Abstract
Mud volcanoes (MVs) are visible signs of oil and gas reserves present deep beneath land and sea. The Marac MV in Trinidad is the only MV associated with natural hydrocarbon seeps. Petrogenic polyaromatic hydrocarbons (PAHs) in its sediments must undergo biogeochemical cycles of detoxification as they can enter the water table and aquifers threatening ecosystems and biota. Recurrent hydrocarbon seep activity of MVs consolidates the growth of hydrocarbonoclastic fungal communities. Fungi possess advantageous metabolic and ecophysiological features for remediation but are underexplored compared to bacteria. Additionally, indigenous fungi are more efficient at PAH detoxification than commercial/foreign counterparts and remediation strategies remain site-specific. Few studies have focused on hydrocarbonoclastic fungal incidence and potential in MVs, an aspect that has not been explored in Trinidad. This study determined the unique biodiversity of culturable fungi from the Marac MV capable of metabolizing PAHs in vitro and investigated their extracellular peroxidase activity to utilize different substrates ergo their extracellular oxidoreductase activity (> 50% of the strains decolourized of methylene blue dye). Dothideomycetes and Eurotiomycetes (89% combined incidence) were predominantly isolated. ITS rDNA sequence cluster analysis confirmed strain identities. 18 indigenous hydrocarbonoclastic strains not previously reported in the literature and some of which were biosurfactant-producing, were identified. Intra-strain variability was apparent for PAH utilization, oil-tolerance and hydroxylase substrate specificity. Comparatively high levels of extracellular protein were detected for strains that demonstrated low substrate specificity. Halotolerant strains were also recovered which indicated marine-mixed substrata of the MV as a result of deep sea conduits. This work highlighted novel MV fungal strains as potential bioremediators and biocatalysts with a broad industrial applications.
Highlights
Trinidad (10.6918° N, 61.2225° W) lies just 11 km northeast of Venezuela in the South American continent and is the last island in the Lesser Antilles volcanic island arc system of the West I ndies[1]
With soil as a natural sink for petrogenic Polyaromatic hydrocarbons (PAHs), high molecular weight (HMW) PAHs retained in soil particles and are of great interest especially since their migration into the multimedia environment can lead to human exposure
Few studies link PAH fungal consumption with chronically polluted natural hydrocarbon seeps spiked with PAHs such as Mud volcanoes (MVs)
Summary
Trinidad (10.6918° N, 61.2225° W) lies just 11 km northeast of Venezuela in the South American continent and is the last island in the Lesser Antilles volcanic island arc system of the West I ndies[1]. Few studies link PAH fungal consumption with chronically polluted natural hydrocarbon seeps spiked with PAHs such as MVs. Fungi are capable of transforming a wide range of organic pollutants[15,16,17,18,19]. The majority of fungal pollutant-degraders belong to Ascomycota and Basidiomycota phyla primarily, followed by subphylum Mucoromycotina[20]. Such fungi carry out intracellular hydroxylation of PAHs that produce water-soluble products which are excreted[21,22,23]. Other studies have reported the use extracellular or secreted oxidoreductases by specific fungal strains that mineralize very carcinogenic, high-molecular-mass PAHs e.g. b enzo[a]pyrene[22,23]. Marcano et al.[29] explained the ability of Fusarium alkanophilum to extract water from light hydrocarbons which enables this fungal species to thrive in water-deficient hydrocarbon matrices; perhaps debunking the absolute requirement of water for life
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
