Bacillus methanolicus: a candidate for industrial production of amino acids from methanol at 50°C

Amino acids are among the major products in biotechnology in both volume and value, and the global market is growing. Microbial fermentation is the dominant method used for industrial production, and today the most important microorganisms used are Corynebacteria utilizing sugars. For low-prize bulk amino acids, the possibility of using alternative substrates such as methanol has gained considerable interest. In this mini review, we highlight the unique genetics and favorable physiological traits of thermotolerant methylotroph Bacillus methanolicus, which makes it an interesting candidate for overproduction of amino acids from methanol. B. methanolicus genes involved in methanol consumption are plasmid-encoded and this bacterium has a high methanol conversion rate. Wild-type strains can secrete 58 g/l of l-glutamate in fed-batch cultures at 50°C and classical mutants secreting 37 g/l of l-lysine have been selected. The relative high growth temperature is an advantage with respect to both reactor cooling requirements and low contamination risks. Key genes in l-lysine and l-glutamate production have been cloned, high-cell density methanol fermentation technology established, and recently a gene delivery method was developed for this organism. We discuss how this new knowledge and technology may lead to the construction of improved l-lysine and l-glutamate producing strains by metabolic engineering.