Toward a More Comprehensive Understanding of Autochthonous Bioaugmentation (ABA): Cases of ABA for Phenanthrene and Biphenyl by Ralstonia sp. M1 in Industrial Wastewater

Abstract

Although autochthonous bioaugmentation (ABA) has been applied to remove organic pollutants from wastewater, few studies have evaluated the roles of autochthonous microbes in eliminating polychlorinated biphenyls or polyaromatic hydrocarbons to reveal the mechanisms of ABA. Little research has been done to date to confirm the actual performance of introduced degraders in pollutant degradation in ABA and to explore a real-world scenario in which multiple pollutants coexist. Here, ABA by autochthonous strain Ralstonia sp. M1 was used to enhance the biodegradation of phenanthrene and biphenyl. The results showed a marked improvement in phenanthrene and biphenyl degradation in ABA, and the stable-isotope probing results first confirmed the direct involvement of Ralstonia sp. M1 in phenanthrene and biphenyl degradation. Additionally, ABA significantly altered the active degrading communities, and the abundance of the active degraders shared by both phenanthrene and biphenyl metabolisms was significantly improved in ABA, indicating their pivotal roles in improving phenanthrene and biphenyl degradation efficiency. Furthermore, ABA by strain Ralstonia sp. M1 promoted the interactions between the active degraders and other core microbes, consistent with the trends of pollutant removal. Collectively, our findings provide a better view of the mechanisms of ABA and offer new insights into the simultaneous degradation of multiple pollutants during ABA.

In Situ Discrimination and Cultivation of Active Degraders in Soils by Genome-Directed Cultivation Assisted by SIP-Raman-Activated Cell Sorting

“…The addition was performed using a syringe, following the methodology established in our previous study. 35 Two biotic treatments including soil with 12 C-toluene ( 12 C_Toluene) and soil with 13 C-toluene ( 13 C_Toluene) were established as well as a sterile control using sterilized soils amended with unlabeled toluene. For each treatment, six replicates were used.…”

“…DNA was extracted from each sample using the PowerSoil DNA Isolation Kit (MO BIO, Carlsbad, CA), according to the manufacturer's instructions. After detection with a NanoDrop 2000 spectrophotometer, DNA from the 12 C_Toluene and 13 C_Toluene microcosms was used for the CsCl gradient ultracentrifugation as previously described. 9,36 Briefly, approximately 5 μg of DNA was mixed with tris EDTA/CsCl solution at a buoyancy density (BD) value of ∼1.77 g/mL and transferred to the Quick-Seal polyallomer tubes (13 × 51 mm, 5.1 mL, Beckman Coulter, Pasadena, CA, USA).…”

“…In each of the 12 C-toluene and 13 Ctoluene microcosms, 500 bacterial cells were examined by SCRS. Among them, 11 cells from the 13 C-toluene microcosms exhibited Raman bands significantly shifting compared to those in the 12 C-toluene microcosms (Figure 3a), explained by 13 C incorporation. All cells from the 12 C-toluene microcosms exhibited three identical Raman bands as biomarkers for unlabeled cells, 49 while active degraders assimilated 13 C in the 13 C-toluene microcosms, showing significant red shifts from 1002 to 966 cm −1 , 1578 to 1537 cm −1 , and 1665 to 1626 cm −1 , consistent with previous studies; 49,57 however, no bacterial cells with 13 C red shifts were observed in the 12 C-toluene treatments.…”

“…To detect the active toluene-assimilating organisms, the relative abundance of each OTU in all the DNA fractions from the 12 C_Toluene and 13 C_Toluene microcosms was calculated, and the top 100 OTUs were selected for further analysis. Based on our previous methods, the toluene-assimilating organisms characterized by OTUs were significantly enriched in the heavy DNA ( 13 C-DNA) fractions from 13 C_toluene microcosms compared to those from 12 C_toluene microcosms. 4,5 2.4.…”

The catabolic pathways of in situ rhizosphere PAH degraders and the main factors driving PAH rhizoremediation in oil‐contaminated soil

“…Phenanthrene (PHE) is a typical model compound used to study PAH biodegradation because of its ubiquitous nature and fused‐ring angular structure (Seo et al ., 2009; Luo et al ., 2021). Here, we selected 13 C‐labelled PHE as a metabolic tracer and first applied SIP‐metagenomics and MENA to compare the influences of different plant rhizospheres (RG, TF, SG) on the structure, diversity and metabolic features of the active PHE‐degrading microbial communities, discuss their correlations with other members, and explore the driving factors of PAH rhizoremediation.…”