Fluidic bacterial diodes rectify magnetotactic cell motility in porous environments.

Directed motility enables swimming microbes to navigate their environment for resources via chemo-, photo-, and magneto-taxis. However, directed motility competes with fluid flow in porous microbial habitats, affecting biofilm formation and disease transmission. Despite this broad importance, a microscopic understanding of how directed motility impacts the transport of microswimmers in flows through constricted pores remains unknown. Through microfluidic experiments, we show that individual magnetotactic bacteria directed upstream through pores display three distinct regimes, whereby cells swim upstream, become trapped within a pore, or are advected downstream. These transport regimes are reminiscent of the electrical conductivity of a diode and are accurately predicted by a comprehensive Langevin model. The diode-like behavior persists at the pore scale in geometries of higher dimension, where disorder impacts conductivity at the sample scale by extending the trapping regime over a broader range of flow speeds. This work has implications for our understanding of the survival strategies of magnetotactic bacteria in sediments and for developing their use in drug delivery applications in vascular networks.

Patterns of bacterial motility in microfluidics-confining environments.

Understanding the motility behavior of bacteria in confining microenvironments, in which they search for available physical space and move in response to stimuli, is important for environmental, food industry, and biomedical applications. We studied the motility of five bacterial species with various sizes and flagellar architectures (Vibrio natriegens, Magnetococcus marinus, Pseudomonas putida, Vibrio fischeri, and Escherichia coli) in microfluidic environments presenting various levels of confinement and geometrical complexity, in the absence of external flow and concentration gradients. When the confinement is moderate, such as in quasi-open spaces with only one limiting wall, and in wide channels, the motility behavior of bacteria with complex flagellar architectures approximately follows the hydrodynamics-based predictions developed for simple monotrichous bacteria. Specifically, V. natriegens and V. fischeri moved parallel to the wall and P. putida and E. coli presented a stable movement parallel to the wall but with incidental wall escape events, while M. marinus exhibited frequent flipping between wall accumulator and wall escaper regimes. Conversely, in tighter confining environments, the motility is governed by the steric interactions between bacteria and the surrounding walls. In mesoscale regions, where the impacts of hydrodynamics and steric interactions overlap, these mechanisms can either push bacteria in the same directions in linear channels, leading to smooth bacterial movement, or they could be oppositional (e.g., in mesoscale-sized meandered channels), leading to chaotic movement and subsequent bacterial trapping. The study provides a methodological template for the design of microfluidic devices for single-cell genomic screening, bacterial entrapment for diagnostics, or biocomputation.

Parasitic 'Candidatus Aquarickettsia rohweri' is a marker of disease susceptibility in Acropora cervicornis but is lost during thermal stress.

Holobiont phenotype results from a combination of host and symbiont genotypes as well as from prevailing environmental conditions that alter the relationships among symbiotic members. Corals exemplify this concept, where shifts in the algal symbiont community can lead to some corals becoming more or less thermally tolerant. Despite linkage between coral bleaching and disease, the roles of symbiotic bacteria in holobiont resistance and susceptibility to disease remains less well understood. This study thus characterizes the microbiome of disease-resistant and -susceptible Acropora cervicornis coral genotypes (hereafter referred to simply as 'genotypes') before and after high temperature-mediated bleaching. We found that the intracellular bacterial parasite 'Ca. Aquarickettsia rohweri' was strikingly abundant in disease-susceptible genotypes. Disease-resistant genotypes, however, had notably more diverse and even communities, with correspondingly low abundances of 'Ca. Aquarickettsia'. Bleaching caused a dramatic reduction of 'Ca. Aquarickettsia' within disease-susceptible corals and led to an increase in bacterial community dispersion, as well as the proliferation of opportunists. Our data support the hypothesis that 'Ca. Aquarickettsia' species increase coral disease risk through two mechanisms: (i) the creation of host nutritional deficiencies leading to a compromised host-symbiont state and (ii) the opening of niche space for potential pathogens during thermal stress.

Multifunctional Periphytic Biofilms: Polyethylene Degradation and Cd2+ and Pb2+ Bioremediation under High Methane Scenario.

Priority pollutants such as polyethylene (PE) microplastic, lead (Pb2+), and cadmium (Cd2+) have attracted the interest of environmentalists due to their ubiquitous nature and toxicity to all forms of life. In this study, periphytic biofilms (epiphyton and epixylon) were used to bioremediate heavy metals (HMs) and to biodegrade PE under high (120,000 ppm) methane (CH4) doses. Both periphytic biofilms were actively involved in methane oxidation, HMs accumulation and PE degradation. Epiphyton and epixylon both completely removed Pb2+ and Cd2+ at concentrations of 2 mg L-1 and 50 mg L-1, respectively, but only partially removed these HMs at a relatively higher concentration (100 mg L-1). Treatment containing 12% 13CH4 proved to be most effective for biodegradation of PE. A synergistic effect of HMs and PE drastically changed microbial biota and methanotrophic communities. High-throughput 16S rRNA gene sequencing revealed that Cyanobacteria was the most abundant class, followed by Gammaproteobacteria and Alphaproteobacteria in all high-methane-dose treatments. DNA stable-isotope probing was used to label 13C in a methanotrophic community. A biomarker for methane-oxidizing bacteria, pmoA gene sequence of a 13C-labeled fraction, revealed that Methylobacter was most abundant in all high-methane-dose treatments compared to near atmospheric methane (NAM) treatment, followed by Methylococcus. Methylomonas, Methylocystis, Methylosinus, and Methylocella were also found to be increased by high doses of methane compared to NAM treatment. Overall, Cd+2 had a more determinantal effect on methanotrophic activity than Pb2+. Epiphyton proved to be more effective than epixylon in HMs removal and PE biodegradation. The findings proved that both epiphyton and epixylon can be used to bioremediate HMs and biodegrade PE as an efficient ecofriendly technique under high methane concentrations.

When bacteria meet mitochondria: The strange case of the tick symbiont Midichloria mitochondrii†.

Mitochondria are key eukaryotic organelles that perform several essential functions. Not surprisingly, many intracellular bacteria directly or indirectly target mitochondria, interfering with innate immunity, energy production or apoptosis, to make the host cell a more hospitable niche for bacterial replication. The alphaproteobacterium Midichloria mitochondrii has taken mitochondrial targeting to another level by physically colonising mitochondria, as shown by transmission electron micrographs of bacteria residing in the mitochondrial intermembrane space. This unique localization provokes a number of questions around the mechanisms allowing, and reasons driving intramitochondrial tropism. We suggest possible scenarios that could lead to this peculiar localization and hypothesize potential costs and benefits of mitochondrial colonisation for the bacterium and its host.

High-speed motility originates from cooperatively pushing and pulling flagella bundles in bilophotrichous bacteria.

Bacteria propel and change direction by rotating long, helical filaments, called flagella. The number of flagella, their arrangement on the cell body and their sense of rotation hypothetically determine the locomotion characteristics of a species. The movement of the most rapid microorganisms has in particular remained unexplored because of additional experimental limitations. We show that magnetotactic cocci with two flagella bundles on one pole swim faster than 500 µm·s-1 along a double helical path, making them one of the fastest natural microswimmers. We additionally reveal that the cells reorient in less than 5 ms, an order of magnitude faster than reported so far for any other bacteria. Using hydrodynamic modeling, we demonstrate that a mode where a pushing and a pulling bundle cooperate is the only possibility to enable both helical tracks and fast reorientations. The advantage of sheathed flagella bundles is the high rigidity, making high swimming speeds possible.

Diel cycling of the cosmopolitan abundant Pelagibacter virus 37-F6: one of the most abundant viruses on earth.

The spatiotemporal dynamics for marine viral populations has only recently been explored. However, nothing is known about temporal activities of the uncultured Pelagibacter virus vSAG 37-F6, which was discovered by single-virus genomics as potentially the most abundant marine virus. Here, we investigate the diel cycling of 37-F6 virus and the putative SAR11 host using coastal and oceanic transcriptomic and viromic time-series data from Osaka Bay and North Pacific Subtropical Gyre. Virus 37-F6 and relatives displayed diel cycling of transcriptional activities synchronized with its putative host. In both virus and host, the lowest transcription rates were observed at 14:00-15:00, coinciding roughly with maximum solar irradiance, while higher transcriptional rates were detected during the night/early morning and afternoon. Diel abundance of free viruses of 37-F6 in seawater roughly mirrored the transcriptional activities of both virus and host. In Osaka Bay, among viral relatives (genus level), virus 37-F6 specifically showed the highest ratio of transcriptional activity to virome abundance, a proxy for viral transcriptional activity relative to free viral particle abundance. This high ratio suggests high infection rate efficiencies in vSAG 37-F6 virus compared to viral relatives. Thus, time-series data revealed temporal transcript activities in one of the most abundant viruses in Earth.

Physiological and genomic features of Paraoceanicella profunda gen. nov., sp. nov., a novel piezophile isolated from deep seawater of the Mariana Trench.

A novel piezophilic alphaproteobacterium, strain D4M1T , was isolated from deep seawater of the Mariana Trench. 16S rRNA gene analysis showed that strain D4M1T was most closely related to Oceanicella actignis PRQ-67T (94.2%), Oceanibium sediminis O448T (94.2%), and Thioclava electrotropha ElOx9T (94.1%). Phylogenetic analyses based on both 16S rRNA gene and genome sequences showed that strain D4M1T formed an independent monophyletic branch paralleled with the genus Oceanicella in the family Rhodobacteraceae. Cells were Gram-stain-negative, aerobic short rods, and grew optimally at 37°C, pH 6.5, and 3.0% (w/v) NaCl. Strain D4M1T was piezophilic with the optimum pressure of 10 MPa. The principal fatty acids were C18:1 ω7c/C18:1 ω6c and C16:0 , major respiratory quinone was ubiquinone-10, and predominant polar lipids were phosphatidylglycerol, phosphatidylethanolamine, and an unidentified aminophospholipid. The complete genome contained 5,468,583-bp with a G + C content of 70.2 mol% and contained 4,855 protein-coding genes and 78 RNA genes. Genomic analysis revealed abundant clues on bacterial high-pressure adaptation and piezophilic lifestyle. The combined evidence shows that strain D4M1T represents a novel species of a novel genus in the family Rhodobacteraceae, for which the name Paraoceanicella profunda gen. nov., sp. nov. is proposed (type strain D4M1T  = MCCC 1K03820T  = KCTC 72285T ).

Diel changes and diversity of pufM expression in freshwater communities of anoxygenic phototrophic bacteria.

The anoxygenic phototrophic bacteria (APB) are an active component of aquatic microbial communities. While DNA-based studies have delivered a detailed picture of APB diversity, they cannot provide any information on the activity of individual species. Therefore, we focused on the expression of a photosynthetic gene by APB communities in two freshwater lakes (Cep lake and the Rímov Reservoir) in the Czech Republic. First, we analyzed expression levels of pufM during the diel cycle using RT-qPCR. The transcription underwent a strong diel cycle and was inhibited during the day in both lakes. Then, we compared DNA- (total) and RNA-based (active) community composition by sequencing pufM amplicon libraries. We observed large differences in expression activity among different APB phylogroups. While the total APB community in the Rímov Reservoir was dominated by Betaproteobacteria, Alphaproteobacteria prevailed in the active library. A different situation was encountered in the oligotrophic lake Cep where Betaproteobacteria (order Burkholderiales) dominated both the DNA and RNA libraries. Interestingly, in Cep lake we found smaller amounts of highly active uncultured phototrophic Chloroflexi, as well as phototrophic Gemmatimonadetes. Despite the large diversity of APB communities, light repression of pufM expression seems to be a common feature of all aerobic APB present in the studied lakes.

Phagocytosis-like cell engulfment by a planctomycete bacterium.

Phagocytosis is a key eukaryotic feature, conserved from unicellular protists to animals, that enabled eukaryotes to feed on other organisms. It could also be a driving force behind endosymbiosis, a process by which α-proteobacteria and cyanobacteria evolved into mitochondria and plastids, respectively. Here we describe a planctomycete bacterium, 'Candidatus Uab amorphum', which is able to engulf other bacteria and small eukaryotic cells through a phagocytosis-like mechanism. Observations via light and electron microscopy suggest that this bacterium digests prey cells in specific compartments. With the possible exception of a gene encoding an actin-like protein, analysis of the 'Ca. Uab amorphum' genomic sequence does not reveal any genes homologous to eukaryotic phagocytosis genes, suggesting that cell engulfment in this microorganism is probably not homologous to eukaryotic phagocytosis. The discovery of this "phagotrophic" bacterium expands our understanding of the cellular complexity of prokaryotes, and may be relevant to the origin of eukaryotic cells.

Martelella lutilitoris sp. nov., isolated from a tidal mudflat.

A novel, Gram-stain-negative marine bacterium, designated GH2-6T, was isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia) collected in Gangwha Island, the Republic of Korea. The cells of the organism were strictly aerobic, oxidase- and catalase-positive, non-flagellated rods. Growth occurred at 20-45°C, pH 5-10, and 0.5-9 (w/v) NaCl. The requirement of Na+ for growth (0.5-3%) was observed. The major respiratory quinone was Q-10. The major polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an aminolipid and a glycolipid. The predominant fatty acids were C18:1ω7c, C18:0, C16:0, C19:0 cyclo ω8c, C18:1ω7c 11-methyl and summed feature 2 (C14:0 3-OH and/or C16:1 iso I). The genome size was 4.45 Mb and the G+C content of the genomic DNA was 61.9 mol%. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain GH2-6T belonged to genus Martelella and formed a tight cluster with M. radicis BM5-7T and M. endophytica YC6887T. Levels of 16S rRNA gene sequence similarity between the novel isolate and members of the genus were 99.3-95.5%, but strain GH2-6T possessed an extended loop (49 nucleotides in length) between positions 187 and 213 of the 16S rRNA gene sequence (E. coli numbering). DDH values in vitro between the novel isolate and the closest relatives were 23.2±12.8-46.3±5.2%. On the basis of polyphasic data presented in this study, the type strain GH2-6T (= KACC 19403T = KCTC 62125T = NBRC 113212T) represents a novel species of the genus Martelella for which the name Martelella lutilitoris sp. nov. is proposed.

Complete Genome Sequence of Qipengyuania sediminis CGMCC 1.12928T, Shed Light on Its Role in Matter-Cycle and Cold Adaption Mechanism of the Genus Qipengyuania.

Qipengyuania sediminis CGMCC 1.12928T, a family member of Erythrobacteraceae, the class of Alphaproteobacteria, was isolated from a borehole sediment sample collected from Qiangtang Basin in Qinghai-Tibetan Plateau, the largest permafrost in China. Understanding bacterial molecular feature may shed light on the ecological strategy in the extreme environment. Here we describe the complete genome sequence and annotation of strain CGMCC 1.12928T, including the complete genome sequence and annotation. The genome of strain CGMCC 1.12928T consist of a single-circular chromosome, comprises 2,416,000 bp with an average G + C content of 66.7 mol%, and contains 2414 genes; including 2367 CDSs, 44 tRNA genes, as well as one operon of 16S-23S-5S rRNA genes. Genomic properties indicated that strain CGMCC 1.12928T has a relatively smaller genome size and higher G + C content within the family Erythrobacteraceae. In addition, genomic analysis revealed its genome contains multiple function genes responsible for nitrogen, sulfur and phosphorus cycles and explained the cold adaption mechanism. Thus, this strain plays an active role in the biogeochemical cycle in cold niche. The whole-genome of this isolate will widen our understanding of the ecological role of the genus Qipengyuania in permafrost.

Jiella endophytica sp. nov., a novel endophytic bacterium isolated from root of Ficus microcarpa Linn. f.

A Gram-negative, aerobic, short rodshaped, asporogenous bacterium, designated CBS5Q-3T, was isolated from a surface-sterilised root of Ficus microcarpa Linn. f. collected from Guangxi, China and investigated by a polyphasic approach to determine its taxonomic position. Strain CBS5Q-3T was found to grow optimally with 2% (w/v) NaCl at 30 °C, pH 7.0-8.0. Substrate mycelia and aerial mycelia were not formed, and no diffusible pigments were observed on the media tested. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CBS5Q-3T is closely related to species of genus Jiella and shares high 16S rRNA gene sequence similarity of 98.1% with Jiella aquimaris JCM 30119T. The average nucleotide identity and in silico DNA-DNA hybridization values between strain CBS5Q-3T and J. aquimaris JCM 30119T were 82.8% and 26.0%, respectively. The DNA G + C content of strain CBS5Q-3T was determined to be 66.5 mol %. The cell wall peptidoglycan was found to contain meso-diaminopimelic acid and ubiquinone Q-10 identified as the respiratory lipoquinone. The polar lipids were found to be comprised of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylmonomethylethanolamine, phosphatidylethanolamine and three unidentified aminolipids, while the major fatty acids were identified as C18:1ω7c and cyclo-C19:0ω8c. On the basis of phylogenetic, chemotaxonomic and phenotypic data, strain CBS5Q-3T can be concluded to represent a novel species of the genus Jiella, for which the name Jiella endophytica sp. nov. is proposed. The type strain is CBS5Q-3T (= JCM 33167T = CGMCC 1.13863T).

ACC deaminase plays a major role in Pseudomonas fluorescens YsS6 ability to promote the nodulation of Alpha- and Betaproteobacteria rhizobial strains.

Ethylene acts as a major regulator of the nodulation process of leguminous plants. Several rhizobial strains possess the ability to modulate plant ethylene levels through the expression of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase; however, rhizobia present low enzymatic activities. One possible alternative to this problem resides on the use of free-living bacteria, such as Pseudomonas, presenting high levels of ACC deaminase activity that may be used as adjuvants in the nodulation process by decreasing inhibitory ethylene levels. Nevertheless, not much is understood about the specific role of ACC deaminase in the possible role of free-living bacteria as nodulation adjuvants. Therefore, this work aims to study the effect of ACC deaminase in the plant growth-promoting bacterium, Pseudomonas fluorescens YsS6, ability to facilitate alpha- and beta-rhizobia nodulation. The ACC deaminase-producing P. fluorescens YsS6 and its ACC deaminase mutant were used in co-inoculation assays to evaluate their impact in the nodulation process of alpha- (Rhizobium tropici CIAT899) and beta-rhizobia (Cupriavidus taiwanensis STM894) representatives, in Phaseolus vulgaris and Mimosa pudica plants, respectively. The results obtained indicate that the wild-type P. fluorescens YsS6, but not its mutant defective in ACC deaminase production, increase the nodulation abilities of both alpha- and beta-rhizobia, resulting in an increased leguminous plant growth. Moreover, this is the first report of the positive effect of free-living bacteria in the nodulation process of beta-rhizobia. The modulation of inhibitory ethylene levels by free-living ACC deaminase-producing bacteria plays an important role in facilitating the nodulation process of alpha- and beta-rhizobia.

Pathogen infections and primary biliary cholangitis.

Primary biliary cholangitis (PBC) is a multi-factorial disease caused by the interaction of both genetic predisposition and environmental triggers. Bacterial infection has been investigated most intensively, both epidemiologically and experimentally, as a prime environmental aetiology in PBC. The association of recurrent history of urinary tract infection (UTI) with PBC has been frequently confirmed by several large-scale, case-control studies, despite variation in geographic area or case-finding methods. Escherichia coli is a predominant pathogen in most cases with UTI. Animal studies and molecular mimicry analysis between the human and E. coli E2 subunit of the 2-oxo-acid dehydrogenase complexes demonstrated that E. coli infection is a key factor in breaking immunological tolerance against the mitochondria, resulting in the production of anti-mitochondrial autoantibodies (AMA), the disease-specific autoantibodies of PBC. Novosphingobium aromaticivorans, a ubiquitous xenobiotic-metabolizing bacterium, is another candidate which may be involved in the aetiology of PBC. Meanwhile, improved environmental hygiene and increased prevalence of PBC, especially in males, may argue against the aetiological role of bacterial infection in PBC. Multiple mechanisms can result in the loss of tolerance to mitochondrial autoantigens in PBC; nonetheless, bacterial infection is probably one of the dominant pathways, especially in female patients. Notably, there is a rising prevalence of male patients with PBC. With increasing exposure to environmental xenobiotics in both genders, studies directed towards identifying the environmental culprit with systematically designed case-control studies are much needed to further determine the environmental factors and role of bacterial infections in PBC.

Diverse cellular colonizing endophytic bacteria in field shoots and in vitro cultured papaya with physiological and functional implications.

The study was envisaged to assess the extent of normally uncultivable endophytic bacteria in field papaya plants and in vitro established cultures adopting cultivation vs molecular analysis and microscopy. Surface-sterilized axillary shoot-buds of papaya 'Arka Surya' revealed high bacterial diversity as per 16S rRNA metagene amplicon sequencing (6 phyla, 10 classes, 21 families) with an abundance of Pseudomonas (Gammaproteobacteria), which also formed a common contaminant for in vitro cultured field explants. Molecular analysis of seedling shoot-tip-derived healthy proliferating cultures of three genotypes ('Arka Surya', 'Arka Prabhath', 'Red Lady') with regular monthly subculturing also displayed high bacterial diversity (11-16 phyla, >25 classes, >50 families, >200 genera) about 12-18 months after initial establishment. 'Arka Surya' and 'Red Lady' cultures bore predominantly Actinobacteria (75-78%) while 'Arka Prabhath' showed largely Alphaproteobacteria corroborating the slowly activated Methylobacterium sp. Bright-field direct microscopy on tissue sections and tissue homogenate and epi-fluorescence microscopy employing bacterial DNA probe SYTO-9 revealed abundant intracellular bacteria embracing the next-generation sequencing elucidated high taxonomic diversity. Phylogenetic investigation of communities by reconstruction of unobserved states- PICRUSt- functional annotation suggested significant operational roles for the bacterial-biome. Metabolism, environmental information processing, and genetic information processing constituted major Kyoto Encyclopedia of Genes and Genomes KEGG attributes. Papaya stocks occasionally displayed bacterial growth on culture medium arising from the activation of originally uncultivable organisms to cultivation. The organisms included Bacillus (35%), Methylobacterium (15%), Pseudomonas (10%) and seven other genera (40%). This study reveals a hidden world of diverse and abundant conventionally uncultivable cellular-colonizing endophytic bacteria in field shoots and micropropagating papaya stocks with high genotypic similarity and silent participation in various plant processes/pathways.

The evolution of abdominal microbiomes in fungus-growing ants.

The attine ants are a monophyletic lineage that switched to fungus farming ca. 55-60 MYA. They have become a model for the study of complex symbioses after additional fungal and bacterial symbionts were discovered, but their abdominal endosymbiotic bacteria remain largely unknown. Here, we present a comparative microbiome analysis of endosymbiotic bacteria spanning the entire phylogenetic tree. We show that, across 17 representative sympatric species from eight genera sampled in Panama, abdominal microbiomes are dominated by Mollicutes, α- and γ-Proteobacteria, and Actinobacteria. Bacterial abundances increase from basal to crown branches in the phylogeny reflecting a shift towards putative specialized and abundant abdominal microbiota after the ants domesticated gongylidia-bearing cultivars, but before the origin of industrial-scale farming based on leaf-cutting herbivory. This transition coincided with the ancestral single colonization event of Central/North America ca. 20 MYA, documented in a recent phylogenomic study showing that almost the entire crown group of the higher attine ants, including the leaf-cutting ants, evolved there and not in South America. Several bacterial species are located in gut tissues or abdominal organs of the evolutionarily derived, but not the basal attine ants. The composition of abdominal microbiomes appears to be affected by the presence/absence of defensive antibiotic-producing actinobacterial biofilms on the worker ants' cuticle, but the significance of this association remains unclear. The patterns of diversity, abundance and sensitivity of the abdominal microbiomes that we obtained explore novel territory in the comparative analysis of attine fungus farming symbioses and raise new questions for further in-depth research.

First insight into microbiome profile of fungivorous thrips Hoplothrips carpathicus (Insecta: Thysanoptera) at different developmental stages: molecular evidence of Wolbachia endosymbiosis.

Insects' exoskeleton, gut, hemocoel, and cells are colonized by various microorganisms that often play important roles in their host life. Moreover, insects are frequently infected by vertically transmitted symbionts that can manipulate their reproduction. The aims of this study were the characterization of bacterial communities of four developmental stages of the fungivorous species Hoplothrips carpathicus (Thysanoptera: Phlaeothripidae), verification of the presence of Wolbachia, in silico prediction of metabolic potentials of the microorganisms, and sequencing its mitochondrial COI barcode. Taxonomy-based analysis indicated that the bacterial community of H. carpathicus contained 21 bacterial phyla. The most abundant phyla were Proteobacteria, Actinobacteria, Bacterioidetes and Firmicutes, and the most abundant classes were Alphaproteobacteria, Actinobacteria, Gammaproteobacteria and Betaproteobacteria, with different proportions in the total share. For pupa and imago (adult) the most abundant genus was Wolbachia, which comprised 69.95% and 56.11% of total bacterial population respectively. Moreover, similarity analysis of bacterial communities showed that changes in microbiome composition are congruent with the successive stages of H. carpathicus development. PICRUSt analysis predicted that each bacterial community should be rich in genes involved in membrane transport, amino acid metabolism, carbohydrate metabolism, replication and repair processes.