Temperature drives the continental-scale distribution of key microbes in topsoil communities.

Global warming will likely force terrestrial plant and animal species to migrate toward cooler areas or sustain range losses; whether this is also true for microorganisms remains unknown. Through continental-scale compositional surveys of soil crust microbial communities across arid North America, we observed a latitudinal replacement in dominance between two key topsoil cyanobacteria that was driven largely by temperature. The responses to temperature of enrichment cultures and cultivated strains support this contention, with one cyanobacterium (Microcoleus vaginatus) being more psychrotolerant and less thermotolerant than the other (M.

A comparative genomics approach to understanding the biosynthesis of the sunscreen scytonemin in cyanobacteria.

Background: The extracellular sunscreen scytonemin is the most common and widespread indole-alkaloid among cyanobacteria. Previous research using the cyanobacterium Nostoc punctiforme ATCC 29133 revealed a unique 18-gene cluster (NpR1276 to NpR1259 in the N. punctiforme genome) involved in the biosynthesis of scytonemin.

Modestobacter versicolor sp. nov., an actinobacterium from biological soil crusts that produces melanins under oligotrophy, with emended descriptions of the genus Modestobacter and Modestobacter multiseptatus Mevs et al. 2000.

A novel isolate, CP153-2(T), was obtained from topsoil biological crusts in the Colorado Plateau (USA). Colonies were black in colour due to melanin-like pigments when grown on oligotrophic medium, but not when grown on copiotrophic medium. Induction of melanogenesis was independent of growth phase or illumination conditions, including exposure to UVB and UVA radiation, but exposure to UVB could enhance total pigment production and growth under low nitrogen prevented its synthesis.