Isolation and molecular identification of microorganisms withbiotechnological importance from olive oil factory wastes

Microorganisms play a significant role in the biosynthesis of many industrially important products. Today, many products of microbial origin are widely used in various industries. These products, shaped by the metabolic pathways of microorganisms and find a wide range of applications in different biotechnological fields, emphasize the importance of isolating microbes from various ecosystems and determining their potential to produce valuable industrial products. The current study aimed to isolate bacteria and yeasts from the waste of olive oil factories with biotechnological importance. A total of 84 microbial isolates, including 28 bacteria and 56 yeast, were obtained. The biosurfactant production potential of the isolates was determined by a series of screening tests, including the oil spreading test, drop collapse test, parafilm M test, and calculation of emulsification index (E24). The highest clearance zones of 45 and 42 mm in the oil spreading assay were recorded for strain OLV-21 and strain OLV-13, respectively. Moreover, the highest emulsification indexes equal to %48, %50, and %3 were calculated against benzene, toluene, and diesel oil when cell-free supernatant from the strain OLV-65 was applied. Bacteria and yeast isolates giving the best results in screening tests were molecularly characterized by sequence analysis of the 16S rDNA region and the D1/D2 domains of the 26S rDNA region, respectively. Sequencing analysis demonstrated that bacterial isolates belong to Shimwellia (Shimwellia sp. OLV-51, OLV-53, OLV-56, OLV-61, and OLV-63), Pseudocitrobacter (Pseudocitrobacter sp. OLV-65), and Micrococcus (Micrococcus sp. OLV-74) genera, while the yeast strains belong to Pichia (Pichia manshurica OLV-5, Pichia kluyveri OLV-13, OLV-16, OLV-21, OLV-41, and OLV-43), Saccharomyces (S. cerevisiae OLV-17), Nakazawaea (Nakazawaea sp. OLV-20, OLV-22, and OLV-25), and Ogataea (O. polymorpha OLV-64) genera. To our knowledge, this study is the first report demonstrating biosurfactant production by Pichia kluyveri and Ogataea polymorpha. Thanks to the identified strains, new microbial strains with the production potential of industrially important products, such as environmentally friendly biosurfactants, have been introduced in the literature for further investigation.