Isolation and characterization of strain exiguobacterium sp. Krl4, a producer of bioactive secondary metabolites from a Tibetan glacier
View/ Open
Date
2021Author
Tedesco, Pietro
Esposito, Fortunato Palma
van Zyl, Leonardo Joaquim
Metadata
Show full item recordAbstract
Extremophilic microorganisms represent a unique source of novel natural products. Among
them, cold adapted bacteria and particularly alpine microorganisms are still underexplored. Here,
we describe the isolation and characterization of a novel Gram-positive, aerobic rod-shaped alpine
bacterium (KRL4), isolated from sediments from the Karuola glacier in Tibet, China. Complete
phenotypic analysis was performed revealing the great adaptability of the strain to a wide range
of temperatures (5–40 ◦C), pHs (5.5–8.5), and salinities (0–15% w/v NaCl). Genome sequencing
identified KRL4 as a member of the placeholder genus Exiguobacterium_A and annotation revealed
that only half of the protein-encoding genes (1522 of 3079) could be assigned a putative function. An
analysis of the secondary metabolite clusters revealed the presence of two uncharacterized phytoene
synthase containing pathways and a novel siderophore pathway. Biological assays confirmed that
the strain produces molecules with antioxidant and siderophore activities. Furthermore, intracellular
extracts showed nematocidal activity towards C. elegans, suggesting that strain KRL4 is a source of
anthelmintic compounds.