Exponential Growth and Solvents-Production of <i>Clostridium acetobutylicum</i> ATCC 824 on TYA Media Containing Sucrose and Glucose as Different Sole Carbon Sources

Abstract

Abstract:Clostridium acetobutylicum ATCC 824 is a solventogenic, obligate anaerobic bacterium that can grow on various types of carbohydrates and are capable of producing spores. In the present study, Clostridium acetobutylicum was successfully grown on TYA medium (tryptone, yeast, acetate medium) containing two different carbon sources, glucose and sucrose coupled with the production of acids (butyric and acetic acid) and solvents, ABE (acetone, butanol and ethanol). An investigation was undertaken to determine the impact of the two types of carbon sources on the solvent production and growth of Clostridium acetobutylicum. HPLC and GC analysis revealed the amount of acids and solvents produced respectively, as well as the amount of unutilized sugars. The amount of combined ABE produced on glucose (0.19g/l A, 0.39g/l B, 0.06g/l E) was higher than on sucrose as carbon source (0.15g/l A, 0.30g/l B, 0.03g/l E). The colony forming units of Clostridium acetobutylicum grown on glucose (4.70 x 10 5 units/ml) was higher than on sucrose (0.1 x 10 5 ) as judged by dilution spread plating on agar. Hence, Glucose was confirmed as the carbon source characterized by the best performance for solvents production and growth of the bacterium. The whole production process on both glucose and sucrose was observed to mainly influence the production of butanol with the concentration of 0.39g/l and 0.30g/l respectively, over the production of other solvents. Higher amount of solvents was produced at lower pH in both cultures with the different carbon sources. Wet-mounts, gram stain and endospore stain were used to determine the motility, type and sporulation of Clostridium acetobutylicum respectively. Acidogenic phase which seems to couple with the growth of vegetative cells, results into production of acetic and butyric acids. Solventogenic phase commences with a drop in pH and is accompanied by the onset of sporulation.