Enrichment and isolation of the oil emulsifying microbe in medium with olive oil as sole carbon source. a Cell growth is associated with production of biosurfactant activity. X- and Y-axes indicate time (h) and cell density (g L−1, solid circle) or oil spreading zone (OSZ, cm2 µL−1, open circle). b Microbial populations enriched in cultures with olive oil as sole carbon source. mT-RFLP analysis shows the level changes of three major populations (or fragments), two of which decrease (see arrows) and one increase (see ZS6). c mT-RFLP pattern of individual isolates. A non-specific fragment (see asterisk) is found to be associated with 16 rDNA PCR fragment in ZS6. Biosurfactant activity of individual isolates is shown in the bottom panel. d The phylogenetic tree analysis is based on 16S rDNA sequences whose GenBank accession number (ZS6, MF977715) is shown in parentheses. ZS6 isolate belongs to the member of Serratia spp.