Screening for antimicrobial activities of bacteria from Antarctica

• Main Author: Chung, Hung Hui
• Format: Text
• Language: English
• Published: 2008
• Subjects: Antarc*; Antarctica
• Online Access: http://eprints.ums.edu.my/id/eprint/20519/; http://eprints.ums.edu.my/id/eprint/20519/1/Screening%20for%20antimicrobial.pdf

Naturally produced antimicrobial agent or antibiotics is a low molecular weight natural substance produced by microorganism to inhibit the growth of or kill other microorganisms. Antibiotics from microbes have been used to develop drugs to combat various pathogens. Nevertheless many pathogens have developed resistance to the existing antibiotics. Additionally, the pipeline of new drugs is running dry and the incentives to develop new antimicrobials to address the global problems of drug resistance are required. Hence the aims of this study were to isolate and characterize bacteria which produce antimicrobial agent. Bacteria from soil sample in Antarctica were screened for antimicrobial activities by using Escherichia coli 0157: H7, Klebsiella pneumoniae 14x and Salmonella typhimurium (S. Tm 13) as tester strains. Two out of the 356 bacterial isolates exhibited antagonistic effect on the tester strains which were then labeled as SS157 and SR13. Characterization of both strains indicated that their optimal growth temperature was 20°C, salt tolerance up to 3% (w/v) and an optimal growth at pH 7. SR13 was found to be Gram positive rods while Gram stain of SS157 shows that it is a Gram negative coccus. Biochemical tests performed revealed common significant taxa for both as Pseudomonas fluorescens with a percentage identity up to 99.9%. These were then further identified based on their 16S rDNA gene sequences. The 16S rDNA gene was partially sequenced and sequences with length of 1531 and 1536 base pair were obtained for SS157 and SR13 respectively. BLASTn search results revealed that SS157 bears a close phylogenetic relationship to Pseudomonas congelans DSM 14939T( -99%) while SRI 3 was found to bear a close phylogenetic relationship to Pseudomonas tremae CFBP 6111T (-98%).