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Ecotoxicology and Environmental Safety Dec 2020Work in wastewater treatment plants (WWTPs) can be associated with respiratory symptoms and diarrhea. The aim of this study was to obtain knowledge about WWTP workers'...
Work in wastewater treatment plants (WWTPs) can be associated with respiratory symptoms and diarrhea. The aim of this study was to obtain knowledge about WWTP workers' exposure to airborne bacteria and endotoxin, and the inflammatory potential (TIP) of their exposure, and to evaluate the risk posed by the exposure by 1) calculating a hazard index and relating the exposure to suggested occupational exposure limits (OELs), 2) estimating the potential deposition of bacteria in the airways, 3) relating it to the risk group classification of bacteria by the European Union, and 4) estimating the TIP of the personal exposure. A cohort of 14 workers were followed over one year. Bioaerosols were collected using personal and stationary samplers in a grid chamber house and an aeration tank area. Airborne bacteria were identified using (MALDI-TOF MS), and TIP of exposure was measured using HL-60 cells. A significant effect of season, work task, and person was found on the personal exposure. A hazard index based on exposure levels indicates that the risk caused by inhalation is low. In relation to suggested OELs, 14% and 34% of the personal exposure were exceeded for endotoxin (≥50 EU/m) and bacteria (≥500 CFU/m). At least 70% of the airborne bacteria in the grid chamber house and the aeration tank area could potentially deposit in the lower respiratory tract. From the personal samples, three of 131 bacterial species, Enterobacter cloacae, Staphylococcus aureus, and Yersinia enterocolitica are classified within Risk Group 2. Seven additional bacteria from the stationary samples belong to Risk Group 2. The bacterial species composition was affected significantly by season (p = 0.014) and by sampling type/area (p = 0.001). The TIP of WWTP workers' exposure was higher than of a reference sample, and the highest TIP was measured in autumn. TIP of personal exposure correlated with bacterial exposure. Based on the geometric average exposures to endotoxin (9.2 EU/m) and bacteria (299 CFU/m) and based on the calculated hazard index, the risk associated with exposure is low. However, since 43 of 106 exposure levels exceed suggested OELs, the TIP of exposure was elevated and associated with bacterial exposure, and WWTP workers were exposed to pathogenic bacteria, a continued focus on preventive measures is important. The identification of bacteria to species level in personal samples was necessary in the risk assessment, and measurement of the microbial composition made the source tracking possible.
Topics: Air Microbiology; Air Pollutants, Occupational; Bacteria; Endotoxins; Environmental Monitoring; Humans; Inhalation Exposure; Occupational Exposure; Seasons; Waste Disposal Facilities; Waste Disposal, Fluid; Wastewater
PubMed: 32977286
DOI: 10.1016/j.ecoenv.2020.111365 -
Plant Disease Nov 2022Strawberry (Fragaria × ananassa) is an economically important crop in China, and a crucial part of urban agriculture in Beijing. In November 2020, wilt symptoms were...
Strawberry (Fragaria × ananassa) is an economically important crop in China, and a crucial part of urban agriculture in Beijing. In November 2020, wilt symptoms were observed in strawberry seedlings in several greenhouses in the Pinggu District of Beijing city (40.14° N; 117.12° E). The average disease incidence was 20%. Water-soaked lesions appeared along the veins of diseased strawberry leaves and bacterial ooze was also present on severely affected leaves. Bisected crowns had a reddish-brown discoloration in the xylem which later turned black. Three diseased strawberry seedlings were collected for pathogen identification. Isolations were conducted from stem, crown, leaf, and roots of diseased strawberry plants. Samples were surface sterilized by immersion in 70% ethanol for 30 s and rinsed three times with sterile distilled water, before being placed on potato dextrose agar (PDA) medium and incubated at 28℃. Several bacterial colonies grew on the medium after 24 h. Colonies were then purified on Lysogeny broth (LB) agar plates using the streak plate method. Twenty-nine isolates were obtained from 36 diseased tissue samples, which were from stem(10), crown(12), leaf(2) and roots(5) separately. All isolates appeared white, round, opaque and smooth on LB plates. To identify the isolates, genomic DNA was extracted from nine purified bacterial colonies (CM1 to CM9). The fragments of atpD, gyrB, infB and rpoB gene were amplified and sequenced with primers atpD 01-F/ atpD 02-R, gyrB 01-F/ gyrB 02-R, and infB 01-F/ infB 02-R (Brady et al. 2008) and RpoB-F/ RpoB-R (Mollet et al. 1997), respectively. All atpD, gyrB, infB and rpoB sequences belonging to the isolates were identical. The sequences of atpD, gyrB, infB and rpoB gene of isolates CM1 and CM3 were deposited in GenBank under accession numbers ON055247, ON055248, ON055249, ON055250, ON055251, ON055252, OL771192 and OL771193. BLAST searches were conducted with the sequences of atpD, gyrB, infB and rpoB. The atpD, gyrB, infB and rpoB sequences of the obtained isolate showed 99.53%, 99.06%, 99.19% and 99.80% identity with the corresponding sequences of Enterobacter mori strains, respectively. Phylogenetic analysis was performed using the maximum likelihood (ML) method with the CIPRES Science Gateway platform (http://www.phylo.org/) based on the combined atpD, gyrB, infB and rpoB sequences (Brady et al. 2013; Palmer et al. 2018). In the phylogenetic tree, the isolates were clustered together with E. mori strain LMG 25706. To confirm the pathogenicity, 200 μL of bacterial suspensions (108 CFU/mL) of the two isolates were injected into the crown of six healthy Fragaria × ananassa cv. Bennihope strawberry seedlings respectively with 1 mL sterilized syringe, and the control seedlings were injected with sterile water. The seedlings were kept in a moist chamber (28°C, 16-h light and 8-h dark period) for 2 days. Then all the seedlings were transferred to the greenhouse with conditions similar to those where the diseased plants were collected. Forty days after inoculation, old leaves started to wilt and leaf midvein necrosis, along with xylem discoloration, was observed in inoculated plants. No symptoms were observed in the control group. Pathogenicity tests were conducted three times with similar results. The bacteria were re-isolated from the symptomatic diseased strawberry plants and confirmed as E. mori by morphological and sequence analyses as above, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of strawberry bacterial wilt caused by E. mori. Due to the significant crop loss from this disease, more research is needed in epidemiology and disease management.
PubMed: 36366829
DOI: 10.1094/PDIS-08-22-1895-PDN -
PeerJ 2023Plant-growth promoting rhizobacteria (PGPR) play a vital role in soil fertility and crop production. The rhizosphere of many crop plants has been well documented by...
Plant-growth promoting rhizobacteria (PGPR) play a vital role in soil fertility and crop production. The rhizosphere of many crop plants has been well documented by screening PGPR for their plant-growth promoting (PGP) mechanisms. However, the rhizosphere of grass species that may act as potential habitats for novel PGPR remains relatively unexplored. is a noxious weed that has invaded more than 40 tropical and subtropical countries in Asia, Oceania, Africa, and Europe. Its presence has led to changes in plant species composition, reducing their biodiversity and destroying ecosystem function. In this study, we screened 1,200 bacterial strains isolated from the rhizosphere soil of in three floristic regions in Yunnan Province, China. Samples were screened for their ability for N-fixation, production of the plant growth regulator indole-3-acetic acid (IAA), and the synthesis of 1-amino-cyclopropane-1-carboxylate (ACC) deaminase, which controls the levels of ethylene in developing plant roots. We found that 144 strains showed at least one of these PGP attributes. 16S rRNA gene sequencing showed that most (62.5%) of the samples were bacteria closely related to members of the genera (27 strains), (20 strains), (14 strains), (12 strains), (nine strains), and (eight strains). Their abundance and biodiversity in the soil of individual floristic regions correlate positively with the invasion history of . From these PGP bacterial strains, KM_A34 (), KM_C04 (), and KM_A57 (), which had the greatest ability of N-fixation, and IAA and ACC deaminase production, respectively, were selected. The strains were evaluated for their effect on the seed germination and growth of soybean, faba bean, pea, wheat, and Chinese cabbage other than . Chamber experiments showed these strains significantly ( < 0.05) increased (14.2-43.4% over the controls) germination rates of the soybean, faba bean, pea, and/or Chinese cabbage seeds. They also reduced relative seed germination times (20.8-48.8% over the controls) of soy bean, faba bean and/or wheat seeds. Greenhouse pot experiments showed that they significantly ( < 0.05) promoted the aboveground and belowground height of plant foliage (12.1-23.1% and 11.5-31.4% over the controls, respectively) and/or the dry weights (16.1-33.5% and 10.6-23.4% over the controls, respectively) of the soy bean, faba bean, pea, wheat and/or Chinese cabbage. These data indicate that the rhizosphere microbiota of contain a PGPR pool that may be used as bioinoculants to improve the growth and productivity of these crops.
Topics: Plant Weeds; Ageratina; Rhizosphere; Ecosystem; RNA, Ribosomal, 16S; China; Rhizobiaceae; Soil
PubMed: 36923499
DOI: 10.7717/peerj.15064 -
Veterinarni Medicina Jun 2023Thirteen adult healthy captive skinks, six Gidgee spiny-tailed skinks (), three Hosmer's spiny-tailed skinks () and four tree crevice-skinks (), were submitted to the...
Thirteen adult healthy captive skinks, six Gidgee spiny-tailed skinks (), three Hosmer's spiny-tailed skinks () and four tree crevice-skinks (), were submitted to the study. The weight of the animals ranged from 28 g to 146 g. All skinks were explored during their putative mating season, which is December. Lizards were restrained manually and positioned in ventral recumbence. Cloacoscopy was performed with the rigid endoscope, protecting channel, endocamera and recording system Telepack-Pal (Karl Storz Endoskope, Tuttlingen, Germany). While the endoscope was gently introduced into the cloaca and advanced into the coprodeum sterile saline was flushed into the cloaca through the protecting channel. The endoscope was then slowly withdrawn to allow visualization of the main structures of the urodeum and proctodeum. Male skinks are characterized by the presence of urethral and only one horizontal septum which divides the chamber of the urodeum into two subchambers. Female skinks are characterised by the presence of two septa. The central-dorsal fold that divides the urodeum into two pouches in female skinks is absent in males. Cloacoscopy proved an effective method of sex identification and can be considered a valuable method for breeding and conservation in monomorphic skink lizards.
PubMed: 37982004
DOI: 10.17221/3/2023-VETMED -
Microorganisms Jul 2023It is evident that legume root nodules can accommodate rhizobial and non-rhizobial bacterial endophytes. Our recent nodule microbiome study in peanuts described that...
It is evident that legume root nodules can accommodate rhizobial and non-rhizobial bacterial endophytes. Our recent nodule microbiome study in peanuts described that small nodules can harbor diverse bacterial endophytes. To understand their functional role, we isolated 87 indigenous endophytes from small nodules of field-grown peanut roots and characterized them at molecular, biochemical, and physiological levels. The amplified 16S rRNA genes and phylogenetic analysis of these isolates revealed a wide variety of microorganisms related to the genera , , , , , , , and . It was observed that 37% (100% identity) and 56% (>99% identity) of the isolates matched with the amplified sequence variants (ASVs) from our previous microbiome study. All of these isolates were tested for stress tolerance (high temperature, salinity, acidic pH) and phosphate (P) solubilization along with ammonia (NH), indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate deaminase (ACCD), and siderophore production. The majority (78%) of the isolates were found to be halotolerant, thermotolerant, and acidophilic, and a few of them showed a significant positive response to the production of IAA, NH, siderophore, ACCD, and P-solubilization. To evaluate the plant growth promotion (PGP) activity, plant and nodulation assays were performed in the growth chamber conditions for the selected isolates from both the non-rhizobial and rhizobial groups. However, these isolates appeared to be non-nodulating in the tested conditions. Nonetheless, the isolates 2 (), 17 (), 21 (), 33o (), and 77 ( sp.) showed significant PGP activity in terms of biomass production. Our findings indicate that these isolates have potential for future biotechnological applications through the development of biologicals for sustainable crop improvement.
PubMed: 37630501
DOI: 10.3390/microorganisms11081941 -
Journal of Dairy Science Jun 2021Commercial Cheddar cheese production uses an automated, continuous production system that provides favorable conditions for specific undesirable bacterial subpopulations...
Commercial Cheddar cheese production uses an automated, continuous production system that provides favorable conditions for specific undesirable bacterial subpopulations in certain sections of the processing system. The draining and matting conveyor (DMC) is a large, fully enclosed series of conveyor belts that separates curd and whey on the first drain belt and supports the cheddaring process in subsequent sections. In a previous study, we demonstrated that coliforms increase in the draining section of the DMC (pH 6.0-6.3, 36°C) over a typical 18-h production shift and can lead to detectable coliforms in finished cheese. Sampling at the commercial plant indicated 2 sources of very low levels of coliforms: (1) subpasteurized whey and curd entering the DMC and (2) surfaces in the DMC after sanitation. Mitigation of these sources would require different approaches. The aim of this study was to investigate whether naturally low levels of coliforms in whey could increase in the bulk liquid and attach to different surface materials within 18 h. A laboratory-scale system was created to mimic the conditions of the initial draining section of the DMC and consisted of single-pass, naturally contaminated whey (pH 6.3, 35°C) flowing through a bioreactor (1.11 L/h) containing coupons of surface types found in the DMC (stainless steel and polypropylene). Whey inside the bioreactor chamber and surface coupons were enumerated for bacterial subpopulations on selective media for planktonic and attached bacteria, respectively, at 0, 12, 15, and 18 h. Bacterial isolates were identified by 16S rDNA sequencing. Nonstarter bacteria present in the whey at 0 h included coliforms (Enterobacter), Pseudomonas, and Acinetobacter (0.80, 2.55, and 2.32 log cfu/mL, respectively), with each increasing significantly in whey (6.18, 7.00, and 5.89 log cfu/mL) and on coupons (5.20, 6.85, and 5.29 log cfu/cm, respectively) after 18 h in the continuous flowing system. Scanning electron microscopy confirmed bacterial attachment on both surfaces, with early biofilm development evident on polypropylene coupons by 18 h. Results from this laboratory-scale study demonstrated that naturally low levels of coliforms entering the DMC in the whey could replicate within the conditions of the draining section of the DMC to the levels found in the commercial production environment.
Topics: Animals; Bacteria; Biofilms; Colony Count, Microbial; Rivers; Stainless Steel; Whey
PubMed: 33741166
DOI: 10.3168/jds.2020-19837 -
Scientific Reports Nov 2023Hexavalent chromium [Cr(VI)] is one of the most carcinogenic and mutagenic toxins, and is commonly released into the environemt from different industries, including...
Insights on hexavalent chromium(VI) remediation strategies in abiotic and biotic dual chamber microbial fuel cells: electrochemical, physical, and metagenomics characterizations.
Hexavalent chromium [Cr(VI)] is one of the most carcinogenic and mutagenic toxins, and is commonly released into the environemt from different industries, including leather tanning, pulp and paper manufacturing, and metal finishing. This study aimed to investigate the performance of dual chamber microbial fuel cells (DMFCs) equipped with a biocathode as alternative promising remediation approaches for the biological reduction of hexavalent chromium [Cr(VI)] with instantaneous power generation. A succession batch under preliminary diverse concentrations of Cr(VI) (from 5 to 60 mg L) was conducted to investigate the reduction mechanism of DMFCs. Compared to abiotic-cathode DMFC, biotic-cathode DMFC exhibited a much higher power density, Cr(VI) reduction, and coulombic efficiency over a wide range of Cr(VI) concentrations (i.e., 5-60 mg L). Furthermore, the X-ray photoelectron spectroscopy (XPS) revealed that the chemical functional groups on the surface of biotic cathode DMFC were mainly trivalent chromium (Cr(III)). Additionally, high throughput sequencing showed that the predominant anodic bacterial phyla were Firmicutes, Proteobacteria, and Deinococcota with the dominance of Clostridiumsensu strict 1, Enterobacter, Pseudomonas, Clostridiumsensu strict 11 and Lysinibacillus in the cathodic microbial community. Collectively, our results showed that the Cr(VI) removal occurred through two different mechanisms: biosorption and bioelectrochemical reduction. These findings confirmed that the DMFC could be used as a bioremediation approach for the removal of Cr(VI) commonly found in different industrial wastewater, such as tannery effluents. with simultaneous bioenergy production.
Topics: Bioelectric Energy Sources; Chromium; Bacteria; Wastewater
PubMed: 37978236
DOI: 10.1038/s41598-023-47450-9 -
Plant Disease Nov 2022Tomato (Solanum lycopersicum L.), as one of the most economically important and highly nutritious vegetable crops across the world, is widely cultivated in China, one of...
Tomato (Solanum lycopersicum L.), as one of the most economically important and highly nutritious vegetable crops across the world, is widely cultivated in China, one of the largest tomato-concuming countries in the world (Ye et al., 2020; Wang and Liu, 2021). At present, major bacterial diseases in tomato include bacterial speck disease, tomato bacterial wilt and bacterial canker, all of which affect the tomato production around the world (Rosli et al., 2021; Peritore-Galve et al., 2021; Wang et al., 2022). In April 2022, a new bacterial disease was discovered on leaves, stems and fruits of tomato in a farmer's greenhouse located in Longfeng District in DaQing (125°07`-125°15`E, 46°28`-46°32`N), Heilongjiang Province, China. This field had tomato disease incidences approximately 50%. Apparent brown discolorations were found on fruits, leaves and stems in tomato plants. Symptoms were similar to fungal brown spots caused by Phytophthora infestans of tomato (Zhi et al.,2021; Liu et al.,2021) (Supplementary Figure S1). To isolate and identify the pathogen, the tissues of infected fruits, leaves and stems with typical symptoms were excised from diseased plants separately, and were disinfected with 75% ethanol for 10 s followed by 2% NaClO for 3 min and then washed five to eight times with sterile water (Wang et al., 2017). Afterwards, the samples were plated on nutrient agar (NA) solid medium and incubated. After incubation at 30°C for 2-3 days, bacterial colonies were isolated, then purified on nutrient agar (NA) solid medium at least twice by a streak plate method (Dou et al., 2019; Li et al, 2021; Zhao et al., 2022). White colonies grew on the NA medium after incubating for 2 days, showing round, opaque and smooth, which was similar to characteristics described as Enterobacter cloacae (García-González et al., 2018; Li et al, 2021). To further confirm the speculation on the identity of the isolated bacterium, the fragments of 16S rRNA were amplified and sequenced. The sequence of 16S rRNA was uploaded into GeneBank with accession numbers (OP077195.1). BLAST analysis of the sequence showed 97.68% identity with one corresponding sequence of E. cloacae in GeneBank (namely MK937637.1). Furthermore, a phylogenetic tree based on the sequence of 16S rRNA gene revealed that the isolate was grouped in the same clade as E. cloacae (Supplementary Figure S2). Based on Koch postulates to test pathogenicity of isolated bacteria, bacteria were inoculated on 30 day-old healthy tomato plants with three leaves stages, and the re-isolation of bacteria were carried out after 2 days of inoculation. To confirm pathogenicity, the isolates were cultured on LB medium at 30℃ for 2 days to prepare suspensions and adjusted to an optical density (OD) of 0.2 at A600, with a final concentration of 1ⅹ108 CFU/ml. Eight potted tomato plants were sprayed with bacteria suspensions, and eight control potted plants were sprayed with sterile distilled water. These seedlings were incubated in a chamber at 30°C with a 12 h light/dark photoperiod, with 85% relative humidity. After 2 days, inoculated tomato seedlings showed irregular small spots in leaves and brown necrosis at blade tips, and 8 to 10 days later, the leaves of tomato plants browned and died. The symptoms were the same with those of the initial diseased leaves of tomato plants (Supplementary Figure S1). No symptoms were observed on the control leaves (Supplementary Figure S3). Pathogenicity tests were repeated three biological times with same results. Meanwhile, the bacteria strains were re-isolated from symptomatic inoculated seedlings and confirmed as E. cloacae by culture and sequence methods as above. In China, there are no detailed records about the causal agent of this disease on tomato in a published paper in Chinese and English. To our knowledge, this is the first report of Enterobacter leaf brown necrosis caused by E. cloacae on tomato in China. Those results are of great significance for the production and management of tomato in greenhouse and control of the disease.
PubMed: 36366833
DOI: 10.1094/PDIS-08-22-1749-PDN -
Plant Disease Apr 2024Tomato (Solanum lycopersicum L.) is one of the most important vegetable crops in China. In October 2023, a new bacterial disease was discovered on tomato plants in a...
Tomato (Solanum lycopersicum L.) is one of the most important vegetable crops in China. In October 2023, a new bacterial disease was discovered on tomato plants in a 0.3-acre farm's greenhouse (35.514806N, 118.996106E) in Longshan Town, Shandong Province, China. Over 50% of the tomato plants showed symptoms of stem rot, leaf wilt, or plant death. Three diseased tomato plants were collected for pathogen isolation and purification. Two leaf samples, each about 1 cm2, were cut from the junction area of healthy and diseased parts and disinfected with 75% alcohol for 60 s, followed by 0.1% HgCl2 for 90 s, and then washed three times with sterilized H2O. The samples were subsequently ground with 1.0 mL sterilized H2O. The ground samples were diluted to 10-4, 10-5, and 10-6 and then were plated on a potato dextrose agar (PDA) plate, respectively. White mucous bacterial colonies appeared at 28℃ for 24~48 h, no fungal colony was observed. Six bacterial colonies were randomly selected for gram staining and found to be gram-negative. To further determine their species classification, fragments of the 16SrDNA, hsp60, gyrB, and rpoB genes were separately amplified using previously reported PCR conditions and with primer pairs, including 27F/1492R (Wu et al., 2023), HSP60-F /HSP60-R (Gül et al., 2023), gyrB UP-1 / gyrB UP-2r (Yamamoto et al., 1995) and rpoB CM81-F / rpoB CM32b-R (Brady et al., 2008). Sequence analysis showed that the obtained sequences of the 16SrDNA, hsp60, gyrB, and rpoB genes among these six colonies were identical and 100%, 100%, 99.31%, and 99.36% similar to those of Enterobacter mori accessions OP601841 (with a coverage of 100%), MT199160 (83%), OP676246 (100%), and MN594495 (100%), at nucleotide level, respectively. Sequences of the above four genes of 23LSFQ were submitted to GenBank under the accession numbers PP461247, PP474090, PP136037, and PP136038, respectively. We selected one of these six colonies, 23LSFQ, for further analysis. The phylogenetic tree based on the concatenated sequences of the above four genes using the maximum likelihood method with MEGAX software showed that 23LSFQ is grouped with E. mori LMG25706 (NCBI: txid980518). To determine the pathogenicity of 23LSFQ , we sprayed 23LSFQ (OD600=0.8) onto five 30-day-old healthy plants of the tomato cultivars Alisa Craig, Jinpeng NO.1, and Chaobei, respectively. These seedlings were incubated in a chamber at 28°C with a 16 h light/ 8h dark photoperiod and 60% relative humidity. The leaves of the inoculated plants became curled and wilted at two days post inoculation (dpi) and appeared necrotic at 10 dpi. The symptoms were similar to those observed in field-infected tomato plants. No symptoms were observed on the plants inoculated with water. We further sequenced the re-isolated bacteria from the symptomatic inoculated seedlings. Results showed that they belong to E. mori. The experiment was repeated three times. E. mori has been found to cause diseases on peaches (Ahmad et al., 2021), watermelons (Wu et al., 2023), Canna indica, (Zhang et al., 2023), and strawberries (Ji et al., 2023). E. cloacae has been found to cause diseases on tomatoes in Heilongjiang province (Jin et al., 2023). This is the first report of E. mori causing leaf yellowing and wilting on tomatoes in China. These results are significant for the safe production and disease control of greenhouse tomatoes.
PubMed: 38687577
DOI: 10.1094/PDIS-01-24-0174-PDN -
PloS One 2013Insects feeding on plant sap, blood, and other nutritionally incomplete diets are typically associated with mutualistic bacteria that supplement missing nutrients....
Insects feeding on plant sap, blood, and other nutritionally incomplete diets are typically associated with mutualistic bacteria that supplement missing nutrients. Herbivorous mammal dung contains more than 86% cellulose and lacks amino acids essential for insect development and reproduction. Yet one of the most ecologically necessary and evolutionarily successful groups of beetles, the dung beetles (Scarabaeinae) feeds primarily, or exclusively, on dung. These associations suggest that dung beetles may benefit from mutualistic bacteria that provide nutrients missing from dung. The nesting behaviors of the female parent and the feeding behaviors of the larvae suggest that a microbiome could be vertically transmitted from the parental female to her offspring through the brood ball. Using sterile rearing and a combination of molecular and culture-based techniques, we examine transmission of the microbiome in the bull-headed dung beetle, Onthophagus taurus. Beetles were reared on autoclaved dung and the microbiome was characterized across development. A ~1425 bp region of the 16S rRNA identified Pseudomonadaceae, Enterobacteriaceae, and Comamonadaceae as the most common bacterial families across all life stages and populations, including cultured isolates from the 3(rd) instar digestive system. Finer level phylotyping analyses based on lepA and gyrB amplicons of cultured isolates placed the isolates closest to Enterobacter cloacae, Providencia stuartii, Pusillimonas sp., Pedobacter heparinus, and Lysinibacillus sphaericus. Scanning electron micrographs of brood balls constructed from sterile dung reveals secretions and microbes only in the chamber the female prepares for the egg. The use of autoclaved dung for rearing, the presence of microbes in the brood ball and offspring, and identical 16S rRNA sequences in both parent and offspring suggests that the O. taurus female parent transmits specific microbiome members to her offspring through the brood chamber. The transmission of the dung beetle microbiome highlights the maintenance and likely importance of this newly-characterized bacterial community.
Topics: Animals; Bacteria; Cattle; Coleoptera; Comamonadaceae; DNA, Bacterial; Enterobacteriaceae; Female; Host-Pathogen Interactions; Larva; Manure; Microbiota; Molecular Sequence Data; Phylogeny; Pseudomonadaceae; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Symbiosis
PubMed: 24223880
DOI: 10.1371/journal.pone.0079061