Knockout of pgdS and ggt genes improves -PGA yield in B. subtilis

One of the emerging biopolymers that are currently under active investigation is bacterial poly(-glutamic acid) (-PGA). However, before its full industrial exploitation, a substantial increase in microbial productivity is required. -PGA obtained from the Bacillus subtilis laboratory strain 168 offers the advantage of a producer characterized by a well defined genetic framework and simple manipulation techniques. In this strain, the knockout of genes for the major -PGA degrading enzymes, pgdS and ggt, leads to a considerable improvement in polymer yield, which attains levels analogous to the top wild -PGA producer strains. This study highlights the convenience of using the laboratory strain of B. subtilis over wild isolates in designing strain improvement strategies aimed at increasing -PGA productivity. Biotechnol. Bioeng. 2013; 110: 2006-2012. (c) 2013 Wiley Periodicals, Inc.