431141 A Novel Soft Sensor Approach for Estimating Individual Biomass in Mixed Cultures (Rapid Fire)

Wednesday, November 11, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Kyle Stone, Chemical Engineering, Auburn University, Auburn, AL, Devarshi Shah, Chemical Engineering, Auburn Unviversity, Auburn, AL, Q. Peter He, Chemical Engineering, Tuskegee University, Tuskegee, AL, Jin Wang, Auburn University, Auburn, AL and Alejandro Zamora, University of Arizona, Tuscon, AZ

A novel soft sensor approach for estimating individual biomass in mixed cultures

Kyle Stone1, Devarshi Shah1, Q. Peter He2, and Jin Wang1

1Department of Chemical Engineering, Auburn University, Auburn, AL, 36849, USA

2Department of Chemical Engineering, Tuskegee University, Tuskegee, AL, 36088, USA <>Abstract:

Mixed cultures are ubiquitous in nature but their applications as biocatalysts in biochemical processes have been very limited. Until recently the application of mixed culture has been limited to wastewater treatment, but more diversified applications have started to emerge. For instance, Norferm Danmark A/S utilized a mixed culture of Methylococcus capsulatus (Bath) with  heterotrophic bacteria to sustain growth on methane in a process to convert biomass into single cell protein for animal feed[1], and co-culture of xylose-fermenting strains have been paired with Saccharomyces cerevisiae to ferment lignocellulosic hydrolysate[2], [3]. Compared to single culture, there are several benefits of mixed culture. For example, a mixed culture can provide more versatile metabolic machinery due to a larger pool of collective genes, and tend to be more robust to different disturbances such as variations in feedstock composition and operation conditions. The main reason for the limited application of mixed culture approach is the difficulty associated with modeling, understanding and controlling of mixed culture.

To understand the metabolomic interactions of a mixed culture, quantitative analyses that can differentiate the dynamic properties of the mixed culture from those of monoculture are essential. One of the challenges in studying a mixed culture is to obtain the biomass concentration of each organism in the mixed culture. Cell count and fluorescent labelling have been used for microbial enumeration in mixed culture. But the former is time consuming and may not be accurate; the latter is also time consuming and may lack genetic tools and experimental protocols for some microbes. To address this challenge, we propose an absorbance spectra-based soft sensor to estimate individual biomass concentration in a mixed culture.

Soft sensor is commonly used in analytical chemistry and process industry to estimate variables (such as concentration) that are difficult to measure by using other easily obtainable measurements (such as absorbance spectra) [4], [5]. In this work, we propose to use absorbance spectra of the mixed culture broth, instead of the absorbance at a single wavelength, to estimate the biomass concentration of each individual strain. The proposed procedure is shown below:

Case studies are carried out to show that the proposed soft sensor is highly accurate in estimating the individual biomass concentration from absorbance spectra of the mixed culture.


[1]        H. Bothe, K. M. Jensen, A. Mergel, J. Larsen, C. Jørgensen, H. Bothe, and L. Jørgensen, “Heterotrophic bacteria growing in association with Methylococcus capsulatus (Bath) in a single cell protein production process,” Appl. Microbiol. Biotechnol., vol. 59, pp. 33–39, 2002.

[2]        M. H. Kim, M. Liang, Q. P. He, and J. Wang, “A novel reactor for systematic investiagtion of co-culture systems,” Bioresour. Technol., (submitted) 2015.

[3]        M. H. Kim, M. Liang, Q. P. He, and J. Wang, “Simultaneous fermentation of glucose and xylose by co-culture in a novel bioreactor,” in Proceedings of Sun Grant Initiative 2012 National Conference, 2012, pp. 97–101.

[4]        H. J. Galicia, Q. P. He, and J. Wang, “Comparison of the performance of a reduced-order dynamic PLS soft sensor with different updating schemes for digester control,” Control. Eng. Pract., vol. 20, pp. 747–760, 2012.

[5]        H. J. Galicia, Q. P. He, and J. Wang, “A reduced order soft sensor approach and its application to a continuous digester,” J. Process. Control., vol. 21, pp. 489–500, 2011.


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See more of this Session: Poster Session: Bioengineering
See more of this Group/Topical: Food, Pharmaceutical & Bioengineering Division