Response of Bacteria Isolated from Spent Engine Oil Contaminated Soil to Hydrocarbons, Metals and Antibiotics

Automobile Mechanic Workshops (AMWs) in Low- and Middle-Income Countries (LMIC) contribute to the problem of soil contamination with petroleum hydrocarbons and toxic heavy metals as a result of indiscriminate disposal of spent engine oil (SEO). Such contaminated soil ecosystems can serve as reservoirs of bacteria harboring adaptive tolerance to metals and hydrocarbons as well as resistance to antibiotics. This study investigated the growth response of bacteria isolated from spent engine oil contaminated soils collected from AMWs in South-West, Nigeria to different concentrations of petroleum hydrocarbons, heavy metals (Cu, Zn, Pb and their mixture) and clinically relevant antibiotics. Sixty percent of the bacterial isolates (n = 192) from the hydrocarbon contaminated soil samples possess the unique ability to metabolize various hydrocarbons, tolerate heavy metals and resist at least one of the tested antibiotics. The isolates were identified as members of the Genera <i>Pseudomonas, Bacillus, Enterobacter, Burkholderia, Micrococcus, Staphylococcus, Actinomycetes, Citrobacter</i> and <i>Serratia</i>. Significant correlation (<i>p</i> &lt; .05) was observed between hydrocarbon utilization and antibiotic resistance. Results showed SEO contamination plays a role in the development and spread of antibiotic resistance in the soil ecosystem. Thus, it is necessary to enforce stricter regulations on the disposal of SEO and other petroleum hydrocarbons to limit their human and environment associated hazards.

低收入和中等收入国家（Low- and Middle-Income Countries, LMIC）的汽车维修厂（Automobile Mechanic Workshops, AMWs）因随意处置废机油（spent engine oil, SEO），加剧了石油烃类与有毒重金属引发的土壤污染问题。此类受污染的土壤生态系统，可成为兼具金属与烃类适应性耐受、以及抗生素耐药性的细菌储存库。本研究针对从尼日利亚西南部汽车维修厂周边受废机油污染土壤中分离得到的细菌，探究其在不同浓度石油烃类、重金属（铜（Cu）、锌（Zn）、铅（Pb）及其复合混合物）以及临床相关抗生素环境下的生长响应。本研究共分离得到192株细菌，其中60%的菌株具备代谢多种烃类、耐受重金属并抵抗至少一种受试抗生素的独特能力。经鉴定，这些分离株隶属于假单胞菌属（*Pseudomonas*）、芽孢杆菌属（*Bacillus*）、肠杆菌属（*Enterobacter*）、伯克霍尔德菌属（*Burkholderia*）、微球菌属（*Micrococcus*）、葡萄球菌属（*Staphylococcus*）、放线菌纲（*Actinomycetes*）、柠檬酸杆菌属（*Citrobacter*）以及沙雷菌属（*Serratia*）。研究发现，烃类利用能力与抗生素耐药性之间存在显著相关性（*p* < 0.05）。结果表明，废机油污染在土壤生态系统的抗生素耐药性产生与传播过程中发挥了关键作用。因此，有必要针对废机油及其他石油烃类的处置推行更为严格的监管规范，以限制其对人类健康与生态环境所带来的相关危害。