Abstract: An improved process for the biomethanation of an organic substrate includes treating the substrate in a first reactor to form organic acid anions, passing an aqueous preparation containing dissolved organic anions through an ion exchanger so that the organic acid anions are adsorbed and separated from the remainder of the aqueous preparation, desorbing; the organic acid anions and passing the desorbed acids to a second reactor containing methanogenic bacteria which convert the acids to methane. In a preferred embodiment, a bicarbonate solution is produced in the second reactor and it is used to desorb the organic acid anions and regenerate the anion exchanger into the bicarbonate form. A preferred apparatus first and second reactors, and a pair of anion exchangers connected by tubing to both reactors also is disclosed.

Abstract: A formate salt is used as part of the fermentable carbon-containing material in an anaerobic fermentation to produce acetic acid. Acetate salt formed in the fermentation is converted to free acetic acid with formic acid, which in turn is changed to formate salt. This formate salt then is used as a carbon source for another fermentation.

Abstract: A process for the production of 3,4-dideoxyhexitol and for its cyclodehydration to 2,5-bis(hydroxymethyl)tetrahydrofuran. The 3,4-dideoxyhexitol is obtained by hydrogenolysis in the presence of a copper chromite catalyst, of hexitols, or of compound which undergo reaction with hydrogen to give hexitols.

Abstract: Acetic, propionic, and butyric acids are produced by a two-step fermentation process. Lactate salts formed in the second fermentation step, a biochemical acidification step, are used as the carbon source in the first fermentation step.

Abstract: An improved method of preparing high maltose conversion syrups and other sweeteners from starch substrates comprises saccharifying the starch at higher temperatures than presently used with environmentally compatible thermostable .beta.-amylase and other thermostable enzymes.

Abstract: An improved process for the biomethanation of an organic substrate includes treating the substrate in a first reactor to form organic acid anions, passing an aqueous preparation containing dissolved organic anions through an anion exchanger so that the organic acid anions are adsorbed and separated from the remainder of the aqueous preparation, desorbing the organic acid anions and passing the desorbed acids to a second reactor containing methanogenic bacteria which convert the acids to methane. In a preferred embodiment, a bicarbonate solution is produced in the second reactor and it is used to desorb the organic acid anions and regenerate the anion exchanger into the bicarbonate form.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.