title: Label-free, non-invasive light scattering sensor for rapid screening of Bacillus colonies.
abstract: Bacillus species are widely distributed in nature and have great significance both as industrially beneficial microbes and as public health burdens. We employed a novel light-scattering sensor, BARDOT (bacterial rapid detection using optical scattering technology) for instant screening of colonies of Bacillus species on agar plates. A total of 265 Bacillus and non-Bacillus isolates from our collection were used to develop and verify scatter image libraries including isolates from food, environmental and clinical samples. All Bacillus species (n=118) were detected with a high positive predictive value, PPV (≥90%) while non-Bacillus spp. had very low PPV (<5%) when compared with scatter images from the library. Among all media tested for culturing, Bacillus colonies on phenol red mannitol (PRM) generated the highest differential scatter patterns and were used in subsequent studies. Surface plot analysis of scatter patterns confirmed differences for Bacillus and non-Bacillus isolates. BARDOT successfully detected Bacillus from inoculated baby formula, cheese, and naturally contaminated bovine unpasteurized milk in 7-16h. Ten of 129 colonies (isolates) from seven milk samples were Bacillus and remainders were non-Bacillus spp. BARDOT results were confirmed by PCR and 16S rDNA sequencing. This study demonstrates that BARDOT could be used as a screening tool to identify relevant Bacillus colonies from a community prior to genome sequencing.
authors.affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA.
authors.forename: Atul K
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA.
authors.forename: Xiulan
authors.initials: X
authors.lastname: Sun
authors.affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA.
authors.forename: Xingjian
authors.initials: X
authors.lastname: Bai
authors.affiliation: School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA.
authors.forename: Huisung
authors.initials: H
authors.lastname: Kim
authors.affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA.
authors.forename: Maha Usama
authors.initials: MU
authors.lastname: Abdalhaseib
authors.affiliation: School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA.
authors.forename: Euiwon
authors.initials: E
authors.lastname: Bae
authors.affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA; Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, USA. Electronic address: bhunia@purdue.edu.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Bhunia
mesh_terms: D001407:Bacillus / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification*; D001431:Bacteriological Techniques / Q000379:methods*; D055598:Chemical Phenomena; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008403:Mass Screening / Q000379:methods; D008969:Molecular Sequence Data; D061848:Optical Imaging / Q000295:instrumentation* / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S
keywords: BARDOT; Bacillus; Bacterial colony; Detection; Light scattering sensor; Screening