Isolating and Identifying New Antibiotic Producing Bacteria (Non-Scientist)

Since the 1940’s a boom of antibiotics like penicillin and streptomycin were discovered, the discovery of antibiotics have revolutionized medicine.  Today because of the excessive abuse of antimicrobial drugs more resistant strains of pathogenic bacteria are emerging and threatening modern society².  It is difficult to discover or develop a new antibiotics or antimicrobial agent, most of the antibiotics were discovered by screening cultivable soil samples³. 

                About 99% of microbes have remained uncultured.  Lately uncultivable microorganisms have been reported to produce interesting compounds, the purpose of the research was to develop a method to grow uncultivable microorganisms by cultivating it in its natural environment using a multichannel device called an iChip³.  The iChip dilutes a soil sample which isolates one bacterial cell per chamber, the chamber allows the diffusion of nutrients and growth factor³.  This method presents a 50% chance of growing uncultivable bacteria (compared to a petri dish 1%)¹.  Screening for antimicrobial activity were performed by extracting isolated cells form the iChip and inoculating them on plates with Staphylococcus aureus. 

Ling and his research team detected a new antibiotic producing bacteria by using iChip methodology.  To determine the species of the bacteria the cells were sequenced by Illumina (around 800bp) and amplified on 16SrDNA using GoTaq Green Master Mix and universal primers E8F and U1510R, the sequence was submitted to RAST server to produce closest relatives.  RAST predicted relativity to: Alicycliphilus denitrificans, Leptothrix cholodnii, Methylibium petroleiphilum, and Rubrivivax gelatinosus¹.  Then DNA-DNA hybridization was performed on these genomes, the analysis revealed that the bacteria belonged to a new genus related to Aquabacteria, named Eleftheria terrae¹.  The compound produced by the new genus was purified and analyzed by NMR and mass spectrometry, the results were not reported in an available data base.  As a result they discovered a new antibiotic producing cell, the compound, named teixobactin, inhibited grampositive bacterias.

                Teixobactin is the first member of a new class of lipid II binding antibiotics, judging by the properties of teixobactin it has evolved to minimize resistance in specific microorganisms.  With the growth of resistant pathogenic bacteria, employment of new technology and genomic techniques can help isolate and identify new antibiotic producing bacterias.  Most likely more antibiotic compounds like teixobactin are found in nature and are waiting to be discovered.

References:

1.       Losee L. Ling and et al.  2015.  A new antibiotic kills pathogens without detectable resistance.  Nature.  517.

2.       POPSCI.  ICHIP: THE FUTURE OF ANTIBIOTIC DISCOVERY.  2015.  Retrived from: http://www.popsci.com/ichip-new-way-find-antibiotics-and-other-key-drugs

 

3.       WHO.  Antimicrobial Resistance. 2014.  Retrived from: http://www.who.int/mediacentre/factsheets/fs194/en/