Influence of nickel on butanol production by Clostridium beijerinckii using hydrolyzate from green coconut shell

Abstract

The improvement of biotechnological processes capable of transforming agro-industrial waste into products with high added value has stood out in the area of renewable energies, promoting positive impacts to the environment. Thus, the present work evaluated the influence of nickel on the conversion of fermentable sugars, present in the green coconut shell hydrolyzate (GCSH), into butanol and other products. Fermentation assays were performed at 37 °C, starting with 19.4 g.L-1 of sugars and 1.0 g.L-1 of inoculum (C. beijerinckii). The GCSH was supplemented with tryptone, yeast extract, ammonium acetate, minerals and phosphate buffer. Two conditions were tested: with and without addition of nickel. Concentrations of sugars (glucose and xylose), intermediate products (organic acids), acetone, butanol, and ethanol were determined by high performance liquid chromatography (HPLC). The results show that the butanol production was higher from GCSH without addition of nickel, reaching a concentration of 2.14 g.L-1 of butanol. Therefore, the presence of nickel in the hydrolyzate was not favorable in the production of butanol under the studied process conditions.