Hydrocarbon degradation potential of salt marsh plant–microorganisms associations

Abstract

Estuaries are often considered sinks for contaminants and the cleanup of salt marshes, sensitive ecosystems with a major ecological role, should be carried out by means of least intrusive approaches, such as bioremediation. This study was designed to evaluate the influence of plant-microorganisms associations on petroleum hydrocarbons fate in salt marshes of a temperate estuary (Lima River, NW Portugal). Sediments un-colonized and colonized (rhizosediments) by different plants (Juncus maritimus, Phragmites australis, Triglochin striata and Spartina patens) were sampled in four sites of the lower and middle estuary for hydrocarbon degrading microorganisms (HD), total cell counts (TCC) and total petroleum hydrocarbons (TPHs) assessment. In general, TPHs, HD and TCC were significantly higher (P < 0.05) in rhizosediments than in un-colonized sediments. Also recorded were differences on the abundance of hydrocarbon degraders among the rhizosediment of the different plants collected at the same site (J. maritimus < P. australis < T. striata), with statistically significant differences (P < 0.05) between J. maritimus and T. striata. Moreover, strong positive correlations-0.81 and 0.84 (P < 0.05), between biotic (HD) and abiotic (organic matter content) parameters and TPHs concentrations were also found. Our data clearly suggest that salt marsh plants can influence the microbial community, by fostering the development of hydrocarbon-degrading microbial populations in its rhizosphere, an effect observed for all plants. This effect, combined with the plant capability to retain hydrocarbons around the roots, points out that salt marsh plant-microorganisms associations may actively contribute to hydrocarbon removal and degradation in estuarine environments.

Halophyte plant colonization as a driver of the composition of bacterial communities in salt marshes chronically exposed to oil hydrocarbons

“…In this study, hydrocarbon concentrations were lower than reported in other salt marshes (Hwang et al, 2006;Watts et al, 2006;Ribeiro et al, 2011). Previous studies have, however, shown that relatively low levels of hydrocarbons in the sediment had an effect on the structural diversity of bacterial communities (Castle et al, 2006;Labb e et al, 2007).…”

Is the increase in oil pollution a possibility of the presence of diverse microorganisms? An experimental dataset on oil prevalent areas of Goa, India

“…Collected samples were refrigerated immediately in ice box after collection until use. Microorganisms isolated in the laboratory using Zobell Marine agar, R2A medium, Mannitol salt agar and Blood agar medium [9], [10], [11], [12].…”

Salt Marsh Plants’ Potential for the Remediation of Hydrocarbon-Contaminated Environments

“…The few studies published (Lin and Mendelssohn 2008 ;2009 ;Ribeiro et al 2011 ) indicated that these plant species can be suitable to remediate hydrocarboncontaminated sediments, and the study reported in the previous section clearly indicated that some have that potentiality, contributing for the recovering of estuarine impacted sites. However, hydrocarbon contamination affects not only estuarine and coastal areas but also terrestrial nonsaline area, as, for example, those where refi nery facilities are implemented.…”

“…On the other hand, root exudates may enhance desorption of contaminants from soil as plants have been shown to secrete enzymes and secondary metabolites that also have a surfactant activity, which may increase available contaminant concentration in soil (Chaudhry et al 2005 ). Moreover, when design cost-saving rhizoremediation strategies, plant capabilities to foster microbial pollutant degraders in their rhizosphere may be a useful tool (Ribeiro et al 2011 ).…”