Metabolism of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane in the mouse

The metabolites of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) found in the urine of female Swiss mice are reported. The metabolites of DDT are DDD, 1-chloro-2,2-bis(p-chlorophenyl)ethene (DDMU), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (DDE), 2,2-bis(p-chlorophenyl)acetic acid (DDA), 2-hydroxy-2,2-bis(p-chlorophenyl)acetic acid (αOH-DDA) and 2,2-bis(p-chlorophenyl)ethanol (DDOH), while DDD afforded DDMU, DDE, DDA, αOH-DDA and DDOH. The relative excreted levels of DDA and DDOH and the absence of 2,2-bis(p-chlorophenyl)acetaldehyde (DDCHO) are not consistent with the generally accepted path way for DDA formation, which involves sequential metabolism of DDT and DDD via DDOH to afford DDA. The quantitative results are interpreted to mean that DDA is formed by hydroxylation at the chlorinated sp³-side chain carbon of DDD to give 2,2-bis(p-chlorophenyl)acetyl chloride (DDA-Cl), which in turn is hydrolyzed to DDA. The excretion of αOH-DDA from both DDT- and DDD-treated mice has never been previously observed. It is suggested that this metabolite arises from the initial epoxidation of DDMU, a metabolite of DDT and DDD, to yield 1,2-epoxy-1-chloro-2,2-bis(p-chlorophenyl)ethane (DDMU-epoxide). This chloroepoxide is then hydrolyzed and oxidized to produce the αOH-DDA.     

Reactions of vitamin B12r with polyhalogenated hydrocarbon pesticides

The reaction of vitamin B_12r, generated by photolysis of methylcobalamin under a nitrogen atmosphere, with 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), results in extensive dechlorination and formation of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) as the major products. Minor quantities of 1,1-bis(p-chlorophenyl)-2-chloroethane (DDMS), 1,1-bis(p-chlorophenyl)-2-chloroethylene (DDMU), 1,1-bis(p-chlorophenyl)ethane (DDO), and 1,1-bis(p-chlorophenyl)ethylene (DDNU) were also formed. Reaction of vitamin B_12r with DDD results in the production of DDMU and DDMS, the latter of which can react to produce DDNU and DDO. DDE and DDMU do not react with vitamin B_12r. The results obtained are suggestive of a vitamin B_12r-mediated dechlorination pathway for polyhalogenated hydrocarbon pesticides.     

Dechlorination of 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane by Aerobacter aerogenes: I. Metabolic Products

Whole cells or cell-free extracts of Aerobacter aerogenes catalyze the degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in vitro to at least seven metabolites: 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD); 1-chloro-2,2-bis(p-chlorophenyl)ethylene (DDMU); 1-chloro-2,2-bis(p-chlorophenyl)ethane (DDMS); unsym-bis(p-chlorophenyl)ethylene (DDNU); 2,2-bis(p-chlorophenyl)acetate (DDA); and 4,4'-dichlorobenzophenone (DBP). The use of metabolic inhibitors together with pH and temperature studies indicated that discrete enzymes are involved. By use of the technique of sequential analysis, the metabolic pathway was shown to be: DDT --> DDD -->DDMU -->DDMS --> DDNU --> DDA --> DBP, or DDT --> DDE. Dechlorination was marginally enhanced by light-activated flavin mononucleotide.     

Metabolism of 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene by Alcaligenes denitrificans

Metabolism of 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), a persistent metabolite of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), by an Alcaligenes denitrificans was optimal under `non-shaking' conditions, was accelerated by adding 1 g glucose l^–1, and inhibited by 1 g sodium acetate l^–1 or 1 g sodium succinate l^–1. Addition of biphenyl, in the vapor form, to the reaction mixture did not enhance DDE metabolism. During the reaction, accumulation of conventional metabolites, 1-chloro-2,2-bis(4-chlorophenyl)ethylene (DDMU) and 4-chlorobenzoate, was not observed.     

Biodegradation of organochlorine pesticides by bacteria grown in microniches of the porous structure of green bean coffee

In this paper, the authors propose a model for DDT biodegradation by bacteria grown in microniches created in the porous structure of green bean coffee. Five bacteria isolated from coffee beans, identified as Pseudomonas aeruginosa, P. putida, Stenotrophomonas maltophilia, Flavimonas oryzihabitans, and Morganella morganii. P. aeruginosa and F. oryzihabitans, were selected for pesticide degradation. Bacteria were selected according to their ability to grow on mineral media amended with: (a) glucose (10 g l⁻¹), (b) peptone (2 g l⁻¹), and (c) ground coffee beans (2 g l⁻¹). These three media were supplemented with 50 mg l⁻¹ of 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) and endosulfan. GC/MS analysis demonstrated that the greatest DDT removal was obtained in the medium supplemented with coffee beans, where 1,1-dichloro-2,2′-bis (4-chlorophenyl)ethylene (DDE), 1-chloro-2,2-bis (4-chlorophenyl) ethane (DDMU) and 2,2′-bis (p-chlorophenyl)ethanol (DDOH) were detected. DDMU is a product of the reductive dechlorination of DDE, which in this system could be carried out under the anaerobic conditions in microniches present in the porous structure of the coffee bean. This was supported by scanning electron microscopy. Green bean coffee could be used as a nutrient source and as a support for bacterial growth in pesticide degradation.     

A novel metabolic pathway for biodegradation of DDT by the white rot fungi, <Emphasis Type="Italic">Phlebia lindtneri</Emphasis> and <Emphasis Type="Italic">Phlebia brevispora</Emphasis>

1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) was used as the substrate for a degradation experiment with the white rot fungi Phlebia lindtneri GB-1027 and Phlebia brevispora TMIC34596, which are capable of degrading polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated biphenyls (PCBs). Pure culture of P. lindtneri and P. brevispora with DDT (25 μmol l⁻¹) showed that 70 and 30% of DDT, respectively, disappeared in a low-nitrogen medium after a 21-day incubation period. The metabolites were analyzed using gas chromatography/mass spectrometry (GC/MS). Both fungi metabolized DDT to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), 2,2-bis(4-chlorophenyl)acetic acid (DDA) and 4,4-dichlorobenzophenone (DBP). Additionally, DDD was converted to DDA and DBP. DDA was converted to DBP and 4,4-dichlorobenzhydrol (DBH). While DBP was treated as substrate, DBH and three hydroxylated metabolites, including one dihydroxylated DBP and two different isomers of monohydroxylated DBH, were produced from fungal cultures, and these hydroxylated metabolites were efficiently inhibited by the addition of a cytochrome P-450 inhibitor, piperonyl butoxide. These results indicate that the white rot fungi P. lindtneri and P. brevispora can degrade DBP/DBH through hydroxylation of the aromatic ring. Moreover, the single-ring aromatic metabolites, such as 4-chlorobenzaldehyde, 4-chlorobenzyl alcohol and 4-chlorobenzoic acid, were found as metabolic products of all substrate, demonstrating that the cleavage reaction of the aliphatic-aryl carbon bond occurs in the biodegradation process of DDT by white rot fungi.     

Tissue Residue Guideline for ∑DDT for Protection of Aquatic Birds in China

DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is a chlorinated hydrocarbon insecticide that has been used worldwide. While the use of DDT has been phased out in many countries, it is still produced in some parts of the world for use to control vectors of malaria. DDE (1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene) and DDD (1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) are primary metabolites of DDT and have similar chemical and physical properties. DDT and its metabolites (DDE and DDD) are collectively referred to as ∑DDT. The lipophilic nature and persistence of the ∑DDT result in biomagnification in wildlife that feed at higher trophic levels in the food chain. Wildlife in aquatic ecosystems depend on aquatic biota as their primary source of food, which provide the main route of exposure to ∑DDT. Studies about effects of ∑DDT on birds were reviewed. The tissue residue guidelines for DDT (TRGs) for protection of birds in China were derived using species sensitivity distribution (SSD) and toxicity percentile rank method (TPRM) based on the available toxicity data. Risks of ∑DDT to birds were assessed by comparing the TRGs and ∑DDT concentrations in fishes from China. The tissue residue guideline for protection of birds in China is recommended to be 12.0 ng ∑DDT/g food.     

Biodegradation of DDT [1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane] by the white rot fungus Phanerochaete chrysosporium

Extensive biodegradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) by the white rot fungus Phanerochaete chrysosporium was demonstrated by disappearance and mineralization of [14C]DDT in nutrient nitrogen-deficient cultures. Mass balance studies demonstrated the formation of polar and water-soluble metabolites during degradation. Hexane-extractable metabolites identified by gas chromatography-mass spectrometry included 1,1,-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol), 2,2-dichloro-1,1-bis(4-chlorophenyl)ethanol (FW-152), and 4,4'-dichlorobenzophenone (DBP). DDD was the first metabolite observed; it appeared after 3 days of incubation and disappeared from culture upon continued incubation. This, as well as the fact that [14C]dicofol was mineralized, demonstrates that intermediates formed during DDT degradation are also metabolized. These results demonstrate that the pathway for DDT degradation in P. chrysosporium is clearly different from the major pathway proposed for microbial or environmental degradation of DDT. Like P. chrysosporium ME-446 and BKM-F-1767, the white rot fungi Pleurotus ostreatus, Phellinus weirii, and Polyporus versicolor also mineralized DDT.     

Biodegradation of DDT [1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane] by the white rot fungus Phanerochaete chrysosporium.

Extensive biodegradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) by the white rot fungus Phanerochaete chrysosporium was demonstrated by disappearance and mineralization of [14C]DDT in nutrient nitrogen-deficient cultures. Mass balance studies demonstrated the formation of polar and water-soluble metabolites during degradation. Hexane-extractable metabolites identified by gas chromatography-mass spectrometry included 1,1,-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol), 2,2-dichloro-1,1-bis(4-chlorophenyl)ethanol (FW-152), and 4,4'-dichlorobenzophenone (DBP). DDD was the first metabolite observed; it appeared after 3 days of incubation and disappeared from culture upon continued incubation. This, as well as the fact that [14C]dicofol was mineralized, demonstrates that intermediates formed during DDT degradation are also metabolized. These results demonstrate that the pathway for DDT degradation in P. chrysosporium is clearly different from the major pathway proposed for microbial or environmental degradation of DDT. Like P. chrysosporium ME-446 and BKM-F-1767, the white rot fungi Pleurotus ostreatus, Phellinus weirii, and Polyporus versicolor also mineralized DDT.     

Pesticide-induced changes in hepatic microsomal enzyme systems. Some effects of 1,1-di(p-chlorophenyl)-2,2-dichloroethylene (DDE) and 1,1-di(p-chlorophenyl)-2-chloroethylene (DDMU) in the rat and Japanese quail

Hepatic microsomal protein, cytochrome P₄₅₀, aniline hydroxylase and N-ethylmorphine demethylase as well as tissue residues were measured following the feeding of low levels of 1,1-di(p-chlorophenyl)-2,2-dichloroethylene (DDE) or 1,1-di(p-chlorophenyl)-2-chloroethylene (DDMU) to rats and Japanese quail. DDMU caused considerable elevation of the levels of most of the parameters measured in the quail even by comparison to the potent inducer, DDE, which gave greater tissue residues. In the rat where tissue residues of both DDE and DDMU were lower than those in quail, DDE caused greater changes in the measured enzyme levels than DDMU. Most of the changes caused by DDMU in the quail were larger than those observed following the ingestion of comparable levels of any other 1,1-di(p-chlorophenyl)-2,2,2-trichloroethane (DDT) metabolite in the rat or the quail. In the light of these and other published results it is suggested that the metabolic pathway for DDT in birds differs from that in mammals and probably gives rise through a pathway involving DDMU to a highly active liver inducer.     

Enhancement of hepatic microsomal drug oxidation and glucuronidation in rat by 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT)

A single dose of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) (160 mg/kg i.p.) enhanced the monooxygenase step of drug biotransformation in rat liver. The O-demethylation of p-nitroanisole was especially increased, a peak in activity approximately 5-fold compared with controls being attained in 7 days. On the other hand, there was only a 2-fold increase in aryl hydrocarbon hydroxylase activity.DDT increased the cytochrome P-450 content of the liver, this increase coincided well with that in p-nitroanisole O-demethylation activity.The UDPglucuronosyltransferase activity of liver microsomes was not enhanced by DDT administration, unless the microsomes were pretreated to reveal latent activity prior to assay. After trypsin digestion of microsomes a maximum increase in activity of approximately 3-fold was observed as a result of DDT dosage. The canonic surfactant cetylpyridinium chloride was less active in revealing the latent UDP-glucuronosyltransferase activity, and two other membrane perturbants, the detergent digitonin and phospholipase A, were unable to show enhancement in UDPglucuronosyltransferase as a result of DDT dosage.     

Cytogenetic and mutagenic effects of DDT and DDE in a Chinese hamster cell line

The mutagenic and cytogenetic effects of the chlorinated hydrocarbon 1,11-trichloro-2,2-bis(p-chlorophenyl)ethane] (DDT), and its metabolite [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] (DDE) were investigated in vitro using a Chinese hamster cell line. A forward mutation system utilizing the 8-azaguanine sensitive to 8-azaguanine resistant marker was used as the index of mutagenic action. Methyl methanesulfonate (MMS) was used as the positive control. In all experiments, DDE consistently produced a significant increase in the mutation frequency over the control level, while DDT proved inactive.Resultsof the cytogenetic studies indicated that DDE-treated cells had a significant increase in chromosome aberrations over those occuring in the control population; exchange figures and chromatid breaks wre evident. DDT produced no significant increase in chromosome abnormalities. The Chinese hamster cell populations exposed to DDE also manifested an increased number of polyploid cells over the control level.     

Degradation of chlorinated pesticide DDT by litter-decomposing basidiomycetes

One hundred and two basidiomycete strains (93 species in 41 genera) that prefer a soil environment were examined for screening of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) biodegradation. Three strains within two litter-decomposing genera, Agrocybe and Marasmiellus, were selected for their DDT biotransformation capacity. Eight metabolites; 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), two monohydroxy-DDTs, monohydroxy-DDD, 2,2-dichloro-1,1-bis(4-chlorophenyl)ethanol, putative 2,2-bis(4-chlorophenyl)ethanol and two unidentified compounds were detected from the culture with Marasmiellus sp. TUFC10101. A P450 inhibitor, 1-ABT, inhibited the formation of monohydroxy-DDTs and monohydroxy-DDD from DDT and DDD, respectively. These results indicated that oxidative pathway which was catalyzed by P450 monooxygenase exist beside reductive dechlorination of DDT. Monohydroxylation of the aromatic rings of DDT (and DDD) by fungal P450 is reported here for the first time.     

Biodegradation of DDT by a <Emphasis Type="Italic">Pseudomonas</Emphasis> Species

A bacterial strain capable of degrading 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) was isolated from insecticide-contaminated soil by biphenyl enrichment culture and identified as a Pseudomonas species. The organism degraded DDT through the intermediate formation of 2,3-dihydroxy-DDT, which undergoes meta-ring cleavage, ultimately yielding 4-chlorobenzoic acid as a stable metabolite.     

A dehydrochlorinase-based pH change assay for determination of DDT in sprayed surfaces

A glutathione S-transferase (GST) from the mosquito Aedes aegypti (aagste2), selected in the field as a major metabolic resistance enzyme for this parasite vector, was employed to produce a highly specific assay for the determination of DDT [1,1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene]. Detection is based on the pH change occurring in an appropriate buffer system by the concomitant release of H⁺ during the aagste2-catalyzed dehydrochlorination reaction and is monitored potentiometrically or colorimetrically in the presence of a pH marker. The theoretical limit of detection (LOD) of the assay is 3.8 μg/ml, and the linear range of quantification is 12 to 250 μg/ml. The method does not recognize biologically inactive DDT analogues or major DDT photodegradants and breakdown molecules, and it is highly specific for the insecticidal p.p’DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane]. The biosensor was validated with a number of insecticide swabs from DDT-sprayed surfaces and found to be reproducible and reliable as compared with high-performance liquid chromatography (HPLC) (correlation coefficient R² = 0.98). Given the current expansion of DDT residual sprayings in many regions of Africa as a key strategic intervention for malaria vector control, this simple assay to monitor DDT levels for vector control spraying programs could have an important impact on malaria control.     

Metabolism of DDT and Kelthane in cell suspension cultures of parsley (Petroselinum hortense,Hoffm.) and soybean (Glycine max L.)

Cell suspension cultures of parsley and soybean were incubated for 44 to 48 h with¹⁴C-labeled DDT or Kelthane; autoclaved cultures were used as controls. Most of the radioactivity became associated with the cells, and metabolites were isolated by a sequential extraction procedure. The metabolites amounted to 0.6 to 2.2% of the applied pesticide. Relatively non-polar metabolites were identified as DDE in the case of DDT, and remained unidentified in the case of Kelthane. Polar metabolites were also isolated and are as yet unidentified. They were chromatographically different from the known and less polar metabolites of DDT and Kelthane reported from animal and insect studies. [DDT-1,1,1-Trichloro-2,2-bis-(4-chlorophenyl)-ethane; Kelthane=(1,1-bis-(4-chlorophenyl)-2,2,2-trichloro-ethanol; DDE=1,1-Dichloro-2,2-bis-(4-chlorophenyl)-ethylene.]Abbreviations DDT 1,1,1-Trichloro-2,2-bis-(4-chlorophenyl)-ethane - Kelthane (1,1-bis-(4-chlorophenyl)-2,2,2-trichloro-ethanol - DDE 1,1-Dichloro-2,2-bis-(4-chlorophenyl)-ethylene - DDA 2,2-bis-(4-chlorophenyl)-acetic acid - DDOH 2,2-bis-(4-chlorophenyl)-ethanol - DDD 1,1-Dichloro-2,2-bis-(4-chlorophenyl)-ethane - DBP 4,4-Dichloro-benzophenone - DDMU 1-Chloro-2,2-bis-(4-chlorophenyl)-ethylene - DDM Bis-(4-chlorophenyl)-methane - FW-152 1,1-Bis-(4-chlorophenyl)-2,2-dichloro-ethanol - SDS sodium dodecylsulphate     

Metabolism of DDT [1,1,1-Trichloro-2,2-bis(4-chlorophenyl)ethane] by <Emphasis Type="Italic">Alcaligenes denitrificans</Emphasis> ITRC-4 Under Aerobic and Anaerobic Conditions

An isolated bacterium, Alcaligenes denitrificans ITRC-4, metabolizes 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) under both aerobic and anaerobic conditions. The aerobic metabolism is inhibited by 38% and 47% in the presence of 1.0 g L⁻¹ of sodium acetate and sodium succinate, respectively, but remains uninhibited in the presence of 1.0 g L⁻¹ of glucose. Also, the metabolism is inhibited completely in the presence of biphenyl vapors, as well as 0.8 g L⁻¹ of 2,2′-bipyridyl. Under anaerobic conditions, DDT is metabolized into 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), which is further enhanced by 50% in the presence of 1.0 g L⁻¹ of glucose. Besides, the bacterium also metabolizes 4-chlorobenzoate, which is accompanied by the release of chloride ions. Received: 13 March 2002 / Accepted: 8 April 2002     

Bacterial and fungal cometabolism of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) and its breakdown products.

Resting cells of bacteria grown in the presence of diphenylmethane oxidized substituted analogs such as 4-hydroxydiphenylmethane, bis(4-hydroxyphenyl)methane, bis(4-chlorophenyl)methane (DDM), benzhydrol, and 4,4'-dichlorobenzhydrol. Resting cells of bacteria grown with benzhydrol as the sole carbon source oxidized substituted benzhydrols such as 4-chlorobenzhydrol, 4,4'-dichlorobenzhydrol, and other metabolites of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), such as DDM and bis(4-chlorophenyl)acetic acid. Bacteria and fungi converted 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane, DDM, 4,4'-dichlorobenzhydrol, and 4,4'-dichlorobenzophenone. Aspergillus conicus converted 55% of bis(4-chlorophenyl)acetic acid to unidentified or unextractable water-soluble products. Aspergillus niger and Penicillium brefeldianum converted 12.4 and 24.6%, respectively, of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane to water-soluble and unidentified products. 4-Chlorophenylacetic acid, a product of ring cleavage, was formed from DDM by a false smut fungus of rice. A. niger converted 4,4'-dichlorobenzophenone to 4-chlorobenzophenone and a methylated 4-chlorobenzophenone.     

Bacterial and fungal cometabolism of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) and its breakdown products

Resting cells of bacteria grown in the presence of diphenylmethane oxidized substituted analogs such as 4-hydroxydiphenylmethane, bis(4-hydroxyphenyl)methane, bis(4-chlorophenyl)methane (DDM), benzhydrol, and 4,4'-dichlorobenzhydrol. Resting cells of bacteria grown with benzhydrol as the sole carbon source oxidized substituted benzhydrols such as 4-chlorobenzhydrol, 4,4'-dichlorobenzhydrol, and other metabolites of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), such as DDM and bis(4-chlorophenyl)acetic acid. Bacteria and fungi converted 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane, DDM, 4,4'-dichlorobenzhydrol, and 4,4'-dichlorobenzophenone. Aspergillus conicus converted 55% of bis(4-chlorophenyl)acetic acid to unidentified or unextractable water-soluble products. Aspergillus niger and Penicillium brefeldianum converted 12.4 and 24.6%, respectively, of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane to water-soluble and unidentified products. 4-Chlorophenylacetic acid, a product of ring cleavage, was formed from DDM by a false smut fungus of rice. A. niger converted 4,4'-dichlorobenzophenone to 4-chlorobenzophenone and a methylated 4-chlorobenzophenone.     

Metabolism of DDT [1,1,1-Trichloro-2,2-bis(4-chlorophenyl)ethane] by Alcaligenes denitrificans ITRC-4 under aerobic and anaerobic conditions

An isolated bacterium, Alcaligenes denitrificans ITRC-4, metabolizes 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) under both aerobic and anaerobic conditions. The aerobic metabolism is inhibited by 38% and 47% in the presence of 1.0 g L(-1) of sodium acetate and sodium succinate, respectively, but remains uninhibited in the presence of 1.0 g L(-1) of glucose. Also, the metabolism is inhibited completely in the presence of biphenyl vapors, as well as 0.8 g L(-1) of 2,2'-bipyridyl. Under anaerobic conditions, DDT is metabolized into 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), which is further enhanced by 50% in the presence of 1.0 g L(-1) of glucose. Besides, the bacterium also metabolizes 4-chlorobenzoate, which is accompanied by the release of chloride ions.