Bacterial responses to background organic pollutants in the northeast subarctic Pacific Ocean

Abstract

Thousands of man-made synthetic chemicals are released to oceans and compose the anthropogenic dissolved organic carbon (ADOC). Little is known about the effects of this chronic pollution on marine microbiome activities. In this study, we measured the pollution level at three sites in the Northeast Subarctic Pacific Ocean (NESAP) and investigated how mixtures of three model families of ADOC at different environmentally relevant concentrations affected naturally occurring marine bacterioplankton communities' structure and metabolic functioning. The offshore northernmost site (North) had the lowest concentrations of hydrocarbons, as well as organophosphate ester plasticizers, contrasting with the two other continental shelf sites, the southern coastal site (South) being the most contaminated. At North, ADOC stimulated bacterial growth and promoted an increase in the contribution of some Gammaproteobacteria groups (e.g. Alteromonadales) to the 16 rRNA pool. These groups are described as fast responders after oil spills. In contrast, minor changes in South microbiome activities were observed. Gene expression profiles at Central showed the coexistence of ADOC degradation and stress-response strategies to cope with ADOC toxicities. These results show that marine microbial communities at three distinct domains in NESAP are influenced by background concentrations of ADOC, expanding previous assessments for polar and temperate waters.

Repeated introduction of micropollutants enhances microbial succession despite stable degradation patterns

“…In all treatments, a greater number of sensitive OTUs (41-64), a moderate number of tolerant OTUs (6)(7)(8)(9)(10)(11)(12)(13)(14)(15), and fewer opportunistic OTUs (0-3) were identified across phases 1 (B1−B2), 2 (B3−B4), and 3(B5−B7) (Table 1; Fig. 5).…”

“…Many studies have assessed the eco-toxicity of micropollutants to humans and animals [e.g., [14][15][16][17]. However, little is known about the mechanisms by which micropollutants impact the turnover of aquatic microbial communities [6,18,19], especially those of freshwater bacteria [20,21], and the role of microbes on trace micropollutant degradation.…”

“…Nonetheless, little is known about the mechanisms by which micropollutants impact the turnover of aquatic microbial communities (Cerro-Gálvez et al, 2021;Martinez-Varela et al, 2021;Vila-Costa et al, 2020), especially those of freshwater bacteria (Adyari et al, 2020;Tlili et al, 2020), and the role of microbes on trace micropollutant degradation.…”

“…The micropollutants gradually accumulate at sites of their release and reach concentrations high enough to exert disruptive effects on aquatic organisms such as fish, invertebrates, and microbes [9][10][11][12][13]. Nonetheless, little is known about the mechanisms by which micropollutants impact the turnover of aquatic microbial communities [7,14,15], especially those of freshwater bacteria [16,17], and the role of microbes on trace micropollutant degradation.…”

Polycyclic Aromatic Hydrocarbon Degradation in the Sea-Surface Microlayer at Coastal Antarctica

“…Highly polluted sites, such as oil spill-affected areas from temperate and polar regions, have provided the current knowledge of the biogeochemical and molecular basis for the biodegradation of PAHs ( Lors et al, 2012 ; Dombrowski et al, 2016 ; Ghosal et al, 2016 ; Gupte et al, 2016 ; Joye et al, 2018 ). However, in situ measurements of PAHs degradation rates are comparatively scarce, and only few studies have focused on the microbial responses to airborne PAHs, semivolatile aromatic-like compounds, and other organic pollutants at environmentally relevant concentrations ( Cerro-Gálvez et al, 2019 ; González-Gaya et al, 2019 ; Vila-Costa et al, 2019 ; Martinez-Varela et al, 2021 ).…”