Bacteria in Crude Oil Survived Autoclaving and Stimulated Differentially by Exogenous Bacteria

Abstract

Autoclaving of crude oil is often used to evaluate the hydrocarbon-degrading abilities of bacteria. This may be potentially useful for bioaugmentation and microbial enhanced oil recovery (MEOR). However, it is not entirely clear if “endogenous” bacteria (e.g., spores) in/on crude oil survive the autoclaving process, or influence subsequent evaluation of the hydrocarbon-degradation abilities of the “exogenous” bacterial strains. To test this, we inoculated autoclaved crude oil medium with six exogenous bacterial strains (three Dietzia strains, two Acinetobacter strains, and one Pseudomonas strain). The survival of the spore-forming Bacillus and Paenibacillus and the non-spore-forming mesophilic Pseudomonas, Dietzia, Alcaligenes, and Microbacterium was detected using a 16S rRNA gene clone library and terminal restriction fragment length polymorphism (T-RFLP) analysis. However, neither bacteria nor bacterial activity was detected in three controls consisting of non-inoculated autoclaved crude oil medium. These results suggest that detection of endogenous bacteria was stimulated by the six inoculated strains. In addition, inoculation with Acinetobacter spp. stimulated detection of Bacillus, while inoculation with Dietzia spp. and Pseudomonas sp. stimulated the detection of more Pseudomonas. In contrast, similar exogenous bacteria stimulated similar endogenous bacteria at the genus level. Based on these results, special emphasis should be applied to evaluate the influence of bacteria capable of surviving autoclaving on the hydrocarbon-degrading abilities of exogenous bacteria, in particular, with regard to bioaugmentation and MEOR. Bioaugmentation and MEOR technologies could then be developed to more accurately direct the growth of specific endogenous bacteria that may then improve the efficiency of treatment or recovery of crude oil.

Paradevosia shaoguanensis gen. nov., sp. nov., Isolated from a Coking Wastewater

“…Although strain J5-3 T could not degrade phenol and pyridine, it might survive by using the metabolites of other microorganisms, potentially contributing indirectly to coking wastewater treatment. However, further research is needed to study whether strain J5-3 T formed a consortium and played a ''team work'' with other microorganisms for coking wastewater treatment [9,21].…”

Microbial and Geochemical Investigation down to 2000 m Deep Triassic Rock (Meuse/Haute Marne, France)

“…was recorded in the deep subsurface, at the interface between basaltic oceanic crust and deep seawater [66]. The taxon belonging to Methylophilus was closely related to sequences found in crude oil [67] and accretion ice samples from the subglacial Vostok Lake [68]. The two last taxa related to the potentially indigenous category were affiliated to Rhodococcus and Anoxybacillus.…”

“…The "indigenous" and "potentially indigenous" 16S rRNA gene sequences belonged to Firmicutes and α-, β-, and γ-Proteobacteria. These phylogenetic groups are ubiquitous in surface environments but sequences that are related to Shewanella, Mezorhizobium, and Curvibacter have also been found in deep marine sediments [66,73,76] and those related to Methylophilus and Rhodococcus were found in oil fields and mines [67,69]. One of the Firmicute-related sequences, (K20.17-3), comes from bacteria that are cultivated from petroleum crude oil and subsurface sediments at the Hanford Site 300 Area [72,87] and seems to be restricted to the subsurface confined biosphere, arguing in favor of its indigenous origin.…”

Glycocaulis alkaliphilus sp. nov., a dimorphic prosthecate bacterium isolated from crude oil

“…In an investigation into a crude oil microbial community (Gong et al , 2012), a novel strain 6B-8 T was isolated from crude oil. It shared high 16S rRNA gene sequence similarity with diverse environmental clones retrieved from deep-sea hydrothermal vents, petroleum-contaminated saline soil, phototrophic biofilms in an athalassohaline epsomite lake, a brackish water system, sediment of the East Pacific Ocean and surface seawater from the South China Sea (Achuthan et al , 2006; Abraham et al , 2013; Lv et al , 2014).…”