Production of multiple extracellular enzyme activities by novel submerged culture of Aspergillus kawachii for ethanol production from raw cassava flour

Abstract

Cassava is a starch-containing root crop that is widely used as a raw material in a variety of industrial applications, most recently in the production of fuel ethanol. In the present study, ethanol production from raw (uncooked) cassava flour by simultaneous saccharification and fermentation (SSF) using a preparation consisting of multiple enzyme activities from Aspergillus kawachii FS005 was investigated. The multi-activity preparation was obtained from a novel submerged fermentation broth of A. kawachii FS005 grown on unmilled crude barley as a carbon source. The preparation was found to consist of glucoamylase, acid-stable α-amylase, acid carboxypeptidase, acid protease, cellulase and xylanase activities, and exhibited glucose and free amino nitrogen (FAN) production rates of 37.7 and 118.7 mg/l/h, respectively, during A. kawachii FS005-mediated saccharification of uncooked raw cassava flour. Ethanol production from 18.2% (w/v) dry uncooked solids of raw cassava flour by SSF with the multi-activity enzyme preparation yielded 9.0% (v/v) of ethanol and 92.3% fermentation efficiency. A feasibility study for ethanol production by SSF with a two-step mash using raw cassava flour and the multi-activity enzyme preparation manufactured on-site was verified on a pilot plant scale. The enzyme preparation obtained from the A. kawachii FS005 culture broth exhibited glucose and FAN production rates of 41.1 and 135.5 mg/l/h, respectively. SSF performed in a mash volume of about 1,612 l containing 20.6% (w/v) dry raw cassava solids and 106 l of on-site manufactured A. kawachii FS005 culture broth yielded 10.3% (v/v) ethanol and a fermentation efficiency of 92.7%.

Cassava pulp enzymatic hydrolysis process as a preliminary step in bio-alcohols production from waste starchy resources

“…1). This concurs with the reported by Sugimoto et al (2011) that the starch granules in cassava are large and complex structures, and so a high level of enzyme in the reactor is required. Without freeing the starch from the hemicelluloses and lignin in CP, the conversion of starch to glucose, and thus the yields of both released reducing sugars and consequentially ethanol or ABE fermented products, may not be very successful.…”

Viscosity reduction of cassava for very high gravity ethanol fermentation using cell wall degrading enzymes from Aspergillus aculeatus

“…Ethanol production by SSF of raw cassava flour (18.2% dried solid) using a complex enzyme from Aspergillus kawachii consisting glucoamylase, acidstable ␣-amylase, cellulase, xylanase, and protease activities in pilot scale was also reported with high efficiency [34]. In contrast, a non-thermal un-cooked process for ethanol production by VHG fermentation from cassava was employed in this study.…”

Production of cellulolytic enzymes from ascomycetes: Comparison of solid state and submerged fermentation

“…The reducing sugars can then be measured by either using DNS reagent [16] or the method of Somogyi-Nelson [19,20]. Furthermore, for increased sensitivity of sugar detection high performance liquid chromatography (HPLC) [21,22] or high performance anion exchange chromatography (HPAEC) can be used [23]. Measurement of monomer sugars via HPLC has been applied for analysis of carbohydrate content of liquid fractions obtained from biomass pretreatment [24].…”