Abstract
Although many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide. Among the main approaches for the discovery of new bioactive agents, the prospect of microbial secondary metabolites represents an effective source for the development of drug leads. In this study, we investigated the actinobacterial diversity associated with an endemic Antarctic species, Deschampsia antarctica, by integrated culture-dependent and culture-independent methods and acknowledged this niche as a reservoir of bioactive strains for the production of antitumour compounds. The 16S rRNA-based analysis showed the predominance of the Actinomycetales order, a well-known group of bioactive metabolite producers belonging to the Actinobacteria phylum. Cultivation techniques were applied, and 72 psychrotolerant Actinobacteria strains belonging to the genera Actinoplanes, Arthrobacter, Kribbella, Mycobacterium, Nocardia, Pilimelia, Pseudarthrobacter, Rhodococcus, Streptacidiphilus, Streptomyces and Tsukamurella were identified. The secondary metabolites were screened, and 17 isolates were identified as promising antitumour compound producers. However, the bio-guided assay showed a pronounced antiproliferative activity for the crude extracts of Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653. The TGI and LC50 values revealed the potential of these natural products to control the proliferation of breast (MCF-7), glioblastoma (U251), lung/non-small (NCI-H460) and kidney (786-0) human cancer cell lines. Cinerubin B and actinomycin V were the predominant compounds identified in Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653, respectively. Our results suggest that the rhizosphere of D. antarctica represents a prominent reservoir of bioactive actinobacteria strains and reveals it as an important environment for potential antitumour agents.
Highlights
Many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide
Bacterial community associated with Deschampsia antarctica rhizosphere
We reported the presence of many pathways related to the biosynthesis of antibiotics such as streptomycin, novobiocin, phenylpropanoids, pyridine alkaloids, stilbenoids, neomycin, vancomycin, and tetracyclines, indicating a great bioactive potential of the bacterial community associated with D. antarctica (Table S5—Supplementary Material)
Summary
Many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide. We investigated the actinobacterial diversity associated with an endemic Antarctic species, Deschampsia antarctica, by integrated culture-dependent and culture-independent methods and acknowledged this niche as a reservoir of bioactive strains for the production of antitumour compounds. Bioprospecting studies have advanced into auspicious ecological niches, which tend to favour the prevalence of exotic metabolisms and endemic s pecies[10,11] In this context, the Antarctic continent has been considered one of the most promising bioprospecting ecosystems and a valuable source to isolate new and diverse microorganisms due to its environmental peculiarities, such as extremely low temperatures and precipitation, high levels of UV radiation, ocean flooding, high salinity rates, and large unexplored a reas[12,13,14,15,16]. Studies exploring the potential of this microbiome to access novel cultivable strains and bioactive compounds are still scarce
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