title: Impact of seasonal changes on fungal diversity of a semi-arid ecosystem revealed by 454 pyrosequencing.
abstract: Fungi play fundamental ecological roles in terrestrial ecosystems. However, their distribution and diversity remain poorly described in natural communities, particularly in arid and semi-arid ecosystems. In order to identify environmental factors determining fungal community structure in these systems, we assessed their diversity in conjunction with soil physicochemical characteristics in a semi-arid ecosystem in Baja California, Mexico, endemic for Coccidioidomycosis (Valley Fever). Two different microhabitats, burrows (influenced by rodent activity) and topsoil, were compared in winter and summer. Using a metagenomic approach, the ITS1 region of nuclear ribosomal DNA was used as barcode. A total of 1940 Operational Taxonomic Units (OTUs) were identified from 362 332 ITS1 sequences obtained by 454 pyrosequencing. Differences in fungal composition between seasons were clearly identified. Moreover, differences in composition between microhabitats were mainly correlated to significant differences in environmental factors, such as moisture and clay content in topsoil samples, and temperature and electrical conductivity in burrow samples. Overall, the fungal community structure (dominated by Ascomycota and Basidiomycota) was less variable between seasons in burrow than in topsoil samples. Coccidioides spp. went undetected by pyrosequencing. However, a nested PCR approach revealed its higher prevalence in burrows.
authors: Department of Microbiology, Center for Scientific Research and Higher Education of Ensenada (CICESE), Ctra. Ensenada-Tijuana No. 3918, Ensenada, Baja California, 22860, Mexico.
authors: Lluvia
authors: L
authors: Vargas-Gastélum
authors: Department of Ecology and Evolutionary Biology, University of California-Irvine, 321 Steinhaus Hall, Irvine, CA 92697, USA.
authors: Adriana L
authors: AL
authors: Romero-Olivares
authors: National Laboratory of Sustainability Sciences (LANCIS) Ecology Institute, National Autonomous University of Mexico (UNAM), Tercer Circ. Ext. next to Jardín Botánico, Ciudad Universitaria, 70275, Mexico.
authors: Ana E
authors: AE
authors: Escalante
authors: Department of Biological Oceanography, Center for Scientific Research and Higher Education of Ensenada (CICESE), Ctra. Ensenada-Tijuana No. 3918, Ensenada, Baja California, 22860, Mexico.
authors: Axayácatl
authors: A
authors: Rocha-Olivares
authors: Department of Computer Sciences, Center for Scientific Research and Higher Education of Ensenada (CICESE), Ctra. Ensenada-Tijuana No. 3918, Ensenada, Baja California, 22860, Mexico.
authors: Carlos
authors: C
authors: Brizuela
authors: Department of Microbiology, Center for Scientific Research and Higher Education of Ensenada (CICESE), Ctra. Ensenada-Tijuana No. 3918, Ensenada, Baja California, 22860, Mexico riquelme@cicese.mx.
authors: Meritxell
authors: M
authors: Riquelme
mesh_terms: D001203:Ascomycota / Q000145:classification* / Q000235:genetics; D001483:Base Sequence; D001487:Basidiomycota / Q000145:classification* / Q000235:genetics; D003045:Coccidioides / Q000235:genetics / Q000302:isolation & purification; D003047:Coccidioidomycosis / Q000453:epidemiology* / Q000382:microbiology; D058893:DNA Barcoding, Taxonomic; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D004463:Ecology; D017753:Ecosystem; D008800:Mexico; D012621:Seasons; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D021903:DNA, Ribosomal Spacer; D012987:Soil
keywords: ITS1 region; metagenomics; molecular ecology; mycobiota