In the last few years, useful information and techniques have been developed to engineer the cell factory H. jecorina. With the sequencing of the H. jecorina genome (Martinez et al., 2008) and the development of a high-frequency gene-targeting

tool on a high-throughput scale (Guangtao et al., 2009), two prerequisites for targeted modification of strains are available. However, further improvement of the tools and methods to facilitate multiple genetic modifications is highly desirable. Such genetic modifications require the use of selectable markers for efficient isolation and selection of transformed click here cells, but only a few selectable markers are available. Although a number of alternative methods are available, Neratinib purchase which include marker rescue (Hartl & Seiboth, 2005), a straightforward method would be the generation of strains with multiple auxotrophies. Although classical mutagenesis with chemical mutagens or radiation has had great success in developing auxotrophic strains, a serious disadvantage of these methods is the occurrence of additional mutations that can be detrimental to the performance of the mutated strain. Gene knockout is therefore the preferential tool

for the introduction of new auxotrophies. The H. jecorina strains used today in biotechnology are derived from a single isolate and were described to be asexual (Martinez et al., 2008). Only recently, this wild-type strain was also described to be accessible for sexual crossings (Seidl et al., 2009). Therefore, it is now possible to knockout specific genes of H. jecorina that lead to auxotrophies for amino acids, vitamins, etc. By sexual crossing of such strains, different auxotrophies can now be combined within a single strain, which can then be used for multiple genetic modifications. In summary, we successfully developed hxk1 as an efficient homologous metabolic marker for H. jecorina. Development of novel selectable markers in combination with information from the genomic database of H. jecorina will greatly accelerate the elucidation

of gene function and metabolic engineering of H. jecorina into a versatile cell factory. This work was supported Niclosamide by Grants from the National Natural Science Foundation of China (nos 30670029 and 30800024) and the National High Technology Research and Development Program of China (no. 2007AA05Z455). B.S. was supported by the Austrian Science Foundation (P19421). Fig. S1. (a) Schematic map of phxk1-EGFP. (b) Schemetic representation of hxk1 loci with SalI restriction sites. Please note: Wiley-Blackwell is not responsible for the content or functionality of any supporting materials supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article. “
“Little is known about the ability of phages to successfully colonize contrasting aquatic niches.