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

Abstract

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 degrees 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.

Overexpression of Wild-Type Aspartokinase Increases l -Lysine Production in the Thermotolerant Methylotrophic Bacterium Bacillus methanolicus

“…We have previously demonstrated that wild-type B. methanolicus produces 58 g/liter of L-glutamate (6), while mutants generated by random chemical mutagenesis have been reported to produce up to 37 g/liter of L-lysine (16,23,34). Favorable properties of B. methanolicus, such as a lack of sporulation at high temperatures, utilization of methanol as an energy and carbon source, a high methanol conversion rate, a high theoretical yield of L-lysine, and an optimal growth temperature of 50°C, indicate that this organism may represent a possible future noncarbohydrate substrate alternative for large-scale production of L-lysine (5).…”

Analysis and Manipulation of Aspartate Pathway Genes for l -Lysine Overproduction from Methanol by Bacillus methanolicus

“…Methanol has several unique properties that make it an interesting alternative to molasses for such uses (5,36). So far, mainly three different methylotrophic bacteria have been explored to various levels for such purposes: the Gram-negative and obligate methylotrophs Methylophilus methylotrophus and Methylobacillus glycogenes and the Grampositive, thermotolerant, and restricted methylotroph Bacillus methanolicus (5,7).…”

Characterization of Fructose 1,6-Bisphosphatase and Sedoheptulose 1,7-Bisphosphatase from the Facultative Ribulose Monophosphate Cycle Methylotroph Bacillus methanolicus

“…1). Regeneration of Ru5-P involves enzymes shared with glycolysis and the pentose phosphate pathway (9) (Fig. 1).…”