Study of the cold adaptive mechanisms in Antarctic bacteria and investigation of the chemotherapeutic and antimicrobial potential of their pigments

• Main Author: Mojib, Nazia
• Format: Text
• Language: unknown
• Published: UAB Digital Commons 2011
• Subjects: Antarctica; anticancer; antimycobacterial; Cold shock protein D; Janthinobacterium sp. Ant5-2; purple violet pigment; Doctor of Philosophy (PhD) College of Arts and Sciences; Arts and Humanities; Antarc*; Antarctic; McMurdo Dry Valleys
• Online Access: https://digitalcommons.library.uab.edu/etd-collection/2494; https://digitalcommons.library.uab.edu/context/etd-collection/article/3486/viewcontent/Mojib_uab_0005D_10435.pdf

Antarctic ecosystems are extreme environments to study the biodiversity, survival and adaptation of bacteria. The current study describes the rich and diverse heterotrophic bacterial communities from seasonally ice-free open lakes in East Antarctic Schirmacher Oasis and a perennially ice-covered Lake Joyce in West An-tarctic McMurdo Dry Valleys using culture-dependent and culture-independent approaches. Heterotrophic bacteria from three different Phyla: Proteobacteria, Bacteroidetes and Actinobacteria were cultured from lakes of Schirmacher Oasis using 16S rRNA gene-based taxonomic analysis. However, similar approach applied on the community DNA of the Black Hole sediments in Lake Joyce exhibited previously undescribed heterotrophs from seven different phyla: Proteobacteria, Planctomycetes, Bacteroidetes, Candidate Division OP10, Verrucomicrobia, Chloroflexi and Gemmatimonadetes. The results of DNA-DNA hybridization, physiological and biochemical tests allowed characterization of a proposed new species, Janthinobacterium schirmacherense strain Ant5-2T from a proglacial Lake Podprudnoye in Schirmacher Oasis. An overall framework of the structure and function of a constitutively expressed cold shock protein, CspD from Ant5-2T was established. In silico analysis and in vitro DNA binding assay revealed that CspD forms a highly stable domain-swapped dimer and binds to ssDNA, suggesting its RNA-binding property necessary for cold adaptation. Further, vioA of the operon vioABCD involved in the biosynthesis of purple violet pigment (PVP) from Ant5-2 was identified, cloned and sequenced. A non-pigmented vioA mutant strain was obtained following mini-Tn10 transposon mutagenesis that exhibited significantly reduced survival compared to the wild-type upon exposure to UV suggesting the role of PVP in UV tolerance in Ant5-2. The PVP also proved to be a broad spectrum compound possessing antimycobacterial and anticancer activities. The minimum inhibitory concentration (MIC) of PVP for virulent M. tuberculosis H37Rv strain was ...