African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12237

Full Length Research Paper

Enhanced biomass production study on probiotic Bacillus subtilis SK09 by medium optimization using response surface methodology

  G. Sreekumar1* and Soundarajan Krishnan2  
  1Department of Biotechnology, St. Joseph’s College of Engineering, Chennai, India. 2Department of Chemical Engineering, Sathyabama University, Chennai, India.  
Email: [email protected]

  •  Accepted: 08 October 2010
  •  Published: 22 November 2010



The culture conditions of lactose fermenting, spore forming probiotic Bacillus subtilis SK09 isolated from dairy effluent were optimized by response surface methodology to maximize the biomass production. The student’s t-test of the Placket-Burman screening design revealed that the effects of pH, ammonium citrate and peptone were more significant and these variables were further optimized using central composite design. The various effects of the variables were studied using Fisher’s F-test for analysis of variance and a second order polynomial model was developed which fitted well with high statistical reliability and significance. The optimal value of significant variables was found to be pH (6.72), ammonium citrate (0.164%) and peptone (0.85%). At these optimized conditions, the maximum biomass yield was estimated to be 10.051*109 CFU/ml. By employing this statistical design, enhanced yield of probiotic biomass B. subtilisSK09 was achieved using cost-effective medium.


Key words: Probiotics, response surface methodology, central composite design,Bacillus subtilis SK09, lactose intolerance disorder.



Abbreviations: RSM, Response surface methods; CCD, complete central composite design.