concentration.

4. 4. The self-inhibition of binding activity at high protein concentrations arises from a competition between ligand binding by oligomers and self-association of these oligomers into multimeric species which have little or no binding activity.

Ubiquitin-dependent proteolysis of native and alkylated bovine serum albumin: effects of protein structure and ATP concentration on selectivity

The susceptibility of bovine serum albumin to degradation by the ubiquitin-dependent system of proteolysis depends on the severity of the iodination conditions [Wilkinson, K.D., & Audhya, T.K. (1981) J. Biol. Chem. 256, 9235-9241]. To evaluate if other modifications of the protein changed its susceptibility to degradation, chemically modified derivatives of bovine serum albumin have been synthesized, characterized, and tested as substrates for the ubiquitin-dependent system. Serum albumin was reduced or reduced and alkylated with iodoacetic acid or iodoacetamide. Only the alkylated derivatives exhibit saturation kinetics. Both alkylated proteins competitively inhibit the degradation of the other. These substrates are useful for assay of the intact proteolysis system in crude extracts and in assays for other substrates using competitive alternate substrate inhibition. The physical properties of these proteins suggest that charge, denaturation, or aggregation is not correlated with the degradation rate of these proteins by this system. However, the selectivity of the ubiquitin-dependent proteolysis depends strongly on the ATP concentration. At saturating substrate concentrations, both alkylated substrates are degraded equally. At low ATP concentrations, there is a 2.4-fold difference in the degradation rates of the alkylated proteins. The results presented here indicate that the ubiquitin-dependent protein degradation system is selective and responsive to ATP concentrations and that not all abnormal proteins are equally preferred substrates. Thus, the system may be more selective than previously thought.     

Sulphate-mediated phosphorus mobilization in riverine sediments at increasing sulphate concentration, River Spree, NE Germany

The study focuses on the response of a sulphate rich lowland river (River Spree) to a further increase in sulphate concentration as a result of mining activities in its catchments. It was hypothesized that riverine sediments could be conservative against an increase in sulphate concentration relating to both the intensity of sulphate reduction and the accompanying P mobilization. The usually lower amount of organic matter, compared to lakes or wetlands, and the high contents of iron oxides in the Spree sediment from discharged mining waters should counteract an enhanced P mobilization. Three short-term incubation experiments were carried out to test the sensitivity of different sediment horizons (0–10, 10–20 and 20–30 cm), the influence of temperature (5 and 25 °C) and the effect of a rising sulphate concentration (2.6–7.8 mM) on P mobilization rates (PMR) and sulphate reduction rates (SRR). Contrary to our initial hypothesis sulphate played a key role for P mobilization in riverine sediments because (1) all sulphate treated horizons showed a significant increase in pore water P concentrations, (2) increasing sulphate concentrations led to rising SRR and PMR, (3) the highest response on sulphate-mediated P mobilization was observed by a temperature enhancement of 20 °C. PMR increased one order of magnitude at all tested sulphate concentrations, but these increases in PMR only slightly effected the P concentrations in the overlying water. In conclusions, an increase of internal P load is only expected in case of doubling the recent in situ sulphate concentrations, but extended warm periods as an effect of climate change or increasing temperature, respectively, could be of more importance.     

Mammalian Ddi2 is a shuttling factor containing a retroviral protease domain that influences binding of ubiquitylated proteins and proteasomal degradation

Although several proteasome subunits have been shown to bind ubiquitin (Ub) chains, many ubiquitylated substrates also associate with 26S proteasomes via “shuttling factors.” Unlike the well-studied yeast shuttling factors Rad23 and Dsk2, vertebrate homologs Ddi2 and Ddi1 lack a Ub-associated domain; therefore, it is unclear how they bind Ub. Here, we show that deletion of Ddi2 leads to the accumulation of Ub conjugates with K11/K48 branched chains. We found using affinity copurifications that Ddi2 binds Ub conjugates through its Ub-like domain, which is also required for Ddi2 binding to proteasomes. Furthermore, in cell extracts, adding Ub conjugates increased the amount of Ddi2 associated with proteasomes, and adding Ddi2 increased the binding of Ub conjugates to purified proteasomes. In addition, Ddi2 also contains a retroviral protease domain with undefined cellular roles. We show that blocking the endoprotease activity of Ddi2 either genetically or with the HIV protease inhibitor nelfinavir increased its binding to Ub conjugates but decreased its binding to proteasomes and reduced subsequent protein degradation by proteasomes leading to further accumulation of Ub conjugates. Finally, nelfinavir treatment required Ddi2 to induce the unfolded protein response. Thus, Ddi2 appears to function as a shuttling factor in endoplasmic reticulum–associated protein degradation and delivers K11/K48-ubiquitylated proteins to the proteasome. We conclude that the protease activity of Ddi2 influences this shuttling factor activity, promotes protein turnover, and helps prevent endoplasmic reticulum stress, which may explain nelfinavir’s ability to enhance cell killing by proteasome inhibitors.     

Whole-Cell Kinetics of Trichloroethylene Degradation by Phenol Hydroxylase in a Ralstonia eutropha JMP134 Derivative

The rate, progress, and limits of trichloroethylene (TCE) degradation by Ralstonia eutropha AEK301/pYK3021 whole cells were examined in the absence of aromatic induction. At TCE concentrations up to 800 μM, degradation rates were sustained until TCE was no longer detectable. The K_s and V_max for TCE degradation by AEK301/pYK3021 whole cells were determined to be 630 μM and 22.6 nmol/min/mg of total protein, respectively. The sustained linear rates of TCE degradation by AEK301/pYK3021 up to a concentration of 800 μM TCE suggest that solvent effects are limited during the degradation of TCE and that this construct is little affected by the formation of toxic intermediates at the TCE levels and assay duration tested. TCE degradation by this strain is subject to carbon catabolite repression.     

Biodegradation of 2-Chlorobenzoic Acid by Enterobacter cloacae: Growth Kinetics and Effect of Growth Conditions

Enterobacter cloacae was originally isolated from soil irrigated with wastewater on the basis of its ability to grow with linear alkylbenzene sulfonate (LAS) as the sole source for carbon and energy. The isolated bacterium was grown in batch cultures using a 2-chlorobenzoic acid (2-CBA)-containing minimal salt medium (MSM). 2-CBA was found to be the sole source for carbon and energy. 2-CBA inhibited the growth rate with a maximum concentration of 10 mM, after which no growth occurred. The Haldane model was used to predict the specific growth rate concentration data. 2-CBA degradation by starved E. cloaca cells was faster than that of nonstarved cells. The maximum growth rates on 2-CBA (2 mM) for starved and nonstarved cells reached only 0.34 and 0.28 h^?1, respectively. Glucose, lactose, sucrose, maltose, succinic acid, and mannitol as additional carbon sources at a fixed concentration (0.2%) caused the degradation rate of 2-CBA to proceed faster at ranges between 1.08- and 1.5-fold higher than that of the control. In contrast, using only fructose and sorbitol as the carbon sources showed catabolic repression of the degradation activity of 2-CBA by E. cloaca cells, although their cell mass was improved. All nitrogen sources supplied caused an increase in cell mass, whereas only lysine, alanine, glutamine, casein, and yeast extract caused a decrease in the degradation rate of 2-CBA, with a range between 12% and 28%. The activity of C120 could be detected in a crude extract of E. cloacae cells, indicating that the chloroaromatic ring fission occurs through the ortho pathways, not through the meta pathways. The data showed that different initial cell (inocula) densities did not affect the induction time for 2-CBA degradation. However, doubling the initial cell densities reduced the time required for reaching the complete degradation. 2-CBA degradation was optimally achieved at a 37°C incubation temperature and a pH of 7.5.