Cancer remains one of the leading causes of morbidity and mortality worldwide, and despite major advances in surgery, chemotherapy, radiotherapy, and immunotherapy, important therapeutic limitations persist, including systemic toxicity, therapeutic resistance, and poor drug penetration into hypoxic tumor regions. These challenges have renewed interest in alternative biological strategies, particularly the use of bacteria and bacterial toxins as antitumor agents. Certain bacterial species possess intrinsic tumor-targeting properties, including the ability to selectively colonize hypoxic and necrotic regions of solid tumors that are poorly accessible to conventional therapies. This review provides a comprehensive analysis of the mechanisms underlying bacteria-mediated anticancer activity, including selective tumor colonization, direct oncolysis, immune activation, and toxin-mediated cytotoxicity. Both obligate anaerobes (e.g., Clostridium and Bifidobacterium) and facultative anaerobes (e.g., Salmonella, Escherichia coli, and Listeria monocytogenes) are examined for their tumor-targeting potential. In addition, we discuss the oncological applications of several bacterial toxins and toxin-derived therapeutic constructs, including Cytolysin A (ClyA), Clostridium difficile toxin B (TcdB), diphtheria toxin, Pseudomonas aeruginosa exotoxin A, and Clostridium perfringens enterotoxin (CPE). Emerging strategies such as recombinant immunotoxins and bacterial-directed enzyme prodrug therapy (BDEPT) are also reviewed. Finally, current translational challenges, including pharmacokinetic limitations, immune clearance, and biosafety considerations, are analyzed, highlighting future directions for integrating bacteria-based platforms into next-generation cancer therapies. This approach reflects the growing interest in microbial strategies for oncology and underscores the potential of bacteria and their toxins as innovative tools in the development of targeted anticancer therapies.

Fishery products represent a key source of essential nutrients and play a strategic role in global food security, particularly in the context of increasing demand and the rapid expansion of aquaculture. This review provides an integrated analysis of fish nutritional composition and the main challenges related to food safety, with emphasis on emerging microbiological risks under current environmental changes. Fish muscle is characterised by a high content of proteins of high biological value, long-chain omega-3 polyunsaturated fatty acids (EPA and DHA), and essential micronutrients with high bioavailability. However, these properties also increase susceptibility to microbiological and oxidative spoilage, posing challenges for preservation and safety. Along the supply chain, fishery products are exposed to multiple contamination sources, including environmental chemicals and microorganisms from aquatic ecosystems and processing environments. Intrinsic factors such as pH and water activity, together with extrinsic conditions like temperature and handling, significantly influence microbial growth. Emerging pathogens such as Vibrio spp., alongside persistent pathogens including Listeria monocytogenes and opportunistic species such as Aeromonas spp., are of increasing concern. Additionally, antimicrobial resistance in aquatic environments represents a critical public health issue, highlighting the need for integrated control strategies based on surveillance and advanced monitoring tools.