Poaceae with PGPR Bacteria and Arbuscular Mycorrhizae Partnerships as a Model System for Plant Microbiome Manipulation for Phytoremediation of Petroleum Hydrocarbons Contaminated Agricultural Soils

Abstract

Total petroleum hydrocarbons (TPHs) are a persistent environmental organic contaminant. The possibility of obtaining synergistic effects between plants and microorganisms has further increased the possibility of alternative techniques for bioremediation. Oloptum miliaceum (L.) Röser & H.R. Hamasha and Pennisetum setaceum (Forssk.) Chiov. are, undoubtedly, good model plants for phytoremediation because they have large roots, leaf biomass, and a fast and effective renewal capacity, also, they have a great capacity to host endophytes in their roots. Gas chromatography-mass spectrometry (GC-MS) based on carbon fraction number was a basic technique used to determine the hydrocarbon degradation, and microorganism’s population was identified by high-throughput sequencing of 16s rRNA. The microbial consortium used allows the plant to increase overall biomass, adapt more in terms of redox biology (Superoxide dismutase SOD, catalase CAT, ascorbate peroxidase APX, guaiacol peroxidase GPX), and stress markers (Glutathione S-transferase GST, Phenylalanine Ammonia Lyase PAL, Proline content, and lipid peroxidation MDA). In addition, the photosynthetic efficiency and the soil dehydrogenase activity were monitored. After 240 days, the percentage of TPHs removed in Group 2 was 94%, whereas in Group 1, it was 78% in Oloptum miliaceum and Pennisetum setaceum. The removal of aliphatic hydrocarbons (C13–C36) was observed in Oloptum miliaceum and Pennisetum setaceum inoculated with the consortium of indigenous bacteria selected from rhizosphere soil and mycorrhizae strains. Our data demonstrate that, the Poaceae, in relation to its great ecological and vegetative potential, could be a great candidate for extensive remediation of soils contaminated by TPHs.

Plant-Soil-Microbiota Combination for the Removal of Total Petroleum Hydrocarbons (TPH): An In-Field Experiment

“…After 270 days, MDA level decreased in leaf samples of all the investigated plant species. These findings are in accordance with other research highlighting that MDA levels in leaves increased with increasing crude oil concentration in soil and decreased with exposure time ( Shukry et al, 2013 ; Guarino et al, 2020 ). The decreasing MDA trend over time may indicate that, under hydrocarbons’ degradation, repairing mechanisms start to keep pace with oxidative damage.…”

“…These results indicate that the uptake of petroleum hydrocarbons in roots is enhanced through a rhizodegradation mechanism. In rhizodegradation, organic pollutants are degraded in soil through the bioactivity of the rhizosphere, which derives from the production and exudation of enzymes and proteins by plants or soil microorganisms such as bacteria or fungi ( Guarino et al, 2020 ). The lower levels of TPH in leaves may be related to the hydrocarbons phytotransformation or phytodegradation occurring within the plant itself.…”

“…Library preparation and sequencing were performed in soil of the contaminated chosen area prior (BPH) and after (APH) the experimental trial and in soil of a neighboring uncontaminated area (CPH) used as control. Analysis were centered on the genes engaged in hydrocarbon degradation research ( Guarino et al, 2020 ).…”

“…The sequencing run was performed on MiSeq (Illumina, San Diego, CA), sequencing 300 cycles per read. Base calling and demultiplexing were performed on integrated analysis software (Guarino et al, 2019(Guarino et al, , 2020. The sequenced genes, obtained from Uniprot, are listed below: Alkane-1 monooxygenase (Uniprot code O05895 and P12691), Cytochrome P450 alkane hydroxylase (Uniprot code A9CMS7 and Q2MHE2), Protocatechuate 3,4-dioxygenase (Uniprot code P20372 and Q8NN15), Catechol 1,2-dioxygenase (Uniprot code P07773 and P95607), Catechol 2,3-dioxygenase (Uniprot code Q53034 and P06622), Gentisate 1,2-dioxygenase (Uniprot code Q0SFK9 and Q13ZY3), Homogentisate 1,2-dioxygenase (Uniprot code Q828S5 and B8H072), and Protocatechuate 4,5-dioxygenase (Uniprot code P20371 and P22635).…”

Biotransformation ability of endophytic fungi: from species evolution to industrial applications

“…Endophytic fungi can produce various phytohormones, such as phytohormone indole-3-acetic acid, gibberellic acid, cytokinin, and phytoalexins, which were successively found from the endophytic fungi Serendipita indica , F. fujikuroi MI58289, and Piriformospora indica DSM11827 (Inaji et al 2020 ; Niehaus et al 2016 ; Li et al 2016b ). This finding indicated that endophytic fungi can participate in host signal regulation and affect host physiological and metabolic activities (Yuan et al 2016 ; Bilal et al 2018 ; Guarino et al 2020 ).…”