Continuous outbreaks of Shigella spp. have raised concerns about the lack of rapid and on-site applicable biosensor method for Shigella detection. Since a bacteriophage has recently been employed as an emerging bio-recognition element in biosensor method, Shigella sonnei-specific bacteriophage was isolated and purified from a slaughterhouse with the final concentration of 2.0×1012 PFU/mL in this study. Analysis of purified S. sonnei-specific bacteriophage using transmission electron microscopy indicated that it possessed an icosahedral head with a relatively long non-contractile tail. It was therefore classified as a member of the Siphoviridae family. Head width, head length, and tail length were 69.9±11.2 nm, 77.5±8.8 nm, and 264.4±33.9 nm, respectively. The genomic DNA size of the S. sonnei-specific bacteriophage was determined to be approximately 25 kb by using 0.4% agarose gel electrophoresis. In specificity test with 43 food-associated microorganisms, the S. sonnei-specific bacteriophage exhibited a clear plaque against S. sonnei only. In addition, the S. sonnei-specific bacteriophage was stable within a wide range of pH values (pH 3-11) and temperatures (4-37 ). Thus, the present study demonstrated the excellent specificity and stability of the S. sonnei-specific bacteriophage as a novel bio-recognition element for S. sonnei detection in foods.

Carotenoids of squash play an important role in human health by acting as sources of provitamin A or as protective antioxidants. Among the 60 accessions of squash germplasm, fluorescent yellow and yellow types of flesh color got the highest count, followed by the orange, whitish yellow and greenish yellow. The redness and yellowness values of the flesh powder ranged from -2.45 to 86.09 and from 13.77 to 39.80, respectively. While the lightness and the total color difference values of flesh color varied from 67.64 to 86.09 and from 19.77 to 51.79, respectively. Colorimetric values of redness and yellowness showed positive correlation, and the correlation coefficient (r) was as high as 0.7386. The five accessions represented each flesh color types, IT195043 (orange), IT136696 (fluorescent yellow), IT186365 (yellow), IT137963 (whitish yellow), and IT180449 (greenish yellow). The total amount of carotenoid contents was in the order of orange color (104.64 mg/100 g), greenish yellow color (70.82 mg/100 g), fluorescent yellow color (32.41 mg/100 g), yellow color (8.73 mg/100 g), and whitish yellow color (4.73 mg/ 100 g). Both lutein and β-carotene were the predominant pigments of carotenoids, and lycopene was only separated and identified in the orange color flesh. According to the results, colorimetric analysis can aid breeders interested in increasing carotenoid content in squash, which could be accurately measured using a simple, reliable, and cost- and labor-efficient method for the evaluation of carotenoid pigments.