Yong, T.-S. | Search bioRxiv

bioRxiv2021

Reduced production of the major allergen Bla g 1 and Bla g 2 in Blattella germanica after antibiotic treatment

PurposeAllergens present in the feces or frass of cockroaches can cause allergic sensitization in humans. The use of fecal and frass extracts for immunotherapy has been previously investigated but has not yet been fully standardized. Here, we treated cockroaches with ampicillin to produce extracts with reduced amounts of total bacteria. MethodsWe performed targeted high-throughput sequencing of 16S rDNA to compare the microbiomes of ampicillin-treated and untreated (control) cockroaches. RNA-seq was performed to identify differentially expressed genes (DEGs) in ampicillin-treated cockroaches. ResultsAnalysis of the microbiome revealed that alpha diversity was lower in the ampicillin-treated group than in the control group. Beta diversity analysis indicated that ampicillin treatment altered bacterial composition in the microbiome of cockroaches. Quantitative polymerase chain reaction revealed that almost all bacteria were removed from ampicillin-treated cockroaches. RNA-seq analysis revealed 1,236 DEGs in ampicillin-treated cockroaches (compared to untreated cockroaches). Unlike bacterial composition, the DEGs varied between the two groups. Among major allergens, the expression of Bla g 2 decreased significantly in ampicillin-treated cockroaches (compared to untreated group). ConclusionsIn this study, the reduced level of allergens observed in cockroaches may be related to lower amounts of total bacteria caused by treatment with antibiotics. It is possible to make a protein extract with few bacteria for use in immunotherapy.

bioinformatics↗

bioRxiv2019

Comparative microbiomes of three species of laboratory-reared Periplaneta cockroaches

Cockroaches are the most primitive insects, and are often used as the basic insect model in many studies. Three species of Periplaneta cockroaches were raised in the laboratory for many generations under the same conditions. We conducted 16S rRNA-targeted high-throughput sequencing to evaluate the overall bacterial composition in the microbiomes of three species of cockroaches. The number of operational taxonomic units (OTUs) was not significantly different between the three cockroach species. With respect to the Shannon and Pielou indexes, the microbiome of Periplaneta americana presented higher values than that of either P. japonica or P. fulginosa. In terms of species composition, endosymbionts accounted for over half of all the bacterial species in P. japonica and P. fulginosa. The beta diversity analysis showed that P. japonica and P. fulginosa exhibit a similar microbiome composition, which is different from that of P. americana. However, we also identified that P. japonica and P. fulginosa are hosts to distinct bacterial species. Thus, although the composition of the microbiome may vary based on multiple conditions, it is possible to identify distinct compositions of the microbiome among the different Periplaneta cockroach species even when individuals are reared under the same conditions.\n\nImportanceCockroaches inhabit various habitats--which are known to be related to their microbiome--and exhibit different features depending on the species. It is expected that their microbiomes would vary according to species depending on these features. Cockroach microbiomes are known to vary based on the diet or environmental shifts. In this study, we compare the diversity of bacteria in the three cockroach species under conditions of reduced diet and environment shifts. This study can establish the basic microbiomes of three Periplaneta species and can be the basic data for cockroach research.

microbiology↗