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PubMed1991

Quantitative assessment of the effects of metals on microbial degradation of organic chemicals.

Biodegradation inhibition of a benchmark chemical, 2,4-dichloro-phenoxyacetic acid methyl ester (2,4-DME), was used to quantify the inhibitory effects of heavy metals on aerobic microbial degradation rates of organic chemicals. This procedure used lake sediments and aufwuchs (floating mats) collected in the field or from laboratory microcosms. Effects of CuCl2, HgCl2, ZnCl2, Cd(NO3)2, and Cr(NO3)3 at initial concentrations ranging from 0.3 microM to 73 mM (approximately 0.1 to 10,000 mg liter-1) were investigated. In general, such metallic compounds appeared to be considerably more inhibitory to the biodegradation of an organic chemical than high concentrations of microbially toxic organics studied previously. Effects of various metal concentrations were evaluated based on the following: (i) estimated MICs, (ii) concentrations that caused a significant effect on biodegradation parameters (both a greater than 10% decrease in Vmax and a greater than 10% increase in t1/2 for 2,4-DME degradation), and (iii) concentrations that caused biodegradation half-life doublings (HLDs). The MICs of metals in sediment were lowest for Zn2+ (0.10 microM) and highest for Cd2+ and Cu2+ (0.9 and 1.2 microM, respectively). The MICs of metals in aufwuchs were lowest for Hg2+ (0.01 microM), intermediate for Cu2+ and Zn2+ (0.42 and 0.62 microM, respectively), and highest for Cr3+ and Cd2+ (3.4 and 5.6 microM, respectively). Compared with Cu2+ on aufwuchs, 70 times more Zn2+, 250 times more Cr3+, and 1,000 times more Cd2+ was required to significantly affect aufwuchs biodegradation rate parameters and coefficients (Vmax and t1/2). Aufwuchs was significantly affected by the lowest Hg2+ concentration tested (5 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

2,4-Dichlorophenoxyacetic Acid↗

PubMed1964

MICROBIAL DEGRADATION OF CORRINOIDS. 3. PIGMENTS DERIVED FROM VITAMIN B12 BY PSEUDOMONAS RUBESCENS.

Burgus, R. C. (Wayne State University, Detroit, Mich.), J. B. Hufham, W. M. Scott, and J. J. Pfiffner. Microbial degradation of corrinoids. III. Pigments derived from vitamin B(12) by Pseudomonas rubescens. J. Bacteriol. 88:1139-1144. 1964.-Products derived from vitamin B(12) by Pseudomonas rubescens under anaerobic conditions were examined. After incubation of the organism in broth containing Co(57)- or P(32)- vitamin B(12), electrophoresis of the extracted corrinoids yielded two major, yellow, radioactive fractions, designated A and B, with spectral and electrophoretic properties similar to pigments I and II, derived from vitamin B(12) by Aerobacter aerogenes. Fractions A and B were essentially inactive in promoting the growth of Lactobacillus leichmannii. Chromatography on carboxymethylcellulose separated both fractions A and B into four yellow, radioactive fractions. The absorption spectrum of each of the major subfractions showed a maximum in the ultraviolet region characteristic of a 5,6-dimethylbenzimidazole nucleotide, but lacked a maximum in the 360-mmu region characteristic of vitamin B(12) and many of its analogues and derivatives. The pigments were stable to cyanide and, although they were more stable to air and light than were the vitamin B(12) coenzymes and coenzyme analogues, they were apparently slowly decomposed by light. The data suggest that the bacteria alter the corrin nucleus of vitamin B(12).

Benzimidazoles↗

PubMed1994

Identification of metabolic intermediates in microbial degradation of phenol using laser desorption time-of-flight mass spectrometry.

Laser desorption time-of-flight (LD-TOF) mass spectrometry was utilized to determine the metabolic intermediates in microbial degradation of phenol. The identified components were in good agreement with the well-documented pathway. This technique also demonstrated excellent precision. Analytical merits, instrumentation and methodology are discussed.

Environmental Monitoring↗

PubMed2005

A quantitative assay for linking microbial community function and structure of a naphthalene-degrading microbial consortium.

A comprehensive culture-independent assay, called Q-FAST, was developed for concurrent identification and quantification of active microorganisms involved a specific function in a given microbial community. The development of Q-FAST was achieved by integrating the concept of stable isotope probing technique into a new quantitative fingerprinting assay called real-time-t-RFLP for microbial community structure analysis. The Q-FAST was successfully validated by using a three-member artificial microbial community containing a known naphthalene-utilizing bacterium (Pseudomonas putida G7) and two nonnaphthalene-degrading bacteria (Escherichia coli and Bacillus thuringiensis). The application of Q-FAST to identify and quantify a guild of naphthalene-utilizing microorganisms in soils revealed the involvement of eight members, with six members relating to several phylogenetic groups of eubacteria (three in beta-proteobacteria, two in gamma-proteobacteria, and one in genera Intrasporangium of Gram-positive bacteria) and two members showing no close phylogenetic affiliation to any known bacterial sequences deposited in GenBank. The quantity of three members belonging to beta-proteobacteria accounted for 34% of total 16S rDNA copies measured from the "heavier" fraction of DNA that was contributed from the DNA of microorganisms capable of incorporating 13C-labeled naphthalene into their genetic biomarkers. The other five members composed 66% of total 16S rDNA copies of active naphthalene-utilizing populations measured. Offering a powerful tool for studying microbial ecology, Q-FAST thus opens a new avenue for deeper exploration of microbial-mediated processes, mainly the quantitative relationship between microbial diversity and microbial activity in a given environment.

Bacillus thuringiensis↗

PubMedDate not supplied

[Intensification of microbial degradation of crude oil and oil products in the presence of perfluorodecalin].

The possibility of using perfluorinated organic compounds for growing microorganisms and degrading xenobiotics has been demonstrated for the first time with perfluorodecalin (PFD), a gas-transporting component of the blood substitute Perftoran. In particular, this is promising for intensifying microbial degradation of oil and oil products and production of biodegrader biomass in synthetic mineral media. Addition of PFD to a mineral medium with crude oil and masut increased 4.5-10.2 times maximum concentrations and growth rates of all bacterial strains under study (Pseudomonas, Rhodococcus, and Bacillus genera). The degree of oil product consumption was increased 8.7-12.7 times.

Bacillus↗

PubMed1975

[Microorganisms in gums. IV. Microbial degradation of plant exudates and seaweed extracts (author's transl)].

The three plant exudates gum traganth, gum arabic, and gum karaya and the two seaweed extracts carrageenan and alginate were degraded by five different Bacilli which were isolated from these gums: Bacillus coagulans, B. lentus, B. cereus, B. licheniformis, and B. firmus. After 14 days all the gums have been degraded by these Bacilli to a different extent after addition of trace elements. The fractions of degraded gums by TLC, GLC, and IR-spectroscopy have been examined with the following results: 1. Except the already known monomers of the above mentioned gums no other monosaccharides could be found. 2. The microbial degradation of gum karaya and alginate resulted in products with a high molecularweight. Monomers could not be determined. 3. Carrageenan has been degraded to oligosaccharides with molecularweights of about 500, 3,6-anhydrogalactose has been partly identified. 4. Gum arabic has been partly degraded to rhamnose and arabinose. 5. Gum traganth has been partly degraded to arabinose and xylose and partly to polysaccharides with molecularweights under 3000.

Acacia↗

PubMedDate not supplied

Rapid microbial degradation of organic nitrates in rat excreta. Re-examination of the urinary and fecal metabolite profiles of pentaerythritol tetranitrate in the rat.

The in vitro stabilities of three organic nitrates, viz. pentaerythritol tetranitrate ( PETN ), nitroglycerin (NTG), and isosorbide dinitrate (ISDN) in rat urine, and of PETN in rat feces were examined. PETN , NTG, and ISDN degraded completely in rat urine following incubation for 24 hr at either 25 or 37 degrees C. Degradation of PETN , NTG, and ISDN was absent in sterilized urine under the same conditions. These data suggested that decomposition of organic nitrates in untreated urine was usually rapid and extensive, and was primarily of microbial origin. Stability of these organic nitrates could also be maintained when urine samples were stored in packed ice. Rapid and extensive microbial degradation of PETN was also found in rat fecal homogenates, suggesting the possibility of organic nitrate metabolism by intestinal microflora. The metabolic profiles of PETN in rat urine and feces following intra-arterial and oral dosing of this organic nitrate were then re-examined. The data confirmed a previous finding that in vivo PETN excretion in urine was minimal. However, contrary to data which showed about 8% fecal recovery after oral dosing, our results suggested a smaller (2%) fecal PETN recovery with oral dosing. It appeared likely then that unabsorbed PETN might be further metabolized by gut flora.

Administration, Oral↗

PubMed1971

Microbial degradation of organic matter in the deep sea.

Food materials from the sunken and recovered research submarine Alvin were found to be in a strikingly well-preserved state after exposure for more than 10 months to deep-sea conditions. Subsequent experiments substantiated this observation and indicated that rates of microbial degradation were 10 to 100 times slower in the deep sea than in controls under comparable temperatures.

Acetates↗

PubMed2001

Microbial degradation and fate in the environment of methyl tert-butyl ether and related fuel oxygenates.

Oxygenates, mainly methyl tert-butyl ether (MTBE), are commonly added to gasoline to enhance octane index and improve combustion efficiency. Other oxygenates used as gasoline additives are ethers such as ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and alcohols such as tert-butyl alcohol (TBA). As a result of its wide use, MTBE has been detected, mainly in the USA, in groundwater and surface waters, and is a cause of concern because of its possible health effects and other undesirable consequences. MTBE is a water-soluble and mobile compound that generates long pollution plumes in aquifers impacted by gasoline releases from leaking tanks. Field observations concur in estimating that, because of recalcitrance to biodegradation, natural attenuation is slow (half-life of at least 2 years). However, quite significant advances have been made in recent years concerning the microbiology of the degradation of MTBE and other oxygenated gasoline additives. The recalcitrance of these compounds results from the presence in their structure of an ether bond and of a tertiary carbon structure. For the most part, only aerobic microbial degradation systems have been reported so far. Consortia capable of mineralizing MTBE have been selected. Multiple instances of the cometabolism of MTBE with pure strains or with microflorae, growing on n-alkanes, isoalkanes, cyclohexane or ethers (diethyl ether, ETBE), have been described. MTBE was converted into TBA in all cases and was sometimes further degraded, but it was not used as a carbon source by the pure strains. However, mineralization of MTBE and TBA by several pure bacterial strains using these compounds as sole carbon and energy source has recently been reported. The pathways of metabolism of MTBE involve the initial attack by a monooxygenase. In several cases, the enzyme was characterized as a cytochrome P-450. After oxygenation, the release of a C -unit as formaldehyde or formate leads to the production of TBA, which can be converted to 2-hydroxyisobutyric acid and further metabolized. Developments in microbiology make biological treatment of water contaminated with MTBE and other oxygenates an attractive possibility. Work concerning ex situ treatment in biofilters by consortia and by pure strains, and involving or not cometabolism, is under way. Furthermore, the development of in situ treatment processes is a promisinggoal.

Bacteria↗

PubMed2001

Microcosm studies of microbial degradation in a coal tar distillate plume.

Investigation of a groundwater plume containing up to 24 g l(-1) phenolic compounds suggested that over a period of nearly 50 years, little degradation had occurred despite the presence of a microbial community and electron acceptors within the core of the plume. In order to study the effect of contaminant concentration on degradation behaviour, laboratory microcosm experiments were performed under aerobic and anaerobic conditions at four different concentrations obtained by diluting contaminated with uncontaminated groundwater. The microcosms contained groundwater with total phenols at ca. 200, 250, 660 and 5000 mg l(-1), and aquifer sediment that had been acclimatised within the plume for several months. The microcosms were operated for a period of 390-400 days along with sterile controls to ascertain whether degradation was microbially mediated or abiotic. Under aerobic conditions, degradation only occurred at concentrations up to 660 mg l(-1) total phenols. At phenol concentrations below 250 mg l(-1) a benzoquinone intermediate, thought to originate from the degradation of 2,5-dimethylphenol, was isolated and identified. This suggested an unusual degradative pathway for this compound; its aerobic degradation more commonly proceeding via catecholic intermediates. Under anaerobic conditions, degradation only occurred in the most dilute microcosm (total phenols 195 mg l(-1)) with a loss of p-cresol accompanied by a nonstoichiometric decrease in nitrate and sulphate. By inference, iron(III) from the sediment may also have been used as a terminal electron acceptor, in which case the amount of biologically available iron released was calculated as 1.07 mg Fe(III)/g of sediment. The study shows that natural attenuation is likely to be stimulated by dilution of the plume.

Aerobiosis↗

PubMed1995

Microbial degradation of monoterpenes in the absence of molecular oxygen.

Anaerobic degradation of natural monoterpenes by microorganisms was evaluated by using Pseudomonas citronellolis DSM 50332 and enrichment cultures containing nitrate as an electron acceptor. P. citronellolis grew anaerobically on 3,7-dimethyl-1-octanol and citronellol but not on geraniol, nerol, and alicyclic monoterpenes. In contrast, several a-, mono-, and bicyclic monoterpenes supported microbial growth and denitrification in enrichment cultures. We found that consumption of linalool, menthol, menth-1-ene, alpha-phellandrene, limonene, 2-carene, alpha-pinene, and fenchone in enrichment cultures depended on the presence of living microorganisms and nitrate. In these experiments, the ratios of number of electrons derived from complete substrate oxidation to number of electrons derived from nitrate reduction ranged from 1.2:1 to 2.9:1. Microbial degradation was accompanied by the formation of small traces of monoterpenes, which were characterized by gas chromatography-mass spectroscopy. The formation of geraniol and geranial from linalool suggested that a 3,1-hydroxyl-delta 1-delta 2-mutase reaction initiates linalool degradation. Seven strains of motile, oval to rod-shaped, facultatively denitrifying bacteria were isolated on agar bottle plates by using linalool, menthol, menth-1-ene, alpha-phellandrene, 2-carene, eucalyptol, and alpha-pinene as sole carbon and energy sources.

Anaerobiosis↗

PubMed1990

Microbial degradation of chelating agents used in detergents with special reference to nitrilotriacetic acid (NTA).

The extensive use of phosphate-based detergents and agricultural fertilizers is one of the main causes of the world-wide eutrophication of rivers and lakes. To ameliorate such problems partial or total substitution of phosphates in laundry detergents by synthetic, non-phosphorus containing complexing agents is practiced in several countries. The physiological, biochemical and ecological aspects of the microbial degradation of the complexing agents most frequently used, such as polyphosphates, aminopolycarboxylates (especially of nitrilotriacetic acid), and phosphonates are reviewed.

Biodegradation, Environmental↗

PubMed2001

Concerted chemical and microbial degradation of sulfophthalimides formed from sulfophthalocyanine dyes by white-rot fungi.

3- and 4-sulfophthalimide (SPI) have recently been shown to be the major product formed by white-rot fungi upon decolorization of sulfophthalocyanine (SPC) textile dyes. To make use of this metabolic potential in textile wastewater treatment, the fungal breakdown products should be degradable by activated sludge. Here,the aerobic degradation of SPI was studied in die-away tests, and biodegradation intermediates and degradation products were analyzed by liquid chromatography-electrospray ionization-mass spectrometry. The degradation of SPI is initiated by a chemical hydrolysis to sulfophthalamic acid (SPAA) with half-lives of 8 and 40 h at pH 6.5 for 4- and 3-SPI, respectively. Then, 4-SPAA can be mineralized by aerobic mixed cultures, while 3-SPAA remained stable throughout the experiment (35 d). Analogously, the potential intermediate in 4-SPAA degradation, the 4-sulfophthalic acid, but not its 3-isomer, can be completely mineralized aerobically by mixed cultures. In all chemical and microbialtransformations of these aromatic sulfonates the 4-sulfo-isomer is more reactive than the 3-isomer. The triade of fission of the SPC-system by white-rot fungi to SPI, chemical hydrolysis of SPI to SPAA, and microbial degradation of SPAA offers a pathway to mineralize the major part of the SPC system of textile dyes, whether in a respective effluent treatment system or in the aquatic environment. More general, these results illustrate on a molecular level how white-rot fungi and bacteria may cooperate in mineralizing structurally complex colored substances.

Bacteria, Aerobic↗

PubMedDate not supplied

[Monitoring of microbial degraders in manned space stations].

Samples of microorganisms from the surface of constructions of Mir Space Station (Mir SS) were taken and examined after 13 years of operation. The following microorganisms were isolated and identified: 12 fungal species belonging to the genera Penicillium, Aspergillus, Cladosporium, and Aureobasidium; 3 yeast species belonging to the genera Debaryomyces, Candida, and Rhodotorula; and 4 bacterial species belonging to the genera Bacillus, Myxococcus, and Rhodococcus. The predominant species in all samples was Penicillium chrisogenum. It was shown that the fungi isolated could damage polymers and induce corrosion of aluminum-magnesium alloys. We commenced a study of microbial degraders on constructions of the Russian section of the International Space Station (RS ISS). Twenty-six species of fungi, bacteria, yeasts, and actinomycetes, known as active biodegraders, were identified in three sample sets taken at intervals. We founded a collection of microorganisms surviving throughout space flights. This collection can be used to test spacecraft production materials, in order to determine their resistance to biodegradation.

Bacteria↗

PubMed1986

Effect of dietary fat and residues on fecal loss of sterols and on their microbial degradation in cystic fibrosis.

Although various etiologic factors have been implicated, the mechanism responsible for bile acid malabsorption in CF remains unknown. Eight CF children studied twice on a normal diet supplemented with pancreatic enzymes and once during a one-month period of Vivonex administered by continuous nasogastric infusion were compared to age-matched controls. On the fat and residue-free elemental diet, there was a modest decrease in steatorrhea and no change in the daily excretion of nitrogen and neutral sterols. However, normalization of bile acid output (485.6 +/- 65.0 to 160.6 +/- 29.2 mg/24 hr) to control levels (150.2 +/- 60.7) was noted. Diminished microbial degradation of both neutral and acidic sterols and a smaller amount of bile acids adsorbed to decreased residues were also found. The data do not support the possibility of a bile acid ileal transport defect and suggest that the most important single factor responsible for the intraluminal sequestration of bile acids in CF is dietary residues. Because of significant ongoing losses of nitrogen and lipids, pancreatic enzymes should be given to CF patients on elemental diets.

Bile Acids and Salts↗

PubMed1999

Microbial degradation of 4-chlorophenol by microorganisms entrapped in carrageenan-chitosan gels.

A new cell immobilization method based on the replacement of KCl by KCl + chitosan as gelling agent was developed. The results showed that through addition of chitosan into gelling agent, the mechanical strength and thermal stability of the carrageenan gel were greatly improved. The new immobilization method was used to entrap a chlorophenol-degrading microorganism. The immobilized microbial cells were applied for chlorophenol biodegradation. The experiments demonstrated that immobilized cells exhibit a higher bioactivity in the degradation of chlorophenol than free cells.

Biodegradation, Environmental↗

PubMed2002

Reductive deamination as a new step in the anaerobic microbial degradation of halogenated anilines.

In this paper we report the isolation and characterization of an anaerobic enrichment culture as well as of a Rhodococcus sp. strain 2 capable of degrading 3,4-dihaloanilines under nitrate reducing conditions. Using mass spectrometry several of the intermediates formed in the process of 3,4-dichloroaniline conversion were identified. Most interesting is the observation of reductive deamination and the formation of 1,2-dichlorobenzene as one of the intermediates. Using 19F NMR and fluorinated 3,4-dihaloaniline model substrates it was corroborated that reductive deamination of the anilines to give dihalobenzene intermediates represents a new initial step in the anaerobic microbial degradation of these halogenated anilines.

Anaerobiosis↗

PubMed1976

Microbial degradation of the thiolcarbamate herbicide, diallate, in soils and by pure cultures of soil microorganisms.

The disappearance of the herbicide, Avadex (40% diallate), from five agricultural soils (differing in either pH, carbon content, or nitrogen content), incubated under sterile and non-sterile conditions, was followed for a period of 20 weeks. Avadex was rapidly lost from microbiologically active soils, with over 50% of the applied (2.5 ppm) dosage disappearing within four weeks; losses from sterile soils were much slower with recoveries of over 50% after 20 weeks. Incubation of soil with Avadex to which 14C-labeled diallate had been added resulted in rapid formation of 14CO2 from microbiologically active samples and only very slow 14CO2 formation from sterile samples. Substantial quantities of radioactivity were retained as unextractable residues in both sterile and non-sterile soils after senven days incubation. From these data it was concluded that the disappearance of the herbicide from non-sterile soils was mainly due to microbial degradation and to binding of diallate or its metabolites as residues to undefined soil components. Losses from sterile soils were attributed to both binding of residues and to a slow chemical degradation. Avadex degradation by pure cultures was studied using representative fungi isolated from the five soils. Of the fungi tested, Phoma eupyrena, Penicillium janthinellum, and Trichoderma harzianium coudl degrade at least 20% of the applied (2.5 ppm) herbicide after ten days incubation. Degradation of Avadex in soil cultures of T. harzianum was found to be slower than degradation in liquid nutrient cultures.

Biodegradation, Environmental↗