Community Of Microorganisms Research Articles

Effect of Seed Dressing and Soil Chemical Properties on Communities of Microorganisms Associated with Pre-Emergence Damping-Off of Broad Bean Seedlings

Combating soil pathogens that disable plant emergence is among the most difficult challenges of global agriculture. Legumes, preferred in sustainable cultivation systems, are particularly sensitive to pre-emergence damping-off of seedlings. Seed dressing is therefore a very important element in the cultivation technology. The aim of this study was to compare the impact of biological (Pythium oligandrum) and chemical (carboxin + thiuram) seed dressing on the quantitative and qualitative composition of microorganisms participating in the epidemiology of this disease, under specific hydrothermal conditions and chemical properties of the soil (pH, humus, macro-, and micronutrient). Microorganism identification was done using the MALDI-TOF MS (Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry) technique. Species were assigned to frequency groups, and populations of pathogens, saprophytes, and antagonists were identified. The biodiversity of these communities was expressed with Simpson’s Reciprocal, Shannon–Wiener, and Evenness (Shannon) indices. In individual variants of seed pre-treatment, the correlations between individual edaphic factors and the suppression of pre-emergence damping-off, the number of isolates obtained from infected seedlings, and the share of individual trophic groups of fungi were assessed. The main causes of pre-emergence damping-off of broad bean seedlings are Ilyonectria destructans, Globisporangium irregulare, Fusarium equiseti, Rhizoctonia solani, and Fusarium solani. Eliminating seed treatment results in a seedling mortality rate of 33.5–42.5%. The effectiveness of the chemical protection product is 44.2% and 25.9%. Carboxin and thiuram reduce the diversity of microorganisms involved in the pathogenesis of pre-emergence damping-off and limit the presence of antagonistic fungi. Under the influence of P. oligandrum, there was a five-fold increase in the population of antagonists. An increase in humus in the soil reduces the percentage of diseased broad bean seedlings.

Wound Chronicity, Impaired Immunity and Infection in Diabetic Patients.

Diabetic foot ulcers are a common diabetic complication leading to alarming figures of amputation, disability, and early mortality. The diabetic glucooxidative environment impairs the healing response, promoting the onset of a 'wound chronicity phenotype'. In 50% of ulcers, these non-healing wounds act as an open door for developing infections, a process facilitated by diabetic patients' dysimmunity. Infection can elicit biofilm formation that worsens wound prognosis. How this microorganism community is able to take advantage of underlying diabetic conditions and thrive both within the wound and the diabetic host is an expanding research field. 1) Offer an overview of the major cellular and molecular derangements of the diabetic healing process versus physiological cascades in a non-diabetic host. 2) Describe the main immunopathological aspects of diabetics' immune response and explore how these contribute to wound infection susceptibility. 3) Conceptualize infection and biofilim in diabetic foot ulcers and analyze their dynamic interactions with wound bed cells and matrices, and their systemic effects at the organism level. 4) Offer an integrative conceptual framework of wound-dysimmunity-infection-organism damage. We retrieved 683 articles indexed in Medline/PubMed, SciELO, Bioline International and Google Scholar. 280 articles were selected for discussion under four major subheadings: 1) normal healing processes, 2) impaired healing processes in the diabetic population, 3) diabetic dysimmunity and 4) diabetic foot infection and its interaction with the host. The diabetic healing response is heterogeneous, torpid and asynchronous, leading to wound chronicity. The accumulation of senescent cells and a protracted inflammatory profile with a pro-catabolic balance hinder the proliferative response and delay re-epithelialization. Diabetes reduces the immune system's abilities to orchestrate an appropriate antimicrobial response and offers ideal conditions for microbiota establishment and biofilm formation. Biofilm-microbial entrenchment hinders antimicrobial therapy effectiveness, amplifies the host's pre-existing immunodepression, arrests the wound's proliferative phase, increases localized catabolism, prolongs pathogenic inflammation and perpetuates wound chronicity. In such circumstances the infected wound may act as a proinflammatory and pro-oxidant organ superimposed onto the host, which eventually intensifies peripheral insulin resistance and disrupts homeostasis. The number of lower-limb amputations remains high worldwide despite continued research efforts on diabetic foot ulcers. Identifying and manipulating the molecular drivers underlying diabetic wound healing failure, and dysimmunity-driven susceptibility to infection will offer more effective therapeutic tools for the diabetic population.

Deciphering the low abundance microbiota of presumed aseptic hip and knee implants.

16S rRNA gene sequencing of DNA extracted from clinically uninfected hip and knee implant samples has revealed polymicrobial populations. However, previous studies assessed 16S rRNA gene sequencing as a technique for the diagnosis of periprosthetic joint infections, leaving the microbiota of presumed aseptic hip and knee implants largely unstudied. These communities of microorganisms might play important roles in aspects of host health, such as aseptic loosening. Therefore, this study sought to characterize the bacterial composition of presumed aseptic joint implant microbiota using next generation 16S rRNA gene sequencing, and it evaluated this method for future investigations. 248 samples were collected from implants of 41 patients undergoing total hip or knee arthroplasty revision for presumed aseptic failure. DNA was extracted using two methodologies—one optimized for high throughput and the other for human samples—and amplicons of the V4 region of the 16S rRNA gene were sequenced. Sequencing data were analyzed and compared with ancillary specific PCR and microbiological culture. Computational tools (SourceTracker and decontam) were used to detect and compensate for environmental and processing contaminants. Microbial diversity of patient samples was higher than that of open-air controls and differentially abundant taxa were detected between these conditions, possibly reflecting a true microbiota that is present in clinically uninfected joint implants. However, positive control-associated artifacts and DNA extraction methodology significantly affected sequencing results. As well, sequencing failed to identify Cutibacterium acnes in most culture- and PCR-positive samples. These challenges limited characterization of bacteria in presumed aseptic implants, but genera were identified for further investigation. In all, we provide further support for the hypothesis that there is likely a microbiota present in clinically uninfected joint implants, and we show that methods other than 16S rRNA gene sequencing may be ideal for its characterization. This work has illuminated the importance of further study of microbiota of clinically uninfected joint implants with novel molecular and computational tools to further eliminate contaminants and artifacts that arise in low bacterial abundance samples.

Langmuir Monolayer Techniques for the Investigation of Model Bacterial Membranes and Antibiotic Biodegradation Mechanisms.

The amounts of antibiotics of anthropogenic origin released and accumulated in the environment are known to have a negative impact on local communities of microorganisms, which leads to disturbances in the course of the biodegradation process and to growing antimicrobial resistance. This mini-review covers up-to-date information regarding problems related to the omnipresence of antibiotics and their consequences for the world of bacteria. In order to understand the interaction of antibiotics with bacterial membranes, it is necessary to explain their interaction mechanism at the molecular level. Such molecular-level interactions can be probed with Langmuir monolayers representing the cell membrane. This mini-review describes monolayer experiments undertaken to investigate the impact of selected antibiotics on components of biomembranes, with particular emphasis on the role and content of individual phospholipids and lipopolysaccharides (LPS). It is shown that the Langmuir technique may provide information about the interactions between antibiotics and lipids at the mixed film surface (π–A isotherm) and about the penetration of the active substances into the phospholipid monolayer model membranes (relaxation of the monolayer). Effects induced by antibiotics on the bacterial membrane may be correlated with their bactericidal activity, which may be vital for the selection of appropriate bacterial consortia that would ensure a high degradation efficiency of pharmaceuticals in the environment.

Diversity and Co-Occurrence Patterns of Fungal and Bacterial Communities from Alkaline Sediments and Water of Julong High-Altitude Hot Springs at Tianchi Volcano, Northeast China.

Simple SummaryVolcanic hot springs are considered of particular interest in biology as precious sources of peculiar microorganisms adapted to extreme environmental conditions. The Julong high-altitude volcanic hot springs in northeast China are characterized by alkali, sulfur and metal enrichment. The microbial communities colonizing these intriguing habitats still remain completely unknown. We carried out the present study in order to shed light on the Julong hot springs fungal and bacterial community diversity, structure and interactions, and to understand the impact of pH on the microorganisms colonizing the investigated environment. We detected a large variety of typical photosynthetic, thermophilic, alkalophilic, antimicrobial-active, and sulfide- and metal-oxidizing microbial taxa representing clear links to the extreme properties of the studied environment. Results showed a striking microorganism community variation strongly influenced by pH under clearly alkaline conditions. Our analyses suggests that mutualistic relationships might be common among microorganisms coexisting in the Julong hot springs, especially for the bacterial community. This study provides new insights in the diversity and ecological interactions of microorganisms living in high-altitude volcanic hot springs and contributes to our knowledge of abiotic factors influencing the microbial community in the analyzed extreme environment. The Julong high-altitude volcanic hot springs in northeast China are of undeniable interest for microbiological studies due to their unique, extreme environmental conditions. The objective of this study was to provide a comprehensive analysis of the unexplored fungal and bacterial community composition, structure and networks in sediments and water from the Julong hot springs using a combination of culture-based methods and metabarcoding. A total of 65 fungal and 21 bacterial strains were isolated. Fungal genera Trichoderma and Cladosporium were dominant in sediments, while the most abundant fungi in hot spring water were Aspergillus and Alternaria. Bacterial communities in sediments and water were dominated by the genera Chryseobacterium and Pseudomonas, respectively. Metabarcoding analysis revealed significant differences in the microorganism communities from the two hot springs. Results suggested a strong influence of pH on the analyzed microbial diversity, at least when the environmental conditions became clearly alkaline. Our analyses indicated that mutualistic interactions may play an essential role in shaping stable microbial networks in the studied hot springs. The much more complicated bacterial than fungal networks described in our study may suggest that the more flexible trophic strategies of bacteria are beneficial for their survival and fitness under extreme conditions.

The Role of Microbiota in Gastrointestinal Cancer and Cancer Treatment: Chance or Curse?

The gastrointestinal (GI) tract is home to a complex and dynamic community of microorganisms, comprising bacteria, archaea, viruses, yeast, and fungi. It is widely accepted that human health is shaped by these microbes and their collective microbial genome. This so-called second genome plays an important role in normal functioning of the host, contributing to processes involved in metabolism and immune modulation. Furthermore, the gut microbiota also is capable of generating energy and nutrients (eg, short-chain fatty acids and vitamins) that are otherwise inaccessible to the host and are essential for mucosal barrier homeostasis. In recent years, numerous studies have pointed toward microbial dysbiosis as a key driver in many GI conditions, including cancers. However, comprehensive mechanistic insights on how collectively gut microbes influence carcinogenesis remain limited. In addition to their role in carcinogenesis, the gut microbiota now has been shown to play a key role in influencing clinical outcomes to cancer immunotherapy, making them valuable targets in the treatment of cancer. It also is becoming apparent that, besides the gut microbiota’s impact on therapeutic outcomes, cancer treatment may in turn influence GI microbiota composition. This review provides a comprehensive overview of microbial dysbiosis in GI cancers, specifically esophageal, gastric, and colorectal cancers, potential mechanisms of microbiota in carcinogenesis, and their implications in diagnostics and cancer treatment.

Microbial fuel cell affected the filler pollution accumulation of constructed wetland in the lab-scale and pilot-scale coupling reactors

This study investigated electrochemical performance, the filler pollution and microorganism community in constructed wetland (CW) and constructed wetland-microbial fuel cell coupling reactor (CW-MFC). CW-MFC could purify the wastewater and affect the filler pollution in different scales (lab-scale and pilot-scale), filler (gravel and activated carbon) and feeding modes (intermittent and continuous influent) reactors. Our study found that the best electrochemical performance (106 mW/m2 of power density) at the lab-scale level was obtained in I-G-CW-MFC (I = intermittent flow condition, G = gravel). The highest yield of hydrogen peroxide (2.91 mg/L) was detected in I-AC-CW-MFC (AC = activated carbon). At the pilot-scale (316 L effective volume), the specific surface area of P-CW-MFC-B (B = the bottom of the reactor) (928.4 ± 12.0 m2/g) was larger than that of the P-CW-B (810.6 ± 4.0 m2/g), and P-CW-NS (819.0 ± 12.5 m2/g) was larger than P-CW-MFC-NS (749.5 ± 2.1 m2/g), which indicated that the filler pollution contamination of the CW-MFC was lighter than that of CW. The biomass accumulation of filler in CW-MFC coupling system (0.048 ng/g) was less than that of CW (0.021 ng/g), which further demonstrated that the CW-MFC coupling system could reduce filler pollution to a certain extent. The intermittent pilot-scale CW-MFC coupling system could change the distribution of pollutants in the filler and reduce the accumulation of pollutants. These results demonstrated that MFC had a significant effect on the filler pollution accumulation of constructed wetland in the pilot-scale system, which may offer opportunities for clogging reduction of filler in CW.

Next Generation Microbiome Research: Identification of Keystone Species in the Metabolic Regulation of Host-Gut Microbiota Interplay.

The community of the diverse microorganisms residing in the gastrointestinal tract, known as the gut microbiota, is exceedingly being studied for its impact on health and disease. This community plays a major role in nutrient metabolism, maintenance of the intestinal epithelial barrier but also in local and systemic immunomodulation. A dysbiosis of the gut microbiota, characterized by an unbalanced microbial ecology, often leads to a loss of essential functions that may be associated with proinflammatory conditions. Specifically, some key microbes that are depleted in dysbiotic ecosystems, called keystone species, carry unique functions that are essential for the balance of the microbiota. In this review, we discuss current understanding of reported keystone species and their proposed functions in health. We also elaborate on current and future bioinformatics tools needed to identify missing functions in the gut carried by keystone species. We propose that the identification of such keystone species functions is a major step for the understanding of microbiome dynamics in disease and toward the development of microbiome-based therapeutics.

Nesterenkonia ebinurensis sp. nov., a Novel Actinobacterium Isolated From Populus euphratica.

During our studies focused on the microorganism diversity and community structure of Populus euphratica at Ebinur lake wetland nature reserve in Xinjiang Uyghur Autonomous Region, PR China, a Gram-positive, aerobic, short rod-shaped bacterium without flagellum, designated as MD2T, was isolated from a piece of resina on Populus euphratica. The isolate grew at temperature of 10-45°C (optimum 37°C), pH of 7.0-12.0 (optimum pH 8.0) and NaCl concentration of 1-18% (optimum 3%, w/v). Based on the 16S rRNA gene sequences and the phylogenetic analysis, the strain shared the highest sequence similarities to Nesterenkonia alkaliphila JCM 19766T (96.3%), Nesterenkonia populi KCTC 29119T (95.9%), Nesterenkonia alba CCTCC AB 207011T (95.5%), and was placed within the radiation of Nesterenkonia species in the phylogenetic trees. The draft genome of the isolate was sequenced, which comprised 3,739,891bp with G + C content of 63mol%, and was annotated to contain 3614 protein-coding genes, 44 tRNA genes and 5 rRNA genes. Chemotaxonomic analysis indicated that the main respiratory quinones were MK-8 and MK-9, the predominant cellular fatty acids were anteiso-C17:0, anteiso-C15:0 and iso-C16:0, the major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol andphosphatidylinositol. According to the phenotypic, chemotaxonomic and phylogenetic features, strain MD2T is considered to represent a novel species, for which the name Nesterenkonia ebinurensis sp. nov. is proposed. The type strain is MD2T (= KCTC 52999T = MCCC 1K03343T).

Paradigm shift in the pathogenesis and treatment of oral cancer and other cancers focused on the oralome and antimicrobial-based therapeutics.

The oral microbiome is a community of microorganisms, comprised of bacteria, fungi, viruses, archaea, and protozoa, that form a complex ecosystem within the oral cavity. Although minor perturbations in the environment are frequent and compensable, major shifts in the oral microbiome can promote an unbalanced state, known as dysbiosis. Dysbiosis can promote oral diseases, including periodontitis. In addition, oral dysbiosis has been associated with other systemic diseases, including cancer. The objective of this review is to evaluate the epidemiologic evidence linking periodontitis to oral, gastrointestinal, lung, breast, prostate, and uterine cancers, as well as describe new evidence and insights into the role of oral dysbiosis in the etiology and pathogenesis of the cancer types discussed. Finally, we discuss how antimicrobials, antimicrobial peptides, and probiotics may be promising tools to prevent and treat these cancers, targeting both the microbes and associated carcinogenesis processes. These findings represent a novel paradigm in the pathogenesis and treatment of cancer focused on the oral microbiome and antimicrobial‐based therapies.

Exploring the effect of attractive and repulsive magnetic field on electricity generation and microbial community in microbial fuel cells

External magnetic field technology enhances microbial electrochemical reactions in biological processes. This study added Neodymium-Iron-Boron magnets to the outside of a double-chamber cubic microbial fuel cell (MFC) to explore the attractive or repulsive magnetic field effects at various intensities (0, 60, and 120 mT) on MFC performance. The results show that an extra 120 mT repulsive magnetic field can generate a peak power density of 144 mW/m2 and a maximum current density of 1558 mA/m2. This value is 45 and 8 times higher, respectively, compared without adding the magnetic field. Moreover, adding 120 mT repulsive magnetic field can increase coulombic efficiency (CE) to 63.0%, which is higher than the CE of 25.9% without magnetic field addition. Taxonomy profiling classification results show that Geobacter and Pseudomonas, which can achieve e-pili and redox mediators, were the domain microorganism community. Magnetic fields enhance the electron movement efficiency through extracellular electron transfer mechanisms, including e-pili and redox mediators provided by the exoelectrogenic microorganism to enlarge the chemical oxygen demand removal efficiency and CE value as well as increase the electron transfer probability to the electrode.

Bioremediation of polycyclic aromatic hydrocarbons from an aged contaminated agricultural soil using degrading bacteria and soil amendments

The combined effects of degrading bacteria (Paracoccus sp. LXC), humic acid (HA), and soil amendments, including chicken manure, biochar, and wormcast, were investigated through 84 d of incubation in order to improve the remediation of polycyclic aromatic hydrocarbon (PAH) in aged contaminated agricultural soil. PAH concentrations and dissipation kinetics were analyzed, and the biomass and communities of microorganisms and soil enzyme activities were examined to clarify the possible mechanism. The highest removal efficiency of PAHs was 42.1% when treated with Paracoccus sp. LXC combined with biochar and HA. PAH dissipation was consistent with the first-order kinetics model and the half-life of PAHs decreased from 2323.3 d in the natural attenuation to 103–277 d in the amended microcosms. Soil amendments and HA promoted the development of PAH-degrading bacteria and diversity of bacterial communities in soil but not that of fungi. The removal efficiency of PAHs was positively correlated with the density of PAH-degrading bacteria and soil urease (Ure), dehydrogenase (Deh), and manganese-dependent peroxidase (Mnp) activities (r = 0.824–0.941, p < .01). The Paracoccus sp. LXC apparently removed 2–4-ring PAHs, and biochar and wormcast were effective in removing 2–4-ring and 5–6-ring PAHs, respectively. The combined bioremediation strategy using degrading bacteria with soil amendments and HA has high potential for PAH removal in aged contaminated agricultural soil and the possible mechanism was the combination of bioaugmentation with Paracoccus sp. LXC and biostimulation with HA and soil amendments.

Oxidative stress in the skin: Impact and related protection.

Skin, our first interface to the external environment, is subjected to oxidative stress caused by a variety of factors such as solar ultraviolet, infrared and visible light, environmental pollution, including ozone and particulate matters, and psychological stress. Excessive reactive species, including reactive oxygen species and reactive nitrogen species, exacerbate skin pigmentation and aging, which further lead to skin tone unevenness, pigmentary disorder, skin roughness and wrinkles. Besides these, skin microbiota are also a very important factor ensuring the proper functions of skin. While environmental factors such as UV and pollutants impact skin microbiota compositions, skin dysbiosis results in various skin conditions. In this review, we summarize the generation of oxidative stress from exogenous and endogenous sources. We further introduce current knowledge on the possible roles of oxidative stress in skin pigmentation and aging, specifically with emphasis on oxidative stress and skin pigmentation. Meanwhile, we summarize the science and rationale of using three well-known antioxidants, namely vitamin C, resveratrol and ferulic acid, in the treatment of hyperpigmentation. Finally, we discuss the strategy for preventing oxidative stress-induced skin pigmentation and aging.

Microbial community responses to multiple soil disinfestation change drivers

Soil continuous cropping obstacles lead to yield and economic losses in agriculture. Reductive soil disinfestation (RSD) is an effective technology for alleviating it. However, the key factors influencing microbial community composition and how do they promote functional transformation of core microbes under RSD practice remain poorly understood. Hence, a short-term field experiment was performed integrating real-time polymerase chain reaction, average well color development (AWCD), and MiSeq pyrosequencing to investigate relationships between environmental factors and microorganisms in five different disinfestation treatments, i.e., untreated monoculture soil (CK), soil with high temperature heating (HT), soil with dazomet (DZ), RSD with sugarcane bagasse (SB), or with bean dregs (BD). The results showed that compared to non-RSD treatments, both RSD treatments significantly increased soil microbial abundance and soil available K and organic matter (OM). Further analysis found that available K and OM were the key factors inducing microbial community change. Additionally, relative to non-RSD treatments, the relative abundances of phyla Proteobacteria, Acidobacteria, Rokubacteria, and Ascomycota were higher, whereas those of Actinobacteria, Gemmatimonadetes, and Basidiomycota were lower in RSD treatments. Changes in microbial diversity and abundance led to variation of soil microbial community functions. AWCD and community function prediction showed that, in contrast with non-RSD treatments, soil metabolism activity significantly increased, bacterial community functions including terpenoids and polyketides metabolism, signal transduction and cell motility increased, and the number of saprotroph fungi increased under RSD treatments. Overall, RSD incorporated with sugarcane bagasse or bean dregs efficiently improved soil fertility, and considerably increased soil microbial activity and function, which may benefit future sustainable agriculture production. Key points • Reductive soil disinfestation can alleviate continuous cropping obstacles by improving soil fertility. • Organic matter and available potassium as the key factors affected microbial community reconstruction and function. • Reductive soil disinfestation can improve soil metabolic activity and functional diversity by altering microorganism community.

The Role of Gut Microbiota in Aging and Aging Related Neurodegenerative Disorders: Insights from Drosophila Model.

Aging is characterized by a time dependent impairment of physiological function and increased susceptibility to death. It is the major risk factor for neurodegeneration. Neurodegenerative disorders including Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the main causes of dementia in the old population. Gut microbiota is a community of microorganisms colonized in the gastrointestinal (GI) tract. The alteration of gut microbiota has been proved to be associated with aging and aging related neurodegeneration. Drosophila is a powerful tool to study microbiota-mediated physiological and pathological functions. Here, we summarize the recent advances using Drosophila as model organisms to clarify the molecular mechanisms and develop a therapeutic method targeting microbiota in aging and aging-related neurodegenerative disorders.

The Role of Microbiome in Sexually Transmitted Infections

Background: Several studies have shown that abnormal vaginal flora associated with sexually transmitted infections (STIs). Content: Microbiome can be defined as an ecological community of commensal, symbiotic, and pathogenic microorganisms that literally share the living in human body space. Studies showed that uncircumcised men are more likely to be populated by gram-positive and negative bacteria or other pathogens. The vaginal community is grouped into five microbiomes: community-state type (CST) I is dominated by L. crispatus; CST II by L. gasseri; CST III by L. iners; and CST V by L. jensenii. Whereas CST IV is heterogeneous and characterized by higher proportion of obligate anaerobic bacteria. Lactobacillus produces lactic acid and bacteriocin, which contribute to prevent bacterial growth by maintaining a low vaginal pH (pH 3.0 - 4.5). Bacterial vaginosis (BV) is a syndrome that occurs due to dysbiosis in vaginal microbiome. The protective mechanism by Lactobacillus compromises in BV, which becomes an entry point for pathogenic organisms. Protection against C. trachomatis infection is mainly generated by lactic acid produced by Lactobacillus. The low pH is also known to inhibit the survival of N. gonorrhoeae. Protection mechanism by Lactobacillus against viral infections such as HIV, HSV-2, and HPV can occur direct or indirectby several complex and integrated mechanisms. Conclusion: microbiome-based approaches have promising outcomes for both preventive and curative measures for sexually transmitted infections.

The importance of intestinal microbiota and its role in the nosocomial infection

The gastrointestinal tract houses the largest and most complex community of microorganisms, and this bacterial colonization of the human intestine by environmental microbes begins immediately after the birth. The intestinal microbiota has several important and unique functions, including metabolic functions such as the biotransformation of drugs and the digestion of dietary compounds; a mucosal barrier function by inhibiting the invasion of pathogens and an immunomodulatory function. On the other hand, some commensal bacteria can be pathogenic, causing infections if the natural host is compromised and, in predisposed hosts, the intestinal microbiota can be involved in nosocomial infection. The translocation of bacteria through the intestinal wall is considered one of the main causes of nosocomial infections. The aim of this review is to provide a comprehensive view of the human gut microbiota, its main functions, its role in health and disease, addressing the correlation between intestinal microbial composition and nosocomial infections.

Community Structure of Bacteria and Archaea Associated with Geotextile Filters in Anaerobic Bioreactor Landfills

Landfills are an example of an environment that contains highly complex communities of microorganisms. To evaluate the microbial community structure, four stainless steel pilot-scale bioreactor landfills with single- and double-layered geotextile fabric were used. Two reactors (R-1 and R-2) contained municipal solid waste (MSW) and sewage sludge, while the other two reactors (R-3 and R-4) contained only MSW. A single layer of geotextile fabric (R2GT3 and R3GT3) was inserted in the drainage layers of the two reactors (R-2 and R-3), while a double layer of geotextile fabric (R4GT2 and R4GT1) was inserted in one of the reactors (R-4). Scanning electron microscopy demonstrated that biomass developed on the geotextile fabrics after 540 days of bioreactor operation. The metagenomics analyses of the geotextile samples by 16S rRNA gene sequencing indicated that the geotextile bacterial communities were dominated by the phyla Firmicutes, Bacteroidetes, and Thermotogeae, while Proteobacteria were detected as the rarest bacterial phylum in all the geotextile samples. Treponema, Caldicoprobacter, and Clostridium were the most dominant anaerobic and fermentative bacterial genera associated with the geotextile fabric in the bioreactors. Euryarchaeota was the predominant archaean phylum detected in all the geotextile samples. In the archaeal communities, Methanosarcina, and Vadin CA11 were identified as the predominant genera. The diversity of microorganisms in landfill bioreactors is addressed to reveal opportunities for landfill process modifications and associated operational optimization. Thus, this study provides insights into the population dynamics of microorganisms in geotextile fabrics used in bioreactor landfills.

Dietary Selection Pressures and Their Impact on the Gut Microbiome.

The human gut microbiota harbors a heterogeneous and dynamic community of microorganisms that coexist with the host to exert a marked influence on human physiology and health. Throughout the lifespan, diet can shape the composition and diversity of the members of the gut microbiota by determining the microorganisms that will colonize, persist, or become extinct. This is no more pronounced than during early-life succession of the gut microbiome when food type and source changes relatively often and food preferences are established, which is largely determined by geographic location and the customs and cultural practices of that environment. These dietary selection pressures continue throughout life, as society has become increasingly mobile and as we consume new foods to which we have had no previous exposure. Dietary selection pressures also come in the form of overall reduction or excess such as with the growing problems of food insecurity (lack of food) as well as of dietary obesity (overconsumption). These are well-documented forms of dietary selection pressures that have profound impact on the gut microbiota that ultimately may contribute to or worsen disease. However, diets and dietary components can also be used to promote healthy microbial functions in the gut, which will require tailored approaches taking into account an individual’s personal history and doing away with one-size-fits-all nutrition. Herein, we summarize current knowledge on major dietary selection pressures that influence gut microbiota structure and function across and within populations, and discuss both the potential of personalized dietary solutions to health and disease and the challenges of implementation.

Dynamics of Microbial Communities across the Life Stages of Nilaparvata lugens (Stål)

Understanding the composition of microorganismal communities hosted by insect pests is an important prerequisite for revealing their functions and developing new pest control strategies. Although studies of the structure of the microbiome of Nilaparvata lugens have been published, little is known about the dynamic changes in this microbiome across different developmental stages, and an understanding of the core microbiota is still lacking. In this study, we investigated the dynamic changes in bacteria and fungi in different developmental stages of N. lugens using high-throughput sequencing technology. We observed that the microbial diversity in eggs and mated adults was higher than that in nymphs and unmated adults. We also observed a notable strong correlation between fungal and bacterial α-diversity, which suggests that fungi and bacteria are closely linked and may perform functions collaboratively during the whole developmental period. Arsenophonus and Hirsutella were the predominant bacterial and fungal taxa, respectively. Bacteria were more conserved than fungi during the transmission of the microbiota between developmental stages. Compared with that in the nymph and unmated adult stages of N. lugens, the correlation between bacterial and fungal communities in the mated adult and egg stages was stronger. Moreover, the core microbiota across all developmental stages in N. lugens was identified, and there were more bacterial genera than fungal genera; notably, the core microbiota of eggs, nymphs, and mated and unmated adults showed distinctive functional enrichment. These findings highlight the potential value of further exploring microbial functions during different developmental stages and developing new pest management strategies.