Safety of microbial enzyme and Allium-probiotic bioproducts in poultry: a review

Microbial enzymes, strain-defined probiotics, and fermented botanical substrates are increasingly developed as poultry bioproducts, but evidence of efficacy does not establish safety itself. This narrative review synthesizes published poultry studies and regulatory/scientific guidance to propose an operational whole-bioproduct framework for microbial enzyme and Allium-probiotic preparations. The framework separates product identity and classification, hazard characterization, exposure assessment, target-animal tolerance, worker/consumer/environmental safety, manufacturing controls, and batch-release specifications. It also distinguishes safety and tolerance endpoints from efficacy and mechanistic outcomes, which are often conflated in poultry additive studies. Particular attention is given to strain-level genomic characterization, antimicrobial-resistance assessment, enzyme allergenicity, dose–response design, Allium-related compositional variability and contaminants, fermentation-derived metabolites, and environmental persistence. Evidence from fermented chives, purple onions, Bacillus and Lactiplantibacillus systems is used as an illustrative case base rather than as proof of class-wide safety. The proposed framework is intended for researchers, product developers, and risk assessors and should be adapted to the applicable jurisdiction. A defensible safety dossier therefore evaluates the defined final product under its intended conditions of use, not a single active component in isolation.