Combining Celery Oleoresin, Limonene and Rhamnolipid as New Strategy to Control Endospore-Forming Bacillus cereus

Abstract

Foodborne diseases (FBD) are a great problem worldwide, leading millions of people to seek medical help and to significant economic losses for industry. Among the agents implicated in FDB is Bacillus cereus, a Gram-positive, toxigenic and endospore-forming bacterium. In this study, rhamnolipid (RL) biosurfactant, celery oleoresin (OR) and limonene (LN) were evaluated as bio-based alternatives for controlling the growth of vegetative cells and endospores of B. cereus. To address their antimicrobial activity, the compounds were tested separately and in combination. Results demonstrate that, when combined with RL, both OR and LN have lower minimal inhibitory concentration (MIC) values and increased endospore inhibition potential. A percentage of endospore inhibition from 73% to 98%, corresponding to a 2.8–3.6 log reduction in spore outgrowth, was observed. RL inhibited B. cereus growth and endospore germination and potentially enhanced the antimicrobial efficacy of the natural hydrophobic compounds tested.

Antibacterial Mechanism of Rhamnolipids against Bacillus cereus and Its Application in Fresh Wet Noodles

“…In 2019, Ferreira established that RLs can significantly impede the vegetative cell state of B. cereus, but did not delve into the underlying antibacterial mechanism [17]. Bertuso et al showed that RLs inhibited the growth and spore germination of B. cereus, augmenting the antimicrobial potency of celery oleoresin and limonene compounds tested [18]. Furthermore, Bertuso et al demonstrated that RLs had an equivalent antibacterial impact on B. cereus vegetative cells and endospores as that observed in skim milk [19].…”