Light-scattering sensor for real-time identification of Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae colonies on solid agar plate.
Bottom Line: Although a limited number of Vibrio species was tested, each produced a unique light-scattering signature that is consistent from colony to colony.The light-scattering signatures were unaffected by subjecting the bacteria to physiological stressors: osmotic imbalance, acid, heat and recovery from a viable but non-culturable state.Furthermore, employing a standard sample enrichment in alkaline peptone water for 6 h followed by plating on selective thiosulphate citrate bile salts sucrose agar at 30°C for ∼ 12 h, the light-scattering sensor successfully detected V. cholerae, V. parahaemolyticus and V. vulnificus present in oyster or water samples in 18 h even in the presence of other vibrios or other bacteria, indicating the suitability of the sensor as a powerful screening tool for pathogens on agar plates.
Affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA.Show MeSH
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Mentions: Vibrio parahaemolyticus and V. vulnificus testing from oysters required approximately 18 h of total growth [6 h of enrichment in alkaline peptone water (APW) followed by 12 h growth on HI or TCBS agar plates] to obtain 1.3 ± 0.2 mm bacterial colonies. BARDOT analysis of the colonies took about 3 s for each colony and the scatter patterns from recovered colonies matched the reference controls (Fig. 6A). BARDOT also generated scatter patterns from multiple colonies that did not match with either V. vulnificus or V. parahaemolyticus. These unmatched colonies were considered background bacteria, isolated more from HI than TCBS (Fig 6B). Select colonies were also tested by colony PCR, which were in agreement with the BARDOT data for both V. vulnificus and V. parahaemolyticus (Fig 6C). All nine uninoculated control oysters were found to be positive for both V. vulnificus and V. parahaemolyticus, and albeit all nine inoculated oysters were also positive (Table 4). Vibrio parahaemolyticus was also successfully detected from spiked sterile tap water (103 CFU ml−1) and negative controls for the tap water (non‐spiked) did not produce any colonies (Fig. S3).
Affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA.