The effect of woodchip bioreactors on microbial concentration in subsurface drainage water and the associated risk of antibiotic resistance dissemination

Feyereisen

et al. 2022

Preprint

Woodchip bioreactors (WBRs) are used to remove nutrients, especially nitrate, from subsurface drainage. The nitrogen removal efficiency of WBRs, however, is limited by low temperature and availability of labile carbon. Bioaugmentation and biostimulation are potential approaches to enhance nitrate removal of WBRs under cold conditions, but their effectiveness is still unclear. Here, we clarified the effects of bioaugmentation and biostimulation on the microbiomes and nitrate removal rates of WBRs. As a bioaugmentation treatment, we inoculated WBR-borne cold-adapted denitrifying bacteria Cellulomonas cellasea strain WB94 and Microvirgula aerodenitrificans strain BE2.4 into the WBRs located at Willmar, MN, USA. As a biostimulation treatment, acetate was added to the WBRs to promote denitrification. Woodchip samples were collected from multiple locations in each WBR before and after the treatments and used for the microbiome analysis. The 16S rRNA gene amplicon sequencing showed that the microbiomes changed by the treatments and season. The high-throughput quantitative PCR for nitrogen cycle genes revealed a higher abundance of denitrification genes at locations closer to the WBR inlet, suggesting that denitrifiers are unevenly present in WBRs. In addition, a positive relationship was identified between the abundance of M. aerodenitrificans strain BE2.4 and those of norB and nosZ in the WBRs. Based on generalized linear modeling, the abundance of norB and nosZ was shown to be useful in predicting the nitrate removal rate of WBRs. Taken together, these results suggest that the bioaugmentation and biostimulation treatments can influence denitrifier populations, thereby influencing the nitrate removal of WBRs.

Section: Discussionmentioning

confidence: 88%

Impacts of Biostimulation and Bioaugmentation on Woodchip Bioreactor Microbiomes

Feyereisen

et al. 2022

Preprint

“…Probe-based qPCR results of inoculants also suggest that the abundance of inoculated strains decreased within 4–6 weeks after the inoculation ( 20 ). Mardani et al ( 32 ) also found that some of the inoculated microbes passed through the bioreactor instead of colonizing on woodchips and establishing robust populations. For the prolonged effect of bioaugmentation, inoculation techniques should be refined, for example, by encapsulating bacteria ( 33 ).…”

Section: Discussionmentioning

confidence: 99%

Impacts of biostimulation and bioaugmentation on woodchip bioreactor microbiomes

Wang,

Feyereisen,

Wang

et al. 2023

Microbiol Spectr

Woodchip bioreactors (WBRs) are used to remove nutrients, especially nitrate, from subsurface drainage. The nitrogen removal efficiency of WBRs, however, is limited by low temperatures and the availability of labile carbon. Bioaugmentation and biostimulation are potential approaches to enhance nitrate removal of WBRs under cold conditions, but their effectiveness is still unclear. Here, we clarified the effects of bioaugmentation and biostimulation on the microbiomes and nitrate removal rates of WBRs. As a bioaugmentation treatment, we inoculated WBR-borne cold-adapted denitrifying bacteria Cellulomonas cellasea strain WB94 and Microvirgula aerodenitrificans strain BE2.4 into the WBRs located at Willmar, MN, USA. As a biostimulation treatment, acetate was added to the WBRs to promote denitrification. Woodchip samples were collected from multiple locations in each WBR before and after the treatments and used for the microbiome analysis. The 16S rRNA gene amplicon sequencing showed that the microbiomes changed by the treatments and season. The high-throughput quantitative PCR for nitrogen cycle genes revealed a higher abundance of denitrification genes at locations closer to the WBR inlet, suggesting that denitrifiers are unevenly present in WBRs. In addition, a positive relationship was identified between the abundance of M. aerodenitrificans strain BE2.4 and those of norB and nosZ in the WBRs. Based on generalized linear modeling, the abundance of norB and nosZ was shown to be useful in predicting the nitrate removal rate of WBRs. Taken together, these results suggest that the bioaugmentation and biostimulation treatments can influence denitrifier populations, thereby influencing the nitrate removal of WBRs. IMPORTANCE Nitrate pollution is a serious problem in agricultural areas in the U.S. Midwest and other parts of the world. Woodchip bioreactor is a promising technology that uses microbial denitrification to remove nitrate from agricultural subsurface drainage, although the reactor’s nitrate removal performance is limited under cold conditions. This study showed that the inoculation of cold-adapted denitrifiers (i.e., bioaugmentation) and the addition of labile carbon (i.e., biostimulation) can influence the microbial populations and enhance the reactor’s performance under cold conditions. This finding will help establish a strategy to mitigate nitrate pollution.

“…Further, other research showed grass or tree‐based strips harbored greater and more diverse microbial biomass and that the addition of large concentrations of antibiotics resulted in short‐term inhibition and stress indicators, but all microbial communities eventually recovered (Unger et al., 2012), suggesting that vegetative strips have mitigation potential. Other best management practices previous explored for potential AMR mitigation include woodchip bioreactors (Mardani et al., 2020) and wetlands (Chen et al., 2016; Sabri et al., 2021), with mixed results.…”

Section: Mitigation Of Amr In Manuresmentioning

confidence: 99%

Antimicrobial resistance in integrated agroecosystems: State of the science and future opportunities

Howe

Soupir

2021

J of Env Quality

As the Journal of Environmental Quality (JEQ) celebrates 50 years of publication, the division of environmental microbiology is one of the newest additions to the journal. During this time, significant advances in understanding of the interconnected microbial community and impact of the microbiome on natural and designed environmental systems have occurred. In this review, we highlight the intractable challenge of antimicrobial resistance (AMR) on humans, animals, and the environment, with particular emphasis on the role of integrated agroecosystems and by highlighting contributions published in JEQ. From early studies of phenotypic resistance of indicator organisms in waters systems to current calls for integrating AMR assessment across “One Health,” publications in JEQ have advanced our understanding of AMR. As we reflect on the state of the science, we emphasize future opportunities. First, integration of phenotypic and molecular tools for assessing environmental spread of AMR and human health risk continues to be an urgent research need for a one health approach to AMR. Second, monitoring AMR levels in manure is recommended to understand inputs and potential spread through agroecosystems. Third, baseline knowledge of AMR levels is important to realize the impact of manure inputs on water quality and public health risk; this can be achieved through background monitoring or identifying the source‐related genes or organisms. And finally, conservation practices designed to meet nutrient reduction goals should be explored for AMR reduction potential.