Ecological response of nitrification to oil spills and its impact on the nitrogen cycle

Abstract

Marine oil spills are catastrophic events that cause massive damage to ecosystems at all trophic levels. While most of the research has focused on carbon-degrading microorganisms, the potential impacts of hydrocarbons on microbes responsible for nitrification have received far less attention. Nitrifiers are sensitive to hydrocarbon toxicity: ammonia-oxidizing bacteria and archaea being 100 and 1000 times more sensitive than typical heterotrophs respectively. Field studies have demonstrated the response of nitrifiers to hydrocarbons is highly variable and the loss of nitrification activity in coastal ecosystems can be restored within 1-2 years, which is much shorter than the typical recovery time of whole ecosystems (e.g., up to 20 years). Since the denitrification process is mainly driven by heterotrophs, which are more resistant to hydrocarbon toxicity than nitrifiers, the inhibition of nitrification may slow down the nitrogen turnover and increase ammonia availability, which supports the growth of oil-degrading heterotrophs and possibly various phototrophs. A better understanding of the ecological response of nitrification is paramount in predicting impacts of oil spills on the nitrogen cycle under oil spill conditions, and in improving current bioremediation practices.

The Effects of Crude Oil and Dispersant on the Larval Sponge Holobiont

“…The sensitivity of the R. odorabile thaumarchaeal symbiont is consistent with recent analyses showing that ammonia-oxidizing archaea are ∼1,000 times more sensitive to hydrocarbon contamination than heterotrophic bacteria (96). However, it could also be that this symbiont is particularly sensitive to environmental perturbation as previous research has demonstrated that it is highly sensitive to heavy metal contamination (60).…”

Bacterial Community Legacy Effects Following the Agia Zoni II Oil-Spill, Greece

“…Archaea are not commonly considered as hydrocarbon-degraders, apart from certain Halobacteria ( McGenity, 2010 ; Oren, 2017 ) which typically do not prevail in coastal seawater (exception herein being the genera Haladaptatus and Halogranum ). There is growing evidence that growth of nitrifying-archaea, especially from the genus Nitrosopumilus , is inhibited by crude oil ( Urakawa et al, 2012 , 2019 ), though some studies do not show any significant inhibition by oil on archaeal populations ( Newell et al, 2014 ; Bernhard et al, 2016 ). In this study, while there were some between-site differences in the relative abundance of OTUs assigned to Nitrosopumilus these were not significantly different.…”

“…The EIHE could be improved further by analyzing microbial community composition at a finer detail, perhaps at a species level, though this would require a tool to phylogenetically match OTUs to known oil-degrading species. Additionally, the inclusion of sentinel microbes, those that are adversely affected by oil-contamination (i.e., ammonia-oxidizing archaea; Urakawa et al, 2012 , 2019 ), would also add comprehension to the index. By advancing the knowledge of oil-spill microbial ecology, understanding the genetics and metabolic capabilities of all hydrocarbon-degrading bacteria and their microbial community interactions, and then combining this with hydrocarbon and environmental data, models such as the EIHE can be improved.…”

Draft Genome Sequence ofNitrosomonassp. Strain APG5, a Betaproteobacterial Ammonia-Oxidizing Bacterium Isolated from Beach Sand

“…Together with ammonia-oxidizing archaea, ammonia-oxidizing bacteria (AOB) play important roles in both natural and artificial environments. However, AOB are sensitive to environmental stressors, such as hydrocarbon contamination (1), and serve as valuable ecological indicators (2).…”