title: Alternative hosts for functional (meta)genome analysis.
abstract: Microorganisms are ubiquitous on earth, often forming complex microbial communities in numerous different habitats. Most of these organisms cannot be readily cultivated in the laboratory using standard media and growth conditions. However, it is possible to gain access to the vast genetic, enzymatic, and metabolic diversity present in these microbial communities using cultivation-independent approaches such as sequence- or function-based metagenomics. Function-based analysis is dependent on heterologous expression of metagenomic libraries in a genetically amenable cloning and expression host. To date, Escherichia coli is used in most cases; however, this has the drawback that many genes from heterologous genomes and complex metagenomes are expressed in E. coli either at very low levels or not at all. This review emphasizes the importance of establishing alternative microbial expression systems consisting of different genera and species as well as customized strains and vectors optimized for heterologous expression of membrane proteins, multigene clusters encoding protein complexes or entire metabolic pathways. The use of alternative host-vector systems will complement current metagenomic screening efforts and expand the yield of novel biocatalysts, metabolic pathways, and useful metabolites to be identified from environmental samples.
authors.affiliation: Lehrstuhl für Mikrobiologie, Technische Universität München, Emil-Ramann-Str. 4, 85654, Freising, Germany, wliebl@wzw.tum.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Liebl
authors.forename: Angel
authors.initials: A
authors.lastname: Angelov
authors.forename: Julia
authors.initials: J
authors.lastname: Juergensen
authors.forename: Jennifer
authors.initials: J
authors.lastname: Chow
authors.forename: Anita
authors.initials: A
authors.lastname: Loeschcke
authors.forename: Thomas
authors.initials: T
authors.lastname: Drepper
authors.forename: Thomas
authors.initials: T
authors.lastname: Classen
authors.forename: Jörg
authors.initials: J
authors.lastname: Pietruszka
authors.forename: Jörg
authors.initials: J
authors.lastname: Pietruzska
authors.forename: Armin
authors.initials: A
authors.lastname: Ehrenreich
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Streit
authors.forename: Karl-Erich
authors.initials: KE
authors.lastname: Jaeger
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D016680:Genome, Bacterial; D054892:Metagenome; D056186:Metagenomics