Change in Bacterial Diversity After Oil Spill in Argentina

During the past few decades, the impact and threat of oil pollution have resulted in extensive research. The anthropogenic origins of petroleum pollution (particularly via leak of coastal oil refineries) have raised interest among the scientific community in oil pollution distribution and its effects in the environment, mainly the marine environment. Tanker accidents are the major cause of oil pollution in marine environments. On December 26th, 2007, a tanker spilled approximately 100 m3 of crude oil into the sea, which impacted on Caleta Cordova coast, Argentina. Being part of Comodoro Rivadavia city, Caleta Cordova is a small village, where the community‘s local economy is based on artisanal fishing. Over the course of two months, local oil companies collaborated to manually clean the coast and hydrocarbon controls were carried out to monitor the hydrocarbon concentration. The province environmental authorities prohibited the use of chemical products to disperse hydrocarbons and the use of any other chemical product, including nitrogen and phosphorus salts to help biodegradation. On the day of the spill, there was an extraordinary high tide (6.4 m), which resulted in the definition of three areas of impact: the high area, which was the most difficult to clean up; the middle area, which was cleaned up with minimal problem and from where the samples in this study were taken; and the low tide line area. Petroleum hydrocarbon can be degraded by microorganisms such as bacteria, fungi, yeast, and microalgae (e.g.,Atlas, 1981) Bacteria are considered to represent the predominant agents of hydrocarbon degradation in the environment and hydrocarbondegrading bacteria are ubiquitous (Pucci et al 2009a, b). Since crude oil is made of a mixture of compounds, and since individual microorganisms metabolize only a limited range of hydrocarbon substrates (Britton, 1984), biodegradation of crude oil requires a mixture of different bacterial groups or consortia functioning to degrade a wider range of hydrocarbons (Bordenave et al., 2007; Cagnon et al., 2011). Contaminated marine environments are inhabited by a range of selected microorganisms able to tolerate and remediate pollutants that impacted the environment, leading to the dominance of pollutant-tolerant bacteria. Hence, bacterial communities in contaminated sites are typically less diverse than those in nonstressed systems (Harayama et al., 2004). Another characteristic of marine environments is that the vast majority of bacteria (90–99%) are uncultivable (Amann et al., 1995); hence, the analysis of microbial communities that