African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12258

Full Length Research Paper

Optimization of biomass production of Acetobacter pasteurianus KU710511 as a potential starter for fruit vinegar production

Majid Mounir
  • Majid Mounir
  • Department of Food Science and Nutrition, Hassan II Institute of Agronomy and Veterinary Medicine, PB 6202 Rabat, Morocco.
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Rasoul Shafiei
  • Rasoul Shafiei
  • Department of Biology, Faculty of Science, University of Isfahan, Isfahan, Iran.
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Raziyeh Zarmehrkhorshid
  • Raziyeh Zarmehrkhorshid
  • Microbial Processes and Interactions, Gembloux Agro-Bio Tech, University of Liège, B-5030 Gembloux, Belgium.
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Allal Hamouda
  • Allal Hamouda
  • Department of Applied Statistics, Hassan II Institute of Agronomy and Veterinary Medicine, PB 6202 Rabat, Morocco.
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Philippe Thonart
  • Philippe Thonart
  • Microbial Processes and Interactions, Gembloux Agro-Bio Tech, University of Liège, B-5030 Gembloux, Belgium.
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Frank Delvigne
  • Frank Delvigne
  • Microbial Processes and Interactions, Gembloux Agro-Bio Tech, University of Liège, B-5030 Gembloux, Belgium.
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Mustapha Ismaili Alaoui
  • Mustapha Ismaili Alaoui
  • Department of Food Science and Nutrition, Hassan II Institute of Agronomy and Veterinary Medicine, PB 6202 Rabat, Morocco.
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  •  Received: 06 March 2016
  •  Accepted: 18 May 2016
  •  Published: 06 July 2016

Abstract

The objective of the present work was first the isolation of novel acetic acid bacteria strains from natural Moroccan habitats, and then, the evaluation of their ability to produce microbial starters for vinegar production on a large scale. The strains were isolated from figs, dates, cactus, and traditional fruit vinegars. Four strains, selected from a total of 63 isolates, were confirmed as belonging to Acetobacter species according to biochemical and molecular studies based on 16s rRNA sequence analysis. Acetous fermentation tests, performed on date and apple fermented juices using selected Acetobacter strains, showed a high capacity of acidification. The most efficient strain KU710511, isolated from Morrocan cactus (Opuntia ficus-indica), was identified as Acetobacter strain closely related to A. pasteurianus and yielded 42.5 g/L acidity in apple juice. Cell growth optimization was carried out for KU710511 using response surface methodology (RSM). The linear, quadratic, and interaction effects of four factors-ethanol, acetic acid, glucose concentrations and pH-were studied by the application of a central composite design. Thirty experiments were designed to predict the maximum concentration of cell biomass. The optimal calculated values of ethanol, acetic acid, glucose and pH allowing the prediction of the maximum biomass production (2.21 g/L) were 28.18, 10.12, 15.15 and 5.33 g/L, respectively. Subsequently, further batch fermentations were carried out in a 6-L lab-bioreactor at optimal conditions. The results were in line with the predicted values. It can be concluded that the studied strain is well suited to be used as a parental strain to prepare a starter for fruit vinegar production.

 

Key words: Isolation, vinegar, starter, Acetobacter, acetic fermentation, response surface methodology.