Concentration measurement of yeast suspensions using high frequency ultrasound backscattering

Elvira, Luis; Vera, Pedro Sánchez; Canadas, F.; Shukla, Shiva Kant; Montero, F.

doi:10.1016/j.ultras.2015.08.009

Cited by 34 publications

(9 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Cells are composed essentially of water (70–80%) and a set of macromolecules (polysaccharides, proteins, lipids and nucleotides) plus a small concentration of salts and ions. Although the actual value of the cell composition (and the EPS produced) will depend on the kind of cell, following [53], a value of 1100 kg/m 3 biofilm density ( ρ ) was assumed. This value was estimated for the yeast S. cerevisiae and taking into account that there are great similarities in the cellular content of diverse microorganisms, which is mainly water, a great deviation from the exact density of the S. epidermidis biofilm is not expected.…”

Section: Resultsmentioning

confidence: 99%

Study of the Relation between the Resonance Behavior of Thickness Shear Mode (TSM) Sensors and the Mechanical Characteristics of Biofilms

Castro¹,

Elvira²,

Maestre

et al. 2017

Sensors

Self Cite

View full text Add to dashboard Cite

This work analyzes some key aspects of the behavior of sensors based on piezoelectric Thickness Shear Mode (TSM) resonators to study and monitor microbial biofilms. The operation of these sensors is based on the analysis of their resonance properties (both resonance frequency and dissipation factor) that vary in contact with the analyzed sample. This work shows that different variations during the microorganism growth can be detected by the sensors and highlights which of these changes are indicative of biofilm formation. TSM sensors have been used to monitor in real time the development of Staphylococcus epidermidis and Escherichia coli biofilms, formed on the gold electrode of the quartz crystal resonators, without any coating. Strains with different ability to produce biofilm have been tested. It was shown that, once a first homogeneous adhesion of bacteria was produced on the substrate, the biofilm can be considered as a semi-infinite layer and the quartz sensor reflects only the viscoelastic properties of the region immediately adjacent to the resonator, not being sensitive to upper layers of the biofilm. The experiments allow the microrheological evaluation of the complex shear modulus (G* = G′ + jG″) of the biofilm at 5 MHz and at 15 MHz, showing that the characteristic parameter that indicates the adhesion of a biofilm for the case of S. epidermidis and E. coli, is an increase in the resonance frequency shift of the quartz crystal sensor, which is connected with an increase of the real shear modulus, related to the elasticity or stiffness of the layer. In addition both the real and the imaginary shear modulus are frequency dependent at these high frequencies in biofilms.

show abstract

Section: Resultsmentioning

confidence: 99%

Study of the Relation between the Resonance Behavior of Thickness Shear Mode (TSM) Sensors and the Mechanical Characteristics of Biofilms

Castro¹,

Elvira²,

Maestre

et al. 2017

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, the attentions of the researchers of this field have been focused on development of appropriate indirect methods during last few years. Laser reflectance measurement ( Expósito et al, 2017 ), measurement of ultrasound attenuation and backscattering ( Rodriguez-Molares et al, 2014 ; Elvira et al, 2016 ), determination of cellular compounds and metabolites content such as adenosine triphosphate (ATP) ( Abushaban et al, 2019 ), respirometry and measurement of oxygen uptake rate (OUR) in aerobic sludge ( Garcia-Ochoa et al, 2010 ), flow cytometry ( Brown et al, 2019 ), density measurement ( Cano et al, 2014 ), and measurement of biomass electrical properties such as permittivity, capacitance, and impedance ( Sarrafzadeh et al, 2005 ; Bobowski and Johnson, 2012 ; Zhang et al, 2012 ; Shariati et al, 2013 ; Pajoum-Shariati et al, 2014 ) are the most applied techniques which have been developed for biomass concentration measurement in different biological systems, especially bacterial ones such as activated sludge. A part of these methods successfully find their commercial place in several biotechnology processes but not in the biological wastewater treatment plants ( Sarrafzadeh et al, 2005 , 2015b ).…”

Section: Introductionmentioning

confidence: 99%

Development of Digital Image Processing as an Innovative Method for Activated Sludge Biomass Quantification

Asgharnejad

Sarrafzadeh

2020

Front. Microbiol.

View full text Add to dashboard Cite

Activated sludge process is the most common method for biological treatment of industrial and municipal wastewater. One of the most important parameters in performance of activated sludge systems is quantitative monitoring of biomass to keep the cell concentration in an optimum range. In this study, a novel method for activated sludge quantification based on image processing and RGB analysis is proposed. According to the results, the intensity of blue color in the macroscopic image of activated sludge culture can be a very accurate index for cell concentration measurement and R 2 coefficient, Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and Mean Absolute Percentage Error (MAPE) which are 0.990, 2.000, 0.323, and 13.848, respectively, prove this claim. Besides, in order to avoid the difficulties of working in the three-parameter space of RGB, converting to grayscale space has been applied which can estimate cell concentration with R 2 = 0.99. Ultimately, an exponential correlation between RGB values and cell concentrations in lower amounts of biomass has been proposed based on Beer-Lambert law which can estimate activated sludge biomass concentration with R 2 = 0.97 based on B index.

show abstract

“…Ultrasonic backscattering techniques are used to provide local heterogeneous medium properties (such as scatterer size distribution and/or volume fraction) in optically opaque suspensions. The main fields of application of these techniques are medicine with flowing blood, 1,2 the food industry, 3 or the mining industry. 4,5 In the field of industrial suspensions, the local volume fraction of concentrated suspensions is derived from the local amplitude of the ultrasonic echo envelope or backscatter intensity.…”

Section: Introductionmentioning

confidence: 99%

“…In all the precited works, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] common assumptions on concentrated suspensions are that (1) the scatterers are much smaller than the wavelength, (2) multiple scattering can be neglected, and (3) the scattering media are homogeneous and isotropic. Little attention has been paid to the influence of shear-induced anisotropic microstructure (i.e., scatterer spatial organization) of suspensions on the US backscattering, which could challenge the third hypothesis of isotropic media.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic backscattering and microstructure in sheared concentrated suspensions

Lombard

Rouyer

Debieu

et al. 2020

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

Quantitative ultrasound techniques based on the parametrization of the backscatter coefficient (BSC) are used to characterize concentrated particle suspensions. Specifically, a scattering model is fit to the measured BSC and the fit parameters can provide local suspension properties. The scattering models generally assume an isotropic microstructure (i.e., spatial organization) of the scatterers, whereas the sheared concentrated suspensions can develop an anisotropic microstructure. This paper studied the influence of the shear-induced anisotropic microstructure of concentrated suspensions on the ultrasonic backscattering. Experiments were conducted on suspensions of polymethylmetacrylate spheres (5.8 μm in radius) sheared in a Couette flow device to obtain anisotropic microstructure and then mixed by hand to obtain isotropic microstructure. Experimental structure factors that are related to the spatial distribution of sphere positions were obtained by comparing the BSCs of one concentrated and one diluted suspension. Finally, Stokesian dynamics numerical simulations of sheared concentrated suspensions are used to determine the pair correlation function, which is linked to the Fourier transform of the structure factor. The experimental structure factors are found to be in good agreement with numerical simulations. The numerical simulation demonstrates that the angular-dependent BSCs and structure factors are caused by the shear-induced anisotropic microstructure within the suspension.

show abstract

Concentration measurement of yeast suspensions using high frequency ultrasound backscattering

Cited by 34 publications

References 39 publications

Study of the Relation between the Resonance Behavior of Thickness Shear Mode (TSM) Sensors and the Mechanical Characteristics of Biofilms

Study of the Relation between the Resonance Behavior of Thickness Shear Mode (TSM) Sensors and the Mechanical Characteristics of Biofilms

Development of Digital Image Processing as an Innovative Method for Activated Sludge Biomass Quantification

Ultrasonic backscattering and microstructure in sheared concentrated suspensions

Contact Info

Product

Resources

About