Actinobacterial diversity in Atacama desert habitats as a road map to biodiscovery
The Atacama Desert ofNorthem Chile, the oldest and driest nonpolar desert on the planet,is known to harbour previously undiscovered actinobacterial taxa with the capacity tosynthesize novel natural products. In the present study, culture-dependent and cultureindependentmethods were used to :fin1:her...
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| Format: | thesis |
| Language: | eng |
| Published: |
2016
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| Online Access: | https://ir.upsi.edu.my/detailsg.php?det=5243 |
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| Summary: | The Atacama Desert ofNorthem Chile, the oldest and driest nonpolar desert on the planet,is known to harbour previously undiscovered actinobacterial taxa with the capacity tosynthesize novel natural products. In the present study, culture-dependent and cultureindependentmethods were used to :fin1:her our understanding of the extent ofactinobacterial diversity in Atacama Desert habitats. The culture-dependent studiesfocused on the selective isolation, screening and dereplication of actinobacteria from highaltitude soils from Cerro Chajnantor. Several strains, notably isolates designated H9 andH45, were found to produce new specialized metabolites. Isolate H45 synthesized sixnovel metabolites, lentzeosides A-F, some of which inhibited HIV-l integrase activity.Polyphasic taxonomic studies on isolates H45 and H9 showed that they represented newspecies of the genera Lentzea and Streptomyces, respectively; it is proposed that thesestrains be designated as Lentzea chajnantorensis sp. nov. and Streptomyces aridus sp.nov.. Additional isolates from sampling sites on Cerro Chajnantor were considered to benuclei of novel species of Actinomadura, Amycolatopsis, Cryptosporangium andPseudonocardia.A majority of the isolates produced bioactive co:mpounds that inlnbited the growthof one or rmre strains from a panel of six wild type microorganisms while those screenedagainst Bacillus subtilis reporter strains inhibited sporulation and cell envelope, cell wall,DNA and fatty acid synthesis.Initial culture- independent studies were carried out to establish the extent ofactinobacterial diversity in a range of hyper- and extreme hyper-arid Atacama Desertsoils. Community DNA extracted from soil collected from the sampling sites wassurveyed for actinobacteria by 454 pyrosequencing; rarefaction analyses indicated goodcoverage at rmst of the sites. The results revealed an amazing and unexpected taxonomicdiversity at the ranks of order, family and genus, much of it novel The total number ofgenera, for instance, is 328, of which around 40% could not be assigned to validlypublished genera. Rank abundancy profiles indicated that much of this diversity can beattnbuted to low abundancy taxa. Similar results were obtained from community DNAextracted from surface and subsurface soil samples collected at three different altitudeson Cerro Chajnantor. Actinobacterial community structure at these sampling sites wasinfluenced by altitude and sampling depth, as wen as several environmental variables thatincluded conductivity, pH, redox potential and organic matter content.It is evident from these studies that the Atacama Desert landscape abounds innovel actinobacterial taxa that synthesize a broad range of specialized metabolites thatcan be developed as drug leads. |
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