Microbial community of retail marinated raw crab: Comprehensive analysis via culture-dependent methods and high-throughput sequencing

Marinated raw crab, a popular pickled seafood product in Korea, is consumed without heat treatment and is therefore considered a potential reservoir for foodborne pathogens. Despite its popularity, microbiological investigations of commercial marinated raw crab remain limited. This study aimed to characterize bacterial profiles using culture-dependent methods and 16S rRNA amplicon sequencing. Crab marinated in soy sauce (n = 120) and spicy sauce (n = 120) were collected across four seasons. Average aerobic plate counts and coliform counts were 4.73 log and 1.41 log CFU/g for soy sauce and 5.31 log and 1.80 log CFU/g for spicy sauce, respectively. 16S rRNA sequencing identified abundant lactic acid bacteria and spoilage-causing or problematic bacteria. While Psychrobacter, Vibrio, and Carnobacterium were dominant in soy sauce, Psychrobacter, Photobacterium, and Weissella prevailed in spicy sauce. Although many bacterial genera were shared, microbial community structure differed by sauce type. Bacillus, Weissella, and Staphylococcus were more abundant in spicy sauce, potentially due to red pepper powder, a key ingredient. Additionally, seasonal analysis revealed significant bacterial count variations for soy sauce samples and higher spoilage organism levels in warmer months for both sauce types, emphasizing the need for proper temperature control. This study characterizes microbial communities in commercial marinated raw crab and provides foundational data to enhance microbiological safety.