Allochthonous bioaugmentation in ex situ treatment of crude oil-polluted sediments in the presence of an effective degrading indigenous microbiome

Abstract

28"Oil-polluted sediment bioremediation depends on both physicochemical and 29" biological parameters, but the effect of the latter cannot be evaluated without the optimization 30" of the former. We aimed in optimizing the physicochemical parameters related to 31" biodegradation by applying an ex-situ landfarming set-up combined with biostimulation to 32" oil-polluted sediment, in order to determine the added effect of bioaugmentation by four 33" allochthonous oil-degrading bacterial consortia in relation to the degradation efficiency of the 34" indigenous community. We monitored hydrocarbon degradation, sediment ecotoxicity and 35"hydrolytic activity, bacterial population sizes and bacterial community dynamics, 36"characterizing the dominant taxa through time and at each treatment. We observed no 37" significant differences in total degradation, but increased ecotoxicity between the different 38" treatments receiving both biostimulation and bioaugmentation and the biostimulated-only 39" control. Moreover, the added allochthonous bacteria quickly perished and were rarely 40" detected, their addition inducing minimal shifts in community structure although it altered the 41" distribution of the residual hydrocarbons in two treatments. Therefore, we concluded that 42" biodegradation was mostly performed by the autochthonous populations while 43" bioaugmentation, in contrast to biostimulation, did not enhance the remediation process. Our 44" results indicate that when environmental conditions are optimized, the indigenous 45" microbiome at a polluted site will likely outperform any allochthonous consortium. 46"47"

Salicornia strobilacea (Synonym of Halocnemum strobilaceum) Grown under Different Tidal Regimes Selects Rhizosphere Bacteria Capable of Promoting Plant Growth

“…DNA was quantified using NanoDrop 1000 spectrophotometer (Thermo Scientific, Waltham, MA, USA). The ARISA fingerprinting was obtained using the primer set ITSF, 5′-GTCGTAACAAGGTAGGCCGTA-3′ and ITSReub, 5′-GCCAAGGCATCCACC-3′, as described elsewhere (Cardinale et al, 2004; Fodelianakis et al, 2015). The output peak matrix was transferred to Microsoft Excel for the following analysis.…”

Microbial Bioremediation of Petroleum Hydrocarbon– Contaminated Marine Environments

“…When they are added into contaminated sites, they cannot easily integrate and adapt to the activities of the indigenous microbial community. Fodelianakis et al [38] confirmed that bioaugmentation with allochthonous hydrocarbon-degrading bacterial consortia did not enhance the remediation process of hydrocarbon-contaminated sediments. Thus, the application of autochthonous microorganism is more effective [35].…”

“…The ABA approach consists on the addition of autochthonous microbial isolates or consortia that are adapted to the contaminated environments [37]. Different studies confirmed the efficiency of autochthonous microorganisms in the decontamination of hydrocarbon-polluted sites based on the fact that environmental conditions are suitable for their growth and metabolism [36,38]. They significantly contribute to the biochemical activities in soil.…”

“…It has been successfully practiced for the remediation of hydrocarbon-contaminated soils [46]. The effectiveness of bioaugmentation in the bioremediation of oil-contaminated sediments, from the Mediterranean Sea, treated ex situ by landfarming was reported [38].…”

“…Numerous and different studies can be carried out, for example, as application of bioremediation processes in the Mediterranean Sea, however, is particularly interesting is the example that can be extracted from the work of Cappello et al [91], Genovese et al [65] and Fodelianakis et al [38].…”