Characterization of bacterial microbiota of insect-based products (novel foods) by 16S rRNA metabarcoding

Insect-based products (IBPs) are novel foods recently introduced in the market of the European Union (EU). Although IBPs could present new challenges in terms of food safety, their microbiological profiles have been poorly investigated. In this study, the bacterial microbiota of processed IBPs sold online in the EU was investigated by 16S rRNA metabarcoding. Diversity indices and microbial composition were computed. Results were statistically analyzed according to the following criteria: 1) the insect species declared on the IBP's label (Tenebrio molitor, Locusta migratoria, Acheta domesticus, and Alphitobius diaperinus), 2) the food category (e.g. 100 % insect powder, or bakery products, pasta, etc. with different percentages of insect powder), 3) the e-commerce platform from which the IBP was purchased(e-CO) and 4) the ingredient pattern (IG), defined as the presence and quantity of non-insect ingredients reported in the IBP's list of ingredients. Bacillota (53.1 %) and Pseudomonadota (37.0 %) were the most frequently detected phyla, while Aeromonadaceae (18.2 %) and Bacillaceae (12.4 %) were the most detected families. Among genera, Aeromonas, Bacillus, Clostridium, Staphylococcus and lactic acid bacteria (LAB) were those of major interest for their food safety impact. Notably, Aeromonas spp. were detected in processed IBPs for the first time, highlighting the need for further risk assessment. Salmonella spp. and Listeria spp. were not detected, in accordance with previous findings reporting the rare presence of these pathogens in processed IBPs, and suggesting a potentially low related risk to consumers. Powdered IBPs appeared particularly susceptible to contamination by bacterial genera associated with hygiene and food safety issues. Significant differences in microbial biodiversity were found only between IBPs declared as made from different insect species. No statistically significant differences were observed for the other considered criteria, except in IBPs made from A. diaperinus. Given the limitations of 16S rRNA metabarcoding in determining viability of microorganisms, future risk assessments should consider a combined approach with traditional methods.