title: Batch, design optimization, and DNA sequencing study for continuous 1,3-propanediol production from waste glycerol by a soil-based inoculum.
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.
authors.affiliation: Institute of Materials Science, University of Connecticut, 97 N. Eagleville Rd., Storrs, CT, 06269, USA.
authors.forename: Baishali
authors.initials: B
authors.lastname: Kanjilal
authors.forename: Iman
authors.initials: I
authors.lastname: Noshadi
authors.forename: Eddy J
authors.initials: EJ
authors.lastname: Bautista
authors.forename: Ranjan
authors.initials: R
authors.lastname: Srivastava
authors.forename: Richard S
authors.initials: RS
authors.lastname: Parnas
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D011409:Propylene Glycols / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007220:Industrial Waste; D011409:Propylene Glycols; D012336:RNA, Ribosomal, 16S; C041787:1,3-propanediol; D005990:Glycerol