Invisorb spin universal kit

Genomic DNA (gDNA) was extracted from fresh bacterial colonies using Invisorb^® Spin Universal Kit (Stratec, Berlin, Germany). The isolated gDNA was stored at −20 °C until its analysis. All strains were confirmed as Salmonella by amplification of a 284 bp fragment of the invA gene (accession number: M90846.1) by endpoint PCR, using S. Enteritidis (ATCC 13076^®) as positive control and E. coli (ATCC 25922^®) as negative control (Table 1).

Salmonella isolates were confirmed by amplifying the invA gene, which is conserved in Salmonella serovars [19 ].
Genomic DNA (gDNA) was extracted from all Salmonella isolates using the Invisorb^® Spin Universal Kit (Stratec, Berlin, Germany) and a fragment of the invA gene was amplified by using the forward (5′-GTGAAATTATCGCCACGTTCGGGCAA-3′) and reverse 5′-(TCATCGCACCGTCAAAGGAACC-3′) primers [20 (link)]. Endpoint PCR was carried out in a total volume of 25 µL, containing 1 µL of gDNA template, 1 µL of forward primer, 1 µL of reverse primer, 1 µL of Taq polymerase, 2.5 µL of buffer 10X, 2 µL of MgCl₂, 2.5 µL dNTP and 14 µL of nuclease free water. PCR was performed in a BIO-RAD T100™ thermal cycler (Bio-Rad, Hercules, CA, USA) with the following conditions—denaturation of 3 min at 95 °C, 35 cycles of amplification with 30 s at 95 °C (denaturation), 30 s at 55 °C (annealing), and 90 s at 72 °C (extension), followed by 5 min at 72 °C for final extension and then resolved by electrophoresis on 2% agarose gel. The reaction products were stained with HydraGreen™ (ACTGene, Piscataway, NJ, USA) and visualized under the UV light by using a trans-illumination system ENDURO^TM GDS (Labnet International, Inc, Woodbridge, NJ, USA).