Study on the Antibacterial Effect from Moonmilk Pindul Cave, Indonesia

Background and Objective: Antibiotic resistance is the ability of microbes to survive antibiotic exposure with standard doses. Regular updating of antibiotics is one solution to overcome antibiotic resistance. One source with potential new antibiotics is moonmilk from caves because it contains various bacteria proven to have antibacterial activity. The objective of the present study is to explore the potential of moonmilk microbes from Pindul cave, Indonesia, as a source of new antibiotic compounds. Materials and Methods: The antibiotic potency test was divided into six groups with various concentrations of isolated moonmilk bacteria (IMM) supernatant 25%, 50%, 75%, 100%, negative control (-), and positive control (+). All groups were further tested for antibiotic susceptibility using the disk diffusion (Kirby and Bauer) method to pathogenic resistant bacteria Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 on Mueller Hinton agar medium. PCR and Sanger sequencing method using 16S rRNA primers was performed to identify species of isolated moonmilk bacteria. Results: The 16S rRNA sequence analysis showed that the IMM shared a 99,64% (1399 nucleotide match) similarity with Bacillus licheniformis strain IND706. The results showed that moonmilk bacteria had antibacterial activity against E. coli ATCC 25922 and S. aureus ATCC 25923. The highest inhibition zone was observed for the bacterial extract concentration of 75% (42 mm) in E. coli ATCC 25922 and 100% (23 mm) in S. aureus ATCC 25923 medium. Conclusion: IMM supernatant extract from Pindul cave, Indonesia, has the potential to control antibiotic-resistant bacterial pathogens.