Cyanotoxin accumulation and growth patterns of biocrust communities under variable environmental conditions.

Biocrusts dominate the soil surface in deserts and are composed of diverse microbial communities that provide important ecosystem services. Cyanobacteria in biocrusts produce many secondary metabolites, including the neurotoxins BMAA, AEG, DAB, anatoxin-a() (guanitoxin), and the microcystin hepatotoxins, all known or suspected to cause disease or illness in humans and other animals. We examined cyanobacterial growth and prevalence of these toxins in biocrusts at millimeter-scales, under a desert-relevant illumination gradient.

A global metagenomic map of urban microbiomes and antimicrobial resistance.

We present a global atlas of 4,728 metagenomic samples from mass-transit systems in 60 cities over 3 years, representing the first systematic, worldwide catalog of the urban microbial ecosystem. This atlas provides an annotated, geospatial profile of microbial strains, functional characteristics, antimicrobial resistance (AMR) markers, and genetic elements, including 10,928 viruses, 1,302 bacteria, 2 archaea, and 838,532 CRISPR arrays not found in reference databases. We identified 4,246 known species of urban microorganisms and a consistent set of 31 species found in 97% of samples that were distinct from human commensal organisms.

Biocrust-Produced Cyanotoxins Are Found Vertically in the Desert Soil Profile.

The fate and persistence of the neurotoxin β-N-methylamino-L-alanine (BMAA) and its isomers N-(2aminoethyl)glycine (AEG) and 2,4-diaminobuytric acid (DAB) in soil profiles is poorly understood. In desert environments, these cyanotoxins are commonly found in both terrestrial and adjacent marine ecosystems; they accumulate in biocrusts and groundwater catchments, and have been previously shown to persist in soil as deep as 25 cm. To determine the depth that BMAA and its isomers can be found, samples were incrementally collected every 5 cm from bedrock to surface in triplicate soil cores in a biocrust field in the terrestrial desert of Qatar.

Analysis of Neurotoxic Amino Acids from Marine Waters, Microbial Mats, and Seafood Destined for Human Consumption in the Arabian Gulf.

Human health risks associated with exposure to algal and cyanobacterial toxins (phycotoxins) have been largely concerned with aquatic habitats. People inhabiting desert environments may be exposed to phycotoxins present in terrestrial environments, where cyanobacterial crusts dominate. Seafood comprises a significant portion of the human diet in desert environments proximal to an ocean or sea.

Microbial Characterization of Qatari Barchan Sand Dunes.

This study represents the first characterization of sand microbiota in migrating barchan sand dunes. Bacterial communities were studied through direct counts and cultivation, as well as 16S rRNA gene and metagenomic sequence analysis to gain an understanding of microbial abundance, diversity, and potential metabolic capabilities. Direct on-grain cell counts gave an average of 5.

Cyanobacteria and cyanotoxins are present in drinking water impoundments and groundwater wells in desert environments.

Desert environments and drylands experience a drastic scarcity of water resources. To alleviate dependence on freshwater for drinking water needs, countries have invested in infrastructure development of desalination plants. Collectively, the countries of the Arabian Gulf produce 45% of the world's desalinated water, which is stored in dams, mega-reservoirs and secondary house water tanks to secure drinking water beyond daily needs.

The isolation and initial characterization of mercury resistant chemolithotrophic thermophilic bacteria from mercury rich geothermal springs.

Mercury rich geothermal springs are likely environments where mercury resistance is critical to microbial life and where microbe-mercury interactions may have evolved. Eleven facultative thermophilic and chemolithoautotrophic, thiosulfate oxidizing bacteria were isolated from thiosulfate enrichments of biofilms from mercury rich hot sulfidic springs in Mount Amiata, Italy. Some strains were highly resistant to mercury (>or=200 muM HgCl(2)) regardless of its presence or absence during primary enrichments, and three reduced ionic mercury to its elemental form.