Degradation of biphenyl by methanogenic microbial consortium

Biphenyl was readily degraded and mineralized to CO₂ and CH₄ by a PCB-dechlorinating anaerobic microbial consortium. Degradation occurred when biphenyl was supplied as a sole source of carbon or as a co-metabolic substrate together with glucose and methanol. p-Cresol was detected and confirmed by mass spectroscopy as a transient intermediate. Production of ¹⁴ C-CO₂ and ¹⁴C-CH₄ from ¹⁴C-biphenyl was observed in the approximate ratio of 1:2. The results indicated the existence of novel pathways for biphenyl degradation in a natural anaerobic microbial community.     

Degradation of crude oil by marine cyanobacteria

The marine cyanobacteria Oscillatoria salina Biswas, Plectonema terebrans Bornet et Flahault and Aphanocapsa sp. degraded Bombay High crude oil when grown in artificial seawater nutrients as well as in plain natural seawater. Oil removal was measured by gravimetric and gas chromatographic methods. Around 45-55% of the total fractions of crude oil (containing 50% aliphatics, 31% waxes and bitumin, 14% aromatics and 5% polar compounds) were removed in the presence of these cultures within 10 days. Between 50% and 65% of pure hexadecane (model aliphatic compound) and 20% and 90% of aromatic compounds (anthracene and phenantherene) disappeared within 10 days. Mixed cultures of the three cyanobacterial species removed over 40% of the crude. Additionally, these cultures formed excellent cyanobacterial mats when grown in mixed cultures, and thus have the potential for use in mitigating oil pollution on seashores, either individually or in combination.     

Towards efficient crude oil degradation by a mixed bacterial consortium

A laboratory study was undertaken to assess the optimal conditions for biodegradation of Bombay High (BH) crude oil. Among 130 oil degrading bacterial cultures isolated from oil contaminated soil samples, Micrococcus sp. GS2-22, Corynebacterium sp. GS5-66, Flavobacterium sp. DS5-73, Bacillus sp. DS6-86 and Pseudomonas sp. DS10-129 were selected for the study based on the efficiency of crude oil utilisation. A mixed bacterial consortium prepared using the above strains was also used. Individual bacterial cultures showed less growth and degradation than did the mixed bacterial consortium. At 1% crude oil concentration, the mixed bacterial consortium degraded a maximum of 78% of BH crude oil. This was followed by 66% by Pseudomonas sp. DS10-129, 59% by Bacillus sp. DS6-86, 49% by Micrococcus sp. GS2-22, 43% by Corynebacterium sp. GS5-66 and 41% by Flavobacterium sp. DS5-73. The percentage of degradation by the mixed bacterial consortium decreased from 78% to 52% as the concentration of crude oil was increased from 1% to 10%. Temperature of 30 degrees C and pH 7.5 were found to be optima for maximum biodegradation.     

Degradation of paracetamol by pure bacterial cultures and their microbial consortium

Three bacterial strains utilizing paracetamol as the sole carbon, nitrogen, and energy source were isolated from a paracetamol-degrading aerobic aggregate, and assigned to species of the genera Stenotrophomonas and Pseudomonas. The Stenotrophomonas species have not included any known paracetamol degraders until now. In batch cultures, the organisms f1, f2, and fg-2 could perform complete degradation of paracetamol at concentrations of 400, 2,500, and 2,000 mg/L or below, respectively. A combination of three microbial strains resulted in significantly improved degradation and mineralization of paracetamol. The co-culture was able to use paracetamol up to concentrations of 4,000 mg/L, and mineralized 87.1 % of the added paracetamol at the initial of 2,000 mg/L. Two key metabolites of the biodegradation pathway of paracetamol, 4-aminophenol, and hydroquinone were detected. Paracetamol was degraded predominantly via 4-aminophenol to hydroquinone with subsequent ring fission, suggesting new pathways for paracetamol-degrading bacteria. The degradation of paracetamol could thus be performed by the single isolates, but is stimulated by a synergistic interaction of the three-member consortium, suggesting a possible complementary interaction among the various isolates. The exact roles of each of the strains in the consortium need to be further elucidated.     

Reclamation of an activated-sludge microbial consortium by selective biostimulation

Our previous study showed that an activated-sludge process broke down at the phenol-loading rate of 1.5 g l⁻¹ day⁻¹, when non-flocculating bacteria (called R6T and R10) overgrew the sludge, resulting in a sludge washout. In this study, we attempted to circumvent this breakdown problem by reclaiming the consortium structure. Activated sludge was fed phenol, and the phenol-loading rate was increased stepwise from 0.5 g l⁻¹ day⁻¹ to 1.0 g l⁻¹ day⁻¹ and then to 1.5 g l⁻¹ day⁻¹. Either galactose or glucose (at 0.5 g l⁻¹ day⁻¹) was also supplied to the activated sludge from the phenol-loading rate of 1.0 g l⁻¹ day⁻¹. Pure culture experiments have suggested galactose to be a preferential substrate for a floc-forming bacterium (R6F) that predominantly degrades phenol under low phenol-loading conditions. Supplying galactose allowed sustainment of the R6F population and suppression of the overgrowth of R6T and R10 at the phenol-loading rate of 1.5 g l⁻¹ day⁻¹. This measure allowed the activated-sludge process to treat phenol at a phenol-loading rate up to 1.5 g l⁻¹ day⁻¹, although it broke down at 2.0 g l⁻¹ day⁻¹. In contrast, supplying glucose reduced the R6F population and allowed the activated-sludge process to break down at the phenol-loading rate of 1.0 g l⁻¹ day⁻¹. This study demonstrated that reclamation of the activated-sludge consortium by selective biostimulation of the floc-forming population improved the phenol-treating ability of the process. Received: 13 January 2000 / Received revision: 10 March 2000 / Accepted: 7 April 2000     

Metagenomic analysis of microbial consortium from natural crude oil that seeps into the marine ecosystem offshore Southern California

Crude oils can be major contaminants of the marine ecosystem and microorganisms play a significant role in the degradation of its main constituents. To increase our understanding of the microbial hydrocarbon degradation process in the marine ecosystem, we collected crude oil from an active seep area located in the Santa Barbara Channel (SBC) and generated a total of about 52 Gb of raw metagenomic sequence data. The assembled data comprised ~500 Mb, representing ~1.1 million genes derived primarily from chemolithoautotrophic bacteria. Members of Oceanospirillales, a bacterial order belonging to the Deltaproteobacteria, recruited less than 2% of the assembled genes within the SBC metagenome. In contrast, the microbial community associated with the oil plume that developed in the aftermath of the Deepwater Horizon (DWH) blowout in 2010, was dominated by Oceanospirillales, which comprised more than 60% of the metagenomic data generated from the DWH oil plume. This suggests that Oceanospirillales might play a less significant role in the microbially mediated hydrocarbon conversion within the SBC seep oil compared to the DWH plume oil. We hypothesize that this difference results from the SBC oil seep being mostly anaerobic, while the DWH oil plume is aerobic. Within the Archaea, the phylum Euryarchaeota, recruited more than 95% of the assembled archaeal sequences from the SBC oil seep metagenome, with more than 50% of the sequences assigned to members of the orders Methanomicrobiales and Methanosarcinales. These orders contain organisms capable of anaerobic methanogenesis and methane oxidation (AOM) and we hypothesize that these orders – and their metabolic capabilities – may be fundamental to the ecology of the SBC oil seep.     

Degradation of crude oil by Acinetobacter calcoaceticus and Alcaligenes odorans

Two types of Indian crude oil (Bombay High and Gujarat) were tested for their biodegradability by Acinetobacter calcoaceticus and Alcaligenes odorans. Acinetobacter calcoaceticus S30 and Alc. odorans P20 degraded Bombay High crude oil by 50% and 45%, while only 29% and 37% of Gujarat crude oil (heavy crude oil) was degraded by these isolates, respectively. Acinetobacter calcoaceticus and Alc. odorans in combination deraded 58% and 40% of Bombay High and Gujarat crude oils, respectively, which were significantly higher than that of by individual cultures. Acinetobacter calcoaceticus S30 degraded more of the alkanes fraction than the aromatics fraction of both crude oils. GC fingerprinting of alkane fraction showed major degradation of heptadecane (C₁₇), octadecane (C₁₈), nonadecane (C₁₉), eicosane (C₂₀), docosane (C₂₂), tricosane (C₂₃) and tetracosane (C₂₄) of crude oil, while the Alc. odorans P20 degraded alkanes and aromatics equally. The asphaltenic component increased in both types of crude oil after biodegradation. The two strains grew very well on n -alkane up to C₃₃ as well as on pristane (branched-chain alkane) but could not grow on cycloalkanes. Acinetobacter calcoaceticus S30 could not grow on pure polycyclic aromatic hydrocarbon (PAH) compounds except naphthalene but Alc. odorans P20 could grow on anthracene, phenanthrene, dibenzothiophene, fluorene, fluoranthene, pyrene and chrysene.     

A microbial consortium isolated from a crude oil sample that uses asphaltenes as a carbon and energy source

A microbial consortium capable of mineralizing asphaltenes was obtained from the Maya crude oil. The enrichment system was built with a glass column reactor containing mineral medium supplied with asphaltenes as energy and carbon source. The consortium growth was evaluated in Casoy agar during 40 weeks. The steady-state phase of the enriched bacterial community was observed after 10 weeks when the culture reach 10(5) to 10(6) CFU ml(-1). The isolates belong to bacterial genus reported for degradation of other hydrocarbons and they were identified as Corynebacterium sp., Bacillus sp., Brevibacillus sp. and Staphylococcus sp. The bacterial consortium growth was evaluated by a viable counts during 14 days exposed to different aeration, temperature, salinity, and pH conditions. The ability of the consortium to mineralize asphaltenes was evaluated using the method of ISO 9439 in glass column reactors of 20 x 3.2 cm during 13 days. Temperatures of 55 degrees C and salinity of 1.8% were growth limiting. The respiration of the microbial consortium using asphaltenes as a sole carbon source (800 micromoles CO2 in 13 days) was significantly higher than those of the samples containing only the microbial consortium (200 micromoles CO2) or only asphaltenes (300 micromoles CO2). These results indicated the existence of asphaltenes-degradating microbes in the crude oil and confirmed that the consortium could mineralize asphaltenes in conditions of room temperature, salinity of 100 ppm, aeration of 1 l min(-1) and pH of 7.4.     

Degradation of raw corn stover powder (RCSP) by an enriched microbial consortium and its community structure

A microbial consortium with a high cellulolytic activity was enriched to degrade raw corn stover powder (RCSP). This consortium degraded more than 51% of non-sterilized RCSP or 81% of non-sterilized filter paper within 8 days at 40 °C under facultative anoxic conditions. Cellulosome-like structures were observed in scanning electron micrographs (SEM) of RCSP degradation residue. The high cellulolytic activity was maintained during 40 subcultures in a medium containing cellulosic substrate. Small ribosomal gene sequence analyses showed the consortium contains uncultured and cultured bacteria with or without cellulolytic activities. Among these bacteria, some are anaerobic others aerobic. Analyses of the culture filtrate showed a typical anoxic polysaccharide fermentation during the culturing process. Reducing sugar concentration increased at early stage followed by various fermentation products that were consumed at the late stage.     

Dechlorination of polychlorinated biphenyl congeners by an anaerobic microbial consortium

  An anaerobic methanogenic microbial consortium, developed in a granular form, exhibited extensive dechlorination of defined polychlorinated biphenyl (PCB) congeners. A 2,3,4,5,6-pentachlorobiphenyl was dechlorinated to biphenyl via 2,3,4,6-tetrachlorobiphenyl, 2,4,6-trichlorobiphenyl, 2,4-dichlorobi-phenyl and 2-chlorobiphenyl (CB). Removal of chlorine atoms from all three positions of the biphenyl ring, i.e., ortho, meta and para, was observed during this reductive dechlorination process. Biphenyl was identified as one of the end-products of the reductive dechlorination by GC-MS. After 20 weeks, the concentrations of the dechlorination products 2,4,6-CB, 2,4-CB, 2-CB and biphenyl were 8.1, 41.2, 3.0 and 47.8 μM respectively, from an initial 105 μM 2,3,4,5,6-CB. The extent and pattern of the dechlorination were further confirmed by the dechlorination of lightly chlorinated congeners including 2-CB, 3-CB, 4-CB, 2,4-CB and 2,6-CB individually. This study indicates that the dechlorination of 2,3,4,5,6-CB to biphenyl is due to ortho, meta and para dechlorination by this anaerobic microbial consortium. Received: 30 April 1996 / Received revision: 26 July 1996 / Accepted: 5 August 1996     

Degradation of substituted indoles by an indole-degrading methanogenic consortium.

Degradation of indole by an indole-degrading methanogenic consortium enriched from sewage sludge proceeded through a two-step hydroxylation pathway yielding oxindole and isatin. The ability of this consortium to hydroxylate and subsequently degrade substituted indoles was investigated. Of the substituted indoles tested, the consortium was able to transform or degrade 3-methylindole and 3-indolyl acetate. Oxindole, 3-methyloxindole, and indoxyl were identified as metabolites of indole, 3-methylindole, and 3-indolyl acetate degradation, respectively. Isatin (indole-2,3-dione) was produced as an intermediate when the consortium was amended with oxindole, providing evidence that degradation of indole proceeded through successive hydroxylation of the 2- and 3-positions prior to ring cleavage between the C-2 and C-3 atoms on the pyrrole ring of indole. The presence of a methyl group (-CH3) at either the 1- or 2-position of indole inhibited the initial hydroxylation reaction. The substituted indole, 3-methylindole, was hydroxylated in the 2-position but not in the 3-position and could not be further metabolized through the oxindole-isatin pathway. Indoxyl (indole-3-one), the deacetylated product of 3-indolyl acetate, was not hydroxylated in the 2-position and thus was not further metabolized by the consortium. When an H atom or electron-donating group (i.e., -CH3) was present at the 3-position, hydroxylation proceeded at the 2-position, but the presence of electron-withdrawing substituent groups (i.e., -OH or -COOH) at the 3-position inhibited hydroxylation.     

Degradation of substituted indoles by an indole-degrading methanogenic consortium.

Degradation of indole by an indole-degrading methanogenic consortium enriched from sewage sludge proceeded through a two-step hydroxylation pathway yielding oxindole and isatin. The ability of this consortium to hydroxylate and subsequently degrade substituted indoles was investigated. Of the substituted indoles tested, the consortium was able to transform or degrade 3-methylindole and 3-indolyl acetate. Oxindole, 3-methyloxindole, and indoxyl were identified as metabolites of indole, 3-methylindole, and 3-indolyl acetate degradation, respectively. Isatin (indole-2,3-dione) was produced as an intermediate when the consortium was amended with oxindole, providing evidence that degradation of indole proceeded through successive hydroxylation of the 2- and 3-positions prior to ring cleavage between the C-2 and C-3 atoms on the pyrrole ring of indole. The presence of a methyl group (-CH3) at either the 1- or 2-position of indole inhibited the initial hydroxylation reaction. The substituted indole, 3-methylindole, was hydroxylated in the 2-position but not in the 3-position and could not be further metabolized through the oxindole-isatin pathway. Indoxyl (indole-3-one), the deacetylated product of 3-indolyl acetate, was not hydroxylated in the 2-position and thus was not further metabolized by the consortium. When an H atom or electron-donating group (i.e., -CH3) was present at the 3-position, hydroxylation proceeded at the 2-position, but the presence of electron-withdrawing substituent groups (i.e., -OH or -COOH) at the 3-position inhibited hydroxylation.     

Responses of arctic marine crustaceans to crude oil and oil-tainted food

The responses of several arctic marine crustaceans to oil masses and oil-tainted food have been investigated. None of the species were attracted to crude oil. Amphipods tended to avoid oil masses; however, the response was significantly diminished if the oil was weathered or if the animals were pre-exposed to light crude oil emulsions. Untainted food was preferentially selected over oil-tainted food. In contrast, an isopod was generally neutral to the presence of oil masses and consumed oil-tainted food as readily as untainted material.     

Biodegradation of Tapis blended crude oil in marine sediment by a consortium of symbiotic bacteria

Biodegradation rate and the high molecular weight hydrocarbons are among the important concerns for bioremediation of crude oil. Inoculation of a non-oil-degrading bacterium as supplementary bacteria increased oil biodegradation from 57.1% to 63.0% after 10 days of incubation. Both the oil-degrading bacteria and the non-oil-degrading bacteria were isolated from Malaysian marine environment. Based on the 16S rDNA sequences, the oil-degrading bacteria was identified as Pseudomonas pseudoalcaligenes (99% similarity) while the non-oil-degrading bacterium was Erythrobacter citreus (99% similarity). E. citreus does not grow on crude oil enriched medium under present experimental condition but it withstands 5000 mg kg^?1 Tapis blended crude oil in sediment. Under optimal condition, the oil-degrading bacterium; P. pseudoalcaligenes, alone utilized 583.3 ± 3.8 mg kg^?1 (57.1%) at the rate of 3.97 × 10^?10 mg kg^?1 cell^?1 day^?1 Tapis blended crude oil from 1000 mg kg^?1 oil-contaminated sediment. Inoculation of E. citreus as the supplementary bacteria to P. pseudoalcaligenes enhanced biodegradation. The bacterial consortium degraded 675.8 ± 18.5 mg kg^?1 (63.0%) Tapis blended crude oil from the 1000 mg kg^?1 oil-contaminated sediment. Biodegradation rate of the bacterial consortium increased significantly to 4.59 × 10^?10 mg kg^?1 cell^?1 day^?1 (p = 0.02). Improvement of the oil degradation by the bacterial consortium was due to the synergetic reaction among the bacterial inoculants. There are two implications: (1) E. citreus may have a role in removing self-growth-inhibiting compounds of P. pseudoalcaligens. (2) P. pseudoalcaligenes degraded Tapis blended crude oil while E. citreus competes for the partially degraded hydrocarbons by P. pseudoalcaligenes. P. pseudoalcaligenes forced to breakdown more hydrocarbons to sustain its metabolic requirement. The bacterial consortium degraded 78.7% of (C₁₂–C₃₄) total aliphatic hydrocarbons (TAHs) and 74.1% of the 16 USEPA prioritized polycyclic aromatic hydrocarbons.     

Bio-hydrolysis of used soybean oil: environmental-friendly technology using microbial consortium

Biodegradation - In this work, strains of Bacillus subtilis were inoculated in consortium with Rhodotorula mucilaginosa into spent soy oil as aiming to biological treatment and low-cost reuse. The...     

Hexadecane aqueous emulsion characterization and uptake by an oil-degrading microbial consortium

In the present work was characterized in abiotic and biotic systems, the droplet size of hexadecane (HXD) in emulsified form. Furthermore it was assessed the uptake of HXD in their both form emulsified (microscopic droplets) and free (macroscopic droplets), using a microbial consortium with the capacity of degrading oil. HXD in emulsified form includes microscopic droplets of 0.1 and 0.5 up to 0.7 μm. In the biotic experiments the kinetic parameters values were determined either by fitting to the Contois model the consumed data of HXD emulsified and by considering also the uptake rate of the free forms of HXD as independent of their own concentration. A comparison of the maximum specific HXD uptake rate (q_max) of the oil-degrading consortium when consumes the two forms of HXD, shows to be 53 times greater for the emulsified HXD that for their free form, suggesting that consumption of HXD is realized mostly by the emulsified form. The specific transfer area decreases with the culture time due to that the HXD is emulsified and consumed by the microbial consortium, being the specific transfer area of emulsified forms (microscopic droplets) a parameter that must be considered in the design of biodegradation processes of insoluble organic pollutants.     

Aerobic degradation of 2,4,6-trichlorophenol by a microbial consortium - selection and characterization of microbial consortium

A microbial consortium that efficiently degrades 2,4,6-TCP (2,4,6-trichlorophenol), as the sole source of carbon and energy under aerobic conditions was selected from municipal activated sludge. Six bacterial strains, designated S(1), S(2), S(3), S(4), S(5) and S(6), were isolated from the selected consortium and five were identified as Sphingomonas paucimobilis (S(2), S(3)), Burkholderia cepacia(S(4)), Chryseomonas luteola (S(5)) and Vibrio metschnikovii (S(6)). After prolonged cultivation followed by successive transfers, the consortium's degradation ability was improved and reached a specific degradation rate of 34 mg 2,4,6-TCP g(-1) dry weight h(-1) (about 51 mg 2,4,6-TCP g(-1) cell protein h(-1)). The soluble chemical oxygen demand, chloride and oxygen uptake balance data clearly indicate the complete dechlorination and mineralization of 2,4,6-TCP. The consortium's activity was not inhibited by 2,4,6-TCP concentrations 相似文献   

Degradation of dicamba by an anaerobic consortium enriched from wetland soil.

The biodegradability of dicamba was investigated under anaerobic conditions with a consortium enriched from wetland soil. Degradation proceeded through an initial demethylation reaction, forming 3,6-dichlorosalicylic acid, followed by reductive dechlorination, forming 6-chlorosalicylic acid. The consortium, consisting of a sulfate reducer, three methanogens, and a fermenter, was unable to mineralize the aromatic ring.