Identification and in situ removal of an inhibitory intermediate to develop an efficient phytosterol bioconversion...

Area of Science:

• Biotechnology
• Microbial Biotransformation
• Steroid Chemistry

Background:

• 9α-hydroxyandrost-4-ene-3,17-dione (9α-OH-AD) is a versatile steroid intermediate.
• Phytosterol (PS) bioconversion using Mycobacterium is a key method for 9α-OH-AD production.
• Metabolic intermediate inhibition limits the efficiency of PS bioconversion.

Purpose of the Study:

• To identify inhibitory metabolic intermediates in PS bioconversion to 9α-OH-AD.
• To enhance 9α-OH-AD production efficiency by mitigating intermediate inhibition.
• To optimize the cyclodextrin-resting cell reaction system for industrial-scale production.

Main Methods:

• Utilized a cyclodextrin-resting cell system for high-concentration PS bioconversion.
• Separated and identified metabolic intermediates using analytical techniques.
• Employed macroporous adsorbent resin D101 for *in situ* removal of inhibitory compounds.

Main Results:

• Identified 4-ene-3-keto steroids as key inhibitory metabolites.
• Addition of D101 resin significantly reduced intermediate inhibition.
• Achieved a 23.15% increase in 9α-OH-AD space-time yield (8.51 g L^-1 d^-1) compared to the control (6.91 g L^-1 d^-1) after 72 hours.

Conclusions:

• 4-ene-3-keto steroids are identified as critical inhibitors in PS to 9α-OH-AD bioconversion.
• Macroporous adsorbent resin D101 effectively removes inhibitory intermediates, enhancing production.
• Resin-assisted bioconversion offers a viable strategy for improving industrial-scale 9α-OH-AD manufacturing.