Biotechnological Production of Methyl-Branched Aldehydes

Abstract

A number of methyl-branched aldehydes impart interesting flavor impressions, and especially 12-methyltridecanal is a highly sought after flavoring compound for savory foods. Its smell is reminiscent of cooked meat and tallow. For the biotechnological production of 12-methyltridecanal, the literature was screened for fungi forming iso-fatty acids. Suitable organisms were identified and successfully grown in submerged cultures. The culture medium was optimized to increase the yields of branched fatty acids. A recombinant carboxylic acid reductase was used to reduce 12-methyltridecanoic acid to 12-methyltridecanal. The efficiency of whole-cell catalysis was compared to that of the purified enzyme preparation. After lipase-catalyzed hydrolysis of the fungal lipid extracts, the released fatty acids were converted to the corresponding aldehydes, including 12-methyltridecanal and 12-methyltetradecanal.

In Vivo Reduction of Medium‐ to Long‐Chain Fatty Acids by Carboxylic Acid Reductase (CAR) Enzymes: Limitations and Solutions

“…Overreduction, a mechanism to minimize cytotoxicity of certain compounds by the cell, constantly interfered with aldehyde titers. For this reason, not many studies focused on fatty aldehydes as the final product . On the contrary, they exploited this effect to optimize fatty alcohol or alkane titers.…”

“…For this reason, not many studies focused on fatty aldehydes as the final product. [46] On the contrary, they exploited this effect to optimize fatty alcohol [28,47] or alkane [27,48] titers. To overcome overreduction of fatty aldehydes, we screened 30 single gene deletion strains of E. coli BW25113 from the Keio Collection [49] to find a strain, which might have a decreased defense mechanism for fatty aldehydes (data not shown).…”

Branched-Chain Fatty Acids as Mediators of the Activation of Hepatic Peroxisome Proliferator-Activated Receptor Alpha by a Fungal Lipid Extract

“…Conidiobolus heterosporus Drechsler 1953, which belongs to the phylum Zygomycota, order Entomophtorales, family Ancylistaceae and the genus Conidiobolus, was obtained from Centraalbureau voor Schimmelcultures (CBS 138.57; Utrecht, Netherlands), and grown in submerged cultures following a previously described method [19]. For the precultures, 100 mL of yeast extract (3 g/L) and malt extract (30 g/L) (YM) medium (Merck KGaA, Darmstadt, Germany) in 250 mL Erlenmeyer flasks was used.…”

“…Total lipids were extracted by the Soxhlet method. After saponification of 150 mg CHLE with 4 mL 0.5 M NaOH in methanol (80 • C, 10 min), free fatty acids were converted into their corresponding fatty acid methyl esters (FAMEs) by addition of 3.5 mL boron trifluoride-methanol solution (20%) and heating to 80 • C for 5 min as described previously [19]. After addition of 1 mL n-hexane and incubation at 80 • C for 1 min, 3 mL saturated NaCl solution was added.…”

Structure-guided function discovery of an NRPS-like glycine betaine reductase for choline biosynthesis in fungi

“…4 CARs also show substantial promise as green biocatalysts for the conversion of aromatic, or aliphatic carboxylic acids into the corresponding aldehydes. Indeed, synthetic applications of CARs have been reported for biocatalytic synthesis of vanillin; 5 preparation of methyl branched aliphatic aldehydes; 6 production of biofuels, [7][8] and other chemical commodities. 9 Prominent metabolic roles of CARs and their biocatalytic potential encouraged us to discover new members with novel functions by genome mining.…”