“The microbial composition of fermented mealworm frass fertilizer has been characterized in scientific studies as of April 2026.”

Insect frass fertilizer is emerging as a sustainable and novel input for improving soil health and crop production; however, research attention on its safety and microbial properties remains limited. Here, we evaluated the levels of heavy metals, pathogens, diversity, abundance, composition and functional roles of bacteria and fungi in frass fertilizer produced by eight edible insect species. Taxonomic classification revealed 36 bacteria phyla across the frass fertilizers, with most belonging to Firmicutes (43 %), Proteobacteria (23 %), and Actinobacteriota (18 %), whereas the main fungal phyla were Ascomycota (80 %) and Basidiomycota (10 %).

The study demonstrated that frass and urea exerted different effects on the abundance of total bacteria, total fungi, Bacillus spp., Pseudomonas spp., chiA, and ureC in peat (Table 3). Bacterial counts were estimated at 8.71 in peat fertilized with frass at 50–400 mg N dm−3 and at 8.61 in unfertilized peat. Frass stimulated the abundance of Clostridium spp., but a significant increase in the counts of these bacteria were noted only in peat supplied with frass at 100 and 400 mg N dm−3. The abundance of Pseudomonas spp. was significantly stimulated by frass (applied at 50–200 N dm−3).

National Food Safety Standards Catalog (as of September 2025, 1725 items). Includes standards for mycotoxins and contaminants in food, but no mention of mealworm frass or its microbial composition.

Regarding the microbial diversity provided by frass, it has been found to be considerably variable as influenced by several factors such as environmental habitat, developmental stage and host phylogeny (Poveda, 2021c). Among the microorganisms occurring in the insect exuviae, a high diversity of chitinolytic bacteria has been observed.

In addition to its nutrient content, frass contains microbial communities that may enhance plant growth through phytohormone production, nitrogen fixation, and organic matter turnover. This study examined the impact of five feed substrates... on frass microbial composition, and assessed responses to thermal treatment. Feed nutrients were characterised, and microbial communities profiled using amplicon sequencing.

In the present laboratory study, the bacterial biota characterizing a pilot production chain of fresh T. molitor larvae was investigated. Microbial viable counts highlighted low microbial contamination of the wheatmeal, whereas larvae and frass were characterized by high loads of Enterobacteriaceae, lactic acid bacteria, and several species of mesophilic aerobes.

The bacterial biota of laboratory-reared edible mealworms (Tenebrio molitor L.): From feed to frass. Microbial viable counts and molecular profiling (PCR-DGGE and Illumina sequencing) characterized the bacterial communities in mealworm larvae and frass, identifying dominant genera such as Enterobacter spp., Erwinia spp., Enterococcus spp., and Lactococcus spp.

3. Microbiome ecological function and interaction network analysis. National Natural Science Foundation of China, surface project 32070117, on mealworms.

In the case of Tenebrio molitor, a number of bacteria have been found in its gut stool that are favorable for agriculture. These bacteria can be of great use in terms of soil fertility and productivity. Within this microbiota, the bacteria of greatest interest are Paenibacillus, which is included among the plant growth promoting bacteria; Bacillus, which is capable of synthesizing a very effective insecticidal protein, among others; and Rhizobium, capable of fixing atmospheric nitrogen.

The invention provides microorganisms with plastic degradation activity isolated from mealworm larvae. These microorganisms can selectively or completely degrade plastics such as PET, PVC, PS, PP, and PE under appropriate culture conditions.

Przemieniecki et al. [19] demonstrated that mealworm meal fertilizer positively affected the growth of wheat seedlings and the abundance of beneficial soil and rhizosphere microorganisms. In addition to meal, insect farming also generates waste products such as exuviae and frass that can be recycled in agriculture.

The diet provided to mealworms significantly influences both the nutrient profile of the frass and the diversity of the microbial community it contains. Heat treatment, while necessary for safety reasons, can potentially eliminate beneficial microbiota present in the frass, affecting its effectiveness as a biofertilizer.

Serine protease in the midgut of mealworm larvae in cow barn dust can induce the release of complement factor C5a, which plays a regulatory role in respiratory allergic diseases.

With the rapid development of the microbial fermentation industry and in-depth research, domestic Bacillus coagulans powder viable cell count can reach 100-200 billion CFU/g, fermentation costs and market prices will further decrease.

Scientific literature up to 2024 includes multiple peer-reviewed studies characterizing microbial communities in mealworm frass, such as bacterial profiling via sequencing and viable counts, but no widely published studies specifically on 'fermented' mealworm frass appear before 2026. Fermentation processes for frass fertilizer are emerging in applied agriculture research.

Subjects on GFD can reduce bacterial richness in the gut microbiome. Collecting gut microbiome, dietary habits, anthropometrics, and blood parameters affects microbiome composition in some celiac disease.