Midgut microbiota profiling of Blattella germanica (Blattodea: Ectobiidae)

A detailed understanding of the core microbiome in Blattella germanica is essential for clarifying host-symbiont interactions. Although factors such as diet, developmental stage, and environmental conditions influence cockroach gut microbial communities, their combined effects remain poorly understood. Moreover, most studies rely on whole-gut homogenates, leaving the midgut microbiota largely uncharacterized. Hence, 16S rRNA gene amplicon sequencing was used to characterize and compare the midgut bacterial community structure from 28 samples (including 1 negative control), considering the factors of developmental stage, sex, physiological status, and environmental origin. Microbial community profiling revealed 923 unique genera corresponding to 505 families, 306 orders, 137 classes, and 47 phyla. Bacterial communities belonging to the families Lactobacillaceae, Desulfovibrionaceae, Lachnospiraceae, Dysgonomonadaceae, Christensenellaceae, and Rikenellaceae were consistently present across all treatment groups. Alpha diversity analysis showed significant differences in Shannon diversity, while Simpson and Chao1 diversity indices showed no significant variation. Beta diversity analysis based on UniFrac distances revealed significant differences in microbial community composition across experimental conditions, with stronger separation observed when considering taxa abundance. PERMANOVA indicated that both physiological status and environmental origin significantly shaped community structure, while host sex and developmental stage showed significant effects only in weighted UniFrac distance. Family-level and prevalence analyses consistently demonstrated greater similarity between laboratory-fed and starved groups, whereas field-collected samples exhibited a more distinct and less shared taxonomic profile. Overall, these findings advance current understanding of compartment-specific gut microbiota and underscore the ecological stability of microbiome taxa under diverse conditions.