ANTIBACTERIAL SCREENING OF ATIS (Annona squamosa) SEED DERIVED OINTMENT Researcher t Garcia, Ma. Zillah P. School : Pampanga State Agricultural University Degree : Bachelor of Science in Biology Date Completed 3 April 2019 Adviser : Maydeen D. Guevarra, M.P.S. This study was conducted to screen the antibacterial property of the Atis (Annona squamosa) seed derived ointment. The study was conducted at the Microbiology Laboratory, College of Arts and Sciences, Pampanga State Agricultural University in PAC, Magalang, Pampanga from November to January. The study made use of the resazurin assay to determine the antibacterial property of the Atis seed ethanolic extract alone and the Atis seed derived ointment and used two bacterial strains; Staphylococcus aureus (ATCC 25923) and Escherichia coli. In the antibacterial screening of ethanolic Atis seed extract, results revealed that it has the potential to inhibit the growth of bacteria since in the visual observation and there was no color change from blue to pink. This means that there are no viable bacterial cells present in the wells. Therefore, there is an observed antibacterial activity of the ethanolic extract of Atis seed. The minimum inhibition concentration of the ethanolic Atis zseed extract is 12.5mg/ml. On the other hand, the antibacterial screening of the derived ointment results revealed that it does not have the potential to inhibit the growth of bacteria as the color changed from blue to pink. It means that there was presence of viable active cells. Hence, this indicates that it does not have antibacterial activity against the bacteria.