Frank W. Welsh

Microbiological and Enzymatic Production of Flavor and Fragrance Chemicals

(1989). Microbiological and Enzymatic Production of Flavor and Fragrance Chemicals. Critical Reviews in Biotechnology: Vol. 9, No. 2, pp. 105-169.

Lipase-mediated production of ethyl butyrate and butyl butyrate in nonaqueous systems

Lipases (EC 3.1.1.3) from Candida cylindracea, porcine pancreas, and Aspergillus niger (two types) were compared as catalysts for ethyl butyrate and butyl butyrate synthesis at 30 and 50°C using hexane as a reaction medium. Each enzyme had a distinct pH profile. The esterification catalysed by each lipase was inhibited by increasing the substrate concentration beyond a defined amount, but the concentration required varied from enzyme to enzyme and with the ester being formed. When the reaction temperature was raised from 30 to 50°C, ethyl butyrate synthesis was inhibited while butyl butyrate synthesis was enhanced with all enzymes tested. Overall, Candida cylindracea lipase produced the highest concentrations and yields of both esters.

Solid carriers for a Clostridium acetobutylicum that produces acetone and butanol

Abstract Several high strength solids have been tested as carriers for acetone-butanol production by Clostridium acetobutylicum ATCC 824. In batch fermentation, coke, kaolinite and Gel White ( a montmorillonite clay ) appeared to have a beneficial effect on this fermentation, although the effectiveness appeared to be dependent on the medium used. One of the least expensive materials, coke, was found to be suitable for use in continuous culture. Steady state conditions could be maintained for more than 30 days with total solvent production, productivity and yield of 12 g/l, 1.12 g l −1 h −1 and 0.3 g TS/g glucose used, respectively .

Production of acetone-butanol from acid whey

SummaryClostridium acetobutylicum ATCC 824 was used to produce butanol and acetone by fermenting acid whey. Results showed that both autoclaving and agitation played roles in solvent production. Maximum production was obtained in 120 h using autoclaved, pH adjusted (6.0) acid whey at 37 °C in a fermentor that was not agitated.

Organic and inorganic nitrogen source effects on the metabolism of Clostridium acetobytulicum

SummaryThe effects of organic and inorganic nitrogen combinations on cell growth, solvent production and nitrogen utilization by Clostridium acetobutylicum ATCC 824 was studied in batch fermentations. Fermentations in media with 10 mM glutamic acid, as the organic nitrogen source, and 0 mM to 10 mM ammonium chloride, as the inorganic nitrogen source had a solvent yield of 0.8 to 1.08 mmol solvent/mmol glucose used, with a slow fermentation rate (2 mmol solvent/l h-1). When media contained 20 mM or 30 mM glutamic acid as well as 2.5 to 7.5 mM ammonium chloride the fermentation rate increased (5.5 mmol/l h-1) while the solvent yield remained constant (0.86 to 0.96 mmol solvent/mmol glucose used). Total solvent production was higher in media containing 20 mM or 30 mM glutamic acid than with 10 mM glutamic acid.

The metabolism of lactose byClostridiumacetobutylicum

SummaryAcetone and butanol biosynthesis byClostridiumacetobutylicum ATCC 824 was affected by lactose concentration and by agitation during the fermentation. At 1% and 3% lactose concentrations acid production predominated, while butanol production predominated at 5% lactose concentration. Higher solvent production was observed in fermentors without agitation than in fermentors with agitation.