Methanogenic Degradation of Phenol and Benzoate in Acclimated Sludges

1989 ◽  
Vol 21 (4-5) ◽  
pp. 55-65 ◽  
Author(s):  
T. Kobayashi ◽  
T. Hashinaga ◽  
E. Mikami ◽  
T. Suzuki

Anaerobic phenol and benzoate degrading consortia were cultivated by acclimation of methanogenic sludges to be capable of degrading completely to CO2 and CH4 1,000 mg/l of phenol within 5–7 days, and 3,000 mg/l of benzoate within 5–7 days, respectively. By using the acclimated sludges, the effect of gaseous atmospheres (H2:CO2/80:20 and N2:CO2/80:20) on the biodegradability and the degradation pathways of phenol and benzoate were examined. Although the anaerobic degradation of phenol was accelerated in the H2/CO2 atmosphere compared with the N2/CO2 atmosphere, benzoate was accumulated. Degradations of benzoate and butyrate were inhibited in the H2/CO2 atmosphere under stirred conditions, but not under static conditions. Through a series of biodegradation tests by using several intermediates in phenol degradation reported previously, the anaerobic degradation pathway of phenol in the N2/CO2 atmosphere was suggested to be phenol → benzoate → cyclohexane carboxylate (or 1-cyclohexene carboxylate) → fatty acids → CO2,CH4.

2019 ◽  
Author(s):  
Yi-Lung Chen ◽  
Sean Ting-Shyang Wei ◽  
Yin-Ru Chiang

AbstractSteroid hormones (androgens and estrogens) are crucial for development, reproduction, and communication of multicellular eukaryotes. The ubiquitous distribution and persistence of steroid hormones in our ecosystems have become an environmental issue due to the adverse effects on wildlife and humans upon long-term exposure. Microbial degradation is critical for the removal of steroid hormones from ecosystems. The aerobic degradation pathways for androgens and estrogens and the anaerobic degradation pathway for androgen have been studied into some details; however, the mechanism for anaerobic estrogen degradation remains completely unknown. Here, we presented the circular genomes of D. oestradiolicum DSM 16959 and Denitratisoma sp. strain DHT3, two betaproteobacteria capable of anaerobic estrogen degradation. We identified the genes involved in steroid transformation and in the anaerobic 2,3-seco pathway in both genomes. Additionally, the comparative genomic analysis revealed that genes exclusively represented in estrogen-degrading anaerobes might play a role in anaerobic estrogen catabolism.


2010 ◽  
Vol 44 (5) ◽  
pp. 1670-1676 ◽  
Author(s):  
Pablo A. Lara-Martín ◽  
Abelardo Gómez-Parra ◽  
José Luis Sanz ◽  
Eduardo González-Mazo

2021 ◽  
Author(s):  
Junhui Li ◽  
Paul Dijkstra ◽  
Qihong Lu ◽  
Shanquan Wang ◽  
Shaohua Chen ◽  
...  

AbstractEffective degradation of N,N-Dimethylformamide (DMF), an important industrial waste product, is challenging as only few bacterial isolates are known to be capable of degrading DMF. Aerobic remediation of DMF has typically been used, whereas anoxic remediation attempts are recently made, using nitrate as one electron acceptor, and ideally include methane as a byproduct. Here, we analyzed 20,762 complete genomes and 28 constructed draft genomes for the genes associated with DMF degradation. We identified 952 genomes that harbor genes involved in DMF degradation, expanding the known diversity of prokaryotes with these metabolic capabilities. Our findings suggest acquisition of DMF-degrading gene via plasmids are important in the order Rhizobiales and genus Paracoccus, but not in most other lineages. Degradation pathway analysis reveals that most putative DMF degraders using aerobic Pathway I will accumulate methylamine intermediate, while members of Paracoccus, Rhodococcus, Achromobacter, and Pseudomonas could potentially mineralize DMF completely under aerobic conditions. The aerobic DMF degradation via Pathway II is more common than thought and is primarily present in α-and β-Proteobacteria and Actinobacteria. Most putative DMF degraders could grow with nitrate anaerobically (Pathway III), however, genes for the use of methyl-CoM to produce methane were not found. These analyses suggest that microbial consortia could be more advantageous in DMF degradation than pure culture, particularly for methane production under the anaerobic condition. The identified genomes and plasmids form an important foundation for optimizing bioremediation of DMF-containing wastewaters.ImportanceDMF is extensively used as a solvent in industries, and is classified as a probable carcinogen. DMF is a refractory compound resistant to degradation, and until now, only few bacterial isolates have been reported to degrade DMF. To achieve effective microbial degradation of DMF from wastewater, it is necessary to identify genomic diversity with the potential to degrade DMF and characterize the genes involved in two aerobic degradation pathways and potential anaerobic degradation for methane production. A wide diversity of organisms has the potential to degrade DMF. Plasmid-mediated degradation of DMF is important for Rhizobiales and Paracoccus. Most DMF degraders could grow anaerobically with nitrate as electron acceptor, while co-cultures are required to complete intermediate methanogenesis for methane production. This is the first genomics-based global investigation into DMF degradation pathways. The genomic database generated by this study provides an important foundation for the bioremediation of DMF in industrial waste waters.Abstract Figure


1991 ◽  
Vol 24 (3-4) ◽  
pp. 431-436 ◽  
Author(s):  
H. V. Hendriksen ◽  
S. Larsen ◽  
B. K. Ahring

The anaerobic degradation of pentachlorophenol (PCP) and phenol was examined in two lab-scale fixed-film reactors. Anaerobic digested sewage sludge from a municipal treatment plant was used as inoculum. The reactors were fed a mineral medium containing PCP (1-2 mg/l) and phenol (4-6 mg/l). In addition one of the reactors received 1 g/l glucose as an easily degradable carbon source. After 6 months of continuous operation, the removal of PCP in the reactor with no glucose added was approximately 60%, whereas the removal in the reactor with glucose reached 98%. Tetrachlorophenol (TeCP) and trichloro-phenol (TCP) were found as degradation products and the removal of these compounds was also significantly enhanced by the presence of glucose. Phenol degradation was approximately 70% with glucose added and 95% without glucose.


2015 ◽  
Vol 63 (32) ◽  
pp. 7151-7160 ◽  
Author(s):  
Zhiqiang Cai ◽  
Jing Wang ◽  
Jiangtao Ma ◽  
Xiaolin Zhu ◽  
Jinyan Cai ◽  
...  

2008 ◽  
Vol 190 (16) ◽  
pp. 5699-5709 ◽  
Author(s):  
Lars Wöhlbrand ◽  
Heinz Wilkes ◽  
Thomas Halder ◽  
Ralf Rabus

ABSTRACT The denitrifying “Aromatoleum aromaticum” strain EbN1 was demonstrated to utilize p-ethylphenol under anoxic conditions and was suggested to employ a degradation pathway which is reminiscent of known anaerobic ethylbenzene degradation in the same bacterium: initial hydroxylation of p-ethylphenol to 1-(4-hydroxyphenyl)-ethanol followed by dehydrogenation to p-hydroxyacetophenone. Possibly, subsequent carboxylation and thiolytic cleavage yield p-hydroxybenzoyl-coenzyme A (CoA), which is channeled into the central benzoyl-CoA pathway. Substrate-specific formation of three of the four proposed intermediates was confirmed by gas chromatographic-mass spectrometric analysis and also by applying deuterated p-ethylphenol. Proteins suggested to be involved in this degradation pathway are encoded in a single large operon-like structure (∼15 kb). Among them are a p-cresol methylhydroxylase-like protein (PchCF), two predicted alcohol dehydrogenases (ChnA and EbA309), a biotin-dependent carboxylase (XccABC), and a thiolase (TioL). Proteomic analysis (two-dimensional difference gel electrophoresis) revealed their specific and coordinated upregulation in cells adapted to anaerobic growth with p-ethylphenol and p-hydroxyacetophenone (e.g., PchF up to 29-fold). Coregulated proteins of currently unknown function (e.g., EbA329) are possibly involved in p-ethylphenol- and p-hydroxyacetophenone-specific solvent stress responses and related to other aromatic solvent-induced proteins of strain EbN1.


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