Diel-scale temporal dynamics recorded for bacterial groups in Namib Desert soil

• Published in: Scientific reports 2017-01, Vol.7 (1), p.40189-40189, Article 40189
• Main Authors: Gunnigle, Eoin, Frossard, Aline, Ramond, Jean-Baptiste, Guerrero, Leandro, Seely, Mary, Cowan, Don A.
• Format: Article
• Language: English
• Subjects: 45; 45/77; 45/90; 45/91; 631/326/171/1818; 704/158/855; Bacteria; Bacteria - classification; Bacteria - genetics; Bioavailability; Biogeochemical cycles; Biota; Carbon cycle; Climate change; Consortia; Desert Climate; Desert soils; Deserts; DNA Fingerprinting; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; DNA, Ribosomal - chemistry; DNA, Ribosomal - genetics; Ecology; Fingerprinting; Fog; Gene expression; Humanities and Social Sciences; Humidity; Hypotheses; Microbial Interactions; multidisciplinary; Namibia; Phylogeny; Polymorphism, Restriction Fragment Length; Precipitation; RNA, Ribosomal, 16S - genetics; rRNA 16S; Science; Science (multidisciplinary); Sequence Analysis, DNA; Soil Microbiology; Soil microorganisms; Temperature; Temperature effects
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep40189

Microbes in hot desert soil partake in core ecosystem processes e.g., biogeochemical cycling of carbon. Nevertheless, there is still a fundamental lack of insights regarding short-term (i.e., over a 24-hour [diel] cycle) microbial responses to highly fluctuating microenvironmental parameters like temperature and humidity. To address this, we employed T-RFLP fingerprinting and 454 pyrosequencing of 16S rRNA-derived cDNA to characterize potentially active bacteria in Namib Desert soil over multiple diel cycles. Strikingly, we found that significant shifts in active bacterial groups could occur over a single 24-hour period. For instance, members of the predominant Actinobacteria phyla exhibited a significant reduction in relative activity from morning to night, whereas many Proteobacterial groups displayed an opposite trend. Contrary to our leading hypothesis, environmental parameters could only account for 10.5% of the recorded total variation. Potential biotic associations shown through co-occurrence networks indicated that non-random inter- and intra-phyla associations were ‘time-of-day-dependent’ which may constitute a key feature of this system. Notably, many cyanobacterial groups were positioned outside and/or between highly interconnected bacterial associations (modules); possibly acting as inter-module ‘hubs’ orchestrating interactions between important functional consortia. Overall, these results provide empirical evidence that bacterial communities in hot desert soils exhibit complex and diel-dependent inter-community associations.