Quality changes, diversity and virulence of Aeromonas spp. in the refrigerated Meretrix meretrix and Paphia undulata clams
Suriya Palamae, Jirakrit Saetang, Mingkwan Yingkajorn, Yadong Zhao, Bin Zhang, Jun Tae Kim, Soottawat Benjakul
Abstract
Aeromonas spp. are opportunistic and widespread bacteria recognized as emerging human pathogens and spoilage bacteria in aquatic foods. These bacteria, often present in undercooked seafood, pose health risks to consumers. This study aimed to assess the prevalence and virulence of Aeromonas spp. in fresh Asian hard clam (HC) and baby clam (BC) along with their refrigerated (HC-R and BC-R) counterparts. A total of 124 isolates were obtained from Aeromonas medium base supplemented with ampicillin . Identification using the API 20 NE kit and MALDI-TOF/MS confirmed that 102 isolates (82 %) belonged to the Aeromonas genus. MALDI-TOF/MS further identified these isolates as A. hydrophila (35 %), A. veronii (23 %), and others (42 %). Refrigerated clams exhibited greater microbial diversity than fresh counterparts. Among them, 34 isolates were randomly selected and tested for virulence profiling. Hemolysis was observed by 61.8 % (21/34) of isolates, while 8.8 % (3/34) displayed protease activity. 16S rRNA sequencing revealed that refrigerated storage altered microbial communities by increasing spoilage-associated genera like Vibrio , Shewanella , Vagococcus , Lactococcus , and Aeromonas . Both fresh and refrigerated clams contained pathogenic and spoilage-associated Aeromonas spp., highlighting the need for stringent seafood processing, storage, and handling measures. Proper cooking and hygiene practices are essential to mitigate health risks from Aeromonas -contaminated clams.