Arhodomonas sp. Strain Seminole and Its Genetic Potential To Degrade Aromatic Compounds under High-Salinity Conditions

Abstract

cArhodomonas sp. strain Seminole was isolated from a crude oil-impacted brine soil and shown to degrade benzene, toluene, phenol, 4-hydroxybenzoic acid (4-HBA), protocatechuic acid (PCA), and phenylacetic acid (PAA) as the sole sources of carbon at high salinity. Seminole is a member of the genus Arhodomonas in the class Gammaproteobacteria, sharing 96% 16S rRNA gene sequence similarity with Arhodomonas aquaeolei HA-1. Analysis of the genome predicted a number of catabolic genes for the metabolism of benzene, toluene, 4-HBA, and PAA. The predicted pathways were corroborated by identification of enzymes present in the cytosolic proteomes of cells grown on aromatic compounds using liquid chromatography-mass spectrometry. Genome analysis predicted a cluster of 19 genes necessary for the breakdown of benzene or toluene to acetyl coenzyme A (acetyl-CoA) and pyruvate. Of these, 12 enzymes were identified in the proteome of toluene-grown cells compared to lactate-grown cells. Genomic analysis predicted 11 genes required for 4-HBA degradation to form the tricarboxylic acid (TCA) cycle intermediates. Of these, proteomic analysis of 4-HBA-grown cells identified 6 key enzymes involved in the 4-HBA degradation pathway. Similarly, 15 genes needed for the degradation of PAA to the TCA cycle intermediates were predicted. Of these, 9 enzymes of the PAA degradation pathway were identified only in PAA-grown cells and not in lactate-grown cells. Overall, we were able to reconstruct catabolic steps for the breakdown of a variety of aromatic compounds in an extreme halophile, strain Seminole. Such knowledge is important for understanding the role of Arhodomonas spp. in the natural attenuation of hydrocarbon-impacted hypersaline environments.

Halophiles and their enzymes: negativity put to good use

“…A Haloferax strain was found to produce surfactants that enhanced hydrocarbon degradation [48]. Additionally, an Arhodomonas strain was reported to have the capability to degrade aromatic compounds, including benzene and toluene [49]. …”

Enhancing tetrabromobisphenol A biodegradation in river sediment microcosms and understanding the corresponding microbial community

“…The in situ remediation of contaminated sediment using microbes is a promising treatment method (Acosta-Gonzalez et al, 2013;Tischer et al, 2013;Dalvi et al, 2014;Islam et al, 2015). In a previous study, a novel bacterium Ochrobactrum sp.…”

Isolation and characterization ofRhizobiumsp. strain YS-1r that degrades lignin in plant biomass

“…2011a; Dalvi et al . ). Also, genes that code for vanillate O ‐demethylase, protocatechuate 3,4‐dioxygenase, 4‐hydroxybenzoate 3‐monooxygenase, gentisate 1,2‐dioxygenase, 4‐carboxymuconolactone decarboxylase and 3‐oxoadipate enol‐lactonase were detected in the genome indicating the organism's ability to metabolize vanillate, 3‐methyl gallate, hydroxybenzoate and protocatechuate, the prominent breakdown products of lignin using the protocatechuate branch of beta‐ketoadipate pathway (Harwood and Parales ; Masai et al .…”

“…,b; Dalvi et al . ). These findings are consistent with the fact that many Rhizobium species have been shown to metabolize flavonoids produced by plants in rhizosphere.…”