Characterization of a polycyclic aromatic ring-hydroxylation dioxygenase from Mycobacterium sp. NJS-P

Chemosphere ◽  
2017 ◽  
Vol 185 ◽  
pp. 67-74 ◽  
Author(s):  
Jun Zeng ◽  
Qinghe Zhu ◽  
Yucheng Wu ◽  
Hong Chen ◽  
Xiangui Lin
Author(s):  
G. Beaven ◽  
A. Bowyer ◽  
P. Erskine ◽  
S. P. Wood ◽  
A. McCoy ◽  
...  

The enzyme 2,4′-dihydroxyacetophenone dioxygenase (or DAD) catalyses the conversion of 2,4′-dihydroxyacetophenone to 4-hydroxybenzoic acid and formic acid with the incorporation of molecular oxygen. Whilst the vast majority of dioxygenases cleave within the aromatic ring of the substrate, DAD is very unusual in that it is involved in C—C bond cleavage in a substituent of the aromatic ring. There is evidence that the enzyme is a homotetramer of 20.3 kDa subunits each containing nonhaem iron and its sequence suggests that it belongs to the cupin family of dioxygenases. By the use of limited chymotrypsinolysis, the DAD enzyme fromAlcaligenessp. 4HAP has been crystallized in a form that diffracts synchrotron radiation to a resolution of 2.2 Å.


2019 ◽  
Author(s):  
Jessica A. Lee ◽  
Sergey Stolyar ◽  
Christopher J. Marx

AbstractMicroorganisms faces many barriers in the degradation of the polycyclic aromatic polymer lignin, one of which is an abundance of methoxy substituents. Demethoxylation of lignin-derived aromatic monomers in aerobic environments releases formaldehyde, a potent cellular toxin that organisms must eliminate in order to further degrade the aromatic ring. Here we provide the first comprehensive description of the ecology and evolution of the catabolism of methoxylated aromatics in the genus Methylobacterium, a plant-associated genus of methylotrophs capable of using formaldehyde for growth. Using comparative genomics, we found that the capacity for aromatic catabolism is ancestral to two clades, but has also been acquired horizontally by other members of the genus. Through laboratory growth assays, we demonstrated that several Methylobacterium strains can grow on p-hydroxybenzoate, protocatechuate, vanillate, and ferulate; furthermore, whereas non-methylotrophs excrete formaldehyde as a byproduct during growth on vanillate, Methylobacterium do not. Finally, we surveyed published metagenome data to find that vanillate-degrading Methylobacterium can be found in many soil and rhizosphere ecosystems but is disproportionately prominent in the phyllosphere, and the most highly represented clade in the environment (the root-nodulating species M. nodulans) is one with few cultured representatives.


2021 ◽  
Vol 19 (3) ◽  
pp. 246-254
Author(s):  
Nur Zaida Zahari ◽  
◽  
Erma Hani Baharudzaman ◽  
Piakong Mohd Tuah ◽  
Fera Nony Cleophas ◽  
...  

Oil spills are one of the environmental pollutions that commonly occur along coastal areas. Tar-balls are one of the products that come from the oil spill pollution. In this study, tar-ball pollution was monitored at 10 points along the coastline of Marintaman Beach in Sipitang, Sabah, Malaysia. This research determined the physical characteristics, composition, and concentration of Polycyclic Aromatic Hydrocarbons (PAHs) in tar-balls. The total number of tar-balls collected was 227 (n=227). The tar-balls were observed in various shapes and the sizes were recorded in the range of 0.1 cm to 6.9 cm. The composition and concentration of Polycyclic Aromatic Hydrocarbons (PAHs) in the outer and inner layer of tar-balls were determined. The results showed that the main Polycyclic Aromatic Hydrocarbons (PAHs) compounds were found in inner layers of the tar-balls with benzo (g,h,i) perylene (72.26 mg/kg), flourene (59.87 mg/kg), dibenzo (a,h) anthracene (44.48 mg/kg), indeno (1,2,3-c,d) pyrene (78.18 mg/kg), and benzo (e) fluoranthene (45.70 mg/kg), respectively. Further research was done with the bioaugmentation study of locally isolated beneficial microorganisms (LIBeM) consortium for treatment of tar-balls in an Aerated Static Pile (ASP) bioreactor system. The results showed that, after 84 days of treatment, this consortium, consisting of C. tropicalis-RETL-Cr1, C. violaceum-MAB-Cr1, and P. aeruginosa-BAS-Cr1, was able to degrade total petroleum hydrocarbon (TPH) by 84% as compared to natural attenuation (19%). The microbial population of this consortium during the biodegradation study is also discussed in this paper.


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