Date Published: May 28, 2018
Publisher: Springer Berlin Heidelberg
Author(s): Jibei Liang, Tao Cheng, Yi Huang, Jianhua Liu.
Enhanced bioremediation is a favorable approach for petroleum pollutant cleanup, which depends on the growth of oil-eating microorganisms. In this study, we show that, by using the modified T-RFLP (mT-RFLP) methodology, one of the four major microbial populations derived from oil sludge has failed to propagate in MS medium supplemented with 2% yeast extract (YE). rDNA sequence-based analysis indicated that the four populations were Donghicola sp. CT5, Bacillus sp. CT6, Alcaligenes sp. CT10, and Pseudomonas sp. ZS1. Four purified strains grow well individually in MS medium supplemented with 2% YE, suggesting that ZS1 growth is antagonized by other strains. Co-growth analysis using mT-RFLP methodology and plate inhibitory assay indicated that ZS1 exhibited antagonistic effect against CT5 and CT6. On the other hand, co-growth analysis and plate inhibition assay showed that CT10 antagonized against ZS1. To investigate the potential compounds responsible for the antagonism, supernatant of CT10 culture was subjected to GC–MS analysis. Analysis indicated that CT10 produced a number of antimicrobial compounds including cyclodipeptide c-(L-Pro-L-Phe), which was known to inhibit the growth of Pseudomonas sp. Growth test using the purified c-(L-Pro-L-Phe) from CT10 confirmed its inhibitory activity. We further showed that, using both gravimetric and GC analysis, CT10 antagonism against the oil-eating ZS1 led to the diminishing of crude oil degradation. Together, our results indicate that bioremediation can be affected by environmental antagonists.
Petroleum leakage is a major threat to land and marine environment (Holliger et al. 1997). Physical methods involving removal of solid and liquid pollutants are tedious and expensive; and chemical methods using chemically synthesized surfactants can cause secondary pollution (Kanaly and Harayama 2010; Murphy et al. 2005). Enhanced bioremediation method using indigenous oil-eating microorganisms and biosurfactants is believed to be a favorable method for oil spill cleanup (Patowary et al. 2016; El-Bestawy et al. 2014; Karamalidis et al. 2010; Al-Mailem et al. 2017; Varjani and Upasani 2016).
Enhanced bioremediation is believed to be a useful method for oil pollutant cleanup (Patowary et al. 2016; El-Bestawy et al. 2014). However, there are limitations (Díaz-Ramírez et al. 2003; Venosa and Zhu 2003). Physical and chemical conditions are known to affect the growth of the oil-eating microorganisms at pollutant sites. In this study, we show that biotic factors such as antagonistic species can also influence the growth of the oil-eating microorganisms (see Figs. 4, 5). Hence, oil degradation during enhanced bioremediation can be complicated by not only physical and chemical factors, but also biological factors.