Phenyl Ethyl Alcohol exists in many plants, especially flowers, such as the essential oils of hyacinth, jasmine, narcissus, lily, etc., but its content is too low to be extracted. The only exception is rose essential oil, from which some species of rose essential oil can obtain Phenyl Ethyl Alcohol in concentrations of more than 60%. However, the production cycle of extracting natural phenylethyl alcohol from roses is long and the cost is high, and large-scale industrial production cannot be carried out to meet the needs of the market.
At present, the vast majority of Phenyl Ethyl Alcohol is chemically synthesized from benzene or styrene, and its raw materials are carcinogens, which are harmful to human health and the environment. In addition, chemical synthesis port-Phenyl Ethyl Alcohol often contains some by-products that are difficult to remove, which seriously affects the product quality.
Synthesis by using microorganisms as production strains can overcome the above shortcomings. Many foods produced by microbial fermentation contain Phenyl Ethyl Alcohol, such as cocoa, coffee, bread, beer, cheese, etc. In particular, Ehrlich (Ehrlich) found that adding phenylalanine (L-Phe) to yeast culture can greatly improve the yield of Phenyl Ethyl Alcohol.
Most microorganisms, especially yeast, can produce Phenyl Ethyl Alcohol through normal metabolic pathways. Phenyl Ethyl Alcohol is produced by yeast by converting phenylalanine in the fermentation broth during the fermentation process. As for the metabolic pathway, phenethyl alcohol can also be synthesized de novo through the shikimate pathway as shown in Figure 2-7. Glucose produces phosphoenolpyruvate through the glycolytic pathway (EMP) and 4-phosphate erythrose through the pentose phosphate pathway (HMP), both in 2-keto-3-deoxy-D-arabinoheptulose. Under the action of acid-7-phosphate synthase (DAHP synthase), shikimic acid is formed through the intermediate DAHP. Shikimic acid passes through the intermediates chorismic acid and prebenzoic acid to form phenylpyruvate under the action of chorismate mutase and prebenzoic acid dehydratase. On the one hand, phenylpyruvate can generate phenylethyl alcohol through phenylacetaldehyde, and on the other hand. In one aspect, L-Phe can also be formed by transamination with L-glutamic acid. DAHP synthase and prephenate dehydratase in the metabolic pathway are feedback-inhibited by L-Phe. L-Phe forms phenylpyruvate through the action of transaminase, which is decarboxylated by phenylpyruvate decarboxylase to form phenylacetaldehyde, which is then catalyzed by alcohol dehydrogenase to generate phenylethyl alcohol. Ehrlich also pointed out that there is a close relationship between the amount of added L-Phe and the final yield of phenethyl alcohol when describing this approach. This pathway is currently the main way to use microbial transformation to produce phenylethanol.
A variety of yeasts have the ability to synthesize JB-Phenyl Ethyl Alcohol de novo. For example, when Kluyveromyces marxianus is fermented for 5 days, it can produce a concentration of 400 mg/L of Phenyl Ethyl Alcohol III. Fermentation of Pichia fermentans for 16h can form Phenyl Ethyl Alcohol with a concentration of 505.5mg/L. In addition, there are Saccharomyces vini, Toru-lopsis utilis, Cladosporium cladosporioides, Kluyveromyces lactis, Saccharomyces cerevisiae, abnormal Hansenula Yeast (Hansenula anomala), etc. can synthesize a certain amount of phenethyl alcohol M 6I de novo during the growth process. This pathway exists widely in microorganisms, but because the metabolic pathway is too long, there are too many branches, and there are various inhibitory effects, the final yield of Phenyl Ethyl Alcohol is very low.
