Journal Article

Bacterial diversity, pigments and nitrogen fixation of biological desert crusts from the Sultanate of Oman

Al Kharusi, Samiha, Schramm, Angela, Robinson, Michael D., Abed, Raeid M.M.

2010

Overview

Biological desert crusts are relatively common in the arid deserts of the Sultanate of Oman; however, little is known about their microbial community composition and role in soil fertilization. We compared three crusts from geographically different locations for their soil texture, bacterial community structure, pigment composition and nitrogenase activity. The crusts were growing on alkaline (pH 7.6-8.7) loamy sand and silty loam soils. Microscopically, Microcoleus vaginatus was the most abundant cyanobacterium, but Nostoc and Scytonema types dominated in cultures. The 16S rRNA gene sequences showed close similarities in the crusts' bacterial composition, with 77-81% of the total clones belonging to cyanobacteria and the rest distributed among Alpha- and Deltaproteobacteria, Bacteriodetes, Gemmatimonas and Planctomycetes. Thirty-seven percent of the cyanobacterial clones were affiliated with heterocystous types such as Nostoc, Scytonema, Brasilonema and Petalonema. Chlorophyll a concentrations suggest a similar abundance of phototrophs in all crusts. High levels of the UVA sunscreen scytonemin were detected in the exposed crusts. The three crusts exhibited comparable acetylene reduction rates in the light and in the dark, with a maximum rate of 58.5±2.6 μmol C₂H₂ reduced m⁻² h⁻¹. We conclude that the crusts, regardless of their geographical location, were rich in heterocystous cyanobacteria that can fix nitrogen and could possibly improve soil stability and productivity.

• Publisher: Oxford, UK : Blackwell Publishing Ltd,Blackwell Publishing Ltd,Blackwell,Oxford University Press
• Subject: Acetylene / Acetylene - metabolism / Acetylene reduction / acetylene reduction rate / analysis / Animal, plant and microbial ecology / Aridity / autotrophs / Bacteria / bacterial communities / Bacteriodetes / Bacteriology / Biodiversity / Biological and medical sciences / biological desert crusts / Chlorophyll / Chlorophyll - analysis / classification / clone libraries / clones / Cloning / Communities / Community composition / Community structure / Crusts / Cyanobacteria / Cyanobacteria - classification / Cyanobacteria - genetics / Cyanobacteria - isolation & purification / delta-Proteobacteria / Desert Climate / desert soils / Deserts / Ecology / Fertilization / Fundamental and applied biological sciences. Psychology / Gene Library / Gene sequencing / genetics / Geographical distribution / Geographical locations / Geography / Indoles / Indoles - analysis / isolation & purification / Loam soils / metabolism / Microbial ecology / Microbiology / Microcoleus vaginatus / Microorganisms / Miscellaneous / nitrogen / Nitrogen Fixation / Nitrogenase / Nitrogenation / Nostoc / nucleotide sequences / Oman / Petalonema / Phenols / Phenols - analysis / Phylogeny / Pigments / Planctomycetes / ribosomal RNA / RNA, Ribosomal, 16S / RNA, Ribosomal, 16S - genetics / rRNA 16S / sand / Scytonema / Silt loam / soil crusts / Soil improvement / Soil Microbiology / Soil microorganisms / Soil properties / Soil stability / Soil structure / Soil texture / Soils / Sun screens / sunscreens / Texture