Storage mites consume stored products in interaction with environmental microorganisms, resulting in the destruction of infested food and providing specific odours. Here we simulated the effect of mite grazing on oat flakes. Spent growth medium (SPGM) was obtained from seven mite cultures and mixed with oat flakes as the source of faeces and microbes. SPGM-treated diets were offered to 4 mite cultures. The microbiomes were analysed using sequencing of V4_16S_DNA. Mite growth tests, food preferences, and microbiome changes were observed in correlation with SPGM type and mite cultures. The microbiome consisted of 41 OTUs belonging to mite-associated bacteria and faeces bacteria. The composition of the microbiome depends more on the source of SPGM than on mite culture. The SPGM diet accelerated mite population growth and influenced mite food choice, although the effect was dependent on both types of SPGM and mite culture. Kocuria, Brevibacterium, Virgibacillus, and Staphylococcus profiles in SPGM added into diets showed positive correlations to mite population growth. The Kocuria profile in the bodies of mites was positively correlated with mite population growth. The results showed that mites are influenced by SPGM-treated diets, and mite feeding influences the environmental microbiome. The most beneficial was the mite interaction with Kocuria.

• Klíčová slova
• allergens, bacteria, digestion, faeces, interaction,
• MeSH
• Acaridae * mikrobiologie   růst a vývoj   MeSH
• Bacteria * klasifikace   genetika   izolace a purifikace   MeSH
• feces mikrobiologie   MeSH
• mikrobiologie životního prostředí * MeSH
• mikrobiota * MeSH
• RNA ribozomální 16S genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA ribozomální 16S MeSH

Dermatophagoides farinae is an important house dust mite species that causes allergies in humans worldwide. In houses, these mites are commonly found in actively used mattresses and pillows, which provide food (i.e. sloughed skin and microorganisms), moisture, and increased temperature for faster mite development. In mattresses, feeding mites prefer the upper sector, as close as possible to the resting human (temperature 32-36 °C, humidity between 55 and 59%). However, mites that are not actively feeding prefer staying at deeper zones of the mattress. Here, we analyzed mite responses to different temperatures (15-35 °C) and relative humidity (62-94% RH) in terms of their population size growth and respiration (CO2 production) using lab mite cultures. The intrinsic rate of population increase had a single maximum at approximately 28 °C and 85% RH. At 30 °C, there were two respiration peaks at RH 90% (smaller peak) and 65% (larger peak). Therefore, there is a mismatch between the optimal temperature/humidity for the population size increase vs. respiration. We propose preliminary hypotheses explaining the two respiration peaks and suggest that future research should be done to elucidate the nature of these peaks.

• Klíčová slova
• Dermatophagoides farinae, House dust mites, Humidity, Physiology, Population growth, Respiration, Temperature,
• MeSH
• alergeny MeSH
• antigeny roztočů domácího prachu MeSH
• Dermatophagoides farinae * fyziologie   MeSH
• lidé MeSH
• populační růst * MeSH
• prach MeSH
• teplota MeSH
• vlhkost MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alergeny MeSH
• antigeny roztočů domácího prachu MeSH
• prach MeSH

Feces have been suggested as a major source of microorganisms for recolonization of the gut of stored product mites via coprophagy. The mites can host microorganisms that decrease their fitness, but their transmission is not known. To address the role of fecal microbiota on mite fitness, we performed an experimental study in which the surfaces of mite (Tyrophagus putrescentiae) eggs were sterilized. Mites eggs (15 per experimental box) were then hatched and grown on feedstock with and without feces. These experiments were conducted with four distinct T. putrescentiae populations (5L, 5K, 5N, and 5P), and mite population density after 21 day of cultivation was used to assess mite fitness and the impact of fecal microbiota on fitness. Population density was not affected by the presence of feces in two of the cultures (5L and 5K), while significant effects of feces were observed in the other cultures (5N and 5P). Mite culture microbial communities were analyzed using cultivation-independent next-generation amplicon sequencing of microbial 16S and 18S ribosomal RNA (rRNA) genes in the fitness influenced populations (5N and 5P). Several microbial taxa were associated with fecal treatments and reduced mite fitness, including Staphylococcus and Bartonella-like bacteria, and the fungal genera Yamadazyma, Candida, and Aspergillus. Although coprophagy is the transmission route mites used to obtain beneficial gut bacteria such as Bartonella-like organisms, the results of this study demonstrate that fecal-associated microorganisms can have negative effects on some populations of T. putrescentiae fitness, and this may counteract the positive effects of gut symbiont acquisition.

• Klíčová slova
• feces, feeding, microorganisms, mite, transmission, yeasts,
• Publikační typ
• časopisecké články MeSH

House dust mites inhabit bed mattresses contaminating them with allergens. A strong temperature/moisture gradient exists in mattresses when it is used by humans daily. Here, we studied migration patterns of the mite Dermatophagoides farinae in continuous and time-discontinuous temperature gradients consisting of five sectors with 19-23, 23-28, 28-32, 32-36 and 36-41 °C, containing dye-labeled diets as an indicator of mite presence and feeding. The mites migrated through the sectors and fed on the labeled diets or stayed unfed. The numbers of mites with the same coloration in their guts and the numbers of unfed mites in the sectors were recorded. Unfed mites provided information on short-term temperature preferences. Apart from a control trial, two experiments were performed: (i) a constant 19-41 °C gradient for 24 h, and (ii) alternating cycles of the same temperature gradient (19-41 °C, 8 h) and room temperature (16 h) for 5 days to model the typical daily occupancy of bed by humans. In both experiments, fed mites preferred a sector with 32-36 °C, suggesting that in mattresses, house dust mites prefer to stay as close as possible to the resting human, thus maximizing allergen exposure. However, the number of unfed mites decreased with increased temperatures in the gradient. Experiment (ii) showed that the fed mites remained at the same optimal distance from the heat source, suggesting that they stay at the upper surface of the regularly used mattress, even when human was temporarily absent during the day. Unfed mites apparently hide deeper in mattresses as suggested by their avoidance of increased temperatures.

• Klíčová slova
• Allergens, Feeding, House dust mites, Temperature, Temperature preferences,
• MeSH
• alergeny MeSH
• antigeny roztočů domácího prachu MeSH
• Dermatophagoides farinae MeSH
• lidé MeSH
• prach analýza   MeSH
• Pyroglyphidae * MeSH
• roztoči * MeSH
• teplota MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alergeny MeSH
• antigeny roztočů domácího prachu MeSH
• prach MeSH

The two common species of house dust mites (HDMs), Dermatophagoides farinae and D. pteronyssinus, are major sources of allergens in human dwellings worldwide. Many allergens from HDMs have been described, but their extracts vary in immunogens. Mite strains may differ in their microbiomes, which affect mite allergen expression and contents of bacterial endotoxins. Some bacteria, such as the intracellular symbiont Cardinium, can affect both the sex ratio and biochemical pathways of mites, resulting in abundance variations of mite allergens/immunogens. Here, we investigated the bacterial microbiomes of D. farinae and D. pteronyssinus males and females using barcode 16S rDNA sequencing, qPCR, and genomic data analysis. We found a single species of Cardinium associated with D. farinae strains from the USA, China and Europe. Cardinium had high abundance relative to other bacterial taxa and represented 99% of all bacterial DNA reads from female mites from the USA. Cardinium was also abundant with respect to the number of host cells-we estimated 10.4-11.8 cells of Cardinium per single female mite cell. In a European D. farinae strain, Cardinium was more prevalent in females than in males (representing 92 and 67% of all bacterial taxa in females and males, respectively). In contrast, D. pteronyssinus lacked any Cardinium species, and the microbiomes of male and female mites were similar. We produced a Cardinium genome assembly (1.48 Mb; GenBank: PRJNA555788, GCA_007559345.1) associated with D. farinae. The ascertained ubiquity and abundance of Cardinium strongly suggest that this intracellular bacterium plays an important biological role in D. farinae.

• Klíčová slova
• Acaridida, Allergen production, Astigmata, Cardinium, Dermatophagoides pteronyssinus, Microbiome,
• MeSH
• Bacteroidetes izolace a purifikace   MeSH
• Dermatophagoides farinae mikrobiologie   MeSH
• Dermatophagoides pteronyssinus mikrobiologie   MeSH
• genom bakteriální * MeSH
• mikrobiota MeSH
• sekvenování celého genomu MeSH
• symbióza MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Čína MeSH
• Evropa MeSH
• Spojené státy americké MeSH