Life Sciences Commons^™

Preservation Of H2 Production Activity In Nanoporous Latex Coatings Of Rhodopseudomonas Palustris Cga009 During Dry Storage At Ambient Temperatures, Magdalena Piskorska, Tanya Soule, J Gosse, C Milliken, M Flickinger, G Smith, C Yeager

Tanya Soule

To assess the applicability of latex cell coatings as an ‘off-the-shelf’ biocatalyst, the effect of osmoprotectants, temperature, humidity and O2 on preservation of H2 production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H2 production. Beyond 2 weeks of storage, sorbitol-treated coatings lost all H2 production activity, whereas considerable H2 production was still detected in sucrose- and trehalose-stabilized coatings. The relative humidity level at which the coatings were stored had a significant impact on the recovery and …

Archaeal Populations In Biological Soil Crusts From Arid Lands In North America, Tanya Soule, Ian J. Anderson, Shannon L. Johnson, Scott T. Bates, Ferran Garcia-Pichel

Tanya Soule

Archaea are common and abundant members of biological soil crust communities across large-scale biogeographic provinces of arid North America. Regardless of microbial community development, archaeal populations averaged 2 × 107 16S rRNA gene copies per gram of soil, representing around 5% of the prokaryotic (total calculated bacterial and archaeal) numbers assessed by quantitative-PCR. In contrast, archaeal diversity, determined by denaturing gradient gel electrophoresis fingerprinting and clone libraries of 16S rRNA genes, was very restricted. Only six different phylotypes (all Crenarchaea) were detected, three of which were very dominant. Some phylotypes were widespread, while others were typical of Southern desert areas.

A Comparative Genomics Approach To Understanding The Biosynthesis Of The Sunscreen Scytonemin In Cyanobacteria, Tanya Soule, Kendra Palmer, Qunjie Gao, Ruth M. Potrafka, Valerie Stout, Ferran Garcia-Pichel

Tanya Soule

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. We provide further genomic characterization of these genes in N. punctiforme and extend it to homologous regions in other cyanobacteria.

Results Six putative genes in the scytonemin gene cluster (NpR1276 to NpR1271 in the N. punctiforme genome), with no previously known protein function and annotated in this study as scyA to scyF, are likely involved in the assembly …

Gene Expression Patterns Associated With The Biosynthesis Of The Sunscreen Scytonemin In Nostoc Punctiforme Atcc 29133 In Response To Uva Radiation, Tanya Soule, Ferran Garcia-Pichel, Valerie Stout

Tanya Soule

Under exposure to UV radiation, some cyanobacteria synthesize sunscreen compounds. Scytonemin is a heterocyclic indole-alkaloid sunscreen, the synthesis of which is induced upon exposure to UVA (long-wavelength UV) radiation. We previously identified and characterized an 18-gene cluster associated with scytonemin biosynthesis in the cyanobacterium Nostoc punctiforme ATCC 29133; we now report on the expression response of these genes to a step-up shift in UVA exposure. Using quantitative PCR on cDNAs from the N. punctiforme transcriptome and primers targeting each of the 18 genes in the cluster, we followed their differential expression in parallel subcultures incubated with and without UVA. All …

Molecular Genetics And Genomic Analysis Of Scytonemin Biosynthesis In Nostoc Punctiforme Atcc 29133, Tanya Soule, Valerie Stout, Wesley Swingley, J C. Meeks, Ferran Garcia-Pichel

Tanya Soule

The indole-alkaloid scytonemin is the most common and widespread sunscreen among cyanobacteria. Previous research has focused on its nature, distribution, ecology, physiology, and biochemistry, but its molecular genetics have not been explored. In this study, a scytonemin-deficient mutant of the cyanobacterium Nostoc punctiforme ATCC 29133 was obtained by random transposon insertion into open reading frame NpR1273. The absence of scytonemin under conditions of induction by UV irradiation was the single phenotypic difference detected in a comparative analysis of the wild type and the mutant. A cause-effect relationship between the phenotype and the mutation in NpR1273 was demonstrated by constructing a …