Project description:Paenarthrobacter strains effectively degrade the fungicide iprodione, exhibiting a specialization rarely seen amongst bacteria. The transformation of iprodione is controlled by an amidase, a deacetylase and a hydrolase encoded by ipaH, ddaH and duaH respectively. We aimed to elucidate the mechanisms of this catabolic specialization and its evolution in Paenarthrobacters. The genomes of two new iprodione-degrading Paenarthrobacter strains TA1.8 and C1 were sequenced and analyzed comparatively with the genomes of two other iprodione-degrading Paenarthrobacter strains YJN-5 and YJN-D. Comparative genomics revealed different gene organization motifs amongst strains which suggest that the strains are at different stages of pathway evolution, in accord with their prior exposure to iprodione. Strains TA1.8, YJN-5 and YJN-D, all isolated from soils heavily exposed to iprodione, carried multiple copies of ipaH, ddaH and duaH in their chromosomes and plasmids that were assigned to two distinct phylogenetic clusters based on genome topology. Conversely, strain C1, isolated from a pristine soil, carried ipaH, ddaH and duaH in the chromosome. Pangenome analysis of the genus Paenarthrobacter placed ipaH and duaH in the core genome reinforcing their specialization in the degradation of iprodione as they need to acquire only ddaH, the sole gene of the pathway associated with transposable elements in strains C1 and TA1.8, to complete the pathway. We propose an evolution route of the iprodione transformation pathway which involves acquisition of ddaH through horizontal gene transfer, gene duplication of the chromosomally encoded ipaH and ddaH, and further genetic rearrangements for pathway optimization, complementing duaH, a core gene in Paenarthrobacters. Transcriptomic analysis of strain TA1.8 verified the involvement of all copies of ipaH, ddaH and duaH in the transformation of iprodione, and identified hydantoinases, upregulated during iprodione degradation, as potential facilitators of the transformation of the hydantoin-containing intermediate N-(3,-5-dichlorophenyl)- 2,4-dioxoimida-zolidine, a step mediated by DdaH.
Project description:The survival, pollutant degradation activity and transcriptome response was monitored in Sphingomonas sp. LH128 inoculated into soil. Cultivable cell numbers were determined by plating, while phenanthrene degradation was monitored by HPLC. The genetic base for the adaptive strategy of LH128 in soil was investigated by using microarray consisting 7,200 gene-coding ORFs. During 4 hours of incubation, 510 genes were differentially expressed (317 increased and 193 reduced expression) while 610 genes were differentially expressed (318 increased and 292 reduced) after 10 days of incubation. Genes with increased expression comprised of gene encoding PAH catabolic enzymes, stress resistance, oxidative stress tolerance, outer membrane proteins/porins and efflux pump proteins while the downregulated genes comprised of genes encoding flagellar biosynthesis, ribosomal proteins and ATPase. Transcriptomic response of phenanthrene degrading Sphingomonas sp. LH128 inoculated into phenanthrene contaminated soil after 4h and after 10 days of incubation was studied using genome-wide gene expression analysis. For this purpose, the strain was pregrown in minimal medium and inoculated at appropriated celld densitites. RNA was extracted both from soil and and from initial inoculum and cDNA was synthesized and labeled with Cy3. Transcriptomic response in soil of three replicates per conditions after both incubation duration were analyzed and compared with the initial inoculum