Biochar has been widely used for the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil, but its mechanism of influencing PAH biodegradation remains unclear. Here, DNA-stable isotope probing coupled with high-throughput sequencing was employed to assess its influence on phenanthrene (PHE) degradation, the active PHE-degrading microbial community and PAH-degradation genes (PAH-RHD α ). Our results show that both Low-BC and High-BC (soils amended with 1 % and 4 % w/w biochar, respectively) treatments significantly decreased PHE biodegradation and bioavailable concentrations with a dose-dependent effect compared to Non-BC treatment (soils without biochar). This result could be attributed to the immobilisation of PHE and alteration of the composition and abundance of the PHE-degrading microbial consortium by biochar. Active PHE degraders were identified, and those in the Non-BC, Low-BC and High-BC microcosms differed taxonomically. Sphaerobacter , unclassified Diplorickettsiaceae , Pseudonocardia , and Planctomyces were firstly linked with PHE biodegradation. Most importantly, the abundances of PHE degraders and PAH-RHD α genes in the 13 C-enriched DNA fractions of biochar-amended soils were greatly attenuated, and were significantly positively correlated with PHE biodegradation. Our findings provide a novel perspective on PAH biodegradation mechanisms in biochar-treated soils, and expand the understanding of the biodiversity of microbes involved in PAH biodegradation in the natural environment.
Lei Miao,Tian Ma,Jiaxi Qi,Yaohui Deng,Yaqi Hong,Xiaoxiao Gong,Hailian Zang,Yi Cheng,Chunyan Li
17β-Estradiol (17β-E2), a persistent endocrine-disrupting compound, threatens ecosystem health through bioaccumulation. While bioaugmentation offers promise for environmental remediation, mechanistic insights into interspecies interactions between exogenous and indigenous degraders remain underexplored. Here, a synthetic microbial consortium (EL) was constructed by combining Rhodococcus erythropolis D310–1 and Microbacterium oxydans ML-6, which reduced the 17β-E2 degradation half-life by 53.65 % compared with that of the noninoculated control while suppressing the accumulation of the toxic intermediate estrone (E1). Temporal 16S rRNA gene amplicon sequencing profiling with co-occurrence network analysis revealed that the consortium EL dynamically reinforced ecological synergies with indigenous functional microbiota, accelerating contaminant mineralization. DNA-stable isotope probing (DNA-SIP) coupled with metagenomics identified Rhodanobacter , Mycobacterium , Rhodococcus , Sphingomonas , and Microbacterium spp. as active 17β-E2 assimilators. Furthermore, high-performance liquid chromatography coupled with quadrupole time flight mass spectrometry (HPLC QTOF MS) was used to predict three complementary degradation pathways in the assembled genomes, revealing related functional enzymes and addressing functional partitioning between exogenous inoculants and indigenous degraders. Two novel gene clusters responsible for 17β-E2 biodegradation were evaluated. This study pioneers DNA-SIP and metagenomics to track 13 C-labelled 17β-E2 fate within bioaugmented soil microbiota, resolving intrakingdom bacteria collaborations that drive 17β-E2 biodegradation in soil. The identification of cross-consortium metabolic handoffs provides a blueprint for engineering syntrophic partnerships targeting steroidal estrogens (SEs) pollutants.
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