Biotechnological Products and Process Engineering

Applied Microbiology and Biotechnology

, Volume 89, Issue 4, pp 1039-1049

Isolation and characterisation of lactic acid bacterium for effective fermentation of cellobiose into optically pure homo l-(+)-lactic acid

  • Mohamed Ali Abdel-RahmanAffiliated withLaboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu UniversityBotany and Microbiology Department, Faculty of Science (Boys), Al-Azhar University
  • , Yukihiro TashiroAffiliated withDepartment of Life Study, Seinan Jo Gakuin University Junior College
  • , Takeshi ZendoAffiliated withLaboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
  • , Keisuke ShibataAffiliated withLaboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
  • , Kenji SonomotoAffiliated withLaboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu UniversityLaboratory of Functional Food Design, Department of Functional Metabolic Design, Bio-Architecture Center, Kyushu University Email author 

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Abstract

Effective utilisation of cellulosic biomasses for economical lactic acid production requires a microorganism with potential ability to utilise efficiently its major components, glucose and cellobiose. Amongst 631 strains isolated from different environmental samples, strain QU 25 produced high yields of l-(+)-lactic acid of high optical purity from cellobiose. The QU 25 strain was identified as Enterococcus mundtii based on its sugar fermentation pattern and 16S rDNA sequence. The production of lactate by fermentation was optimised for the E. mundtii QU25 strain. The optimal pH and temperature for batch culturing were found to be 7.0°C and 43°C, respectively. E. mundtii QU 25 was able to metabolise a mixture of glucose and cellobiose simultaneously without apparent carbon catabolite repression. Moreover, under the optimised culture conditions, production of optically pure l-lactic acid (99.9%) increased with increasing cellobiose concentrations. This indicates that E. mundtii QU 25 is a potential candidate for effective lactic acid production from cellulosic hydrolysate materials.

Keywords

l-Lactic acid production Glucose Cellobiose Mixed sugars Enterococcus mundtii