Exploring microbial lipases: Screening and identification for biocatalyst potential in bioethanol synthesis from glycerol-based biodiesel waste

Lipases are hydrolytic enzymes that break triglycerides into free fatty acids and glycerol. Typically, these enzymes are produced by microorganisms and used as industrial biocatalysts. Microorganisms isolated from oilbased environmental samples were screened for their lipase-producing ability, collecting twenty bacteria and eighteen fungal strains. Through selective media and morphological identification, various microorganisms were identified, including Pseudomonas sp. (12 strains), Escherichia coli (4 strains), Serratia (2 strains), carotenoidproducing bacteria (1 strain), an unknown isolate bacterium, Aspergillus sp. (6 strains), Aspergillus niger (1 strain), Aspergillus flavus (1 strain), Penicillium sp. (3 strains), Saccharomyces sp. (2 strains), Filamentous Black Fungus (2 strains), Omphalina sp. (1 strain), Rhizopus sp. (1 strain), and Trichoderma sp. (1 strain). Based on lipolytic index results, six bacteria exhibited high lipolytic indices, with Pseudomonas sp. having the highest index. After multi-screening, three lipolytic bacteria belonging to the genera Pseudomonas sp., Serratia sp., and Escherichia coli, as well as three lipolytic fungi belonging to the genera Saccharomyces sp., Trichoderma sp., and Aspergillus flavus, respectively, demonstrated the highest lipolytic activity when screened on a lipase assay, reaching 6.3 and 5.01 mU/g at 72 h of incubation. Consequently, these selected microorganisms were chosen for further study on bioethanol synthesis from glycerol. The study has revealed that the isolated bacteria and fungi strains have the potential to be efficient lipase producers.