Isolation and identification of lipase-producing bacteria from effluents contaminated with oily compounds

Introduction: Lipases play a crucial role as biocatalysts, specifically in breaking down lipid ester bonds. Among these biocatalysts, bacterial lipases stand out for their ability to hydrolyze a wide range of substrates, while also being more stable and cost-effective to produce. Unfortunately, the discharge of effluents from oil refineries into surface waters leads to significant environmental pollution. In light of this, the objective of this study is to isolate and identify lipase-producing bacteria from effluents contaminated with oily compounds.Materials and Methods: To identify lipase-producing strains, specific culture media such as tributyrin agar were used, and the secretion of lipase around the bacterial colonies was observed. The isolates were then subjected to biochemical evaluation to determine the strains with the highest enzyme activity. To identify the bacterial strains accurately, PCR was performed targeting conserved ۱۶S rRNA sequences. The PCR products were sequenced and analyzed using the BLAST method for further analysis and identification.Results: To identify lipase-producing strains, different dilutions of contaminated effluent and soil samples were cultured. Four colonies with the widest transparent halo around them were isolated and purified (R۱-R۴). Strain R۲ exhibited the highest lipase activity with a value of ۳.۴۵۲u/ml, whereas strain R۴ displayed the lowest activity at ۱.۹۹۶u/ml. After conducting the molecular evaluation of the isolated strains, it was revealed that strain R۱ belonged to Acinetobacter junii strain B۲, strain R۲ was identified as Rummeliibacillus pycnus strain NBRC ۱۰۱۲۳۱, and strain R۳ was categorized as Pseudomonas aeruginosa strain HX-۲.Discussion and Conclusion: The study identifies a promising local bacterial candidate that holds potential for industrial-scale production of lipase.