title: Soil microbial abundance and diversity along a low precipitation gradient.
abstract: The exploration of spatial patterns of abundance and diversity patterns along precipitation gradients has focused for centuries on plants and animals; microbial profiles along such gradients are largely unknown. We studied the effects of soil pH, nutrient concentration, salinity, and water content on bacterial abundance and diversity in soils collected from Mediterranean, semi-arid, and arid sites receiving approximately 400, 300, and 100 mm annual precipitation, respectively. Bacterial diversity was evaluated by terminal restriction fragment length polymorphism and clone library analyses and the patterns obtained varied with the climatic regions. Over 75% of the sequenced clones were unique to their environment, while ∼2% were shared by all sites, yet, the Mediterranean and semi-arid sites had more common clones (∼9%) than either had with the arid site (4.7% and 6%, respectively). The microbial abundance, estimated by phospholipid fatty acids and real-time quantitative PCR assays, was significantly lower in the arid region. Our results indicate that although soil bacterial abundance decreases with precipitation, bacterial diversity is independent of precipitation gradient. Furthermore, community composition was found to be unique to each ecosystem.
authors.affiliation: Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer, 84990 Israel, ami_bachar@hotmail.com
authors.forename: Ami
authors.initials: A
authors.lastname: Bachar
authors.forename: Ashraf
authors.initials: A
authors.lastname: Al-Ashhab
authors.forename: M Ines M
authors.initials: MI
authors.lastname: Soares
authors.forename: Menachem Y
authors.initials: MY
authors.lastname: Sklarz
authors.forename: Roey
authors.initials: R
authors.lastname: Angel
authors.forename: Eugene D
authors.initials: ED
authors.lastname: Ungar
authors.forename: Osnat
authors.initials: O
authors.lastname: Gillor
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D044822:Biodiversity; D002980:Climate; D004269:DNA, Bacterial / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D019083:Mediterranean Region; D010743:Phospholipids / Q000032:analysis; D012150:Polymorphism, Restriction Fragment Length; D011891:Rain; D054712:Salinity; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D014867:Water
chemical_list: D004269:DNA, Bacterial; D010743:Phospholipids; D012987:Soil; D014867:Water