Changes in bacterial diversity associated with bioremediation of used lubricating oil in tropical soils

Abstract

Used lubricating oil (ULO) is a widespread contaminant, particularly throughout tropical regions, and may be a candidate for bioremediation. However, little is known about the biodegradation potential or basic microbial ecology of ULO-contaminated soils. This study aims to determine the effects of used lubricating oil (ULO) on bacterial community structure and diversity. Using a combination of culture-based (agar plate counts) and molecular techniques (16S rRNA gene sequencing and DGGE), we investigated changes in soil bacterial communities from three different ULO-contaminated soils collected from motorcycle mechanical workshops (soil A, B, and C). We further explored the relationship between bacterial community structure, physiochemical soil parameters, and ULO composition in three ULO-contaminated soils. Results indicated that the three investigated soils had different community structures, which may be a result of the different ULO characteristics and physiochemical soil parameters of each site. Soil C had the highest ULO concentration and also the greatest diversity and richness of bacteria, which may be a result of higher nutrient retention, organic matter and cation exchange capacity (CEC), as well as freshness of oil compared to the other soils. In soils A and B, Proteobacteria (esp. Gammaproteobacteria) dominated the bacterial community, and in soil C, Actinobacteria and Firmicutes dominated. The genus Enterobacter, a member of the class Gammaproteobacteria, is known to include ULO-degraders, and this genus was the only one found in all three soils, suggesting that it could play a key role in the in situ degradation of ULO-contaminated tropical Thai soils. This study provides insights into our understanding of soil microbial richness, diversity, composition and structure in tropical ULO-contaminated soils, and may be useful for the development of strategies to improve bioremediation.

Assessment of Sustainability of Bio Treated Lignocellulose-Based Oleogels

“…We found that addition of lubricants at the assessed concentration did not induce remarkable impact on the soil microbiome: phylogenetic profile of control soil did not dramatically differ from treated soils after the biodegradation process has occurred. Proteobacteria was particularly abundant in the grease-spiked soils compared to the untreated sample, which is consistent with previous studies that have reported Proteobacteria as major phylum in soils added of used oil lubricants or hydrocarbon-containing soils [ 31 ]. In this context, CL soil showed an increased percentage of γ -Proteobacteria , which includes many hydrocarbon-degrading genera as Pseudomonas .…”

Optimization of bioremediation-cocktail for application in the eco-recovery of crude oil polluted soil

“…The presence or absence of nutrients in the process of bioremediation have been associated with the increase of microbial population and moderation of nutrients and other physicochemical parameters of the soil. According to Meeboon et al (2018) finding supporting the presence of nutrients as a key factor that may also affect the microbial population during a treatment process. The application of exogenous nutrients which attached to the soil fraction could serve as limiting nutrients through slow-release ( Khadem & Raiesi, 2017 ).…”

Remediation of Hydrocarbon Polluted Soil Offsets Methanogenic Microbial Communities and Improves Soil Recovery of Crude Oil-Polluted Site

“…Proteobacteria are copiotrophs thus their signi cant increase during remediation is in response to the addition of nutrients to the oilpolluted soil. Also, several species of this phylum are established hydrocarbon degraders [7,45] and may have increased in relative abundance due to more favourable environmental conditions during remediation. Meanwhile, Cyanobacteria are photosynthetic microorganisms that exist in diverse environments and are known to quickly adapt to uctuating environmental nutrient conditions [46,47].…”