A spectrophotometric method for quantitative determination of xylose in fermentation medium

Dave C. Swalm School of Chemical Engineering, Mississippi State University, Mississippi, MS 39762, USA
Biomass and Bioenergy (Impact Factor: 2.98). 04/2011; 35:2814. DOI: 10.1016/j.biombioe.2011.03.006

ABSTRACT Monitoring the consumption of sugars during fermentation is a key to optimizing product formation and maintaining a healthy environment for microorganisms. Diffi-culty arises in the availability of a rapid, inexpensive and sensitive method for the detection of sugars because fermentation media are a complex mix of nutrients, cell debris, waste and target products. A method involving reaction-based UVeVis spectro-photometry for the quantitative determination of xylose as the target sugar was devel-oped. Factors affecting xylose concentration measurements such as hydrochloric acid concentration, heating time and the amount of Fe 3þ catalyst were investigated. A continuous scan revealed the working wavelength to be 671 nm. The effect of other components in the fermentation broth was found to be negligible. Absorbance shows a linear relationship with xylose concentration within a range of 0.1e0.5 g/L. Xylose concentrations from fermentation samples obtained at specific time intervals (0e168 h) were determined with the method and compared with YSI 2700, an enzyme electrode, HPLC-ELSD method, currently a common technique for measuring xylose and GC aldo-nonitrile sugar derivatization method. Dilution is necessary for comparable xylose concentrations with YSI 2700 and HPLC-ELSD. Xylose concentration measurements obtained with the UVeVis spectrophotometric method although quantitatively compa-rable to HPLC-ELSD xylose measurements were easily and conveniently obtained compared to YSI 2700, HPLC-ELSD and GC derivatization methods.

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