Comparison of indigenous and exogenous microbial populations during slurry phase biodegradation of long-term hydrocarbon-contaminated soil

Abstract

In this study, a number of slurry-phase strategies were trialled over a 42 day period in order to determine the efficacy of bioremediation for long-term hydrocarbon-contaminated soil (145 g kg(-1) C(10)-C(40)). The addition of activated sludge and nutrients to slurries (bioaugmentation) resulted in enhanced hydrocarbon removal (51.6 ± 8.5 %) compared to treatments receiving only nutrients (enhanced natural attenuation [ENA]; 41.3 ± 6.4 %) or no amendments (natural attenuation; no significant hydrocarbon removal, P < 0.01). This data suggests that the microbial community in the activated sludge inoculum contributed to the enhanced removal of hydrocarbons in ENA slurries. Microbial diversity in slurries was monitored using DGGE with dominant bands excised and sequenced for identification. Applying the different bioremediation strategies resulted in the formation of four distinct community clusters associated with the activated sludge (inoculum), bioaugmentation strategy at day 0, bioaugmentation strategy at weeks 2-6 and slurries with autoclaved sludge and nutrient additions (bioaugmentation negative control). While hydrocarbon-degrading bacteria genera (e.g. Aquabacterium and Haliscomenobacter) were associated with the hydrocarbon-contaminated soil, bioaugmentation of soil slurries with activated sludge resulted in the introduction of bacteria associated with hydrocarbon degradation (Burkholderiales order and Klebsiella genera) which presumably contributed to the enhanced efficacy for this slurry strategy.

Molecular and Microbiological Insights on the Enrichment Procedures for the Isolation of Petroleum Degrading Bacteria and Fungi

“…These strains are usually obtained through enrichment procedures, aimed at isolating autochthonous microorganisms capable of using the pollutants as sole carbon sources ( Thompson et al, 2005 ). Although many data are available in literature about the assessment of microbial community dynamics following the addition of enriched microbial strains ( MacNaughton et al, 1999 ; Aburto-Medina et al, 2012 ; Fuentes et al, 2014 ), little is known on the developments that occur within the bacterial and fungal communities during the enrichment steps. Furthermore, to the best of our knowledge, no attempt was made to assess how soil samples with a high petroleum hydrocarbons content and collected at different depths affect the organization of the bacterial and fungal communities.…”

Effect of addition of HPBCD on diuron adsorption–desorption, transport and mineralization in soils with different properties

“…Figure 2 shows the kinetics of diuron mineralised by the soil endogenous flora after application of nutrients solution (SNs) and HPBCD x10 in 4 selected soils (Soil 4, 5, 6 and 7). The ability to remediate a contaminated soil from highly persistent herbicides depends mainly on the presence of microorganisms that have the capacity to biodegrade them (Caracciolo et al, 2013), but in most cases they require a small activation (bioestimulation) to achieve an accelerated mineralisation of the pollutant (Alexander, 1999;Aburto-Medina et al, 2012).…”

Petroleum: From Basic Features to Hydrocarbons Bioremediation in Oceans

“…Of the prevalent remediation technologies, none provide such a high efficiency of contaminant removal. However, the effectiveness of pollutant removal from contaminated environments can be enhanced when the remediation methods are used together [88] [89].…”