Batch, design optimization, and DNA sequencing study for continuous 1,3-propanediol production from waste glycerol by a soil-based inoculum

Appl Microbiol Biotechnol. 2015 Mar;99(5):2105-17. doi: 10.1007/s00253-014-6259-5. Epub 2014 Dec 6.

Abstract

1,3-propanediol (1,3-PD) was produced with a robust fermentation process using waste glycerol feedstock from biodiesel production and a soil-based bacterial inoculum. An iterative inoculation method was developed to achieve independence from soil and selectively breed bacterial populations capable of glycerol metabolism to 1,3-PD. The inoculum showed high resistance to impurities in the feedstock. 1,3-PD selectivity and yield in batch fermentations was optimized by appropriate nutrient compositions and pH control. The batch yield of 1,3-PD was maximized to ~0.7 mol/mol for industrial glycerol which was higher than that for pure glycerin. 16S rDNA sequencing results show a systematic selective enrichment of 1,3-PD producing bacteria with iterative inoculation and subsequent process control. A statistical design of experiments was carried out on industrial glycerol batches to optimize conditions, which were used to run two continuous flow stirred-tank reactor (CSTR) experiments over a period of >500 h each. A detailed analysis of steady states at three dilution rates is presented. Enhanced specific 1,3-PD productivity was observed with faster dilution rates due to lower levels of solvent degeneration. 1,3-PD productivity, specific productivity, and yield of 1.1 g/l hr, 1.5 g/g hr, and 0.6 mol/mol of glycerol were obtained at a dilution rate of 0.1 h(-1)which is bettered only by pure strains in pure glycerin feeds.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacteria / classification
  • Bacteria / genetics
  • Bacteria / metabolism
  • Culture Media / chemistry
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Ribosomal / chemistry
  • DNA, Ribosomal / genetics
  • Fermentation
  • Glycerol / metabolism*
  • Hydrogen-Ion Concentration
  • Industrial Waste
  • Microbial Consortia*
  • Molecular Sequence Data
  • Propylene Glycols / metabolism*
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Soil Microbiology*

Substances

  • Culture Media
  • DNA, Bacterial
  • DNA, Ribosomal
  • Industrial Waste
  • Propylene Glycols
  • RNA, Ribosomal, 16S
  • 1,3-propanediol
  • Glycerol

Associated data

  • SRA/SRP047483