Identifying the species of origin in commercial sausages in South Korea

Figures & data

Table 1. Primer information used in this study.

Species	Target gene	Primer name	Nucleotide sequence (5′->3′)	Product size
Pig, chicken, and fish meat	COI	3sp_COI_F	ATYACTATACTACTRACAGACCG	191 bp
		3sp_COI_R	AAKGGTTCTTTTTTACCTGAATAGTA
Pig	CYTB	Pig_CYTB_F	CAACAACGCATTCATTGACC	228 bp
		Pig_CYTB_R	AATATGGATGCTCCGTTTGC
Chicken	CYTB	Gal_CYTB_F	TCTATTCGCCTATGCCATCC	208 bp
		Gal_CYTB_R	TACTGGTTGGCTTCCGATTC
Fish meat	ND2	Fish_mtF	TCTTACCGGGGTTGGAACTTTA	150 bp
		Fish_mtR	AGGGGGATTAGATGAAGGGCTA

Figure 1. Multiple sequence alignments for COI sequences determined in this study. Majority of pigs have two types of DNA sequences (Pig01 and Pig02), but most chickens showed an identical sequence (chicken). Two types of fish meat sources were found from cod and pollock. The underlined sequences indicate the primer sequences for the universal primer set.

Figure 2. PCR amplification patterns in sausage DNA samples. (A) A universal primer set 3sp_COI_F and 3sp_COI_R; (B) pig-specific Pig_CYTB_F and CYTB_R; (C) chicken-specific Gal_CYTB_F and Gal_CYTB_R; (D) fish-specific Fish_mtF and Fish_mtR. + and − indicate the presence and absence of the meat product on the labels of the sausages, respectively. M1 and M2 are DNA size markers, 50-bp and 100-bp ladder, respectively.

Figure 3. Real-time PCR amplification patterns of pig, chicken, and fish meat. (A–C) show amplification patterns for serial dilutions of pig (A), chicken (B), and fish meat (C). (D–F) show the standard curves for (A–C).

Figure 4. Electrophoresis analysis for real-time PCR products. (A) pig; (B) chicken; (C) fish meat. M is DNA size marker, 100-bp ladder. Numbers on top of the lanes indicate DNA concentrations in 1 μl solution used for PCR amplification.

Table 2. Species identification of pig, chicken, and fish meat by DNA sequencing and PCR assays.

Species	No. of records	DNA sequencing	OS-PCR	Real-time PCR
Pig	38	38	38	38
Chicken	13	13	13	13
Fish^a*	6	8	8	8

^aFish-derived PCR amplicons were found in eight sausage DNA samples, of which six samples listed meat on the labels.