DETECTION AND MOLECULAR IDENTIFICATION OF Salmonella spp. IN TRADITIONAL SHRIMP PASTE (TERASI): INSIGHTS FROM MULTIPLEX PCR AND 16S rDNA SEQUENCING

One of the key criteria for quality food products is the absence of pathogenic microbes. Shrimp paste (terasi), a traditionally fermented product, is prone to contamination by unexpected bacteria, including Salmonella spp. This study aimed to isolate and identify Salmonella spp. in traditional shrimp paste using a multiplex polymerase chain reaction (mPCR) approach. The analyzed samples consisted of shrimp paste formulated from shrimp (UA, UB, UC), from fish (IA, IB, IC), and from a combination of both raw materials (CA, CB, CC). The research involved isolating Salmonella, performing biochemical tests with triple sugar iron agar (TSIA) and lysine iron agar (LIA), and molecular detection using mPCR. Isolate identification based on 16S rDNA sequencing was conducted for samples where mPCR failed to detect Salmonella at either the serovar or genus level. The presence of presumptive Salmonella spp. was confirmed through isolation and biochemical characterization in five shrimp paste samples, namely UA, UB, UC, CA, and CC, with the UC sample exhibiting the highest bacterial density at 8.3 × 10⁶ CFU/g. Further TSIA and LIA tests verified that Salmonella spp. was only present in UC. Seven UC isolates showed biochemical characteristics typical of Salmonella spp. (i.e., glucose fermentation, hydrogen sulfide production, and colony morphology on xylose lysine deoxycholate agar). mPCR confirmed these seven UC isolates as belonging to the Salmonella genus, and one of them (UC8) was successfully identified as Salmonella Typhimurium. The 16S rDNA sequencing results showed that six isolates were not identified at the serovar level were classified as Salmonella enterica subsp. enterica serovar Newlands, which is reported for the first time in Indonesian shrimp paste. Meanwhile, one isolate (UC4) that could not be identified at the genus level was confirmed as Proteus mirabilis, indicating non-Salmonella contamination. These findings highlight the importance of improving hygiene in traditional shrimp paste production to minimize the risk of pathogenic microbial contamination.