Grantee Research Project Results
2012 Progress Report: Producing and Characterizing Bacillus Subtilis Biosurfactants with Potentially Lower Environmental Impact for Salt Water Applications
EPA Grant Number: R835181Title: Producing and Characterizing Bacillus Subtilis Biosurfactants with Potentially Lower Environmental Impact for Salt Water Applications
Investigators: Lamsal, Buddhi , Somasundaran, P. , Nyman, John A. , Green, Christopher C. , LeBlanc, Brian D.
Institution: Iowa State University , Columbia University in the City of New York , Louisiana State University - Baton Rouge
EPA Project Officer: Aja, Hayley
Project Period: April 1, 2012 through March 31, 2015 (Extended to March 31, 2016)
Project Period Covered by this Report: April 1, 2012 through March 31,2013
Project Amount: $500,000
RFA: Environmental Impact and Mitigation of Oil Spills (2011) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
Progress Summary:
- For this objective, a pretreatment study on six different fibrous biomasses for utilization of cellulosic and lignocellulosic carbohydrates, as carbon source for the growth of biosurfactants, produced by Bacillus subtillis was conducted.
- Six fibrous feedstocks including, a) switchgrass, b) alfalfa, c) soy hulls, d) soy fiber, e) distillers dry grain solubles (DDGS), and f) bagasse were pretreated with two different pretreatment techniques, i) liquid ammonia pretreatment ii) ultrasonication at varying combinations of concentration, time, temperature and amplitude.
- Post- pretreatment enzymatic hydrolysis for all pretreatment combinations biomass samples was conducted to determine the optimum pretreatment conditions, which were found to be 60 C, 12 hr, for switchgrass, alfalfa, soy hulls and bagasse and 3 min, 100% amplitude ultrasonication for soy fiber and DDGS.
- After determination of best pretreatment conditions, pretreatments were done on 30g (dry weight) of all six fibrous biomasses to produce sufficient carbohydrate from each feedstock to substitute glucose as a carbon source at 2% concentration in 50 mL S-7 fermentation media for production of FA-Glu and surfactin and fermentation growth as a function of absorbance at 650 nm was analyzed for all feedstocks. (Fig 1a, 1b) This study on pretreatment and utilization of carbohydrates from fibrous biomass has shown that biosurfactant producing bacterial strain can grow better or equally well compared to glucose based media which provided a new direction towards a potentially cheaper and environmentally sustainable energy source for biosurfactant production as utilization of fibrous biomass adds value to the sustainable bio-refinery models.
Fig 1a) Growth of Surfactin producing Bacillus subtillis on glucose and pretreated hydrolysates of
switchgrass (SG), alfalfa (AA), Soy hulls (SH), BG (Bagasse)
Fig 1b) Growth of FA-Glu producing Bacillus subtillis on glucose and pretreated hydrolysates of
switchgrass (SG), alfalfa (AA), Soy hulls (SH), BG (Bagasse).
- We conducted three, 15-L, fermentations for Bacillus subtillis on glucose based media to produce surfactin in a larger quantity for isoform separation and structure function characterization for toxicity profile and dispersion activity. We successfully separated surfactin isoforms on the analytical HPLC scale and have been working on large scale preparatory HPLC to fractionate pure isoforms for comparative studies of composite and individual isoform properties. Completion of this part of the project will provide us strong data to analyze the structure and property of individual molecules (isoforms) and will provide a clear picture for dosage, activity and function of FA-Glu and surfactin.
Fig 2. Critical micelle concentration (CMC) of FA-Glu in double
distilled deionized water. The solutions was maintained at
around pH 7.
Future Activities:
- With the preparatory scale fractionation of surfactin and Fa-Glu isoforms, more comprehensive analysis of structure and function of surfactin and Fa-Glu would be conducted that will include, toxicity profiles and dispersion activity of composite and individual isoforms of surfactin and Fa-Glu.
- Media modification of for enhanced growth and higher yield of FA-Glu and surfactin producing strains will be conducted.
In addition to future research activities, a second graduate student will be hired in January 2014 to lead in the development and implementation of all associated public outreach materials and efforts.
Journal Articles:
No journal articles submitted with this report: View all 5 publications for this projectSupplemental Keywords:
Biosurfactants, Surfactin, Bacillus Subtillis, isoforms, oil spill, dispersant, critical micelle concentrationRelevant Websites:
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Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.