Purified VDHs showed activities toward some aromatic selleck chemicals llc aldehydes. These enzymes have the same subunit molecular mass of about 57 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but differed in some of their observed properties. Native molecular masses also differed between the purified enzymes. These were 250 kDa for the enzyme from alkaliphilic strain TA1 and 110 kDa for that from neutrophilic strain TM1, as determined by gel filtration. The enzyme from strain TA1 required NADP+ as a coenzyme for its activity, but that from strain TM1 required NAD+. These results are important because this is the first report of an alkaliphilic bacterium consuming lignin monomers. Vanillin

(4-hydroxy-3-methoxybenzaldehyde) is one of the most important aromatic flavor compounds widely used in the food industry and in fragrances for perfumes. This compound is extracted from the fermented pods of Vanilla orchids. However, only about 0.2% of the market demand for ICG-001 vanillin is met by extraction from Vanilla pods (Krings & Berger, 1998). This natural vanillin is more expensive than the synthesized compound (Priefert et al., 2001). There is an increasing interest

and demand for natural vanillin from consumers. In the United States and European Union, the term ‘natural’ can be applied to a product that is derived from a natural raw material via biological conversions using enzymes or whole cells (Venkitasubramanian et al., 2008). Because of this, numerous studies on natural vanillin biosynthesis using microorganisms or enzymes have been conducted. Several potential feedstocks, including curcumin, Siam benzoin resin, phenolic stilbenes, eugenol, and ferulic acid, have been suggested for the production of vanillin (Ghosh Glycogen branching enzyme et al.,

2007; Unno et al., 2007; Yamada et al., 2007). However, these bioconversions are not yet economically feasible. A genetic approach to metabolic engineering has also been developed for the production of vanillin from eugenol and ferulic acid. Because some Pseudomonas strains metabolize these compounds with vanillin as an intermediate, the inactivation of vanillin dehydrogenase (VDH) enzyme by making a null mutant of the gene for vanillin accumulation has been investigated (Overhage et al., 1999). Vanillin (molar yield of 44.6% relative to the initial eugenol concentration) is obtained from eugenol by blocking vanillin catabolism in the mutant. These metabolic engineering approaches can be effective for vanillin production. Therefore, we attempted a novel approach for producing vanillin using microorganisms or their genetic mutants. Because a high concentration of ferulic acid can be dissolved under alkaline conditions (≥150 g L−1 at pH 10 vs. ≤15 g L−1 at pH 7 in our simple solubility examination), we screened an alkaliphile that can grow on ferulic acid as the sole carbon source.