Regulation of metabolism bacteria Clostridum thermocellum in the fermentation of ethanol [mutagenesis]
1983
Steiner Biocic, I. (Prehrambeno tehnoloski fakultet, Osijek (Yugoslavia)) | Wang, D.I.C. | Korculanin, A.
This paper investigates regulation of Clostridium thermocellum metabolism in fermentation of cellulose into ethanol. Microorganism C. thermocellum 27405 ATCC (American Type Culture Collection, Rochville, Maryland, USA) was used for investigation. The following was concluded: -Small ethanol quantities (1% v/v) inhibit the growth of bacteria by 50% of the best growth achieved in the medium without ethanol. -By gradually accustoming bacteria to increasing ethanol quantities in media with 3 carbohydrate substrates, mutant S-6 was separated. -Ethanol, lactic and acetic acid are formed as fermentation products of pure Solka Folc cellulose and complex maize stalk celluose substrate. -After the mutagenes treatment mutant C. thermocellum S-7 was separated too, having much better properties than C. thermocellum S-6, i.e. fermenting cellulose substrates much more rapidly and giving higher biomass growth, not producing lactic acid and giving more ethanol and less acetic acid, so its emzymes have higher cellulolytic activity. -Much higher tolerance of the S-7 than of S-6 type of ethanol was achieved by gradual accustoming. -C. thermocellum S-7 type does not ferment pentoses, so it is cultivated in companion culture with C. thermosaccharolyticum HG-4 which ferments them, and a complete sugar fermentation with a 100% reducing sugar utilization on ethanol and 45% cellulose utilization on ethanol is achieved.
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