Screening and Molecular Identification of Biosurfactant-Producing Bacteria Isolated from Contaminated Soil and Vegetables in Ago-Iwoye, Nigeria

Biosurfactants play a crucial role in bioremediation processes, wherein bacteria producing these surfactants utilize contaminants or pollutants as energy and nutrient sources. This study aims to screen and molecularly identify bacteria recovered from soil contaminated by cassava effluent and various vegetables for biosurfactant production. Standard methods were used for bacterial counting, isolation, and identification. Blood hemolysis and oil spreading tests evaluated biosurfactant production. High producers were characterized by 16S rRNA sequencing. Mean values compared and significance tested using chi-square. The mean bacterial counts were 67.00±2.54 for Ago-Iwoye soil, 86.00±4.35 or Oru soil, 102.00±3.32 for Ago-Iwoye vegetables, and 109.00±4.83 for Oru vegetables. Isolates AS1, AS2, CSA34, CSA36, CSO48, CSO49 showed partial hemolysis (10.00 – 14.00 mm), while others exhibited complete hemolysis (Isolates FP11, LS15, CSO45). Isolate LS30 showed no hemolytic activity. Among the isolates tested, only LS15 and CSO45 exhibited positive oil spreading ability, with diameters of 5.00 ± 2.50 mm and 7.50 ± 3.54 mm, respectively. Staphylococcus aureus and Bacillus spp. proved to be the highest biosurfactant producer by showing better results. The molecular characterization of the identified isolate LS15 revealed a 100% match with Staphylococcus aureus 8 BWI (accession number KX456108.1), while isolate CSA45 was identified as Bacillus marasmi with 96.6% similarity (accession number NR_147397.1). Therefore, sustained attention to Staphylococcus spp. and Bacillus spp. is warranted, given their consistent success in screening tests as proficient biosurfactant producers. Keywords: Biosurfactant, Bacteria, Staphylococcus spp., Bacillus spp., Cassava, Soil