African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12212

Full Length Research Paper

A comparative study on bacterial conversion of selected agricultural biomass to ethanol

Oso B. A.
  • Oso B. A.
  • Department of Biological Sciences, Afe Babalola University, P. M. B. 5454, Ado-Ekiti, Ekiti State, Nigeria.
  • Google Scholar
Ogunnusi T. A.
  • Ogunnusi T. A.
  • Department of Biological Sciences, Afe Babalola University, P. M. B. 5454, Ado-Ekiti, Ekiti State, Nigeria.
  • Google Scholar
Oyetunji O. A.
  • Oyetunji O. A.
  • Department of Biological Sciences, Afe Babalola University, P. M. B. 5454, Ado-Ekiti, Ekiti State, Nigeria.
  • Google Scholar


  •  Received: 10 October 2017
  •  Accepted: 05 January 2018
  •  Published: 07 February 2018

Abstract

The aim of the study was to investigate the bioethanol production potentials by indigenous bacterial isolates screened for amylolytic and cellulolytic activities. Cassava peels were obtained from local ‘garri’ producers, while corn grains and corn cobs were gotten from retailers within the Erinfun farm settlement along Afe Babalola University Road, Ado-Ekiti, Ekiti State, Nigeria on June 4, 2015. The substrates (corn flour, corn cob and cassava peels) were sundried for 5 days and ground into fine powder using a hammer mill and analyzed for proximate nutrient composition and reconstituted to a 5% concentration in water before fermentation. The fermentation was set up for 20 days using single cultures of bacteria and co-cultures of bacteria and yeast selectively isolated and screened for amylolytic and cellulolytic activities. Parameters such as pH, total titratable acidity, reducing sugar and optical density were taken at intervals of 5 days and ethanol production was analyzed at the end of fermentation. Three bacterial isolates (Bacillus macerans, Bacillus subtilis and Micrococcus varians) yielded ethanol in all the feed stocks. The highest percentage ethanol yield was observed in the fermentation of corn flour and corn cobs with B. macerans which were 3.6 ± 0.009 and 3.5 ± 0.009, respectively. There was reduction in the pH and total titratable acidity and increase in the reducing sugar content and optical density. B. macerans exhibited the highest average ethanol production (3.5±0.07%). A proximate analysis of the feed stocks showed presence of nitrogen, protein, fat, carbohydrate and ash. This study investigated the potentials of wastes (cassava peels and corn cob) used as feed stocks for bio-ethanol production, in substantially replacing major food crops (corn) as a case study.

 

Key words: Fermentation, amylolytic activity, cellulolytic activity, corn flour, corn cob, cassava peels, feed stocks.