Screening a Strain of Klebsiella sp. O852 and the Optimization of Fermentation Conditions for Trans-Dihydrocarvone Production

Abstract

Flavors and fragrances have high commercial value in the food, cosmetic, chemical and pharmaceutical industries. It is interesting to investigate the isolation and characterization of new microorganisms with the ability to produce flavor compounds. In this study, a new strain of Klebsiella sp. O852 (accession number CCTCC M2020509) was isolated from decayed navel orange (Citrus sinensis (L.) Osbeck), which was proved to be capable of converting limonene to trans-dihydrocarvone. Besides, the optimization of various reaction parameters to enhance the trans-dihydrocarvone production in shake flask was performed for Klebsiella sp. O852. The results showed that the yield of trans-dihydrocarvone reached up to 1 058 mg/L when Klebsiella sp. O852 was incubated using LB-M medium for 4 h at 36 °C and 150 rpm, and the biotransformation process was monitored for 36 h after adding 1680 mg/L limonene/ethanol (final ethanol concentration of 0.8% (v/v)). The content of trans-dihydrocarvone increased 16 times after optimization. This study provided a basis and reference for producing trans-dihydrocarvone by biotransformation.

Bioactive properties of the aromatic molecules of spearmint (Mentha spicataL.) essential oil: a review

“…O852 is capable of converting limonene to carveol, carvone and dihydrocarvone, oxidizing carveol to carvone and dihydrocarvone, and catalyzing carvone to form dihydrocarvone. 14,19 In another report, the synthesis of carveol and dihydrocarvone by asymmetric reduction of carvone was performed using ketoreductases and ene-reductases, respectively. Dihydrocarvone obtained was further converted into dihydrocarveol catalyzed by ketoreductases.…”

“…The aromatic molecules of spearmint essential oil are widely used in the industry, mainly as aroma in food (bakery product, candy, chewing gum, beverages, condiments) and as fragrance in cosmetics and toiletries (fragrances, shampoos, toilet soaps, toothpaste). 13,14,154 It is reported that the global market of aromas and fragrances including spearmint aromatic molecules (carvone, USD 350 L −1 ; carveol, USD 529 L −1 ) has reached US$ 28.2 billion in 2017, marking an increase of 4.6% as compared with 2016. It is expected that the market is growing at 4.9% per annum to reach approximately US$ 36 billion in 2022.…”

“…Other spearmint aromatic molecules including carveol, dihydrocarvone, dihydrocarveol and dihydrocarvyl acetate are widely used as taste and appetite enhancers in food and beverages, and as flavor additives in cosmetics, perfumes, shampoos, toilet soaps, toothpastes and other oral hygiene products. 13,14 Carveol ( p -mentha-6,8-dien-2-ol) is a limonene monoterpenoid that is cyclohex-2-en-1-ol substituted by a methyl group at position 2 and a prop-1-en-2-yl group at position 5. It appears as a pale yellow or colorless liquid with a spearminty odour.…”

“…Dihydrocarvone is a component of dill oil, caraway seeds, and the essential oils of M. spicate . 14 Besides, dihydrocarveol (8- p -menthen-2-ol) is a p -menthane monoterpenoid which is the dihydro derivative of carveol. It is a p -menthane monoterpenoid and a secondary alcohol.…”

Identification of functional genes associated with the biotransformation of limonene to trans‐dihydrocarvone in Klebsiella sp. O852

“…The dihydrocarvone biosynthetic pathway and related enzyme genes have been studied and elucidated. To the best of our knowledge, dihydrocarvone could be yielded by carvone hydrogenation or limonene oxidation 14 . Oxidation of limonene to dihydrocarvone can occur via three enzymatic steps, with carveol and carvone as intermediate products 15 .…”