Gallic and ferulic acids suppress proteolytic activities and volatile trimethylamine production in the food-borne spoiler Rahnella aquatilis KM05.

Abstract

Rahnella aquatilis is a recognized microbial threat that alters the sensory properties of seafood. The high frequency with which R. aquatilis is isolated from fish has prompted a search for alternative preservatives. In this work, in vitro and fish-based ecosystem (RS) approaches were used to validate the antimicrobial effects of gallic (GA) and ferulic (FA) acids against R. aquatilis KM05. The results were compared with data describing the response of KM05 to sodium benzoate (SB). Bioinformatics data of the whole genome was used to analyze the potential for fish spoilage by KM05 in detail, and the results revealed the main physiological characteristics that underlie reduced seafood quality. In the KM05 genome, the most abundantly enriched GO terms were 'metabolic process', 'organic substance metabolic process' and 'cellular process'. Through an evaluation of the Pfam annotations, 15 annotations were found to be directly involved in the proteolytic activity of KM05. Peptidase_M20 was the most abundantly represented (abundance value of 14 060). Proteins representing the CutC family (abundance value of 427) indicated the potential for KM05 degradation of TMAO. Subinhibitory concentrations of GA and FA suppressed the proteolytic activities of KM05 both in vitro and in RS medium by an average of 33-45%. These results were confirmed by RT-qPCR experiments, which also showed that the expression levels of genes involved in proteolytic activities and volatile TMA production were also decreased. Phenolic compounds can be used as potential food additives for preventing quality deterioration of fish products. This article is protected by copyright. All rights reserved.