Microbial community composition at an ethane pyrolysis plant site at different hydrocarbon inputs

Abstract

Aerobic biodegradation of C5+, a contaminant at ethane pyrolysis plants, consisting mainly of benzene, toluene, xylene, styrene, dicyclopentadiene (DCPD) and naphthalene, removes all components except the recalcitrant DCPD. The number (N) of total culturable heterotrophs in contaminated and uncontaminated soil cultures increased up to three orders of magnitude upon incubation with C5+, or with C5+ components other than DCPD. Exposure of soil cultures to C5+ for 2-4 weeks and to DCPD for a further 43-52 weeks caused N to increase 3, then decrease two orders of magnitude. Early microbial communities (up to 13 weeks) were dominated by Pseudomonas spp. and late communities (40-60 weeks) by Alcaligenes spp., especially in contaminated soil cultures. The hydrocarbon used (C5+ or one of its components) was a less important determinant of community composition than incubation time. Rates of aerobic degradation of benzene, toluene and styrene by the soil cultures were greater for the pure components than for the components in the C5+ mixture. The difference was less pronounced for m-xylene. The exception, naphthalene, was degraded more slowly when in pure form. However, the combined rate of all C5+ components in the mixture was similar to the highest rates observed for pure components. We conclude that soil communities efficiently metabolize a C5+ mixture or its pure components and that the community composition is hardly affected by different hydrocarbon inputs. Consequently, determination of the community composition does not provide a good indicator of the hydrocarbons being metabolized.

New benzo(a)pyrene-degrading strains of the Burkholderia cepacia complex prospected from activated sludge in a petrochemical wastewater treatment plant

“…Activated Sludge is a powerful tool for the treatment of sewage from different matrices. The complex community of microorganisms that make up activated sludge is associated to and varies according to the type of wastewater that is treated (Greene et al 2002;Shchegolkova et al 2016;Winkler et al 2013;Ye and Zhang 2013;Yi et al 2012). However, while it is known that understanding microbial communities is essential to managing biotechnology and obtaining better microbial services, there is still a long way to go before we can fully understand these communities and their interactions and apply the activated sludge technique to its full potential (Rittmann 2006).…”

“…Since these microorganisms are adapted to environments that are contaminated with toxic and/or stable compounds, they end up having the capacity to degrade specific pollutants with a higher success rate (Ławniczak et al 2020;Cerqueira et al 2012;Ma et al 2009;Moreno-Forero et al 2016;Rodrigues et al 2015). Through classic taxonomy methods and metagenomic techniques, we can better understand the structure of microbial communities in these sites, as well as monitor the impacts generated by the management of bioremediation processes, which over time can reveal a whole new set of microorganisms that are often neglected because they are considered unculturable (Roy et al, 2018;Woźniak-Karczewska et al, 2019;Greene et al 2002;Ju et al 2014;Winkler et al 2013;Ye and Zhang 2013). The combination of next-generation sequencing techniques with advances in knowledge of culture-enrichment methods, using certain nutrients and sufficient time for growth (Pham and Kim 2012;Stewart 2012;Vartoukian et al 2010), allows us to recover "non-culturable" degrading microorganisms, such as PCB-or PAH-degrading bacteria (Cerqueira et al 2011(Cerqueira et al , 2012Leigh et al 2006).…”