Spore germination plays an essential role in the pathogenesis of Clostridium perfringens-associated food poisoning. Germination is initiated when bacterial spores sense various stimuli, including chemicals and enzymes. A previous study showed that dipicolinic acid (DPA) chelated with calcium (Ca-DPA) significantly stimulated spore germination in C. perfringens. However, whether Ca²⁺ or DPA alone can induce germination is unknown. Therefore, we aimed to evaluate the possible roles of Ca²⁺ and other divalent cations present in the spore core, such as Mn²⁺ and Mg²⁺, in C. perfringens spore germination. Our study demonstrated that (i) Ca-DPA, but not DPA alone, induced C. perfringens spore germination, suggesting that Ca²⁺ might play a signaling role; (ii) all tested calcium salts induced spore germination, indicating that Ca²⁺ is critical for germination; (iii) the spore-specific divalent cations Mn²⁺ and Mg²⁺, but not Zn²⁺, induced spore germination, suggesting that spore core-specific divalent cations are involved in C. perfringens spore germination; and (iv) endogenous Ca²⁺ and Mg²⁺ are not required for induction of C. perfringens spore germination, whereas exogenous and partly endogenous Mn²⁺ are required. Collectively, our results suggest that exogenous spore core-specific divalent cation signals are more important than endogenous signals for the induction of spore germination.

Clostridium perfringens is a spore-forming bacterium that causes food poisoning. Given the high heat resistance of its spores, natural antimicrobial agents are considered as alternatives to thermal processing strategies to inactivate or eliminate such spores from food products. A high chitosan concentration (0.2%) can effectively inhibit the growth of C. perfringens spores in cooked chicken meat, whereas nisin cannot (even at concentrations four times higher than those permitted: 250 μM). However, nisin is an effective inhibitor when in combination with other preservatives. Therefore, we evaluated the inhibitory effects of a chitosan–nisin combination on the germination, outgrowth, and vegetative growth of C. perfringens spores in laboratory medium and chicken meat. Among many tested concentration combinations, a 0.025% chitosan and 0.075% nisin mixture was found to be the most effective for inhibiting spore germination and outgrowth in laboratory medium. Furthermore, a mixture of chitosan–nisin, at 0.025% each, blocked the vegetative growth of C. perfringens spores. However, four-times higher concentrations of chitosan–nisin (0.1% each) were required to effectively inhibit C. perfringens spore germination in chicken meat. Collectively, our results suggest that the combination of chitosan and nisin can be considered as an alternative approach to control C. perfringens spore germination in meat products.

The gut microbiome undergoes compositional and functional changes with ageing. However, microbial signatures specifically associated with healthy ageing, independent of age-related diseases, remain poorly defined. This systematic review aimed to identify compositional and functional features of the gut microbiome associated with healthy ageing. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic search was conducted using PubMed, Web of Science and ScienceDirect for studies published up to January 2026. The search strategy focused on gut microbiome, ageing and healthy terms. Risk of bias was assessed using the Newcastle–Ottawa Scale. Gut microbiome composition was reviewed across five predefined age groups, while the functional pathways were reviewed for older adults and centenarians. The included studies represented several regions, including recognized longevity hotspots, although geographic representation remained limited. Most studies used 16S rRNA gene sequencing ( n =24; 58.5%), followed by shotgun metagenomics ( n =13; 31.7%), both ( n =3; 7.4%) or metaproteomics ( n =1; 2.4%). Enrichment of specific taxa such as Akkermansia , Alistipes and Parabacteroides was consistently reported in centenarians, alongside distinct patterns in older adults and long-lived individuals. Functional profiling suggested differences in pathways related to amino acid catabolism, vitamin biosynthesis and pathways potentially linked to immune modulation, inflammatory processes and gut barrier support. This review provides the first structured synthesis of gut microbiome signatures associated with healthy ageing across the lifespan, highlighting consistent functional traits and the need for a wider geographic representation in future research. It supports standardized, multi-omics framework to identify robust biomarkers and potential microbiome-based interventions for promoting healthy ageing.