Transcriptome differences between Cupriavidus necator NH9 grown with 3-chlorobenzoate and that grown with benzoate

Complete genome sequence of Paraburkholderia sp. strain 22B1P capable of utilizing 3-chlorobenzoate as a carbon source

Paraburkholderia sp. strain 22B1P utilizes 3-chlorobenzoate as a carbon source. Complete genome sequencing of strain 22B1P revealed two chromosomes and two plasmids. The genes involved in the conversion of 3-chlorobenzoate to 3-chlorocatechol and those involved in the conversion of 3-chlorocatechol to 3-oxoadipate were located on chromosomes 2 and 1, respectively.

Isolation and Genomic Analysis of 3-Chlorobenzoate-Degrading Bacteria from Soil

The compound 3-chlorobenzoate (3-CBA) is a hazardous industrial waste product that can harm human health and the environment. This study investigates the physiological and genetic potential for 3-chlorobenzoate (3-CBA) degradation. Six 3-CBA Gram-negative degraders with different degradation properties belonging to the genera Caballeronia, Paraburkholderia and Cupriavidus were isolated from the soil. The representative strains Caballeronia 19CS4-2 and Paraburkholderia 19CS9-1 showed higher maximum specific growth rates (µmax, h^-1) than Cupriavidus 19C6 and degraded 5 mM 3-CBA within 20-28 h. Two degradation products, chloro-cis,cis-muconate and maleylacetate, were detected in all isolates using high-performance liquid chromatography and mass spectrometry. Genomic analyses revealed the presence of cbe and tfd gene clusters in strains 19CS4-2 and 19CS9-1, indicating that they probably metabolized the 3-CBA via the chlorocatechol ortho-cleavage pathway. Strain 19C6 possessed cbe genes, but not tfd genes, suggesting it might have a different chlorocatechol degradation pathway. Putative genes for the metabolism of 3-hydroxybenzoate via gentisate were found only in 19C6, which utilized the compound as a sole carbon source. 19C6 exhibited distinct characteristics from strains 19CS4-2 and 19CS9-1. The results confirm that bacteria can degrade 3-CBA and improve our understanding of how they contribute to environmental 3-CBA biodegradation.

Cupriavidus metallidurans CH34 Possesses Aromatic Catabolic Versatility and Degrades Benzene in the Presence of Mercury and Cadmium

Heavy metal co-contamination in crude oil-polluted environments may inhibit microbial bioremediation of hydrocarbons. The model heavy metal-resistant bacterium Cupriavidus metallidurans CH34 possesses cadmium and mercury resistance, as well as genes related to the catabolism of hazardous BTEX aromatic hydrocarbons. The aims of this study were to analyze the aromatic catabolic potential of C. metallidurans CH34 and to determine the functionality of the predicted benzene catabolic pathway and the influence of cadmium and mercury on benzene degradation. Three chromosome-encoded bacterial multicomponent monooxygenases (BMMs) are involved in benzene catabolic pathways. Growth assessment, intermediates identification, and gene expression analysis indicate the functionality of the benzene catabolic pathway. Strain CH34 degraded benzene via phenol and 2-hydroxymuconic semialdehyde. Transcriptional analyses revealed a transition from the expression of catechol 2,3-dioxygenase (tomB) in the early exponential phase to catechol 1,2-dioxygenase (catA1 and catA2) in the late exponential phase. The minimum inhibitory concentration to Hg (II) and Cd (II) was significantly lower in the presence of benzene, demonstrating the effect of co-contamination on bacterial growth. Notably, this study showed that C. metallidurans CH34 degraded benzene in the presence of Hg (II) or Cd (II).