Tat-translocase composition in Corynebacterium glutamicum and the effect of TorD coexpression

White biotechnology employs microorganisms or microbial-derived enzymes for the production of valuable chemicals. The significance of bio-based industrial processes has been steadily increasing during the last decades; especially in facing the risks and challenges of a growing world population and being able to satisfy the growing demand for fine chemicals, food additives for humans and livestock and pharmaceutical products. Modern biotechnology tries to address these needs by presenting bio-based production solutions which are independent of fossil-fuel carbon-sources and thus not only more sustainable but also less hazardous in their waste production. In the course of this development, the biotechnological production of proteins and peptides has rapidly grown in importance. While the market for industrial enzymes was around US$ 3.3 billion in 2010 it is estimated to reach a value of US$ 4.4 billion by 2015 (Adrio and Demain, 2014). Today, technical enzymes are being employed in a multitude of ways, e. g. amylases, xylanases and lipases for the baking industry, pectinases and cellulases for vegetable, fruit and wine processing and amylases and cellulases in the textile industry, many of which are produced in Bacillus spec. and fungi such as Aspergillus spec. or Trichoderma spec. (Sarrouh et al., 2012). Also products of pharmaceutical relevance such as recombinant human insulin produced in Escherichia coli (Schmidt, 2004) or human Interferon (IFN)-? in B. subtilis (Rojas Contreras et al., 2010) have a large demand. Advantageous for downstream processing is the direct secretion of the desired polypeptide product into the culture supernatant which can be accomplished with G ram-positive secretion hosts such as Bacillus ssp. or Corynebacterium glutamicum.