Priority pollutant degradation by the facultative methanotroph, Methylocystis strain SB2

Methylocystis strain SB2, a facultative methanotroph capable of growth on multi-carbon compounds, was screened for its ability to degrade the priority pollutants 1,2-dichloroethane (1,2-DCA), 1,1,2-trichloroethane (1,1,2-TCA), and 1,1-dichloroethylene (1,1-DCE), as well as cis-dichloroethylene (cis-DCE) when grown on methane or ethanol. Methylocystis strain SB2 degraded 1,2-DCA and 1,1,2-TCA when grown on either substrate and cis-DCE when grown on methane. Growth of Methylocystis strain SB2 on methane was inhibited in the presence of all compounds, while only 1,1-DCE and cis-DCE inhibited growth on ethanol. No degradation of any chlorinated hydrocarbon was observed in ethanol-grown cultures when particulate methane monooxygenase (pMMO) activity was inhibited with the addition of acetylene, indicating that competition for binding to the pMMO between the chlorinated hydrocarbons and methane limited both methanotrophic growth and pollutant degradation when this strain was grown on methane. Characterization of Methylocystis strain SB2 found no evidence of a high-affinity form of pMMO for methane, nor could this strain utilize 1,2-DCA or its putative oxidative products 2-chloroethanol or chloroactetic acid as sole growth substrates, suggesting that this strain lacks appropriate dehydrogenases for the conversion of 1,2-DCA to glyoxylate. As ethanol: (1) can be used as an alternative growth substrate for promoting pollutant degradation by Methylocystis strain SB2 as the pMMO is not required for its growth on ethanol and (2) has been used to enhance the mobility of chlorinated hydrocarbons in situ, it is proposed that ethanol can be used to enhance both pollutant transport and biodegradation by Methylocystis strain SB2.     

Inhibition of lipolysis by hydrocarbons and fatty alcohols

The hydrolysis of long-chain triglyceride by pancreatic lipase (EC 3.1.1.3) is inhibited by hydrophobic solutes that are dissolved in the fat. Solutes tested included n-alkanes (C10-C16), aromatic and chlorinated aromatic hydrocarbons (including a PCB and DDT), n-alcohols (C10-C16), and cholesterol. Except for cholesterol, which stimulated lipolysis at low concentrations, all compounds produced roughly similar inhibition curves that followed the pattern of a typical Langmuir adsorption isotherm (Mattson, F. H., R. A. Volpenhein, and L. Benjamin, 1970. J. Biol. Chem. 245: 5335-5340). According to this interpretation, hydrophobic solutes dissolved within fat droplets partition between the interior oil phase and the surface monolayer where lipolysis occurs. Although the aromatic and chlorinated aromatic hydrocarbons were approximately 25% more inhibitory than the long-chain aliphatic hydrocarbons, as a single class, hydrocarbons were 7-10 times weaker inhibitors of lipolysis than fatty alcohols. In contrast to the alcohols whose inhibitory action may involve several mechanisms, the hydrocarbons behaved like simple dilution inhibitors; i.e., at 50% inhibition the mass ratio of hexadecane to triglyceride was 0.42. The lack of a chain length effect indicates that the hydrocarbons are not adsorbed at the interface but interdigitate the triglyceride molecules and align parallel to the lipid acyl chains. Inhibition by hydrophobic solutes was not reversed by the presence of 4 mM taurodeoxycholate and pancreatic procolipase or colipase.     

Effects by heme, insulin, and serum albumin on heme and protein synthesis in chick embryo liver cells cultured in a chemically defined medium, and a spectrofluorometric assay for porphyrin composition.

Primary chick embryo liver cells, which had been previously cultured in Eagle's medium containing 10% fetal bovine serum, had the same characteristics (inducibility of delta-aminolevulinic acid synthetase and synthesis of plasma proteins) when cultured in a completely defined Ham F-12 medium containing insulin. Insulin was active in the physiological range; 2 to 3 nM were sufficient to increase the induced delta-aminolevulinic acid synthetase to 50% of the maximum effect obtained with a saturating amount of insulin (30 nM). Serum albumin added to the Ham-insulin medium caused protoporphyrin but not uroporphyrin, generated in the cultured liver cells, to be transferred to the medium. As little as 10 mug of human serum albumin per ml caused the transfer of one-half of the protoporphyrin. Bovine serum albumin was only about 1/30 as effective. A spectrofluorometric method and calculation procedure are described for quantitation, in the nanomolar range, of total porphyrin and the percentage of this that is protoporphyrin or uroporphyrin plus coproporphyrin. The method is satisfactory for the measurement of porphyrins generated by 1 mg wet weight of cells in culture in 20 hours. Heme (0.1 to 0.3 muM), when added to the medium as hemin, human hemoglobin, or chicken hemoglobin, specifically inhibited the induction of delta-aminolevulinic acid synthetase by one-half. This high sensitivity for heme was observed under conditions in which the defined medium was free of serum and where a chelator of iron was added to the medium to diminish the synthesis of endogenous heme. Heme endogenously generated from exogenous delta-aminolevulinic acid also inhibited the induction; chelators of iron prevented this inhibition. The migration of heme from the mitochondria to other portions of the cell is discussed in terms of the affinities of different proteins for heme. A hypothesis of a steady state of liver heme metabolism, controlled by the concentration of "free" heme, is presented. The different effects of heme on the synthesis of a number of proteins are summarized.     

The effects of dihydropyridine calcium antagonists on heme biosynthesis in chick embryo liver cell culture

A variety of 1,4-dihydropyridine calcium antagonists were tested for porphyrinogenic activity in chick embryo liver cell culture. 3,5-Dimethoxycarbonyl-1,4-dihydro-2, 6-dimethyl-4-(ortho-nitrophenyl)pyridine (nifedipine) was shown to be a potent porphyrinogenic agent. This activity was shared by a number of related analogues, viz., the 4-phenyl, 4-(meta-nitrophenyl), 4-(para-nitrophenyl), 4-(ortho-methoxyphenyl), 4-(meta-trifluoromethylphenyl), and 4-(para-trifluoromethylphenyl) analogues and nitrendipine; nicardipine exhibited very weak activity. The porphyrinogenic potency of the 1,4-dihydropyridines did not parallel their calcium antagonist activity. Nifedipine did not exhibit ferrochelatase-lowering activity in chick embryo liver cell culture and uroporphyrin and heptacarboxylic acid porphyrin were the major porphyrins to accumulate. Nifedipine did not cause suicidal destruction of cytochrome P-450 in chick embryo hepatic microsomes. Because nifedipine possesses comparable porphyrinogenic activity to sodium secobarbital in chick embryo liver cell culture, caution is required if nifedipine or related drugs are administered to patients with hereditary hepatic porphyria.     

Interactions with glutathione S-transferases of porphyrins used in photodynamic therapy and naturally occurring porphyrins.

Several naturally occurring porphyrins and porphyrins used in photodynamic therapy inhibit glutathione S-transferase isoenzymes either purified from rat liver or lung or in cytosol from normal and from cancerous (Morris 7288C hepatoma) liver. Although differences occur in the type and amount of transferases in normal and cancerous liver and in the liver of rats bearing an extrahepatic tumour, these enzymes are potential binding sites for porphyrins. Porphyrin structure is an important factor in determining the affinity of binding, as shown by the relative inhibitory effectiveness. Of the dicarboxylic porphyrins in the mixture used clinically, OO'-diacetylhaematoporphyrin and monohydroxyethylmonovinyldeuteroporphyrin are more effective inhibitors than haematoporphyrin and protoporphyrin IX. Of the naturally occurring porphyrins the order of effectiveness is protoporphyrin IX (dicarboxylic) greater than coproporphyrin (tetracarboxylic) greater than uroporphyrin (octacarboxylic) and type I greater than type III isomers of both uroporphyrin and coproporphyrin, and the synthetic tetra-meso-phenylporphinetetrasulphonate is a better inhibitor (apparent Ki = 250 nM) than coproporphyrin, which contains a comparable number of negative charges. In addition, iron-porphyrin chelates are more effective inhibitors of the transferases, with 25-fold decrease in Ki value, than the free porphyrins. These results indicate that one means whereby porphyrins accumulate in tissues is the occupation of intracellular binding sites, such as the transferases. Since porphyrins inhibit the activity of these important detoxifying enzymes, there will be metabolic consequences to the cell.     

Options for In Situ Remediation of Soil Contaminated with a Mixture of Perchlorinated Compounds

Environments contaminated with mixtures of chlorinated hydrocarbons represent a formidable challenge for bioremediation because biodegradation of all components of the mixture must be demonstrated. In this study a soil site contaminated with hexachloro-1,3-butadiene (HCBD), hexachlorobenzene (HCB), and perchloroethene (PCE) was investigated. Environmental parameters (including toxicity) and microbial community composition were characterized. The lack of scientific literature on HCBD biodegradation led to attempts to develop HCBD-respiring enrichment cultures and to test the hypothesis that known PCE-degrading cultures could dechlorinate HCBD. No HCBD dechlorination was observed. An alternative approach, using electron shuttles to degrade the mixture of chlorinated hydrocarbons, was compared with the activity of zero-valent iron. The authors conclude that electron shuttles offer promise for the in situ treatment of mixtures of chlorinated hydrocarbons.     

In vitro uptake and transfer of chlorinated hydrocarbons among human lipoproteins

The uptake, distribution, and exchange of chlorinated hydrocarbon insecticides (dieldrin and chlordecone) and biphenyls (2,4,5-2',4',5'-hexachlorobiphenyl and 3-chlorobiphenyl) among human lipoproteins was examined by fluorescence quenching, gel filtration, and ultrafiltration. The chlorinated hydrocarbons were rapidly taken up from solution or silica particles by lipoproteins. The distribution of chlorinated hydrocarbons among the lipoproteins was independent of the amount taken up by the lipoproteins. The partition coefficient for each lipoprotein and the serum concentration of individual lipoproteins determined the distribution pattern of chlorinated hydrocarbons among lipoproteins. The chlorinated hydrocarbons attached to albumin or one of the lipoproteins were rapidly transferred to all other lipoproteins. The exchange was complete in less than one minute. The role of rapid exchange of chlorinated hydrocarbons among lipoproteins in removal of these chemicals from blood and distribution to other tissues is discussed.     

Bacterial Diversity and Biogeochemical Processes of Oil-Contaminated Groundwater,Baoding, North China

A total of 43 groundwater samples were collected from 9 multimonitoring wells at a petrochemical site, Baoding City, North China, from June 2008 to December 2009 to investigate the biogeochemical processes and/or bacterial conmmunity using both culture-dependent and -independent methods. The results showed that aromatic hydrocarbons and chlorinated hydrocarbons were the major pollutants in the groundwater. Denitrification and iron reduction might be the main biogeochemical processes in the aquifers at this site, which seemed to transform from denitrification-dominated to iron reduction-dominated in some sections. Denaturing gradient gel electrophoresis (DGGE) revealed that the dominant bacterial groups of the groundwater were related to some oil-degrading bacteria, which can grow under denitrifying, iron-reducing and sulfate-reducing anaerobic conditions. In some serious contaminated groundwater niches, there might be sulfur cycles, as sulfur oxidizer was also abundant, which was further confirmed by 16S rRNA gene cloning analysis. The operational taxonomic units (OTUs) that highly related to Pseudomonas sp., Hydrogenophaga sp., Sphingomonas sp., Ferribacterium sp. and Sulfuricurvum Kujiense etc. were predominant in the groundwater contaminated by chlorinated hydrocarbons (CHCs), benzene, toluene, ethylbenzene, and xylenes (BTEX) and/or polycyclic aromatic hydrocarbons (PAHs), respectively. Biodiversity seemed to be undermined by oil contamination, and varied with seasons. The bacterial community in the contaminated groundwater was largely determined by the groundwater geochemistry.     

专一营养与兼性甲烷氧化菌降解氯代烃的研究现状、动力学分析及展望

生物修复技术被认为是氯代烃类污染物处理处置的最有效途径之一,而甲烷氧化菌在该领域表现出较大的应用潜力。近期研究发现,突破了仅能利用单碳化合物的局限,兼性甲烷氧化菌能够利用多种底物降解氯代烃,这一独特的新陈代谢特性,使其在污染物生物处置领域逐渐受到关注。结合本课题组研究成果,对甲烷氧化菌降解氯代烃进行了全面总结,主要包括:分析了不同菌株(纯菌株和混合菌株)对不同氯代烃的降解效果;比较了不同类型甲烷单加氧酶在不同底物体系中的活性表达和催化特性;总结了模型菌株甲基弯菌Methylosinus trichosporium OB3b降解氯代烃的动力学特性;概述了兼性甲烷氧化菌株降解氯代烃的特性及其应用潜力;最后讨论了甲烷氧化菌降解氯代烃存在的问题及未来发展方向。     

Reproductive injury in English Sole (Pleuronectes vetulus) from the Hylebos Waterway, Commencement Bay, Washington

The effect of exposure to xenobiotic compounds on ovarian development was investigated in prespawning female English sole (Pleuronectes vetulus) from the Hylebos Waterway, an industrial site in Commencement Bay, WA, contaminated with aromatic hydrocarbons (AHs), polychlorinated biphenyls (PCBs)and other chlorinated compounds, including hexachlorobutadiene (HCBD) and hexachlorobenzene (HCB). Reference sole were collected from Colvos Passage, a nearby site with minimal sediment contaminant concentrations. English sole from theHylebos Waterway had significantly higher concentrations of fluorescent aromatic compounds (FACs) in bile, polycyclic aromatic compound-DNA adducts in liver, and dioxin-like and other selected PCB congeners in liver than sole from Colvos Passage. The Hylebos Waterway animals also showed significant alterations in their pattern of reproductive development when compared to Colvos Passage sole. Hylebos Waterway sole entered vitellogenesis at a nearlier age than Colvos Passage sole, with about 50%of fish below 5 years of age maturing in the Hylebos Waterway as compared to 20% of Colvos Passage sole in this age range, with corresponding increases in plasma estradiol concentrations and GSI in Hylebosfish. However, while the proportion of maturing Colvos Passage females increased with age to over70% for fish 5 years of age or greater, the proportion of maturing females in the Hylebos Waterway remained at about 50%. Moreover, plasma estradiol concentrations and gonadosomatic indices in these sole were depressed. Inhibited reproductive development and increased oocyte atresia in adult fish were correlated with elevated concentrations of FACs in bile. Enhanced growth, as well as exposure to both aromatic and chlorinated hydrocarbons, were associated with precocious maturation in sub adult Hylebos Waterway sole. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inhibition of chick embryo hepatic uroporphyrinogen decarboxylase by components of xenobiotic-treated chick embryo hepatocytes in culture. II.

A variety of xenobiotics, viz., 3,3',4,4'-tetrachlorobiphenyl (TCBP), sodium phenobarbital (PB), 3,5-diethoxycarbonyl-2, 4,6-trimethylpyridine (OX-DDC), and nifedipine, cause a decrease in uroporphyrinogen decarboxylase (UROG-D) activity, accompanied by uroporphyrin accumulation, in chick embryo hepatocytes in culture. In this study the activity of 17-day-old chick embryo hepatic UROG-D was determined by measuring the conversion of pentacarboxylporphyrinogen I to coproporphyrinogen I, and it was shown that a UROG-D inhibitor, previously reported to accumulate in TCBP-treated and PB-treated chick embryo hepatocytes in culture, also accumulates in OX-DDC-treated and nifedipine-treated chick embryo hepatocytes in culture. It was concluded that the accumulation of a UROG-D inhibitor provides an explanation for the UROG-D inhibition observed in this culture system with xenobiotics that cause uroporphyrin accumulation. Studies of the UROG-D inhibitory fraction isolated from the 10,000 x g, 40,000 x g, and 100,000 x g supernatant fractions of cultured chick embryo hepatocyte homogenate led to the conclusion that the UROG-D inhibitor is derived from a soluble component of the homogenate.     

Sediment-associated contaminants and liver diseases in bottom-dwelling fish

High concentrations of chemicals have been found in sediments from urban areas of Puget Sound. Hundreds, of organic chemicals (including certain aromatic hydrocarbons [AHs] and various chlorinated compounds) were identified. Statistical methods were used to evaluate possible relationships between the chemistry data and fish diseases. Positive correlations were found between the frequencies of liver neoplasms (e.g., hepatocellular carcinoma) and other liver lesions in English sole (Parophrys vetulus) and concentrations of AHs in sediment; such correlations were not found with chlorinated hydrocarbons. Strong evidence was also obtained to show that many organic chemicals in sediment are bioavailable to bottom-dwelling fish. Stomach contents (consisting mainly of benthic invertebrates) from English sole had concentrations of a number of AHs similar to those in the sediment from which the fish were taken. In these same fish, metabolites of many aromatic compounds were found in bile using a procedure combining HPLC with fluorescence detection. Further, the concentrations of certain xenobiotic metabolites in bile were correlated positively with the occurrence of liver neoplasms in English sole.     

Interactions of chlorinated hydrocarbon insecticides with membranes

Chlorinated hydrocarbon insecticides quench the fluorescence of N-alkyl derivatives of carbazole. We used phospholipids with covalently attached carbazole as probes for the interactions of chlorinated hydrocarbon insecticides with lipid bilayers, the object being to understand better the toxicities of chlorinated hydrocarbons. Fluorescence quenching measurements revealed the lipid-water partition coefficients of the chlorinated hydrocarbons, their diffusion coefficients in the membranes, and the binding capacities of the membranes for the chlorinated hydrocarbons. Active insecticides were compared with inactive analogues to test whether activities correlated with chlorinated hydrocarbon-membrane interactions. Thus DDT and methoxychlor were compared with inactive DDE, and insecticidal γ-lindane was compared with three less active stereoisomers. The partition coefficients, diffusion coefficients and membrane saturation capacities did not correlate with insecticidal potency. The partition coefficients of these chlorinated hydrocarbons were larger in bilayers containing unsaturated fatty acyl chains as compared to bilayers containing saturated fatty acyl chains. Interestingly, neural membranes are known to contain a large percentage of unsaturated lipids. Our results indicate that the activities of chlorinated hydrocarbons are not a result of specific interactions of these compounds with the lipids of membranes. However, the neurotoxicity of chlorinated hydrocarbons may be amplified by selective partitioning in the unsaturated neural membranes.     

Ferritin accumulation and uroporphyrin crystal formation in hepatocytes of C57BL/10 mice: a time-course study

To establish the time-sequence relationship between ferritin accumulation and uroporphyrin crystal formation in livers of C57BL/10 mice, a biochemical, morphological and morphometrical study was performed. Uroporphyria was induced by the intraperitoneal administration of hexachlorobenzene plus iron dextran and of iron dextran alone. Uroporphyrin crystal formation started in hepatocytes of mice treated with hexachlorobenzene plus iron dextran at 2 weeks and in mice treated with iron dextran alone at 9 weeks. In the course of time, uroporphyrin crystals gradually increased in size. Uroporphyrin crystals were initially formed in hepatocytes in the periportal areas of the liver, in which also ferric iron staining was first detected. The amount and the distribution of the main storage form of iron in hepatocytes, ferritin, did not differ between the two treatment groups. Ferritin accumulation preceded the formation of uroporphyrin crystals in hepatocytes in both treatment groups. Moreover, uroporphyrin crystals were nearly always found close to ferritin iron. We conclude that uroporphyrin crystals are only formed in hepatocytes in which also iron (ferritin) accumulates. Hexachlorobenzene accelerates the effects of iron in porphyrin metabolism, but does not influence the accumulation of iron into the liver.     

Study of the origin of urinary porphyrins in experimental hexachlorobenzene-induced porphyria

The activity of the enzyme uroporphyrinogen decarboxylase was determined in the liver and the kidneys of C57BL/6 mice and Wistar albino rats with chronic hexachlorobenzene intoxication and the amount of the deposited uroporphyrin was measured in the both organs. In the control animals the activity of hepatic uroporphyrinogen decarboxylase was several times higher than the renal one. The administration of hexachlorobenzene led to an inhibition of the enzyme activity, which was equally expressed (about 2.5 times) in the liver and kidneys of the both species. The accumulation of uroporphyrin was more pronounced in the hepatic tissue than in the kidneys (about 9 times in mice and 5 times in rats on average). Taking into consideration the much higher uroporphyrin accumulation in the liver, the more active haem biosynthesis in this organ, as well as its larger size, one could accept that the predominant part of the urinary porphyrins in hexachlorobenzene porphyria has a hepatic and not a renal origin.     

Porphyrin Biosynthesis in Cell-free Homogenates from Higher Plants

The porphyrin and phorbin biosynthetic activity of etiolated cucumber (Cucumis sativus, L.) cotyledons was compared to that of cotyledonary homogenates. Etiolated cotyledons incubated with δ-aminolevulinic acid accumulate protoporphyrin, coproporphyrin, small amounts of Mg protoporphyrin monoester, and trace amounts of uroporphyrin. They also incorporate 4-¹⁴C-δ-aminolevulinic acid into free porphyrins, protochlorophyllide, protochlorophyllide phytyl ester, and Mg protoporphyrin monoester. Homogenates incubated with δ-aminolevulinic acid likewise accumulate coproporphyrin, uroporphyrin, Mg coproporphyrin, and trace amounts of protoporphyrin. They also incorporate 4-¹⁴C-δ-aminolevulinic acid into Mg protoporphyrin monoester, Mg coproporphyrin, and free porphyrins. However, the capacity to synthesize protochlorophyllide and protochlorophyllide phytyl ester is lost and the endogenous protochlorophylls gradually disappear. Mg protoporphyrin monoester represents the terminal biosynthetic step in this cell-free system.     

Relative roles of CYP2E1 and CYP1A2 in mouse uroporphyria caused by acetone

Porphyria cutanea tarda is a liver disease characterized by excess production of uroporphyrin. We previously reported that acetone, an inducer of CYP2E1, enhances hepatic uroporphyrin accumulation in mice treated with iron dextran (Fe) and 5-aminolevulinic acid (ALA). Cyp2e1(-/-) mice treated with Fe and ALA were used to investigate whether CYP2E1 is required for the acetone effect. Hepatic uroporphyrin accumulation was stimulated by acetone in Cyp2e1(-/-) mice to the same extent as in wild-type mice. In the absence of acetone, uroporphyrin accumulated in Cyp2e1(-/-) mice treated with Fe and ALA, but less than in wildtype mice. However, in Cypla2(-/-) mice, uroporphyrin accumulation caused by Fe and ALA, with or without acetone, was completely prevented. Acetone was not an inducer of hepatic CYP1A2 in the wild-type mice. Although acetone is an inducer of CYP2E1, CYP1A2 appears to have the essential role in acetone-enhancement of uroporphyria.     

Comparison of liver enzymes in osmerid fishes: key differences between a glycerol accumulating species,rainbow smelt (Osmerus mordax), and a species that does not accumulate glycerol,capelin (Mallotus villosus)

Activities of enzymes associated with glycerol synthesis were compared in the liver of two osmerid fishes, the smelt (Osmerus mordax), which can accumulate high (400 mM) levels of glycerol and capelin (Mallotus villosus) that does not accumulate glycerol. Animals were sampled at approximately the same time of year and temperature thus negating potential seasonal effects. These species are closely related, reducing interpretative issues involving comparison between unrelated species. We found that key enzyme activities were elevated in the smelt relative to the non-glycerol accumulating capelin, namely enzymes involved with glycolysis (phosphofructose kinase-1 and aldolase), amino acid metabolism (aspartate aminotransferase and alanine aminotransferase), gluconeogenesis (phosphoenolpyruvate carboxykinase) and glycerol synthesis (glycerol-3-phosphate dehydrogenase). The enzyme profiles strongly support the hypothesis that smelt can synthesize glycerol by utilizing glycogen and amino acids as the carbon source and that they have increased capacity for metabolic flux through loci required for synthesis of the three carbon intermediate dihydroxyacetone phosphate and subsequently glycerol synthesis.     

Transplacental Transfer of PCBs and Chlorinated Hydrocarbon Pesticides from the Pregnant Striped Dolphin (Stenella coeruleoalba) to Her Fetus

Transplacental transfer of chlorinated hydrocarbons such as PCBs, DDT compounds, HCH isomers and HCB was determined in a pregnant striped dolphin just before parturition. The transfer rates of chlorinated hydrocarbons in the striped dolphin through parturition were estimated as follows: PCBs 4.0%, ΣDDT 4.7%, ΣHCH 8.9% and HCB 9.4%. The concentration ratios of chlorinated hydrocarbons in the blubber of the fetus to that of the mother dolphin were found to be in the order of HCB > HCH isomers > DDT compounds > PCBs. Especially in PCB congeners, these ratios gradually decreased with the increase of chlorine atoms substituted in biphenyls.

These observations indicate that the more lipophilic chemicals, such as higher chlorinated biphenyls and DDT compounds, are less transferable from mother to fetus. The transfer characteristics of chlorinated hydrocarbons can be explained by their equilibrium partitionings between blood and blubber, resulting from the differences of lipid compositions in each.     

Chloroform Cometabolism by Butane-Grown CF8, Pseudomonas butanovora, and Mycobacterium vaccae JOB5 and Methane-Grown Methylosinus trichosporium OB3b

Chloroform (CF) degradation by a butane-grown enrichment culture, CF8, was compared to that by butane-grown Pseudomonas butanovora and Mycobacterium vaccae JOB5 and to that by a known CF degrader, Methylosinus trichosporium OB3b. All three butane-grown bacteria were able to degrade CF at rates comparable to that of M. trichosporium. CF degradation by all four bacteria required O(inf2). Butane inhibited CF degradation by the butane-grown bacteria, suggesting that butane monooxygenase is responsible for CF degradation. P. butanovora required exogenous reductant to degrade CF, while CF8 and M. vaccae utilized endogenous reductants. Prolonged incubation with CF resulted in decreased CF degradation. CF8 and P. butanovora were more sensitive to CF than either M. trichosporium or M. vaccae. CF degradation by all three butane-grown bacteria was inactivated by acetylene, which is a mechanism-based inhibitor for several monooxygenases. Butane protected all three butane-grown bacteria from inactivation by acetylene, which indicates that the same monooxygenase is responsible for both CF and butane oxidation. CF8 and P. butanovora were able to degrade other chlorinated hydrocarbons, including trichloroethylene, 1,2-cis-dichloroethylene, and vinyl chloride. In addition, CF8 degraded 1,1,2-trichloroethane. The results indicate the potential of butane-grown bacteria for chlorinated hydrocarbon transformation.