A New Ciboria sp. for Soil Mycoremediation and the Bacterial Contribution to the Depletion of Total Petroleum Hydrocarbons

Abstract

A Ciboria sp. strain (Phylum Ascomycota) was isolated from hydrocarbon-polluted soil of an abandoned oil refinery in Italy. The strain was able to utilize diesel oil as a sole carbon source for growth. Laboratory-scale experiments were designed to evaluate the use of this fungal strain for treatment of the polluted soil. The concentration of total petroleum hydrocarbons (TPH) in the soil was 8,538 mg/kg. Mesocosms containing the contaminated soil were inoculated with the fungal strain at 1 or 7%, on a fresh weight base ratio. After 90 days of incubation, the depletion of TPH contamination was of 78% with the 1% inoculant, and 99% with the 7% inoculant. 16S rDNA and ITS metabarcoding of the bacterial and fungal communities was performed in order to evaluate the potential synergism between fungi and bacteria in the bioremediation process. The functional metagenomic prediction indicated Arthrobacter, Dietzia, Brachybacerium, Brevibacterium, Gordonia, Leucobacter, Lysobacter, and Agrobacterium spp. as generalist saprophytes, essential for the onset of hydrocarbonoclastic specialist bacterial species, identified as Streptomyces, Nocardoides, Pseudonocardia, Solirubrobacter, Parvibaculum, Rhodanobacter, Luteiomonas, Planomicrobium, and Bacillus spp., involved in the TPH depletion. The fungal metabolism accelerated the onset of specialist over generalist bacteria. The capacity of the Ciboria sp. to deplete TPH in the soil in treatment was also ascertained.

Diversity and Potential Function of the Bacterial Rhizobiome Associated to Physalis Ixocarpa Broth. in a Milpa System, in Michoacan, Mexico

“…Using the same methods (iVikodak) to evaluate the potential function of diverse environments contaminated with uranium, petroleum hydrocarbons, or Polystyrene, the principal functions are more related to the degradation of xenobiotics [22,30,31]. For example, in the case of uranium deposits in Russia, the main functions were: pathways of carbohydrate, nitrogen, and sulfur metabolism, degradation of xenobiotics, benzoate, polycyclic aromatic hydrocarbons, and chlorinated organic compounds [22].…”

“…For example, in the case of uranium deposits in Russia, the main functions were: pathways of carbohydrate, nitrogen, and sulfur metabolism, degradation of xenobiotics, benzoate, polycyclic aromatic hydrocarbons, and chlorinated organic compounds [22]. On the other hand, when the cause of contamination of soil was the petroleum hydrocarbons, the bacterial communities had a higher abundance of xenobiotic biodegradation, in specific: xylene, benzoate, toluene, halogenated compounds, fluorobenzoate, chloroalkane, chlorocyclohexane, and chlorobenzene [30].…”

Main Factors Determining the Scale-Up Effectiveness of Mycoremediation for the Decontamination of Aliphatic Hydrocarbons in Soil

“…They have a stable growth rate and spend more energy on ectoenzyme production and defending against severe environments, which enables them to degrade more complex and toxic organic compounds [182] including through co-metabolism reactions. By contrast, specialist bacterial species are expected to be responsible for the transformation of contaminants in polluted environments, since they can utilize them as a carbon source [183].…”

“…Given the fact that soil is not their ecological niche, WRF were inoculated and persistent during the entire bioremediation experiment for 200 days, while, in other cases, the addition of WRF and substrate did not make any significant difference in biodegradation efficiency compared to the addition of the sole substrate [183]. Equally, in some other cases, the inoculated strain might be active in the first phase and decrease during the process.…”

“…Becarelli [183] studied the succession of bacteria and fungi in a microcosm experiment where biostimulation and bioaugmentation approaches were applied to treat a PH-polluted soil for 90 days. The bioaugmentation approach was applied with two different inoculation ratios (7% and 1%) of a Ciboria sp.…”