The silkworm (Bombyx mori) gut microbiota is involved in metabolic detoxification by glucosylation of plant toxins

Abstract

Herbivores have evolved the ability to detoxify feed components through different mechanisms. The oligophagous silkworm feeds on Cudrania tricuspidata leaves (CTLs) instead of mulberry leaves for the purpose of producing special, high-quality silk. However, CTL-fed silkworms are found to have smaller bodies, slower growth and lower silk production than those fed mulberry leaves. Here, we show that the high content of prenylated isoflavones (PIFs) that occurred in CTLs is converted into glycosylated derivatives (GPIFs) in silkworm faeces through the silkworm gut microbiota, and this biotransformation is the key process in PIFs detoxification because GPIFs are found to be much less toxic, as revealed both in vitro and in vivo. Additionally, adding Bacillus subtilis as a probiotic to remodel the gut microbiota could beneficially promote silkworm growth and development. Consequently, this study provides meaningful guidance for silk production by improving the adaptability of CTL-fed silkworms.

Gut Microbiota Analysis in Silkworms (Bombyx mori) Provides Insights into Identifying Key Bacterials for Inclusion in Artificial Diet Formulations

“…The SY group exhibited the lowest species richness and diversity, suggesting that the mulberry leaf diet supports a specialized and streamlined gut microbiota adapted to the specific nutritional profile of the leaves. This finding is consistent with previous common knowledge that has reported a distinct and conserved gut microbiota in silkworms fed on mulberry leaves [22,30,31]. The low diversity in the SY group may be attributed to the presence of antimicrobial compounds, such as phenolic glycosides and alkaloids, in mulberry leaves that could selectively inhibit the growth of certain microbial taxa.…”

“…The increased xenobiotic degradation capability in the SL group may be linked to the presence of plant-derived compounds, such as flavonoids and tannins, which are components of the soybean meal in the artificial diet [7,35,36]. The downregulation of photosynthesis-related pathways in the SL group is consistent with the lower abundance of Cyanobacteria and chloroplast-derived taxa in this group compared to the SY group [6,30,35].…”

Effects of Habitual Dietary Change on the Gut Microbiota and Health of Silkworms

“…Dietary patterns are considered the most important factor shaping the gut microbiota [1,2]. Similar to mammals, the gut microbiota of silkworms also plays a crucial role in the host's nutritional metabolism and immune defense [3][4][5]. In insect models such as Bombyx mori and Drosophila, as well as in mammalian models such as mice, dietary changes have been shown to affect the plasticity of gut microbiota and to be closely associated with health [6][7][8][9].…”

From phyllosphere to insect cuticles: silkworms gather antifungal bacteria from mulberry leaves to battle fungal parasite attacks

“…The silkworm Bombyx mori is an important domesticated insect for the sericulture industry and a model animal for the research of caterpillar developments and life sciences [ 17 , 18 ]. This oligophagous insect only feeds on mulberry ( Morus alba ) leaves and the change in diets, especially the use of artificial diet, could substantially change the gut microbiotas, growth, and physiology of silkworm larvae [ 19 – 23 ]. Silkworm mass rearing frequently encounters the threat of fungal, bacterial, virus, and microsporidian diseases [ 18 ].…”