Fermentative conversion of raw glycerol into 1,3- propanediol by isolated <i>Klebsiella pneumoniae</i> 141B stain: Optimization of culture variables

Abstract

In this study, 1,3-propanediol (1,3-PDO) production by Klebsiella pneumoniae 141B strain using raw glycerol as substrate was investigated. Taguchi L18 orthogonal array (OA) was adopted to optimize nutritional (raw glycerol, yeast extract and calcium carbonate), physiological (incubation temperature and medium pH) and microbial (inoculum level) fermentation variables. These controlling fermentation factors were selected based on one variable at a time methodology. Raw glycerol, temperature and calcium carbonate were the most significant factors among the selected factors followed by pH and inoculum level. Yeast extract, however, showed the least significance on 1,3-PDO production at individual level, while in combination, it elucidated a remarkable severity index values of 64.81 and 58.17% with pH and temperature, respectively. At optimized environment, 53% contribution towards 1,3- PDO production was observed from selected fermentation parameters. The model was experimentally validated, yielding a 1,3-PDO production of 0.62 mol mol^-1 of raw glycerol, which represented a 19% increase when compared to the non-optimized medium.

Key words: Raw glycerol, 1,3-propanediol, Taguchi methodology, Klebsiella pneumoniae and optimization.