Analysis of gut bacterial diversity in Latheticus oryzae and Rhizopertha dominica in sauce-flavored daqu production

Sauce-flavored Daqu is a complex product characterized by the presence of multiple microbes and enzymes, which attracts numerous insects for feeding during its production process. The mechanisms by which these insects adapt to such a diverse microbial and enzymatic environment, as well as the underlying structure of their gut microbial communities, warrant further comprehensive investigation.

This study employed Illumina MiSeq sequencing technology to examine the gut microbiota composition of two key insect species associated with Daqu, namely Latheticus oryzae and Rhizopertha dominica. Specifically, the V3-V4 regions of the 16S rDNA were sequenced.

The analysis revealed the presence of 3 652 and 1 808 Amplicon Sequence Variants (ASVs) in the gut microbiota of L. oryzae and R. dominica, respectively, with 372 ASVs shared between the two species. These ASVs were classified into 27 different phyla, with Proteobacteria, Firmicutes, and Bacteroidota being the predominant phyla. In L. oryzae, the principal bacterial genera identified were Ralstonia, Bacteroides, Latilactobacillus, Sphingomonas, and Akkermansia, whereas in R. dominica, the dominant genera included Candidatus Sulcia, Ralstonia, Ochrobactrum, and unidentified_Blattabacteriaceae. Alpha diversity analysis revealed significant differences in the Chao1 and Observed_species indices between the gut microbiota of the two insect species, while no significant differences were observed in the Simpson and Shannon indices. Moreover, functional prediction analysis of bacterial communities using PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) demonstrated significant differences in the metabolism of terpenoids and polyketides, lipid metabolism, glycan biosynthesis and metabolism, chemical structure transformation maps, and the abundance of cellular community-prokaryotes between the gut bacteria of the two insect species.

This study offers a novel perspective on how insects in sauce-flavor Daqu adapt to a complex microbial and enzymatic environment and provides a theoretical foundation for Daqu pest management strategies informed by gut microbiome research.