Advisor(s)
Abstract(s)
Bacterial diversity from McMurdo Dry Valleys in Antarctica, the coldest desert on
earth, has become more easily assessed with the development of High Throughput
Sequencing (HTS) techniques. However, some of the diversity remains inaccessible
by the power of sequencing. In this study, we combine cultivation and HTS
techniques to survey actinobacteria and cyanobacteria diversity along different soil
and endolithic micro-environments of Victoria Valley in McMurdo Dry Valleys. Our
results demonstrate that the Dry Valleys actinobacteria and cyanobacteria distribution
is driven by environmental forces, in particular the effect of water availability and
endolithic environments clearly conditioned the distribution of those communities.
Data derived from HTS show that the percentage of cyanobacteria decreases from
about 20% in the sample closest to the water source to negligible values on the
last three samples of the transect with less water availability. Inversely, actinobacteria
relative abundance increases from about 20% in wet soils to over 50% in the driest
samples. Over 30% of the total HTS data set was composed of actinobacterial strains,
mainly distributed by 5 families: Sporichthyaceae, Euzebyaceae, Patulibacteraceae,
Nocardioidaceae, and Rubrobacteraceae. However, the 11 actinobacterial strains
isolated in this study, belonged to Micrococcaceae and Dermacoccaceae families
that were underrepresented in the HTS data set. A total of 10 cyanobacterial strains
from the order Synechococcales were also isolated, distributed by 4 different genera
(Nodosilinea, Leptolyngbya, Pectolyngbya, and Acaryochloris-like). In agreement with
the cultivation results, Leptolyngbya was identified as dominant genus in the HTS data
set. Acaryochloris-like cyanobacteria were found exclusively in the endolithic sample
and represented 44% of the total 16S rRNA sequences, although despite our efforts
we were not able to properly isolate any strain from this Acaryochloris-related group.
The importance of combining cultivation and sequencing techniques is highlighted, as we have shown that culture-dependent methods employed in this study were able
to retrieve actinobacteria and cyanobacteria taxa that were not detected in HTS data
set, suggesting that the combination of both strategies can be usefull to recover both
abundant and rare members of the communities.
Description
Keywords
Actinobacteria Antarctic microenvironments Antarctic soil Bacteria diversity Bacterial cultivability Cyanobacteria Endolitic microbiota
Citation
Rego, Adriana; Raio, Francisco; Martins, Teresa P.; Ribeiro, Hugo; Sousa, António G.G.; Séneca, Joana; Baptista, Mafalda S.; Lee, Charles K.; Craig Cary, S.; Ramos, Vitor; Carvalho, Maria F.; Leão, Pedro N.; Magalhães, Catarina (2019). Actinobacteria and cyanobacteria diversity in terrestrial Antarctic microenvironments evaluated by culture-dependent and independent methods. Frontiers in Microbiology. ISSN -. 10, p.