Biochemical and molecular identification of newly isolated pigmented bacterium and improved production of biosurfactant

A novel bacterium pigmented isolate from Caatinga soil was characterized by biochemical and molecular assays, as well as, by rep-polymerase chain reaction (PCR) and 16S rDNA sequencing, and was identified as Serratia marcescens based on 99% of similarity. The identity of the sequences were compared by pairs of critical species of S. marcescens found in National Center for Biotechnology Information (NCBI) with a 96% homology of the isolated species to species database. The wild strain was able to produce biosurfactant (BS) using cassava (Manihot esculenta Crantz) wastewater, with addition of lactose, and corn oil, according to full factorial design 23, at 28°C, and static condition. The net liquid metabolic reduced the surface tension of the water from 70 to 30.60 mN/m during the stationary phase (assay eight constituted by 6.0% cassava wastewater, 1.0% lactose and 7.5% corn oil), and produced emulsifier agent (4.012 UEA) at the same condition. This study identified the pigmented bacterium as new strain of S. marcescens, and showed it has potential to promote both emulsions formation and surface tension reduction in cassava wastewater (6.0%), lactose (1.0%) and corn oil (7.5%) proved as an alternative economical medium for commercial biosurfactant processes.