In culture, the house dust mite, Dermatophagoides pteronyssinus, shows different growth patterns, but the composition and changes in the associated microbial community during mite culture growth are poorly known. In this study, we analyzed temporal changes in microbial communities including 'internal' communities (inside mites, ingested) and 'environmental' communities (from culture environment). Microbial community structure was correlated with guanine content (a nitrogenous waste product of mites) and mite population density. Both internal and environmental microbial communities were remarkably consistent between biological replicates from the same culture age group and were composed of relatively few dominant taxa-11 bacterial and 3 fungal operational taxonomic units (OTUs). Significant changes over time in microbial community structure in the bulk culture environment and in internal mite samples were observed. The yeast, Saccharomyces cerevisiae, a main component of the mite diet, gradually disappeared during mite culture growth and was replaced by fungi from the genera Aspergillus and Candida in both 'internal' and 'environmental' samples. In environmental samples, bacteria from the genus Lactobacillus and S. cerevisiae were negatively correlated, and Aspergillus and Candida positively correlated, with guanine content. The relative abundance of bacteria from the genus Kocuria increased with mite density but declined with increasing guanine content. The relative abundance of bacteria from the genus Virgibacillus was negatively correlated with mite density in 'internal' samples. Gram-positive bacteria dominated bacterial microbiomes at all time points in our experiments, indicating a more limited possibility for vaccine contamination by bacterial endotoxins (heat-stable lipopolysaccharides produced mostly by Gram-negative bacteria) in our experimental cultures.

Crop Research Institute Drnovska 507 73 CZ 16106 Prague 6 Ruzyne Czechia

Department of Botany and Zoology Faculty of Science Masaryk University Kotlarska 2 CZ 611 37 Brno Czechia

Department of Ecology and Evolutionary Biology University of Michigan 3600 Varsity Drive Ann Arbor MI 48109 USA

Faculty of Agrobiology Food and Natural Resources Czech University of Life Sciences Prague Kamycka 129 CZ 165 00 Prague 6 Suchdol Czechia

Institute of Biology University of Tyumen Pirogova 3 625043 Tyumen Russia

Rush University Department of Internal Medicine Division of Infectious Diseases Rush Medical College 600 S Paulina St Chicago Illinois 60612 USA

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