Plant–microbe association for rhizoremediation of chloronitroaromatic pollutants with Comamonas sp. strain CNB‐1

Abstract

Comamonas sp. strain CNB-1, isolated from activated sludge and having a strong ability to degrade 4-chloronitrobenzene (4CNB), was applied for rhizoremediation of 4CNB-polluted soil through association with alfalfa. Confocal laser scanning microscopy revealed that strain CNB-1 successfully colonized alfalfa roots. Determination of strain CNB-1 populations by cultivation method and by quantitative competitive PCR technique targeting the chloronitrobenzene nitroreductase gene showed that the population of strain CNB-1 in the rhizosphere was about 10-100 times higher than that in the bulk soil. Gnotobiotic and outdoor experiments showed that pollutant 4CNB was completely removed within 1 or 2 days after 4CNB application into soil, and that its phytotoxicity to alfalfa was eliminated by inoculation of strain CNB-1. Results from PCR-denaturing gradient gel electrophoresis and analysis of 16S rRNA gene libraries revealed that the indigenous soil microbial community mainly consisted of alphaproteobacteria, betaproteobacteria, gammaproteobacteria, the CFB bacteria (Cytophaga-Flavabacterium-Bacteriodes), and Acidobacteria. This microbial community was not significantly influenced by inoculation of strain CNB-1. Thus, this study has developed a Comamonas-alfalfa system for rhizoremediation of 4CNB.

The Complete Genome of Comamonas testosteroni Reveals Its Genetic Adaptations to Changing Environments

“…Genes encoding all the aerobic respiratory chain (37) and under microaerobic conditions in nitrogenfixing bacteria (15,22) and in association with animals (21,43). Thus, the robust competitiveness of strain CNB-1 in the rhizosphere and wastewater treatment plants may be attributed to the presence of multiple terminal oxidases (25). Genome analysis suggested a putative transhydrogenase (CtCNB1_0257 to CtCNB1_0258) that might regulate energy metabolism in strain CNB-2 at different oxygen concentrations.…”

“…testosteroni strain CNB-1 was isolated from CNB-contaminated activated sludge and grows with CNB as a sole source of carbon and nitrogen, and it has been used successfully for rhizoremediation of CNB-polluted soil (25). Strain CNB-1 has a circular chromosome and a large plasmid, and the genes involved in the degradation of CNB on plasmid pCNB1 were identified previously (28).…”

Innoculant technology in Populus deltoides rhizosphere for effective bioremediation of Polyaromatic hydrocarbons (PAHs) in contaminated soil, Northern India

“…It has been suggested, that bacteria that attain colony-forming units of about 10 3 per gram or higher on root mass can be considered a good colonizers (Meyer and Abdallah, 1978) and in this study we have obtained the population density higher than 10 3 per gram of soil. Successful application of plant-microbe systems for rhizoremediation relies on in situ establishment of a high level of competence of introduced bacteria (Liu et al, 2007).…”

Bacterial metabolism of polycyclic aromatic hydrocarbons: strategies for bioremediation

“…Such plant-microbes interactions have been exploited for bioremediation of heavy metals [140], toluene [141], polychlorinated biphenyl [142], naphthalene [143], and 2,4-dinitrotoluene [144]. Species of the genera Pseudomonas, Comamonas and Burkholderia are the most commonly used players [141,[145][146][147]. Successful application of plant-microbe systems for rhizoremediation relies on in situ establishment of a high level of competence of the introduced bacteria.…”