The effect of environmental stress on antibiotic production by streptomyces

Antibiotic Resistance is a world-wide issue that increases with every year. The World Health Organisation (WHO) has identified priority pathogenic microorganisms with dangerous resistance to 'last-resort' antibiotics, these are the 'ESKAPE' pathogens.To face this problem, we investigated novel antibiotic-producing bacteria. The majority of currently available originate from organisms belonging to the Actinobacteria Phylum. Unfortunately, no significant compounds have been discovered in decades and so this has lead us to search in sparsely researched locations such as the hyper-arid Atacama Desert in Chile and compare them to more commonly researched North European soil samples which are naturally more hydrated. In this project we studied bacteria isolated from soil samples from Chiles Atacama Desert and the west of Scotland. Relevant strains were selected by unique morphology and by antimicrobial-activity. Bioactivity tests were performed on all isolates grown on 4 different media against 'ESKAPE' pathogens, Bacillus subtilis and Saccharomyces cerevisiae across which all were inhibited in the streak assays and all but Klebsiella pneumoniae and Pseudomonas aeruginosa in plug assays. Those presenting relevant bioactive profiles were taxonomically identified using 16S rRNAgene sequencing as members of the genera; Streptomyces, Micromonospora and Methylobacterium. Amongst those, isolate identified as Streptomyces narbones is presented activity against a clinical isolate of carbapenem-resistant Acinetobacterbaumannii. In Addition, Streptomyces puniceus presented a unique morphology that was not seen before in Streptomyces. Moreover, elicitation of bio-active compounds from antimicrobial-producing isolates was achieved by increasing osmotic stress or supplementing with Nitrogen or Humic acid. Further studies to compliment this project would include whole-genome sequencing of the most interesting strains in tandem with mass spectrometry to identify the active compounds and activation of crypticbiosynthetic gene clusters through elicitation.

Name dc:type.qualificationname

mres

Level dc:type.qualificationlevel

masters-pg

Grantor dc:publisher.institution

University of Strathclyde

Year dc:date.issued

2019

Author dc:creator

• McGahon, Jonathan

Advisor dc:contributor.advisor

• Herron, Paul

DOI

10.48730/2d99-r577

Identifier

T15231

Author Identifier

201669989

OAI identifier oai:identifier

oai:strathclyde:bz60cw294