TRANSSTADIAL - Word Related Documents




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764800.9033Bacterial Associations Across House Fly Life History: Evidence for Transstadial Carriage From Managed Manure. House flies (Diptera: Muscidae; Musca domestica L.) associate with microbe-rich substrates throughout life history. Because larvae utilize bacteria as a food source, most taxa present in the larval substrate, e.g., manure, are digested or degraded. However, some species survive and are present as third-instar larvae begin pupation. During metamorphosis, many bacteria are again lost during histolysis of the larval gut and subsequent remodeling to produce the gut of the imago. It has been previously demonstrated that some bacterial species survive metamorphosis, being left behind in the puparium, present on the body surface, or in the gut of the emerged adult. We used a combined culture-molecular approach to identify viable microbes from managed manure residue and a wild population of house fly larvae, pupae, puparia, and adults to assess transstadial carriage. All larval (10/10), pupal (10/10), and puparial (10/10) cultures were positive for bacteria. Several bacterial species that were present in larvae also were present either in pupae or puparia. Four viable bacterial species were detectable in 6 of 10 imagoes reared from manure. Of note is the apparent transstadial carriage of Bacillus sonorensis, which has been associated with milk spoilage at dairies, and Alcaligenes faecalis, which can harbor numerous antibiotic resistance genes on farms. The potential of newly emerged flies to harbor and disseminate bacteria from managed manure on farms is an understudied risk that deserves further evaluation.201626798138
601010.8971The role of two families of bacterial enzymes in putrescine synthesis from agmatine via agmatine deiminase. Putrescine, one of the main biogenic amines associated to microbial food spoilage, can be formed by bacteria from arginine via ornithine decarboxylase (ODC), or from agmatine via agmatine deiminase (AgDI). This study aims to correlate putrescine production from agmatine to the pathway involving N-carbamoylputrescine formation via AdDI (the aguA product) and N-carbamoylputrescine amidohydrolase (the aguB product), or putrescine carbamoyltransferase (the ptcA product) in bacteria. PCR methods were developed to detect the two genes involved in putrescine production from agmatine. Putrescine production from agmatine could be linked to the aguA and ptcA genes in Lactobacillus hilgardii X1B, Enterococcus faecalis ATCC 11700, and Bacillus cereus ATCC 14579. By contrast Lactobacillus sakei 23K was unable to produce putrescine, and although a fragment of DNA corresponding to the gene aguA was amplified, no amplification was observed for the ptcA gene. Pseudomonas aeruginosa PAO1 produces putrescine and is reported to harbour aguA and aguB genes, responsible for agmatine deiminase and N-carbamoylputrescine amidohydrolase activities. The enzyme from P. aeruginosa PAO1 that converts N-carbamoylputrescine to putrescine (the aguB product) is different from other microorganisms studied (the ptcA product). Therefore, the aguB gene from P. aeruginosa PAO1 could not be amplified with ptcA-specific primers. The aguB and ptcA genes have frequently been erroneously annotated in the past, as in fact these two enzymes are neither homologous nor analogous. Furthermore, the aguA, aguB and ptcA sequences available from GenBank were subjected to phylogenetic analysis, revealing that gram-positive bacteria harboured ptcA, whereas gram-negative bacteria harbour aguB. This paper also discusses the role of the agmatine deiminase system (AgDS) in acid stress resistance.201021404211
605220.8957Safety and technological application of autochthonous Streptococcus thermophilus cultures in the buffalo Mozzarella cheese. Thermophilic and mesophilic lactic acid bacteria (LAB), such as Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, and Lactococcus lactis, play a crucial role in the technological and sensory quality of Mozzarella cheese. In this study, the safety (genes encoding virulence factors and antibiotic resistance) and acidifying activity of autochthonous S. thermophilus cultures were evaluated in order to choose the most suitable strain for industrial application. The safe and good acidifying culture was tested in two buffalo Mozzarella cheese batches: Mozzarella cheeses produced with autochthonous culture (SJRP107) and commercial culture (STM5). The cultivable LAB was evaluated by culture-dependent method (plate counting) and the quantification of S. thermophilus cultures (commercial and autochthonous) were evaluated by culture-independent method RealT-qPCR (real-time quantitative polymerase chain reaction). The texture, physicochemical and proteolytic properties of the Mozzarella cheeses were similar for both batches. The nonstarter LAB count was higher during manufacture than in the storage, and the RealT-qPCR indicated the presence of S. thermophilus culture until the end of storage. S. thermophilus SJRP107 presented high potential for safety application in the production of Mozzarella cheese. Furthermore, considering the culture characteristics and their relationship with product quality, further studies could be helpful to determine their effect on the sensory characteristics of the cheese.202031948624
612730.8936Paenibacillus associated with milky disease in Central and South American scarabs. Thirty-one isolates of bacteria causing milky disease in scarab larvae collected in Central and South America were identified as Paenibacillus popilliae or Paenibacillus lentimorbus by use of DNA similarity analysis. The isolates were more similar to each other than to the North American isolates that are the type strains of the species. All of the bacteria of both species produced parasporal bodies, a characteristic previously believed to be unique to P. popilliae. Screening of the bacteria using PCR with parasporal protein primers revealed differences among the parasporal protein genes of P. popilliae isolates and between the parasporal genes of P. popilliae and P. lentimorbus. In contrast to P. popilliae from North America, none of the isolates from Central and South America was resistant to vancomycin, an indication of an interesting geographic distribution of the resistance genes.200011023744
440.8935Bacteria deplete deoxynucleotides to defend against bacteriophage infection. DNA viruses and retroviruses consume large quantities of deoxynucleotides (dNTPs) when replicating. The human antiviral factor SAMHD1 takes advantage of this vulnerability in the viral lifecycle, and inhibits viral replication by degrading dNTPs into their constituent deoxynucleosides and inorganic phosphate. Here, we report that bacteria use a similar strategy to defend against bacteriophage infection. We identify a family of defensive bacterial deoxycytidine triphosphate (dCTP) deaminase proteins that convert dCTP into deoxyuracil nucleotides in response to phage infection. We also identify a family of phage resistance genes that encode deoxyguanosine triphosphatase (dGTPase) enzymes, which degrade dGTP into phosphate-free deoxyguanosine and are distant homologues of human SAMHD1. Our results suggest that bacterial defensive proteins deplete specific deoxynucleotides (either dCTP or dGTP) from the nucleotide pool during phage infection, thus starving the phage of an essential DNA building block and halting its replication. Our study shows that manipulation of the dNTP pool is a potent antiviral strategy shared by both prokaryotes and eukaryotes.202235817891
871450.8933Tales from the tomb: the microbial ecology of exposed rock surfaces. Although a broad diversity of eukaryotic and bacterial taxa reside on rock surfaces where they can influence the weathering of rocks and minerals, these communities and their contributions to mineral weathering remain poorly resolved. To build a more comprehensive understanding of the diversity, ecology and potential functional attributes of microbial communities living on rock, we sampled 149 tombstones across three continents and analysed their bacterial and eukaryotic communities via marker gene and shotgun metagenomic sequencing. We found that geographic location and climate were important factors structuring the composition of these communities. Moreover, the tombstone-associated microbial communities varied as a function of rock type, with granite and limestone tombstones from the same cemeteries harbouring taxonomically distinct microbial communities. The granite and limestone-associated communities also had distinct functional attributes, with granite-associated bacteria having more genes linked to acid tolerance and chemotaxis, while bacteria on limestone were more likely to be lichen associated and have genes involved in photosynthesis and radiation resistance. Together these results indicate that rock-dwelling microbes exhibit adaptations to survive the stresses of the rock surface, differ based on location, climate and rock type, and seem pre-disposed to different ecological strategies (symbiotic versus free-living lifestyles) depending on the rock type.201829235707
657760.8932Evaluating Microbial and Chemical Hazards in Commercial Struvite Recovered from Wastewater. Controlled struvite (NH(4)MgPO(4)ยท6H(2)O) precipitation has become a well-known process for nutrient recovery from wastewater treatment systems to alleviate the pressures of diminishing, finite rock phosphate reservoirs. Nonetheless, coprecipitation of potential microbial and chemical hazards is poorly understood. On the other hand, antimicrobial resistance (AMR) is a major global public health concern and wastewater is thought to disseminate resistance genes within bacteria. Fecal indicator bacteria (FIB) are typically used as measures of treatment quality, and with multiresistant E. coli and Enterococcus spp. rising in concern, the quantification of FIB can be used as a preliminary method to assess the risk of AMR. Focusing on struvite produced from full-scale operations, culture and qPCR methods were utilized to identify FIB, antibiotic resistance genes, and human enteric viruses in the final product. Detection of these hazards occurred in both wet and dry struvite samples indicating that there is a potential risk that needs further consideration. Chemical and biological analyses support the idea that the presence of other wastewater components can impact struvite formation through ion and microbial interference. While heavy metal concentrations met current fertilizer standards, the presence of K, Na, Ca, and Fe ions can impact struvite purity yet provide benefit for agricultural uses. Additionally, the quantified hazards detected varied among struvite samples produced from different methods and sources, thus indicating that production methods could be a large factor in the risk associated with wastewater-recovered struvite. In all, coprecipitation of metals, fecal indicator bacteria, antimicrobial resistance genes, and human enteric viruses with struvite was shown to be likely, and future engineered wastewater systems producing struvite may require additional step(s) to manage these newly identified public health risks.201930964655
847770.8930Selection of rice breeding lines for resistance to biotic and abiotic stresses. Rice (Oryza sativa L.) grown in many countries around the world with different climatic conditions and a huge number of environmental stresses, both biotic (fungi, bacteria, viruses, insects) and abiotic (cold, drought, salinity) limit rice productivity. In this regard, breeders and scientists are trying to create rice lines that are resistant to multiple stresses. The aim of this work was to screen and select cold and blast resistant rice breeding lines (RBLs) using molecular markers. Molecular screening of RBLs and parental varieties to cold tolerance was carried out using markers RM24545, RM1377, RM231 and RM569 associated with QTLs (qPSST-3, qPSST-7, qPSST-9). It was discovered that the presence of three QTLs characterizes the cold resistance of studied genotypes, and the absence of one of them leads to cold sensitivity. As a result, 21 cold-resistant out of the 28 studied RBLs were identified. These cold resistant 21 RBLs were further tested to blast resistance using markers Pi-ta, Pita3, Z56592, 195R-1, NMSMPi9-1, TRS26, Pikh MAS, MSM6, 9871.T7E2b, RM224 and RM1233. It was revealed that 16 RBLs from 21 studied lines contain 5-6 blast resistance genes. In accordance with the blast resistance strategy, the presence of 5 or more genes ensures the formation of stable resistance to Magnaporthe oryzae. Thus, 16 lines resistant to multiple stresses, such as cold and blast disease were developed. It should be noted that 6 of these selected lines are high-yielding, which is very important in rice breeding program. These RBLs can be used in breeding process as starting lines, germplasm exchange as a source of resistant genes for the development of new rice varieties resistant to multiple stress factors.202438747865
871380.8927Genomic Analysis of 18th-Century Kazakh Individuals and Their Oral Microbiome. The Asian Central Steppe, consisting of current-day Kazakhstan and Russia, has acted as a highway for major migrations throughout history. Therefore, describing the genetic composition of past populations in Central Asia holds value to understanding human mobility in this pivotal region. In this study, we analyse paleogenomic data generated from five humans from Kuygenzhar, Kazakhstan. These individuals date to the early to mid-18th century, shortly after the Kazakh Khanate was founded, a union of nomadic tribes of Mongol Golden Horde and Turkic origins. Genomic analysis identifies that these individuals are admixed with varying proportions of East Asian ancestry, indicating a recent admixture event from East Asia. The high amounts of DNA from the anaerobic Gram-negative bacteria Tannerella forsythia, a periodontal pathogen, recovered from their teeth suggest they may have suffered from periodontitis disease. Genomic analysis of this bacterium identified recently evolved virulence and glycosylation genes including the presence of antibiotic resistance genes predating the antibiotic era. This study provides an integrated analysis of individuals with a diet mostly based on meat (mainly horse and lamb), milk, and dairy products and their oral microbiome.202134943238
798590.8926Differential response of nonadapted ammonia-oxidising archaea and bacteria to drying-rewetting stress. Climate change is expected to increase the frequency of severe drought events followed by heavy rainfall, which will influence growth and activity of soil microorganisms, through osmotic stress and changes in nutrient concentration. There is evidence of rapid recovery of processes and adaptation of communities in soils regularly experiencing drying/rewetting and lower resistance and resilience in nonadapted soils. A microcosm-based study of ammonia-oxidising archaea (AOA) and bacteria (AOB), employing a grassland soil that rarely experiences drought, was used to test this hypothesis and also whether AOB were more resistant and resilient, through greater tolerance of high ammonia concentrations produced during drought and rewetting. Treated soils were dried, incubated for 3 weeks, rewetted, incubated for a further 3 weeks and compared to untreated soils, maintained at a constant moisture content. Nitrate accumulation and AOA and AOB abundance (abundance of respective amoA genes) and community composition (DGGE analysis of AOA amoA and AOB 16S rRNA genes) were poorly adapted to drying-rewetting. AOA abundance and community composition were less resistant than AOB during drought and less resilient after rewetting, at times when ammonium concentration was higher. Data provide evidence for poor adaptation of microbial communities and processes to drying-rewetting in soils with no history of drought and indicate niche differentiation of AOA and AOB associated with high ammonia concentration.201425070168
8831100.8926Search for biocontrol agents among endophytic lipopeptide-synthesizing bacteria Bacillus spp. to protect wheat plants against Greenbug aphid (Schizaphis graminum). Beneficial endophytic bacteria can suppress the development of insect pests through direct antagonism, with the help of metabolites, or indirectly by the induction of systemic resistance through the regulation of hormonal signaling pathways. Lipopeptides are bacterial metabolites that exhibit direct antagonistic activity against many organisms, including insects. Also, lipopeptides are able to trigger induced systemic resistance (ISR) in plants against harmful organisms, but the physiological mechanisms of their action are just beginning to be studied. In this work, we studied ten strains of bacteria isolated from the tissues of wheat and potatoes. Sequencing of the 16S rRNA gene showed that all isolates belong to the genus Bacillus and to two species, B. subtilis and B. velezensis. The genes for lipopeptide synthetase - surfactin synthetase (Bs_srf ), iturin synthetase (Bs_ituA, Bs_ituB) and fengycin synthetase (Bs_fenD) - were identified in all bacterial isolates using PCR. All strains had high aphicidal activity against the Greenbug aphid (Schizaphis graminum Rond.) due to the synthesis of lipopeptides, which was proven using lipopeptide-rich fractions (LRFs) isolated from the strains. Endophytic lipopeptide-synthesizing strains of Bacillus spp. indirectly affected the viability of aphids, the endurance of plants against aphids and triggered ISR in plants, which manifested itself in the regulation of oxidative metabolism and the accumulation of transcripts of the Pr1, Pr2, Pr3, Pr6 and Pr9 genes due to the synthesis of lipopeptides, which was proven using LRF isolated from three strains: B. subtilis 26D, B. subtilis 11VM, and B. thuringiensis B-6066. We have for the first time demonstrated the aphicidal effect of fengycin and the ability of the fengycin-synthesizing strains and isolates, B. subtilis Ttl2, Bacillus sp. Stl7 and B. thuringiensis B-6066, to regulate components of the pro-/antioxidant system of aphid-infested plants. In addition, this work is the first to demonstrate an elicitor role of fengycin in triggering a systemic resistance to S. graminum in wheat plants. We have discovered new promising strains and isolates of endophytes of the genus Bacillus, which may be included in the composition of new biocontrol agents against aphids. One of the criteria for searching for new bacteria active against phloem-feeding insects can be the presence of lipopeptide synthetase genes in the bacterial genome.202438952706
8639110.8925Toad's survivability and soil microbiome alterations impacted via individual abundance. Artificial breeding is a valid strategy for the reverse of current extinction tendency in wild population of amphibian like toads. Considering public health, an alternative to antibiotics is demanded for ameliorating survival of toads during the culture period. Relying on the cognition of probiotics or antagonistic bacteria, the present work investigated viability and soil microorganism variations induced by distribution characteristic on toads using high-throughput sequencing technology. Comparison and analysis of soil metagenome from clustered and depopulated groups distinguished by toad behavior showed differences of bacterial community composition (e.g., Proteobacteria bacterium TMED72 and Nannocystis exedens) and antibiotic resistance genes involving antibiotic efflux and inactivation (e.g., mdtB and acrF). There were 18 and 10 distribution-typical genes independently enriched in Proteobacteria bacterium TMED72 and bacterium TMED88 of clustered group and Nannocystis exedens of depopulated group. In Nannocystis exedens, one of the distribution-typical genes was annotated as 6-phosphogluconate dehydrogenase acting role on bacterial growth restriction. It implied that, compared with the group emerging rare traces, the reduction of soil bacteria which possess genes retarding bacterial growth putatively impairs competitiveness to pathogenic bacteria and results in poor survivability of toads under clustering behavior. With the co-occurrence of virulence genes, more evidences are needed on the antagonistic bacteria Nannocystis exedens as antibiotic substitute.202540478395
8754120.8923Detoxifying bacterial genes for deoxynivalenol epimerization confer durable resistance to Fusarium head blight in wheat. Fusarium head blight (FHB) and the presence of mycotoxin deoxynivalenol (DON) pose serious threats to wheat production and food safety worldwide. DON, as a virulence factor, is crucial for the spread of FHB pathogens on plants. However, germplasm resources that are naturally resistant to DON and DON-producing FHB pathogens are inadequate in plants. Here, detoxifying bacteria genes responsible for DON epimerization were used to enhance the resistance of wheat to mycotoxin DON and FHB pathogens. We characterized the complete pathway and molecular basis leading to the thorough detoxification of DON via epimerization through two sequential reactions in the detoxifying bacterium Devosia sp. D6-9. Epimerization efficiently eliminates the phytotoxicity of DON and neutralizes the effects of DON as a virulence factor. Notably, co-expressing of the genes encoding quinoprotein dehydrogenase (QDDH) for DON oxidation in the first reaction step, and aldo-keto reductase AKR13B2 for 3-keto-DON reduction in the second reaction step significantly reduced the accumulation of DON as virulence factor in wheat after the infection of pathogenic Fusarium, and accordingly conferred increased disease resistance to FHB by restricting the spread of pathogenic Fusarium in the transgenic plants. Stable and improved resistance was observed in greenhouse and field conditions over multiple generations. This successful approach presents a promising avenue for enhancing FHB resistance in crops and reducing mycotoxin contents in grains through detoxification of the virulence factor DON by exogenous resistance genes from microbes.202438593377
8135130.8923Harnessing Genome Editing Techniques to Engineer Disease Resistance in Plants. Modern genome editing (GE) techniques, which include clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system, transcription activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFNs) and LAGLIDADG homing endonucleases (meganucleases), have so far been used for engineering disease resistance in crops. The use of GE technologies has grown very rapidly in recent years with numerous examples of targeted mutagenesis in crop plants, including gene knockouts, knockdowns, modifications, and the repression and activation of target genes. CRISPR/Cas9 supersedes all other GE techniques including TALENs and ZFNs for editing genes owing to its unprecedented efficiency, relative simplicity and low risk of off-target effects. Broad-spectrum disease resistance has been engineered in crops by GE of either specific host-susceptibility genes (S gene approach), or cleaving DNA of phytopathogens (bacteria, virus or fungi) to inhibit their proliferation. This review focuses on different GE techniques that can potentially be used to boost molecular immunity and resistance against different phytopathogens in crops, ultimately leading to the development of promising disease-resistant crop varieties.201931134108
8419140.8920The uncultured luminous symbiont of Anomalops katoptron (Beryciformes: Anomalopidae) represents a new bacterial genus. Flashlight fishes (Beryciformes: Anomalopidae) harbor luminous symbiotic bacteria in subocular light organs and use the bacterial light for predator avoidance, feeding, and communication. Despite many attempts anomalopid symbionts have not been brought into laboratory culture, which has restricted progress in understanding their phylogenetic relationships with other luminous bacteria, identification of the genes of their luminescence system, as well as the nature of their symbiotic interactions with their fish hosts. To begin addressing these issues, we used culture-independent analysis of the bacteria symbiotic with the anomalopid fish, Anomalops katoptron, to characterize the phylogeny of the bacteria and to identify the genes of their luminescence system including those involved in the regulation of luminescence. Analysis of the 16S rRNA, atpA, gapA, gyrB, pyrH, recA, rpoA, and topA genes resolved the A. katoptron symbionts as a clade nested within and deeply divergent from other members of Vibrionaceae. The bacterial luminescence (lux) genes were identified as a contiguous set (luxCDABEG), as found for the lux operons of other luminous bacteria. Phylogenetic analysis based on the lux genes confirmed the housekeeping gene phylogenetic placement. Furthermore, genes flanking the lux operon in the A. katoptron symbionts differed from those flanking lux operons of other genera of luminous bacteria. We therefore propose the candidate name Candidatus Photodesmus (Greek: photo = light, desmus = servant) katoptron for the species of bacteria symbiotic with A. katoptron. Results of a preliminary genomic analysis for genes regulating luminescence in other bacteria identified only a Vibrio harveyi-type luxR gene. These results suggest that expression of the luminescence system might be continuous in P. katoptron.201121864694
8483150.8919Thermodynamic Surface Analyses to Inform Biofilm Resistance. Biofilms are the habitat of 95% of bacteria successfully protecting bacteria from many antibiotics. However, inhibiting biofilm formation is difficult in that it is a complex system involving the physical and chemical interaction of both substrate and bacteria. Focusing on the substrate surface and potential interactions with bacteria, we examined both physical and chemical properties of substrates coated with a series of phenyl acrylate monomer derivatives. Atomic force microscopy (AFM) showed smooth surfaces often approximating surgical grade steel. Induced biofilm growth of five separate bacteria on copolymer samples comprising varying concentrations of phenyl acrylate monomer derivatives evidenced differing degrees of biofilm resistance via optical microscopy. Using goniometric surface analyses, the van Oss-Chaudhury-Good equation was solved linear algebraically to determine the surface energy profile of each polymerized phenyl acrylate monomer derivative, two bacteria, and collagen. Based on the microscopy and surface energy profiles, a thermodynamic explanation for biofilm resistance is posited.202033205020
6380160.8918Seasonal dynamics of anammox bacteria in estuarial sediment of the Mai Po Nature Reserve revealed by analyzing the 16S rRNA and hydrazine oxidoreductase (hzo) genes. The community and population dynamics of anammox bacteria in summer (wet) and winter (dry) seasons in estuarial mudflat sediment of the Mai Po Nature Reserve were investigated by 16S rRNA and hydrazine oxidoreductase (hzo) genes. 16S rRNA phylogenetic diversity showed that sequences related to 'Kuenenia' anammox bacteria were presented in summer but not winter while 'Scalindua' anammox bacteria occurred in both seasons and could be divided into six different clusters. Compared to the 16S rRNA genes, the hzo genes revealed a relatively uniform seasonal diversity, with sequences relating to 'Scalindua', 'Anammoxoglobus', and planctomycete KSU-1 found in both seasons. The seasonal specific bacterial groups and diversity based on the 16S rRNA and hzo genes indicated strong seasonal community structures in estuary sediment of this site. Furthermore, the higher abundance of hzo genes in summer than winter indicates clear seasonal population dynamics. Combining the physicochemical characteristics of estuary sediment in the two seasons and their correlations with anammox bacteria community structure, we proposed the strong seasonal dynamics in estuary sediment of Mai Po to be due to the anthropogenic and terrestrial inputs, especially in summer, which brings in freshwater anammox bacteria, such as 'Kuenenia', interacting with the coastal marine anammox bacteria 'Scalindua'.201121487198
8132170.8918Autoclave treatment of pig manure does not reduce the risk of transmission and transfer of tetracycline resistance genes in soil: successive determinations with soil column experiments. The increasing use of antibiotics, especially tetracycline, in livestock feed adversely affects animal health and ecological integrity. Therefore, approaches to decrease this risk are urgently needed. High temperatures facilitate antibiotic degradation; whether this reduces transmission risk and transfer of tetracycline-resistant bacteria (TRBs) and tetracycline resistance genes (TRGs) in soil remains unknown. Successive experiments with soil columns evaluated the effects of autoclaving pig manure (APM) on soil TRB populations and TRGs over time at different soil depths. The data showed sharp increases in TRB populations and TRGs in each subsoil layer of PM (non-APM) and APM treatments within 30 days, indicating that TRBs and TRGs transferred rapidly. The level of TRBs in the upper soil layers was approximately 15-fold higher than in subsoils. TRBs were not dependent on PM and APM levels, especially in the late phase. Nevertheless, higher levels of APM led to rapid expansion of TRBs as compared to PM. Moreover, temporal changes in TRB frequencies in total culturable bacteria (TCBs) were similar to TRBs, indicating that the impact of PM or APM on TRBs was more obvious than for TCBs. TRBs were hypothesized to depend on the numbers of TRGs and indigenous recipient bacteria. In the plough layer, five TRGs (tetB, tetG, tetM, tetW, and tetB/P) existed in each treatment within 150 days. Selective pressure of TC may not be a necessary condition for the transfer and persistence of TRGs in soil. High temperatures might reduce TRBs in PM, which had minimal impact on the transmission and transfer of TRGs in soil. Identifying alternatives to decrease TRG transmission remains a major challenge.201626517996
6378180.8918Metagenomics reveals the divergence of gut microbiome composition and function in two common pika species (Ochotona curzoniae and Ochotona daurica) in China. Gut microbiome plays crucial roles in animal adaptation and evolution. However, research on adaptation and evolution of small wild high-altitude mammals from the perspective of gut microbiome is still limited. In this study, we compared differences in intestinal microbiota composition and function in Plateau pikas (Ochotona curzoniae) and Daurian pikas (O. daurica) using metagenomic sequencing. Our results showed that microbial community structure had distinct differences in different pika species. Prevotella, Methanosarcina, Rhizophagus, and Podoviridae were abundant bacteria, archaea, eukaryotes, and viruses in Plateau pikas, respectively. However, Prevotella, Methanosarcina, Ustilago, and Retroviridae were dominated in Daurian pikas. Functional pathways related to carbohydrate metabolism that refer to the utilization of pectin, hemicellulose, and debranching enzymes were abundant in Plateau pikas, while the function for degradation of chitin, lignin, and cellulose was more concentrated in Daurian pikas. Pika gut had abundant multidrug resistance genes, followed by glycopeptide and beta-lactamase resistance genes, as well as high-risk antibiotic resistance genes, such as mepA, tetM, and bacA. Escherichia coli and Klebsiella pneumoniae may be potential hosts of mepA. This research provided new insights for adaptation and evolution of wild animals from perspective of gut microbiome and broadened our understanding of high-risk antibiotic resistance genes and potential pathogens of wild animals.202439500545
8697190.8918Deciphering the Root Endosphere Microbiome of the Desert Plant Alhagi sparsifolia for Drought Resistance-Promoting Bacteria. Drought is among the most destructive abiotic stresses limiting crop growth and yield worldwide. Although most research has focused on the contribution of plant-associated microbial communities to plant growth and disease suppression, far less is known about the microbes involved in drought resistance among desert plants. In the present study, we applied 16S rRNA gene amplicon sequencing to determine the structure of rhizosphere and root endosphere microbiomes of Alhagi sparsifolia Compared to those of the rhizosphere, endosphere microbiomes had lower diversity but contained several taxa with higher relative abundance; many of these taxa were also present in the roots of other desert plants. We isolated a Pseudomonas strain (LTGT-11-2Z) that was prevalent in root endosphere microbiomes of A. sparsifolia and promoted drought resistance during incubation with wheat. Complete genome sequencing of LTGT-11-2Z revealed 1-aminocyclopropane-1-carboxylate deaminases, siderophore, spermidine, and colanic acid biosynthetic genes, as well as type VI secretion system (T6SS) genes, which are likely involved in biofilm formation and plant-microbe interactions. Together, these results indicate that drought-enduring plants harbor bacterial endophytes favorable to plant drought resistance, and they suggest that novel endophytic bacterial taxa and gene resources may be discovered among these desert plants.IMPORTANCE Understanding microbe-mediated plant resistance to drought is important for sustainable agriculture. We performed 16S rRNA gene amplicon sequencing and culture-dependent functional analyses of Alhagi sparsifolia rhizosphere and root endosphere microbiomes and identified key endophytic bacterial taxa and their genes facilitating drought resistance in wheat. This study improves our understanding of plant drought resistance and provides new avenues for drought resistance improvement in crop plants under field conditions.202032220847