A pH-controlled fed-batch process can overcome inhibition by formate in NADH-dependent enzymatic reductions using formate dehydrogenase-catalyzed coenzyme regeneration

9α-Hydroxy-4-androstene-3,17-dione (9-OH-AD) is one of the significant intermediates for the preparation of β-methasone, dexamethasone, and other steroids. In general, the key enzyme that enables the biotransformation of 4-androstene-3,17-dione (AD) to 9-OH-AD is 3-phytosterone-9α-hydroxylase (KSH), which consists of two components: a terminal oxygenase (KshA) and ferredoxin reductase (KshB). The reaction is carried out with the concomitant oxidation of NADH to NAD+. In this study, the more efficient 3-phytosterone-9α-hydroxylase oxygenase (KshC) from the Mycobacterium sp. strain VKM Ac-1817D was confirmed and compared with reported KshA. To evaluate the function of KshC on the bioconversion of AD to 9-OH-AD, the characterization of KshC and the compounded system of KshB, KshC, and NADH was constructed. The optimum ratio of KSH oxygenase to reductase content was 1.5:1. An NADH regeneration system was designed by introducing a formate dehydrogenase, further confirming that a more economical process for biological transformation from AD to 9-OH-AD was established. A total of 7.78 g of 9-OH-AD per liter was achieved through a fed-batch process with a 92.11% conversion rate (mol/mol). This enzyme-mediated hydroxylation method provides an environmentally friendly and economical strategy for the production of 9-OH-AD.

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A pH-controlled fed-batch process for dextransucrase production

Journal of Chemical Technology & Biotechnology ◽

10.1002/jctb.280480403 ◽

2007 ◽

Vol 48 (4) ◽

pp. 405-414 ◽

Cited By ~ 20

Author(s):

Donald E. Brown ◽

Alexander McAvoy

Keyword(s):

Batch Process ◽

Fed Batch ◽

Ph Controlled

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Production of Rhamnolipid Biosurfactant from Fed Batch Culture by Pseudomonas aeruginosa using Multiple Substrates

Current Nutrition & Food Science ◽

10.2174/1573401314666181107100127 ◽

2020 ◽

Vol 16 (6) ◽

pp. 928-933

Author(s):

Jujjavarapu S. Eswari

Keyword(s):

Pseudomonas Aeruginosa ◽

Batch Process ◽

Time Interval ◽

Fed Batch ◽

Multiple Substrates ◽

Surface Active Agents ◽

Limiting Nutrients ◽

Limiting Nutrient ◽

Surface Active ◽

Rhamnolipid Biosurfactant

Objective: Biosurfactants are the surface active agents which are used for the reduction of surface and interfacial tensions of liquids. Rhamnolipids are the surfactants produced by Pseudomonas aeruginosa. It requires minimum nutrition for its growth as it can also grow in distilled water. The rhamnolipids produced by Pseudomonas aeruginosa are extra-cellular glycolipids consisting of L-rhamnose and 3-hydroxyalkanoic acid. Methods: The fed-batch method for the rhamnolipid production is considered in this study to know the influence of the carbon, nitrogen, phosphorous substrates as growth-limiting nutrients. Pulse feeding is employed for limiting nutrient addition at particular time interval to obtain maximum rhamnolipid formation from Pseudomonas aeruginosa compared with the batch process. Results: Out of 3 fed batch strategies constant glucose fed batch strategy shows best and gave maximum rhamnolipid concentration of 0.134 g/l.

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