From Metagenomes To Industrially Relevant Enzymes

Microorganisms living in extreme conditions have now been isolated from all type of extreme environments and numerous extremozymes originating from these organisms have been described and characterized. Indeed, most of their potential resides in their enzymes. As stated by Huston in 2008 : “As environmental concerns arise, biological tools are increasingly replacing harsh chemical and physical means of processing materials and they even harbor promise for creating cost-effective sustainable energy sources. It is imperative that we continue investigating ways in which natural products can offer economical alternatives to traditional industrial processes”. In this context the search for valuable extremophiles and their integration in industrial processes will, without any doubt, fulfill these objectives in extending the use of microorganisms and of their products to unexpected transformations.
Extensive investigations on extremophiles were therefore carried out for the reason that the large diversity of these organisms allowed to think that it is probably possible to find within them the appropriate isolate that produces the best possible product for a specific application. Of course these organisms have to be unravelled and their peculiarities sometimes render the culture conditions inappropriate. The recent emergence of the metagenomic approach has, however, modified the context and has now rendered possible the investigation of the world of non cultivable microorganisms.
Indeed, recent advances of the metagenomic highlighted the underestimated gene diversity contained in environmental samples. In order to isolate new valuable cold adapted proteins, Antarctica soil metagenomic libraries were constructed and screened for various activities.
Screenings were performed in industrially derived conditions, when feasible, and allowed the isolation of several new lipases/esterases, proteases, amylases, xylanases, … Hence, thorough characterization of the new enzymes is required prior their integration into industrial processes. We will discuss case-studies on three enzymes primarily isolated for the agro-food industry and displaying particular features.