scholarly journals Optical multi-channel interrogation instrument for bacterial colony characterization

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247721
Author(s):  
Iyll-Joon Doh ◽  
Huisung Kim ◽  
Jennifer Sturgis ◽  
Bartek Rajwa ◽  
J. Paul Robinson ◽  
...  

A single instrument that includes multiple optical channels was developed to simultaneously measure various optical and associated biophysical characteristics of a bacterial colony. The multi-channel device can provide five distinct optical features without the need to transfer the sample to multiple locations or instruments. The available measurement channels are bright-field light microscopy, 3-D colony-morphology map, 2-D spatial optical-density distribution, spectral forward-scattering pattern, and spectral optical density. The series of multiple morphological interrogations is beneficial in understanding the bio-optical features of a bacterial colony and the correlations among them, resulting in an enhanced power of phenotypic bacterial discrimination. To enable a one-shot interrogation, a confocal laser scanning module was built as an add-on to an upright microscope. Three different-wavelength diode lasers were used for the spectral analysis, and high-speed pin photodiodes and CMOS sensors were utilized as detectors to measure the spectral OD and light-scatter pattern. The proposed instrument and algorithms were evaluated with four bacterial genera, Escherichia coli, Listeria innocua, Salmonella Typhimurium, and Staphylococcus aureus; their resulting data provided a more complete picture of the optical characterization of bacterial colonies.

2021 ◽  
Author(s):  
Eva Nowak

The purpose of this study was to characterize microbial floc structure and properties under phosphorus (P) limiting and non-limiting regimes. The P-limitation applied to the biomass did not significantly impact on reactor performance in terms of COD removal and MLSS. The composition of EPS was affected by the P-limitation with significantly increased accumulation of carbohydrates, uronic acids and proteins. CLSM and glycoconjugate mapping revealed that the relative abundance of α and β- N -acetylgalactosaminyl/galactopyranosyl and N -acetylglucosaminyl residues was affected by P-limitation, suggesting changes in microbial populations within the floc structure, which in turn could cause the compositional changes of EPS. The image analysis performed on CLSM images indicated that under non-limiting conditions the cell clumps within the floc were significantly smaller as compared to P-limiting conditions. The fractal dimension and porosity under limiting conditions were either significantly higher or lower than under P-rich conditions.


2020 ◽  
Vol 21 (20) ◽  
pp. 7563
Author(s):  
Mikhail V. Zyuzin ◽  
Dingcheng Zhu ◽  
Wolfgang J. Parak ◽  
Neus Feliu ◽  
Alberto Escudero

Nanostructured silica (SiO2)-based materials are attractive carriers for the delivery of bioactive compounds into cells. In this study, we developed hollow submicrometric particles composed of SiO2 capsules that were separately loaded with various bioactive molecules such as dextran, proteins, and nucleic acids. The structural characterization of the reported carriers was conducted using transmission and scanning electron microscopies (TEM/SEM), confocal laser scanning microscopy (CLSM), and dynamic light scattering (DLS). Moreover, the interaction of the developed carriers with cell lines was studied using standard viability, proliferation, and uptake assays. The submicrometric SiO2-based capsules loaded with DNA plasmid encoding green fluorescence proteins (GFP) were used to transfect cell lines. The obtained results were compared with studies made with similar capsules composed of polymers and show that SiO2-based capsules provide better transfection rates on the costs of higher toxicity.


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