Bacterial Diversity and the Geochemical Landscape in the Southwestern Gulf of Mexico

Abstract

Marine sediments are an example of one of the most complex microbial habitats. These bacterial communities play an important role in several biogeochemical cycles in the marine ecosystem. In particular, the Gulf of Mexico has a ubiquitous concentration of hydrocarbons in its sediments, representing a very interesting niche to explore. Additionally, the Mexican government has opened its oil industry, offering several exploration and production blocks in shallow and deep water in the southwestern Gulf of Mexico (swGoM), from which there are no public results of conducted studies. Given the higher risk of large-scale oil spills, the design of contingency plans and mitigation activities before oil exploitation is of growing concern. Therefore, a bacterial taxonomic baseline profile is crucial to understanding the impact of any eventual oil spill. Here, we show a genus level taxonomic profile to elucidate the bacterial baseline, pointing out richness and relative abundance, as well as relationships with 79 abiotic parameters, in an area encompassing ∼150,000 km2, including a region where the exploitation of new oil wells has already been authorized. Our results describe for the first time the bacterial landscape of the swGoM, establishing a bacterial baseline “core” of 450 genera for marine sediments in this region. We can also differentiate bacterial populations from shallow and deep zones of the swGoM based on their community structure. Shallow sediments have been chronically exposed to aromatic hydrocarbons, unlike deep zones. Our results reveal that the bacterial community structure is particularly enriched with hydrocarbon-degrading bacteria in the shallow zone, where a greater aromatic hydrocarbon concentration was determined. Differences in the bacterial communities in the swGoM were also observed through a comprehensive comparative analysis relative to various marine sediment sequencing projects, including sampled sites from the Deep Water Horizon oil spill. This study in the swGoM provides clues to the bacterial population adaptation to the ubiquitous presence of hydrocarbons and reveals organisms such as Thioprofundum bacteria with potential applications in ecological surveillance. This resource will allow us to differentiate between natural conditions and alterations generated by oil extraction activities, which, in turn, enables us to assess the environmental impact of such activities.

Functional and Genomic Characterization of a Pseudomonas aeruginosa Strain Isolated From the Southwestern Gulf of Mexico Reveals an Enhanced Adaptation for Long-Chain Alkane Degradation

“…The Gulf of Mexico has been continuously exposed to hydrocarbons due to the presence of natural oil seeps, and discharges from anthropogenic activities such as extraction and transport of petroleum (MacDonald et al, 2015). Recently, we reported the bacterial diversity from different sediments in the swGoM, and identified several specialized hydrocarbon-degrading genera at a basal level, whose population size could potentially increase during an oil spill (Godoy-Lozano et al, 2018). We thus became interested in the isolation of bacterial consortia and species indigenous to the swGoM, to study their metabolic capabilities in hydrocarbon degradation.…”

“…Several species from the genera Pseudomonas, Alcanivorax, Acinetobacter, Marinobacter, Bacillus, Dietzia, Rhodococcus, among others, have been reported as able to degrade aromatic and/or aliphatic hydrocarbons (Wentzel et al, 2007;Ghosal et al, 2016). Usually, marine environments hold hydrocarbon-degrading bacteria in low abundance (Godoy-Lozano et al, 2018), but oil spills trigger blooms of such populations, exhibiting a bacterial succession according to the type of hydrocarbons present. For instance, in the Deepwater Horizon (DWH) spill that occurred in the northern Gulf of Mexico in 2010, Oceanospirillales and Pseudomonas taxa dominated the microbial community when the concentration of n-alkanes and cycloalkanes was highest at depth (900-1300 m) during the initial phase of the spill.…”

Population structure determined by comparative amplicon gene sequencing in biofilm and planktonic bacterial communities from pesticide-contaminated water

“…The physicochemical data obtained in our study were compared to those of water with different origins and from environments with different characteristics to determine which water the T1 and T2 waters most resemble. Such environments were that of drinking water [39], the interior transition zone of the ocean [41], the Red Sea [42], southwest part of the Gulf of Mexico [43], a hot water spring in Siloam, South Africa [44], an integrated system of anaerobic-aerobic reactors for the treatment of wastewater (WW) in Ethiopia [45] and the Yeongsan River Basin of South Korea [46]. The two tanks do not significantly differ in chlorine level, but these levels are statistically higher than those found for seawater and potable water (Table 2).…”

Bacterial Microbiota From Wild Freshwater Fish Utilized for Subsistence in Western Mexico

“…Our results provide one of the first accounts of the microbiota from free living fishes in Mexico. Some studies have reported on microbiological conditions of the Gulf of Mexico (Godoy-Lozano et al 2018) and of river waters in Mexico (Arellano-Ríos and Rivera-Pahua 2011, Barrera-Escorcia et al 2013), or have analyzed fish destined for consumption in urban markets (Constantino-Casas et al 1997) but no reports exist on the microbiology of fishes utilized in subsistence fisheries, especially related to natural protected areas.…”