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Kilroot salt mine, a Triassic halite deposit located in County Antrim, Northern Ireland, is the only permanent hypersaline environment on the island of Ireland. In this study, the microbiome of this unstudied environment was profiled for the first time using conventional and enhanced culturing techniques, and culture independent metagenomic approaches. Using both conventional isolation plates and iChip devices, 89 halophilic archaeal isolates from six known genera, and 55 halophilic or halotolerant bacterial isolates from 18 genera were obtained, based on 16S rRNA gene sequencing. The archaeal isolates were similar to those previously isolated from other ancient halite deposits, and as expected, numerous genera were identified in the metagenome which were not represented among the culturable isolates. Preliminary screening of a selection of isolates from this environment identified antimicrobial activities against a panel of clinically important bacterial pathogens from 15 of the bacterial isolates and one of the archaea. This, alongside previous studies reporting the discovery of novel biocatalysts from the Kilroot mine microbiome, suggests that this environment may be a new, untapped source of of chemical diversity with high biodiscovery potential. [ABSTRACT FROM AUTHOR]

Kilroot salt mine, a Triassic halite deposit, is the only hypersaline environment in Ireland. We profiled the culturable and nonculturable microbiota of this unstudied environment using conventional isolation (with the addition of some augmented techniques) and metagenomics. Based on 16S sequencing, 89 extremely halophilic archaea from six genera, and 55 halophilic and halotolerant bacteria from 19 genera were isolated. The archaea were similar to what has been previously isolated from other ancient halite deposits, and as expected, numerous additional genera were identified in the metagenome, indicating the limitations of culture- based approaches. We also observed high levels of phenotypic antimicrobial resistance (AMR) among the isolates. Annotation of whole genome and metagenomic sequence data identified a number of genes which might explain the observed resistant phenotypes, however there were fewer than expected, suggesting that these microorganisms may use novel, as yet unidentified resistance mechanisms. A growing body of evidence suggests AMR is not a modern phenomenon, but that its origins are ancient, long predating modern antibiotic use. Studying AMR in environments that have had little or no exposure to anthropogenic antibiotic sources provides a critical measure of its natural diversity, which has significant implications in our understanding of its prevalence and evolution. [ABSTRACT FROM AUTHOR]