Crenarchaeota are ubiquitous and abundant microbial constituents of soils, sediments, lakes, and ocean waters. To further describe the cosmopolitan nonthermophilic Crenarchaeota, we analyzed the genome sequence of one representative, the uncultivated sponge symbiont Cenarchaeum symbiosum. C. symbiosum genotypes coinhabiting the same host partitioned into two dominant populations, corresponding to previously described a- and b-type ribosomal RNA variants. Although they were syntenic, overlapping a- and b-type ribotype genomes harbored significant variability. A single tiling path comprising the dominant a-type genotype was assembled and used to explore the genomic properties of C. symbiosum and its planktonic relatives. Of 2,066 ORFs, 55.6% matched genes with predicted function from previously sequenced genomes. The remaining genes partitioned between functional RNAs (2.4%) and hypotheticals (42%) with limited homology to known functional genes. The latter category included some genes likely involved in the archaeal-sponge symbiotic association. Conversely, 525 C. symbiosum ORFs were most highly similar to sequences from marine environmental genomic surveys, and they apparently represent orthologous genes from free-living planktonic Crenarchaeota. In total, the C. symbiosum genome was remarkably distinct from those of other known Archaea and shared many core metabolic features in common with its free-living planktonic relatives.
Title: Lipase catalysed resolution of the Lotrafiban intermediate 2,3,4,5-tetrahydro-4-methyl-3-oxo-1 H-1,4-benzodiazepine-2-acetic acid methyl ester in ionic liquids: comparison to the industrial t-butanol process Roberts NJ, Seago A, Carey JS, Freer R, Preston C, Lye GJ Ref: Green Chem, 6:475 , 2004 : PubMed
The Candida antarctica lipase B (Novozyme 435) catalysed resolution of2,3,4,5-tetrahydro-4-methyl-3-oxo-1H-1,4-benzodiazepine-2-acetic acid methyl ester (SB-235349), a key Lotrafiban intermediate, has been investigated in six ionic liquids including [BMIM][PF6] and [BMIM][N(SO2CF3)2]. The initial rate and final yield of the reaction have subsequently been determined in [BMIM][PF6] as a function of initial substrateconcentration (5-40 g L-1), temperature (25-100 oC) and initial water content (3-15% H2O w/w). In each case the results have been compared to those obtained for the optimised industrial process operated in t-butanol (88% v/v). Simply replacing the organic solvent with an ionic liquid under otherwise identical reaction conditions reduced the rate of conversion. However, exploiting the increased solubility of the substrate in ionic liquids and the ability to operate at higher temperatures increased the overall rate of reaction by a factor of four while maintaining the same overall yield of 47%. In each case the ee of the product was 99%. Further experiments demonstrated the ability to re-use the enzyme over 10 reaction cycles and suggested that solute mass transfer in ionic liquids might be an issue for reactions carried out at larger scale. Overall the results suggest that ionic liquids can be very favourable reaction media for industrial bioconversion processes, which also overcome many of the safety and environmental concerns of conventional organic solvents.
