Rhizodegradation of PAHs differentially altered by C3 and C4 plants

Abstract

Pyrosequencing of 16S ribosomal RNA (rRNA) was employed to characterize bacterial communities colonizing the rhizosphere of plants with C3 and C4 photosynthetic pathways grown in soil contaminated with polycyclic aromatic hydrocarbons (PAHs) after 60 and 120 days. The results of this study exhibited a clear difference in bacterial diversity between the rhizosphere and non-rhizosphere samples and between the rhizospheres of the C3 and C4 plants after 120 days. In both C3 and C4 rhizospheres, an incremental change in PAHs degrading bacterial genera was observed in the 120th day samples compared to the 60th day ones. Among the PAHs degrading bacterial genera, Pseudomonas showed good resistance to PAHs in the 120th day rhizosphere of both C3 and C4 plants. Conversely, the genus Sphingomonas showed sensitivity to PAHs in the 120th day rhizosphere soils of C3 plants only. Also, a significant increase in the PAHs degrading genera was observed at 120th day in the C4 rhizosphere in comparison to the C3 rhizosphere, which was reflected in a reduced PAHs concentration measured in the soil remediated with C4 plants rather than C3 plants. These results suggest that the rhizoremediation of PAHs was primarily governed by the plant photosystems, which led to differences in root secretions that caused the variation in bacterial diversity seen in the rhizospheres. This study is the first report to demonstrate the greater effectiveness of C4 plants in enhancing the PAHs degrading bacterial community than C3 plants.

Soil initial bacterial diversity and nutrient availability determine the rate of xenobiotic biodegradation

“…The potential of the C3 and C4 plant species used in this study for remediation of PAHs-contaminated soils has previously been explored (Sivaram et al, , 2020, and a positive effect of plant addition on PAHs biodegradation was reported. Yet, contrary to our expectation, we observed a very limited effect of plant presence on the rate of pyrene biodegradation in both soils.…”

“…To explore the phytoremediation potential of C3 and C4 grasses and the interactive effect of rhizoremediation on the rate of PAHs biodegradation, we used two Australian widespread native grass species (C3 – Rhytidosperma sp., and C4 – Dichanthium sp.) with known phytoremediation abilities (Sivaram et al ., 2018, 2020; Sivaram et al ., 2018). Plant treatments were established by sowing ~ 12 seeds directly into each pot.…”

Algalization of Acid Soils with Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3 Enriches Bacteria of Ecological Importance

“…The rarefaction curves, acquired through MEGAN (Version 5.10.3), were used to analyze the Biological Observation Matrix (biom) from the data file provided by MG-RAST . PAST 4.03 was used to calculate diversity indices such as Richness and Simpson’s by averaging triplicate values …”

Biochemical and Metabolic Plant Responses toward Polycyclic Aromatic Hydrocarbons and Heavy Metals Present in Atmospheric Pollution

“…The presence of PAHs results in a reduction in total chlorophyll content of both C3 and C4 plants, with an increase of the chlorophyll a/b ratio, which is one of the direct indications that the plants are experiencing extremely harmful conditions [45]. PAHs inhibit RuBisCO carboxylation activity, decreasing photosynthetic rates and inhibiting photosystem II activity, blocking the photosynthetic electron flow from photosystem II to photosystem I (Figure 1).…”