42. Isolation and Characterization of Antibiotic Producing Yeast From Soil

Abstract

Microorganisms produce metabolites that help them compete in the environment for limited resources. Some of these compounds are used as antibiotics to fight infectious diseases. Penicillin, Streptomycin, and Erythromycin are a few examples of antimicrobial metabolites produced by soil microorganisms. Since the discovery of the first antibiotic, Penicillin, in 1942, abuse of these compounds has led to widespread antibiotic resistance. Consequently, the need for novel antibiotics is pressing. One approach to the discovery of new antimicrobial agents is to continue the search for novel metabolites produced by soil microorganisms. In this study, we have analyzed a soil sample to identify microorganisms that inhibit antimicrobial activity. Samples were collected and brought to lab to culture. After performing serial dilutions, soil samples were plated and grown on yeast specific media, Sabardough as well as Tryptic Soy Agar, which allow for growth of most microorganisms. Isolated colonies were re-plated on fresh media and overlaid with three different pathogenic bacteria: Escherichia coli, Staphlococcus aureus, and Pseudomonas aeruginosa. Among 14 soil isolates tested, one colony showed a potent activity in growth inhibition of all three pathogens. Upon microscopic examination, the microorganism was classified as yeast. Then, the colony was identified using a RapID Yeast Plus test as a Cryptococcus spp. Currently, we are working on scaling up and optimizing growth conditions of the yeast. Next, we will move forward to isolate and determine the chemical structure of the active metabolite(s).