Syntrophic Hydrocarbon Degradation in a Decommissioned Off-Shore Subsea Oil Storage Structure

Paddy cultivation in degraded karst wetland soil can significantly improve the physiological and ecological functions of carbon-fixing resident microorganisms

Microorganisms play an important role in carbon fixation in karst wetland soils. However, the carbon fixation capacity of karst wetland soils and active microorganisms involved in the carbon fixation process are poorly understood. In this study, carbon fixation capacity and active microorganisms involved in the fixation of inorganic carbon into organic carbon were studied in native, naturally degraded, and reclaimed karst wetland soils by the combination of stable isotope probing (SIP) and high-throughput sequencing. Under light conditions, the soil carbon fixation capacity ranked: the reclaimed wetland soil (1.58 mg C kg-1 day-1) > native wetland soil (1.43 mg C kg-1 day-1) > degraded wetland soil (0.62 mg C kg-1 day-1). In the dark, the soils ranked: the native wetland soil (0.24 mg C kg-1 day-1) > reclaimed wetland soil (0.18 mg C kg-1 day-1) > degraded wetland soil (0.06 mg C kg-1 day-1). Active microorganisms fixing inorganic carbon in the karst wetland soils were mainly Sulfurovum, Thermovirga, Dethiosulfatibacter, Allochromatium, Methylorubrum, and Bradyrhizobium. Thus, paddy cultivation can restore the carbon fixation capacity of microorganisms in the degraded karst wetland soil. This study provides an experimental basis for improving soil carbon fixation capacity and repairing degraded soil in karst wetlands.

Site-specific response of sediment microbial community to supplementation of polyhydroxyalkanoates as biostimulants for PCB reductive dechlorination

The use of biodegradable plastics is constantly raising, increasing the likeliness for these polymers to end up in the environment. Environmental applications foreseeing the intentional release of biodegradable plastics have been also recently proposed, e.g., for polyhydroxyalkanoates (PHAs) acting as slow hydrogen releasing compounds to stimulate microbial reductive dehalogenation processes. However, the effects of their release into the environment on the ecosystems still need to be thoroughly explored. In this work, the use of PHAs to enhance the microbial reductive dechlorination of polychlorobiphenyls (PCBs) and their impact on the metabolic and compositional features of the resident microbial community have been investigated in laboratory microcosms of a polluted marine sediment from Mar Piccolo (Taranto, Italy), and compared with recent findings on a different contaminated marine sediment from Pialassa della Baiona (Ravenna, Italy). A decreased biostimulation efficiency of PHAs on PCBs reductive dechlorination was observed in the sediment from Mar Piccolo, with respect to the sediment from Pialassa della Baiona, suggesting that the sediments' physical-chemical characteristics and/or the biodiversity and composition of its microbial community might play a key role in determining the outcome of this biostimulation strategy. Regardless of the sediment origin, PHAs were found to have a specific and pervasive effect on the sediment microbial community, reducing its biodiversity, defining a newly arranged microbial core of primary degraders and consequently affecting, in a site-specific way, the abundance of subdominant bacteria, possibly cross-feeders. Such potential to dramatically change the structure of autochthonous microbial communities should be carefully considered, since it might have secondary effects, e.g., on the natural biogeochemical cycles.

New insights into the bioremediation of petroleum contaminants: A systematic review

Petroleum product is an essential resource for energy, that has been exploited by wide range of industries and regular life. A carbonaceous contamination of marine and terrestrial environments caused by errant runoffs of consequential petroleum-derived contaminants. Additionally, petroleum hydrocarbons can have adverse effects on human health and global ecosystems and also have negative demographic consequences in petroleum industries. Key contaminants of petroleum products, primarily includes aliphatic hydrocarbons, benzene, toluene, ethylbenzene, and xylene (BTEX), polycyclic aromatic hydrocarbons (PAHs), resins, and asphaltenes. On environmental interaction, these pollutants result in ecotoxicity as well as human toxicity. Oxidative stress, mitochondrial damage, DNA mutations, and protein dysfunction are a few key causative mechanisms behind the toxic impacts. Henceforth, it becomes very evident to have certain remedial strategies which could help on eliminating these xenobiotics from the environment. This brings the efficacious application of bioremediation to remove or degrade pollutants from the ecosystems. In the recent scenario, extensive research and experimentation have been implemented towards bio-benign remediation of these petroleum-based pollutants, aiming to reduce the load of these toxic molecules in the environment. This review gives a detailed overview of petroleum pollutants, and their toxicity. Methods used for degrading them in the environment using microbes, periphytes, phyto-microbial interactions, genetically modified organisms, and nano-microbial remediation. All of these methods could have a significant impact on environmental management.

Oil Biodegradation and Bioremediation in Cold Marine Environment

Petroleum hydrocarbons pose a substantial threat to marine ecosystems [...].

The impact of bacterial diversity on resistance to biocides in oilfields

Extreme conditions and the availability of determinate substrates in oil fields promote the growth of a specific microbiome. Sulfate-reducing bacteria (SRB) and acid-producing bacteria (APB) are usually found in these places and can harm important processes due to increases in corrosion rates, biofouling and reservoir biosouring. Biocides such as glutaraldehyde, dibromo-nitrilopropionamide (DBNPA), tetrakis (hydroxymethyl) phosphonium sulfate (THPS) and alkyl dimethyl benzyl ammonium chloride (ADBAC) are commonly used in oil fields to mitigate uncontrolled microbial growth. The aim of this work was to evaluate the differences among microbiome compositions and their resistance to standard biocides in four different Brazilian produced water samples, two from a Southeast Brazil offshore oil field and two from different Northeast Brazil onshore oil fields. Microbiome evaluations were carried out through 16S rRNA amplicon sequencing. To evaluate the biocidal resistance, the Minimum Inhibitory Concentration (MIC) of the standard biocides were analyzed using enriched consortia of SRB and APB from the produced water samples. The data showed important differences in terms of taxonomy but similar functional characterization, indicating the high diversity of the microbiomes. The APB and SRB consortia demonstrated varying resistance levels against the biocides. These results will help to customize biocidal treatments in oil fields.