We explored quenching of the PlcR–PapR quorum-sensing system in Bacillus cereus. We generated PapR7-peptidic derivatives that inhibit this system and thus the production of virulence factors, reflected by a loss in hemolytic activity, without affecting bacterial growth. To our knowledge, these peptides represent the first potent synthetic inhibitors of quorum-sensing in B. cereus.

BackgroundThe ever-growing world population results in the ineluctable increase of food demand which translates in the augment of the global market of packaging materials. Hence, the concept of active packaging materializes as a technology to enhance the safety, quality and shelf-life of the packaged foods. Active packaging systems can contribute to the reduction of food waste by providing, apart from an inert barrier to external conditions, several functions associated with food preservation, namely absorbing/scavenging, releasing/emitting and removing properties, temperature, microbial and quality control. Scope and approach The purpose of this review is to present a concise (but wide-ranging) appraisal on the latest advances in active agents for active food packaging. Emphasis is placed on active functions such as antimicrobial and antioxidant activity, oxygen and ethylene scavenging, and carbon dioxide emitting. An effort was made to highlight representative articles that prompted research on active agents towards viable market solutions. Key findings and conclusions Active packaging is a thriving field given its duality as barrier to external detrimental factors and active role in food preservation and quality. The use of natural active agents is a flourishing field due to the general concern towards natural-based additives. Nevertheless, research is still in its early stages with a long way to go in the design of innovative and economical active packaging materials containing appropriate active agents. The interaction between packaging, environment and food is the key challenge for achieving commercial translation.

Abstract Binary encoding of peptide sequences into differential antimicrobial mechanisms is reported. Such sequences are random in composition, but controllable in chain length, are assembled from the same two amino acids, but differ in the stereochemistry of one. Regardless of chirality, the sequences lyse bacteria including the “superbugs” methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). Sequences with the same chirality, so-called homochiral sequences, assemble into antimicrobial pores and form contiguous helices that are biologically promiscuous and hemolytic. By contrast, heterochiral sequences that lack such persistence selectively attack bacterial membranes without oligomerizing into visible pores. These results offer a mechanistic rationale for designing membrane-selective and sequence-independent antimicrobials.