Michigan Biotechnology Institute

Hyung-Hwan Hyun

Joseph G Zeikus

A method is disclosed for producing catabolite repression-resistant mutant strains of C. thermosulfurogenes and C. thermohydrosulfuricum. The method comprises challenging a wild strain of the organism with nitrosoguanidine, followed by enrichment on 2-deoxyglucose and culturing an iodine stained starch-glucose containing agar. The colonies which convert starch most efficiently are catabolite repression-resistant. Pure cultures of the mutants and methods employing the mutants to prepare enzymes are also described.

Regulation and enhancement of enzyme production

A thermostable and thermoactive, extracellular .beta.-amylase is produced by Clostridium thermosulfurogenes. Methods of producing the .beta.-amylase and using it to convert starch to maltose are also disclosed.

Thermostable beta-amylase

A thermostable pullulanase and a thermostable glucoamylase are produced by Clostridium thermohydrosulfuricum. Methods of producing the enzymes and using them to hydrolyze starch are also disclosed.

Thermostable starch converting enzymes

Starch is converted directly to ethanol by growing a co-culture of Clostridium thermosulfurogenes and Clostridium thermohydrosulfuricum under anaerobic conditions on a starch containing substrate in a medium comprising essential vitamins, minerals and growth factors. The co-culture also produces the thermostable enzymes .beta.-amylase, glucoamylase and pullulanase.

Growing community of inventors

Madison, WI, United States of America

Hyung-Hwan Hyun