Functional metagenomic strategies for the discovery of novel enzymes and biosurfactants with biotechnological applications from marine ecosystems.

Marine ecosystems are home to bacteria which are exposed to a wide variety of environmental conditions, such as extremes in temperature, salinity, nutrient availability and pressure. Survival under these conditions must have necessitated the adaptation and the development of unique cellular biochemistry and metabolism by these microbes. Thus, enzymes isolated from these microbes have the potential to possess quite unique physiological and biochemical properties. This review outlines a number of function-based metagenomic approaches which are available to screen metagenomic libraries constructed from marine ecosystems to facilitate the exploitation of some of these potentially novel biocatalysts. Functional screens to isolate novel cellulases, lipases and esterases, proteases, laccases, oxidoreductases and biosurfactants are described, together with approaches which can be employed to help overcome some of the typical problems encountered with functional metagenomic-based screens.

Deposition of substituted apatites with anticolonizing properties onto titanium surfaces using a novel blasting process.

A series of doped apatites have been deposited onto titanium (V) substrates using a novel ambient temperature blasting process. The potential of these deposited doped apatites as non-colonizing osteoconductive coatings has been evaluated in vitro. XPS, EDX, and gravimetric analysis demonstrated that a high degree of coating incorporation was observed for each material. The modified surfaces were found to produce osteoblast proliferation comparable to, or better than, a hydroxyapatite finish. Promising levels of initial microbial inhibition were observed from the Sr- and Ag-doped surfaces, with the strontium showing prolonged ability to reduce bacteria numbers over a 30-day period. Ion elution profiles have been characterized and linked to the microbial response and based on the results obtained, mechanisms of kill have been suggested. In this study, the direct contact of coated substrate surfaces with microbes was observed to be a significant contributing factor to the antimicrobial performance and the anticolonizing activity. The silver substituted apatite was observed to out-perform both the SrA and ZnA in terms of biofilm inhibition.

Cloning and functional analysis by gene disruption of a novel gene involved in indigo production and fluoranthene metabolism in Pseudomonas alcaligenes PA-10.

A novel indole dioxygenase (idoA) gene has been cloned from Pseudomonas alcaligenes PA-10, based on its ability to convert indole to indigo. The chromosomally encoded idoA gene exhibits no similarity to previously cloned naphthalene dioxygenases or to aromatic oxygenases from other species at the nucleotide level. Phylogenetic analysis indicates that the idoA gene product is most similar to an acyl-CoA dehydrogenase from Novosphingobium aromaticivorans. The enzyme encoded by the idoA gene is essential for the metabolism of fluoranthene, since a mutant in which the idoA gene has been disrupted looses the ability to degrade this compound. The idoA gene appears to be constitutively expressed in PA-10, but its expression is also subject to regulation following prior exposure to salicylate and to fluoranthene degradative intermediates.