Influence of moisture content and cultivation duration on Clostridium thermocellum 27405 end-product formation in solid substrate cultivation on Avicel

Mari S. Chinn, Sue E. Nokes, Herbert J. Strobel

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Avicel serves as a model microcrystalline cellulose substrate for investigations of cellulolytic microbial performance and cellulase enzyme systems in submerged liquid cultures. Clostridium thermocellum is a thermophilic, anaerobic bacterium capable of degrading lignocellulose and fermenting it to ethanol and other products, suggesting the native growth environment is similar to that supported by solid substrate cultivation. Few studies have examined the effects of process parameters on the metabolism of thermophilic anaerobes in solid substrate cultivation, however. The effects of solid substrate cultivation (SSC) substrate moisture content (30%, 50% and 70% wet-basis) and cultivation duration (2, 4 and 8 days) on the metabolic activity of C. thermocellum 27405 on Avicel was studied. The 70% substrate moisture content SSC culture yielded total end-product concentrations that were comparable to submerged liquid cultures. The SSC cultivation conditions with the highest end-product formation on Avicel were the combination of 70% substrate moisture content and cultivation duration period of 4 days, producing approximately 100 mM of total end-products. The ethanol and lactate concentrations were fairly constant and did not change significantly over time in SSC. Acetate production was more dependent on the cultivation conditions in SSC and was significant for both the 70% substrate moisture content SSC and liquid cultivation experiments, making up on average 56% and 86% of total end-products, respectively. Performance of C. thermocellum 27405 in SSC was more dependent on the kinetic properties rather than the thermodynamic properties of substrate moisture content. High substrate loadings in C. thermocellum cultivation affected product ratios, resulting in the higher observed acetate production. In addition, cessation of metabolism was observed prior to complete Avicel conversion; the mechanisms involved need further investigation.

Original languageEnglish
Pages (from-to)2664-2671
Number of pages8
JournalBioresource Technology
Volume99
Issue number7
DOIs
StatePublished - May 2008

Bibliographical note

Funding Information:
The authors acknowledge the financial support of the US Department of Agriculture (NRI Competitive Grants Program # 2001-35504-10106). The investigation reported in this paper (No. 07-05-058) is part of a project of the Kentucky Agricultural Experiment Station and is published with approval of the director.

Keywords

  • Avicel
  • C. thermocellum
  • Moisture content
  • Solid substrate cultivation (SSC)
  • Thermophilic

ASJC Scopus subject areas

  • Bioengineering
  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Waste Management and Disposal

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