Effect of nutrients in trypticase soy agar on growth kinetics ofsalmonella spp. under micro-cultivation
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Author list: Sangadkit W., Saeaung W., Boonyaprapasorn A., Thipayarat A.
Publication year: 2011
Journal: Thai Journal of Agricultural Science (0049-3589)
Volume number: 44
Issue number: 5
Start page: 422
End page: 429
Number of pages: 8
ISSN: 0049-3589
Languages: English-Great Britain (EN-GB)
Abstract
Growth kinetics of Salmonella spp. colonies was studied to evaluate its growth on different levels of carbon and nitrogen sources in trypticase soy agar (TSA). The logistic model was proposed to describe the Sigmoidal mathematic of the area of colony expansion well under limited carbon and nitrogen supplies. The images of colony expansion were digitized and monitored every hour using a reflected light microscope equipped with a 1.5 megapixel CCD camera. The key kinetic attribute (i.e., the maximum specific growth rate) was estimated from these colony images to compare Salmonella growth subject to different nutrient conditions. The volume of each inoculum in this micro-cultivation scheme was limited to 5 μL and the culture was incubated on TSA at 35°C. The carbon and nitrogen sources were varied at 1.0, 1.5, 2.0, 2.5 and 3.0X strength of the original TSA recipe. The original composition of the carbon and nitrogen sources in the TSA medium did not produce the highest Salmonella growth in the agar plate culture. The nitrogen concentrations between 2.5- and 3.0-fold strength, however, were able to accelerate colony growth rate and enlarge the colony size. Presumably, the higher concentration of nitrogen made the colony growth more susceptible to carbon source alteration. At the 3.0-fold nitrogen level, the optimal carbon concentration at 1.5-fold strength resulted in the fastest growth rate of Salmonella colony having the maximum specific growth rate up to 0.305 hr-1.
Keywords
Growth kinetic, Salmonella growth, Sigmoidal growth model, Specificgrowth rate, Trypticase soy agar
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