title: Diel-scale temporal dynamics recorded for bacterial groups in Namib Desert soil.
abstract: 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.
authors.affiliation: Centre for Microbial Ecology and Genomics, Genomic Research Institute, Department of Genetics, University of Pretoria, South Africa.
authors.forename: Eoin
authors.initials: E
authors.lastname: Gunnigle
authors.affiliation: Centre for Microbial Ecology and Genomics, Genomic Research Institute, Department of Genetics, University of Pretoria, South Africa.
authors.forename: Aline
authors.initials: A
authors.lastname: Frossard
authors.affiliation: Centre for Microbial Ecology and Genomics, Genomic Research Institute, Department of Genetics, University of Pretoria, South Africa.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Ramond
authors.affiliation: Centre for Microbial Ecology and Genomics, Genomic Research Institute, Department of Genetics, University of Pretoria, South Africa.
authors.forename: Leandro
authors.initials: L
authors.lastname: Guerrero
authors.affiliation: Gobabeb Research and Training Centre, Walvis Bay, Namibia.|School of Animal, Plant and Environmental Sciences University of the Witwatersrand, South Africa.
authors.forename: Mary
authors.initials: M
authors.lastname: Seely
authors.affiliation: Centre for Microbial Ecology and Genomics, Genomic Research Institute, Department of Genetics, University of Pretoria, South Africa.
authors.forename: Don A
authors.initials: DA
authors.lastname: Cowan
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics*; D058448:Biota; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D003889:Desert Climate; D006813:Humidity; D056265:Microbial Interactions; D009276:Namibia; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S