Investigating the Potential of Native Soil Bacteria for Diesel Biodegradation

In countries with a long petroleum extraction and processing history, such as Romania, extensive soil areas are often polluted with petroleum and its derivatives, posing significant environmental and human health risks. This study explores the diesel biodegradation potential of two native bacterial consortia isolated from hydrocarbon-polluted soils, focusing on their phenotypic and molecular characteristics, growth kinetics, alkane hydroxylase activity, hydrolase production, and biosurfactant synthesis capabilities. The bacterial consortia, CoP1 and CoP2, were successfully obtained using the standard successive enrichment culture method from two soil samples collected from a region affected by petroleum pollution. The CoP1 and CoP2 consortia demonstrated efficient diesel-degrading capabilities, achieving 50.81-84.32% degradation when cultured in a minimal medium containing 1-10% (<i>v</i>/<i>v</i>) diesel as the sole carbon and energy source. This biodegradation potential was corroborated by their significant alkane hydroxylase activity and the detection of multiple catabolic genes in their genomes. The CoP1 consortium contains at least four catabolic genes (<i>alkB</i>, <i>alkM</i>, <i>todM</i>, <i>ndoM</i>) as well as rhamnosyltransferase 1 genes (<i>rhlAB</i>), while the CoP2 consortium contains only two catabolic genes (<i>ndoM</i>, <i>C23DO</i>). The RND transporter gene (<i>HAE1</i>) was present in both consortia. Secondary metabolites, such as glycolipid-type biosurfactants, as well as extracellular hydrolases (protease, amylase, cellulase, and lipase), were produced by both consortia. The CoP1 and CoP2 consortia demonstrate exceptional efficiency in diesel degradation and biosurfactant production, making them well suited for the bioremediation of soils contaminated with petroleum and its derivatives.