title: Reflected scatterometry for noninvasive interrogation of bacterial colonies.
abstract: A phenotyping of bacterial colonies on agar plates using forward-scattering diffraction-pattern analysis provided promising classification of several different bacteria such as Salmonella, Vibrio, Listeria, and E. coli. Since the technique is based on forward-scattering phenomena, light transmittance of both the colony and the medium is critical to ensure quality data. However, numerous microorganisms and their growth media allow only limited light penetration and render the forward-scattering measurement a challenging task. For example, yeast, Lactobacillus, mold, and several soil bacteria form colorful and dense colonies that obstruct most of the incoming light passing through them. Moreover, blood agar, which is widely utilized in the clinical field, completely blocks the incident coherent light source used in forward scatterometry. We present a newly designed reflection scatterometer and validation of the resolving power of the instrument. The reflectance-type instrument can acquire backward elastic scatter patterns for both highly opaque media and colonies and has been tested with three different bacterial genera grown on blood agar plates. Cross-validation results show a classification rate above 90% for four genera.
authors: Purdue University, School of Mechanical Engineering, Applied Optics Laboratory, West Lafayette, Indiana 47907, United States.
authors: Huisung
authors: H
authors: Kim
authors: Purdue University, School of Mechanical Engineering, Applied Optics Laboratory, West Lafayette, Indiana 47907, United States.
authors: Iyll-Joon
authors: IJ
authors: Doh
authors: Purdue University, Department of Basic Medical Sciences, West Lafayette, Indiana 47907, United States.
authors: Jennifer
authors: J
authors: Sturgis
authors: Purdue University, Molecular Food Microbiology Laboratory, Department of Food Science, West Lafayette, Indiana 47907, United States.
authors: Arun K
authors: AK
authors: Bhunia
authors: Purdue University, Department of Basic Medical Sciences, West Lafayette, Indiana 47907, United StatesdPurdue University, Weldon School of Biomedical Engineering, West Lafayette, Indiana 47907, United States.
authors: J Paul
authors: JP
authors: Robinson
authors: Purdue University, School of Mechanical Engineering, Applied Optics Laboratory, West Lafayette, Indiana 47907, United States.
authors: Euiwon
authors: E
authors: Bae
mesh_terms: D000465:Algorithms; D001419:Bacteria / Q000737:chemistry* / Q000145:classification*; D001431:Bacteriological Techniques / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted; D008027:Light; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted