Screening for Antibiotics Produced by Actinomycetes Isolated from Wells Gray Cave Soil Samples

1. Figure 2. ntibiotic Productin in EB17CM4 Screening for Antibiotics Produced by Actinomycetes Isolated from Wells Gray Cave Soil Samples By Stephanie Richards Supervisor: Dr. Naowarat Cheeptham Co-supervisor: Caroline Fardy Abstract The need for new antibiotics has become increasing apparent in the last 10 years with the rise of antibiotic resistant bacteria. In this study, actinomycetes isolated from Wells Gray cave soil samples were screened for antibiotic activity against Escheriachia coli, Staphylococcus aureus, Salmonella enteriditis, and Candida albicans. Out of 36 isolates screened, one strain showed activity against S. aureus and another showed activity against S. enteritidis. • Results • Out of 43 strains isolated, 36 were screened for activity, the strains EB17CM4 and SR2-5AM5 showed positive activities. • EB17CM4 was active against S.enteritid and antibiotic production peaks on day 4 at pH 4. • SR2-5AM5 was active against S.aureus and antibiotic production peaks on day 4 at pH 9. Figure 1: Time Course for Antibiotic Production Figure 2: pH Profile During Antibiotic Production Discussion and Conclusion The cave at Moul falls was chosen because no one has studied the microbial diversity in Wells Gray park. It is hoped that by studying unique habitats, it will increase the chances of finding previously undiscovered antibiotic producing actinomycetes. The discovery of two antibiotic producing strains indicates that caves can be a potential source of new antibiotics. • Methods • Soil Sample Prep: 13 soil samples air dried and prepared using serial dilution method. • Isolation: 5 media used -HVA, HGA, Sodium Caseinate, Hickey Tresner and Yeast Agar, 20°C and 28°C for 14 days. • Fermentation: 5 different media – TSB, GSSY, LB, Corn meal and Corn Steep at 28°C for 10 days in an orbital shaker at 250 rpm. • Assay: Paper disk diffusion method against E. coli, • S. aureus, S. enteritidis and C. albicans Figure 3: No. of Isolates per Site Number Figure 4: No. of Isolates per Media Future Work Possible future studies include optimization of fermentation conditions to increase antibiotic production and purification of the antibiotics. Thank you to Dr. Bruno Cinel and Joanna Urban of UCC and Wasu Pathom-aree at School of Biology at University of Newcastle, UK for their support and expertise. I am also thankful for financial support from a UCC-SAC grant and Park Use Permit #TR0310284 from Ministry of Water, Land, and Air Protection. Thank you to Eric Bottos for EB17CM4 Cheeptham, N., Higashiyama, T., Phay, N., Tomita, F. 1999. Rapid and Unique Screening System for the Discovery of New Antifungal Antibiotics against Chitin Synthesis in Fungal Cell Walls. J. of Antibiotics 1:31-36. Suzuki, S., Yamamoto, K., Okuda, T., Nishio, M., Nakanishi, N., Komatsubara, S. 2000. Selective Isolation and Distribution of Actinomadura rugatobispora Strains in Soil.Actinomcetol.14: 27-33. Moncheva, P., Tishkov, S., Dimitrova, N., Chipeva, V., Antonova-Nikolova, S., Bogatzevska, N. 2002. Characteristics of Soil Actino Mycetes from Antartica. Journal of Culture Collections. 3: 3-14. Background: Strain EB17CM4 Gram Stain a Figure 1. Collecting the Soil Samples at Well Gray Park Figure 2. The Zone of Inhibition for Strain SR2-5AM5 against S. enteritidis Background: EB17CM4 Gram Stain 100x magnification 1mm