The need for novel antibacterial compounds stimulated the exploration of marine environment for bioactive secondary metabolites. However, many times marine bacterial screening rediscovered known species leading to an inefficient discovery process that was laborious and time consuming. Approach used in this investigation involves, genus and possibly species level identification of a large number of samples from diverse locations, mass spectrometry based finger printing method and creation and expansion of database containing new actinobacterial species. In an initial study, replicate samples from 7 geographical locations and 54 collection sites were analyzed to investigate the diversity of marine actinobacteria in terms of antimicrobial properties and growth environment. 16S rRNA sequencing on extracted, PCR amplified DNA samples helped identification at least to the genus level. Chemical fingerprinting based on chemical analysis of secondary metabolites excreted during cultivation is one possible discovery tool to explore the chemical picture of the produced set of metabolites without their individual isolation. Ultra performance liquid chromatography (UPLC) was found to be an excellent tool for natural product analysis in this study. Ethyl acetate (EA) extracts of the bacterial samples were analyzed by UPLC with data being analyzed using Progenesis QI software. Antibacterial activity was tested for each actinobacterial culture using crude extracts against 5 different resistant pathogens. Actinobacterial library creation is ongoing using Bruker Biotyper software, from samples analyzed in a Bruker UltrafleXtreme, state of the art MALDI-TOF system. Among 80 initial samples, 9 showed antimicrobial activity against Acinetobacter baumannii (AB), Methicillin resistant Staphylococcus aureus (MRSA), and Enterococcus faecalis (EPH). Extension of the database using samples from different geographical locations, combined with antimicrobial activity testing results will make future identification of new, novel actinobacterial species routine.

Diversity, antimicrobial activity and chemical fingerprinting of marine actinomycetes

253rd National Meeting (2017)

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