Dataset Information

Simultaneous saccharification and lactic acid fermentation of the cellulosic fraction of municipal solid waste using Bacillus smithii.

ABSTRACT:

Objective

A primary drawback to simultaneous saccharification and fermentation (SSF) processes is the incompatibility of the temperature and pH optima for the hydrolysis and fermentation steps-with the former working best at 50-55 °C and pH 4.5-5.5. Here, nine thermophilic Bacillus and Parageobacillus spp. were evaluated for growth and lactic acid fermentation at high temperature and low pH. The most promising candidate was then carried forward to demonstrate SSF using the cellulosic fraction from municipal solid waste (MSW) as a feedstock.

Results

B. smithii SA8Eth was identified as the most promising candidate and in a batch SSF maintained at 55 °C and pH 5.0, using a cellulase dose of 5 FPU/g glucan, it produced 5.1 g/L lactic acid from 2% (w/v) MSW cellulosic pulp in TSB media.

Conclusion

This work has both scientific and industrial relevance, as it evaluates a number of previously untrialled bacterial hosts for their compatibility with lignocellulosic SSF for lactic acid production and successfully identifies B. smithii as a potential candidate for such a process.

SUBMITTER: Chacon MG

PROVIDER: S-EPMC7873104 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature

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Publications

Simultaneous saccharification and lactic acid fermentation of the cellulosic fraction of municipal solid waste using Bacillus smithii.

Chacón Micaela G MG Ibenegbu Christopher C Leak David J DJ

Biotechnology letters 20201121 3

<h4>Objective</h4>A primary drawback to simultaneous saccharification and fermentation (SSF) processes is the incompatibility of the temperature and pH optima for the hydrolysis and fermentation steps-with the former working best at 50-55 °C and pH 4.5-5.5. Here, nine thermophilic Bacillus and Parageobacillus spp. were evaluated for growth and lactic acid fermentation at high temperature and low pH. The most promising candidate was then carried forward to demonstrate SSF using the cellulosic fra ...[more]

PMID: 33219874

Similar Datasets

Project description:BackgroundFuture expansion of corn-derived ethanol raises concerns of sustainability and competition with the food industry. Therefore, cellulosic biofuels derived from agricultural waste and dedicated energy crops are necessary. To date, slow and incomplete saccharification as well as high enzyme costs have hindered the economic viability of cellulosic biofuels, and while approaches like simultaneous saccharification and fermentation (SSF) and the use of thermotolerant microorganisms can enhance production, further improvements are needed. Cellulosic emulsions have been shown to enhance saccharification by increasing enzyme contact with cellulose fibers. In this study, we use these emulsions to develop an emulsified SSF (eSSF) process for rapid and efficient cellulosic biofuel production and make a direct three-way comparison of ethanol production between S. cerevisiae, O. polymorpha, and K. marxianus in glucose and cellulosic media at different temperatures.ResultsIn this work, we show that cellulosic emulsions hydrolyze rapidly at temperatures tolerable to yeast, reaching up to 40-fold higher conversion in the first hour compared to microcrystalline cellulose (MCC). To evaluate suitable conditions for the eSSF process, we explored the upper temperature limits for the thermotolerant yeasts Kluyveromyces marxianus and Ogataea polymorpha, as well as Saccharomyces cerevisiae, and observed robust fermentation at up to 46, 50, and 42 °C for each yeast, respectively. We show that the eSSF process reaches high ethanol titers in short processing times, and produces close to theoretical yields at temperatures as low as 30 °C. Finally, we demonstrate the transferability of the eSSF technology to other products by producing the advanced biofuel isobutanol in a light-controlled eSSF using optogenetic regulators, resulting in up to fourfold higher titers relative to MCC SSF.ConclusionsThe eSSF process addresses the main challenges of cellulosic biofuel production by increasing saccharification rate at temperatures tolerable to yeast. The rapid hydrolysis of these emulsions at low temperatures permits fermentation using non-thermotolerant yeasts, short processing times, low enzyme loads, and makes it possible to extend the process to chemicals other than ethanol, such as isobutanol. This transferability establishes the eSSF process as a platform for the sustainable production of biofuels and chemicals as a whole.

Dataset Information

Simultaneous saccharification and lactic acid fermentation of the cellulosic fraction of municipal solid waste using Bacillus smithii.

Objective

Results

Conclusion

Publications

Simultaneous saccharification and lactic acid fermentation of the cellulosic fraction of municipal solid waste using Bacillus smithii.

Similar Datasets

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