Large Enrichment of Anthropogenic Organic Matter Degrading Bacteria in the Sea-Surface Microlayer at Coastal Livingston Island (Antarctica)

Abstract

The composition of bacteria inhabiting the sea-surface microlayer (SML) is poorly characterized globally and yet undescribed for the Southern Ocean, despite their relevance for the biogeochemistry of the surface ocean. We report the abundances and diversity of bacteria inhabiting the SML and the subsurface waters (SSL) determined from a unique sample set from a polar coastal ecosystem (Livingston Island, Antarctica). From early to late austral summer (January-March 2018), we consistently found a higher abundance of bacteria in the SML than in the SSL. The SML was enriched in some Gammaproteobacteria genus such as Pseudoalteromonas, Pseudomonas, and Colwellia, known to degrade a wide range of semivolatile, hydrophobic, and surfactant-like organic pollutants. Hydrocarbons and other synthetic chemicals including surfactants, such as perfluoroalkyl substances (PFAS), reach remote marine environments by atmospheric transport and deposition and by oceanic currents, and are known to accumulate in the SML. Relative abundances of specific SMLenriched bacterial groups were significantly correlated to concentrations of PFASs, taken as a proxy of hydrophobic anthropogenic pollutants present in the SML and its stability. Our observations provide evidence for an important pollutant-bacteria interaction in the marine SML. Given that pollutant emissions have increased during the Anthropocene, our results point to the need to assess chemical pollution as a factor modulating marine microbiomes in the contemporaneous and future oceans.

Enhanced Viral Activity in the Surface Microlayer of the Arctic and Antarctic Oceans

“…On the one hand, it is exposed to more intense solar radiation, higher variations of temperature, salinity gradients, toxic organic substances, and heavy metals than in the subsurface waters (SSW) [3][4][5]. On the other hand, the SML could be enriched with natural and anthropogenic organic material, which favor the development of SML-bound Microorganisms 2021, 9, 317 2 of 22 microbial communities [3,6,7]. Marine viruses, prokaryotes, and other microorganisms (i.e., phytoplankton, small picoeukaryotes) present in the SML originate in underlying surface waters and can achieve very high abundances in the SML ( [8] and references therein).…”

Sampling Constraints and Variability in the Analysis of Bacterial Community Structures in the Sea Surface Microlayer

“…Gammaproteobacteria are often associated with phytoplankton blooming, can respond quickly to nutrient pulses (Tada et al, 2011;Buchan et al, 2014) and have high resistance toward solar radiation (Agogué et al, 2005b). Other studies on the SML have also reported the presence of Pseudomonas in bacterioneustons in marine (Agogué et al, 2005a;Martinez-Varela et al, 2020) and lake (Hugoni et al, 2017) environments. Pseudomonas spp.…”

“…Sphingomonadales is associated with the enrichment of anthropogenic dissolved organic carbon in the SML (Martinez-Varela et al, 2020), and Sphingomonas sp. isolated from the SML show resistance to solar radiation (Santos et al, 2012).…”

Diesel in Antarctica and a Bibliometric Study on Its Indigenous Microorganisms as Remediation Agent

“…Thus, response to accidental oil spill tends to delay or is absent. In this context, the catabolic capacities of Antarctic indigenous microorganisms hold a great potential in removing contaminants while leaving minimal or no side effects [ 12 ]. Antarctic hydrocarbon-degrading microorganisms have optimum enzymatic activity in low temperature and could excellently adapt to the polar temperature [ 64 ].…”

“…Nonetheless, fuel management and contaminants regulation are solely dependent on self-regulation by national operators and their interpretation of the protocol [ 11 ]. Moreover, the availability of machinery and facilities are limited, and constructions of such are also restrained by virtue of the frigid temperature; therefore, the catabolic capacities of indigenous microorganisms capable of degrading hydrocarbons has emerged as one of the most important tools to eliminate or reduce diesel contamination in Antarctica [ 6 , 12 , 13 ]. This paper was aimed at reviewing diesel uses in Antarctica, hydrocarbon pollution, its toxicity as well as the roles and adaptation of microbes in the polar climate for remediating diesel along with its bibliometric analysis.…”