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813400.9930Sweet scents from good bacteria: Case studies on bacterial volatile compounds for plant growth and immunity. Beneficial bacteria produce diverse chemical compounds that affect the behavior of other organisms including plants. Bacterial volatile compounds (BVCs) contribute to triggering plant immunity and promoting plant growth. Previous studies investigated changes in plant physiology caused by in vitro application of the identified volatile compounds or the BVC-emitting bacteria. This review collates new information on BVC-mediated plant-bacteria airborne interactions, addresses unresolved questions about the biological relevance of BVCs, and summarizes data on recently identified BVCs that improve plant growth or protection. Recent explorations of bacterial metabolic engineering to alter BVC production using heterologous or endogenous genes are introduced. Molecular genetic approaches can expand the BVC repertoire of beneficial bacteria to target additional beneficial effects, or simply boost the production level of naturally occurring BVCs. The effects of direct BVC application in soil are reviewed and evaluated for potential large-scale field and agricultural applications. Our review of recent BVC data indicates that BVCs have great potential to serve as effective biostimulants and bioprotectants even under open-field conditions.201626177913
813310.9921Symbiotic bacteria confer insecticide resistance by metabolizing buprofezin in the brown planthopper, Nilaparvata lugens (Stål). Buprofezin, a chitin synthesis inhibitor, is widely used to control several economically important insect crop pests. However, the overuse of buprofezin has led to the evolution of resistance and exposed off-target organisms present in agri-environments to this compound. As many as six different strains of bacteria isolated from these environments have been shown to degrade buprofezin. However, whether insects can acquire these buprofezin-degrading bacteria from soil and enhance their own resistance to buprofezin remains unknown. Here we show that field strains of the brown planthopper, Nilaparvata lugens, have acquired a symbiotic bacteria, occurring naturally in soil and water, that provides them with resistance to buprofezin. We isolated a symbiotic bacterium, Serratia marcescens (Bup_Serratia), from buprofezin-resistant N. lugens and showed it has the capacity to degrade buprofezin. Buprofezin-susceptible N. lugens inoculated with Bup_Serratia became resistant to buprofezin, while antibiotic-treated N. lugens became susceptible to this insecticide, confirming the important role of Bup_Serratia in resistance. Sequencing of the Bup_Serratia genome identified a suite of candidate genes involved in the degradation of buprofezin, that were upregulated upon exposure to buprofezin. Our findings demonstrate that S. marcescens, an opportunistic pathogen of humans, can metabolize the insecticide buprofezin and form a mutualistic relationship with N. lugens to enhance host resistance to buprofezin. These results provide new insight into the mechanisms underlying insecticide resistance and the interactions between bacteria, insects and insecticides in the environment. From an applied perspective they also have implications for the control of highly damaging crop pests.202338091367
863520.9920Techniques for enhancing the tolerance of industrial microbes to abiotic stresses: A review. The diversity of stress responses and survival strategies evolved by microorganism enables them to survive and reproduce in a multitude of harsh environments, whereas the discovery of the underlying resistance genes or mechanisms laid the foundation for the directional enhancement of microbial tolerance to abiotic stresses encountered in industrial applications. Many biological techniques have been developed for improving the stress resistance of industrial microorganisms, which greatly benefited the bacteria on which industrial production is based. This review introduces the main techniques for enhancing the resistance of microorganisms to abiotic stresses, including evolutionary engineering, metabolic engineering, and process engineering, developed in recent years. In addition, we also discuss problems that are still present in this area and offer directions for future research.202031206805
919230.9920Antimicrobial peptides: Sustainable application informed by evolutionary constraints. The proliferation and global expansion of multidrug-resistant (MDR) bacteria have deepened the need to develop novel antimicrobials. Antimicrobial peptides (AMPs) are regarded as promising antibacterial agents because of their broad-spectrum antibacterial activity and multifaceted mechanisms of action with non-specific targets. However, if AMPs are to be applied sustainably, knowledge of how they induce resistance in pathogenic bacteria must be mastered to avoid repeating the traditional antibiotic resistance mistakes currently faced. Furthermore, the evolutionary constraints on the acquisition of AMP resistance by microorganisms in the natural environment, such as functional compatibility and fitness trade-offs, inform the translational application of AMPs. Consequently, the shortcut to achieve sustainable utilization of AMPs is to uncover the evolutionary constraints of bacteria on AMP resistance in nature and find the tricks to exploit these constraints, such as applying AMP cocktails to minimize the efficacy of selection for resistance or combining nanomaterials to maximize the costs of AMP resistance. Altogether, this review dissects the benefits, challenges, and opportunities of utilizing AMPs against disease-causing bacteria, and highlights the use of AMP cocktails or nanomaterials to proactively address potential AMP resistance crises in the future.202235752270
919340.9920The bacteriophage decides own tracks: When they are with or against the bacteria. Bacteriophages, bacteria-infecting viruses, are considered by many researchers a promising solution for antimicrobial resistance. On the other hand, some phages have shown contribution to bacterial resistance phenomenon by transducing antimicrobial resistance genes to their bacterial hosts. Contradictory consequences of infections are correlated to different phage lifecycles. Out of four known lifecycles, lysogenic and lytic pathways have been riddles since the uncontrolled conversion between them could negatively affect the intended use of phages. However, phages still can be engineered for applications against bacterial and viral infections to ensure high efficiency. This review highlights two main aspects: (1) the different lifecycles as well as the different factors that affect lytic-lysogenic switch are discussed, including the intracellular and molecular factors control this decision. In addition, different models which describe the effect of phages on the ecosystem are compared, besides the approaches to study the switch. (2) An overview on the contribution of the phage in the evolution of the bacteria, instead of eating them, as a consequence of different mode of actions. As well, how phage display has helped in restricting phage cheating and how it could open new gates for immunization and pandemics control will be tacked.202134841341
825950.9920Secondary Metabolite Transcriptomic Pipeline (SeMa-Trap), an expression-based exploration tool for increased secondary metabolite production in bacteria. For decades, natural products have been used as a primary resource in drug discovery pipelines to find new antibiotics, which are mainly produced as secondary metabolites by bacteria. The biosynthesis of these compounds is encoded in co-localized genes termed biosynthetic gene clusters (BGCs). However, BGCs are often not expressed under laboratory conditions. Several genetic manipulation strategies have been developed in order to activate or overexpress silent BGCs. Significant increases in production levels of secondary metabolites were indeed achieved by modifying the expression of genes encoding regulators and transporters, as well as genes involved in resistance or precursor biosynthesis. However, the abundance of genes encoding such functions within bacterial genomes requires prioritization of the most promising ones for genetic manipulation strategies. Here, we introduce the 'Secondary Metabolite Transcriptomic Pipeline' (SeMa-Trap), a user-friendly web-server, available at https://sema-trap.ziemertlab.com. SeMa-Trap facilitates RNA-Seq based transcriptome analyses, finds co-expression patterns between certain genes and BGCs of interest, and helps optimize the design of comparative transcriptomic analyses. Finally, SeMa-Trap provides interactive result pages for each BGC, allowing the easy exploration and comparison of expression patterns. In summary, SeMa-Trap allows a straightforward prioritization of genes that could be targeted via genetic engineering approaches to (over)express BGCs of interest.202235580059
937160.9919Coevolutionary history of predation constrains the evolvability of antibiotic resistance in prey bacteria. Understanding how the historical contingency of biotic interactions shapes the evolvability of bacterial populations is imperative for the predictability of the eco-evolutionary dynamics of microbial communities. While microbial predators like Myxococcus xanthus influence the frequency of antibiotic-resistant bacteria in nature, the effect of adaptation to the presence of predators on the evolvability of prey bacteria to future stressors is unclear. Hence, to understand the influence of the coevolutionary history of predation on the evolvability of antibiotic resistance, we propagated variants of E. coli, pre-adapted to distinct biotic and abiotic conditions, in gradually increasing concentrations of antibiotics. We show that pre-adaptation to predators limits the evolution of a high degree of antibiotic resistance. Moreover, lower degree of resistance in the evolved strains also incurs reduced fitness costs while preserving their ancestral ability to resist predation. Together, we demonstrate that the history of biotic interactions can strongly influence the evolvability of bacteria.202540461734
917370.9919Bacterial defences: mechanisms, evolution and antimicrobial resistance. Throughout their evolutionary history, bacteria have faced diverse threats from other microorganisms, including competing bacteria, bacteriophages and predators. In response to these threats, they have evolved sophisticated defence mechanisms that today also protect bacteria against antibiotics and other therapies. In this Review, we explore the protective strategies of bacteria, including the mechanisms, evolution and clinical implications of these ancient defences. We also review the countermeasures that attackers have evolved to overcome bacterial defences. We argue that understanding how bacteria defend themselves in nature is important for the development of new therapies and for minimizing resistance evolution.202337095190
958980.9919Phage Therapy: Going Temperate? Strictly lytic phages have been consensually preferred for phage therapy purposes. In contrast, temperate phages have been avoided due to an inherent capacity to mediate transfer of genes between bacteria by specialized transduction - an event that may increase bacterial virulence, for example, by promoting antibiotic resistance. Now, advances in sequencing technologies and synthetic biology are providing new opportunities to explore the use of temperate phages for therapy against bacterial infections. By doing so we can considerably expand our armamentarium against the escalating threat of antibiotic-resistant bacteria.201930466900
826590.9918Mathematical modelling of CRISPR-Cas system effects on biofilm formation. Clustered regularly interspaced short palindromic repeats (CRISPR), linked with CRISPR associated (Cas) genes, can confer adaptive immunity to bacteria, against bacteriophage infections. Thus from a therapeutic standpoint, CRISPR immunity increases biofilm resistance to phage therapy. Recently, however, CRISPR-Cas genes have been implicated in reducing biofilm formation in lysogenized cells. Thus CRISPR immunity can have complex effects on phage-host-lysogen interactions, particularly in a biofilm. In this contribution, we develop and analyse a series of dynamical systems to elucidate and disentangle these interactions. Two competition models are used to study the effects of lysogens (first model) and CRISPR-immune bacteria (second model) in the biofilm. In the third model, the effect of delivering lysogens to a CRISPR-immune biofilm is investigated. Using standard analyses of equilibria, stability and bifurcations, our models predict that lysogens may be able to displace CRISPR-immune bacteria in a biofilm, and thus suggest strategies to eliminate phage-resistant biofilms.201728426329
9583100.9918Bacteriophages presence in nature and their role in the natural selection of bacterial populations. Phages are the obligate parasite of bacteria and have complex interactions with their hosts. Phages can live in, modify, and shape bacterial communities by bringing about changes in their abundance, diversity, physiology, and virulence. In addition, phages mediate lateral gene transfer, modify host metabolism and reallocate bacterially-derived biochemical compounds through cell lysis, thus playing an important role in ecosystem. Phages coexist and coevolve with bacteria and have developed several antidefense mechanisms in response to bacterial defense strategies against them. Phages owe their existence to their bacterial hosts, therefore they bring about alterations in their host genomes by transferring resistance genes and genes encoding toxins in order to improve the fitness of the hosts. Application of phages in biotechnology, environment, agriculture and medicines demands a deep insight into the myriad of phage-bacteria interactions. However, to understand their complex interactions, we need to know how unique phages are to their bacterial hosts and how they exert a selective pressure on the microbial communities in nature. Consequently, the present review focuses on phage biology with respect to natural selection of bacterial populations.202033170167
8283110.9918Stress responses as determinants of antimicrobial resistance in Gram-negative bacteria. Bacteria encounter a myriad of potentially growth-compromising conditions in nature and in hosts of pathogenic bacteria. These 'stresses' typically elicit protective and/or adaptive responses that serve to enhance bacterial survivability. Because they impact upon many of the same cellular components and processes that are targeted by antimicrobials, adaptive stress responses can influence antimicrobial susceptibility. In targeting and interfering with key cellular processes, antimicrobials themselves are 'stressors' to which protective stress responses have also evolved. Cellular responses to nutrient limitation (nutrient stress), oxidative and nitrosative stress, cell envelope damage (envelope stress), antimicrobial exposure and other growth-compromising stresses, have all been linked to the development of antimicrobial resistance in Gram-negative bacteria - resulting from the stimulation of protective changes to cell physiology, activation of resistance mechanisms, promotion of resistant lifestyles (biofilms), and induction of resistance mutations.201222424589
9144120.9917Metal nanoparticles: understanding the mechanisms behind antibacterial activity. As the field of nanomedicine emerges, there is a lag in research surrounding the topic of nanoparticle (NP) toxicity, particularly concerned with mechanisms of action. The continuous emergence of bacterial resistance has challenged the research community to develop novel antibiotic agents. Metal NPs are among the most promising of these because show strong antibacterial activity. This review summarizes and discusses proposed mechanisms of antibacterial action of different metal NPs. These mechanisms of bacterial killing include the production of reactive oxygen species, cation release, biomolecule damages, ATP depletion, and membrane interaction. Finally, a comprehensive analysis of the effects of NPs on the regulation of genes and proteins (transcriptomic and proteomic) profiles is discussed.201728974225
8243130.9917Rooteomics: the challenge of discovering plant defense-related proteins in roots. In recent years, a strong emphasis has been given in deciphering the function of genes unraveled by the completion of several genome sequencing projects. In plants, functional genomics has been massively used in order to search for gene products of agronomic relevance. As far as root-pathogen interactions are concerned, several genes are recognized to provide tolerance/resistance against potential invaders. However, very few proteins have been identified by using current proteomic approaches. One of the major drawbacks for the successful analysis of root proteomes is the inherent characteristics of this tissue, which include low volume content and high concentration of interfering substances such as pigments and phenolic compounds. The proteome analysis of plant-pathogen interactions provides important information about the global proteins expressed in roots in response to biotic stresses. Moreover, several pathogenic proteins superimpose the plant proteome and can be identified and used as targets for the control of viruses, bacteria, fungi and nematode pathogens. The present review focuses on advances in different proteomic strategies dedicated to the challenging analysis of plant defense proteins expressed during bacteria-, fungi- and nematode-root interactions. Recent developments, limitations of the current techniques, and technological perspectives for root proteomics aiming at the identification of resistance-related proteins are discussed.200818393883
8347140.9917Molecular mechanisms underlying glyphosate resistance in bacteria. Glyphosate is a nonselective herbicide that kills weeds and other plants competing with crops. Glyphosate specifically inhibits the 5-enolpyruvyl-shikimate-3-phosphate (EPSP) synthase, thereby depleting the cell of EPSP serving as a precursor for biosynthesis of aromatic amino acids. Glyphosate is considered to be toxicologically safe for animals and humans. Therefore, it became the most-important herbicide in agriculture. However, its intensive application in agriculture is a serious environmental issue because it may negatively affect the biodiversity. A few years after the discovery of the mode of action of glyphosate, it has been observed that bacteria evolve glyphosate resistance by acquiring mutations in the EPSP synthase gene, rendering the encoded enzyme less sensitive to the herbicide. The identification of glyphosate-resistant EPSP synthase variants paved the way for engineering crops tolerating increased amounts of the herbicide. This review intends to summarize the molecular mechanisms underlying glyphosate resistance in bacteria. Bacteria can evolve glyphosate resistance by (i) reducing glyphosate sensitivity or elevating production of the EPSP synthase, by (ii) degrading or (iii) detoxifying glyphosate and by (iv) decreasing the uptake or increasing the export of the herbicide. The variety of glyphosate resistance mechanisms illustrates the adaptability of bacteria to anthropogenic substances due to genomic alterations.202133876549
8360150.9916Genome mining of Streptomyces scabrisporus NF3 reveals symbiotic features including genes related to plant interactions. Endophytic bacteria are wide-spread and associated with plant physiological benefits, yet their genomes and secondary metabolites remain largely unidentified. In this study, we explored the genome of the endophyte Streptomyces scabrisporus NF3 for discovery of potential novel molecules as well as genes and metabolites involved in host interactions. The complete genomes of seven Streptomyces and three other more distantly related bacteria were used to define the functional landscape of this unique microbe. The S. scabrisporus NF3 genome is larger than the average Streptomyces genome and not structured for an obligate endosymbiotic lifestyle; this and the fact that can grow in R2YE media implies that it could include a soil-living stage. The genome displays an enrichment of genes associated with amino acid production, protein secretion, secondary metabolite and antioxidants production and xenobiotic degradation, indicating that S. scabrisporus NF3 could contribute to the metabolic enrichment of soil microbial communities and of its hosts. Importantly, besides its metabolic advantages, the genome showed evidence for differential functional specificity and diversification of plant interaction molecules, including genes for the production of plant hormones, stress resistance molecules, chitinases, antibiotics and siderophores. Given the diversity of S. scabrisporus mechanisms for host upkeep, we propose that these strategies were necessary for its adaptation to plant hosts and to face changes in environmental conditions.201829447216
8162160.9916Nanotechnology for Targeted Detection and Removal of Bacteria: Opportunities and Challenges. The emergence of nanotechnology has created unprecedented hopes for addressing several unmet industrial and clinical issues, including the growing threat so-termed "antibiotic resistance" in medicine. Over the last decade, nanotechnologies have demonstrated promising applications in the identification, discrimination, and removal of a wide range of pathogens. Here, recent insights into the field of bacterial nanotechnology are examined that can substantially improve the fundamental understanding of nanoparticle and bacteria interactions. A wide range of developed nanotechnology-based approaches for bacterial detection and removal together with biofilm eradication are summarized. The challenging effects of nanotechnologies on beneficial bacteria in the human body and environment and the mechanisms of bacterial resistance to nanotherapeutics are also reviewed.202134558234
8267170.9916Why put up with immunity when there is resistance: an excursion into the population and evolutionary dynamics of restriction-modification and CRISPR-Cas. Bacteria can readily generate mutations that prevent bacteriophage (phage) adsorption and thus make bacteria resistant to infections with these viruses. Nevertheless, the majority of bacteria carry complex innate and/or adaptive immune systems: restriction-modification (RM) and CRISPR-Cas, respectively. Both RM and CRISPR-Cas are commonly assumed to have evolved and be maintained to protect bacteria from succumbing to infections with lytic phage. Using mathematical models and computer simulations, we explore the conditions under which selection mediated by lytic phage will favour such complex innate and adaptive immune systems, as opposed to simple envelope resistance. The results of our analysis suggest that when populations of bacteria are confronted with lytic phage: (i) In the absence of immunity, resistance to even multiple bacteriophage species with independent receptors can evolve readily. (ii) RM immunity can benefit bacteria by preventing phage from invading established bacterial populations and particularly so when there are multiple bacteriophage species adsorbing to different receptors. (iii) Whether CRISPR-Cas immunity will prevail over envelope resistance depends critically on the number of steps in the coevolutionary arms race between the bacteria-acquiring spacers and the phage-generating CRISPR-escape mutants. We discuss the implications of these results in the context of the evolution and maintenance of RM and CRISPR-Cas and highlight fundamental questions that remain unanswered. This article is part of a discussion meeting issue 'The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems'.201930905282
8628180.9916Biofertilizer microorganisms accompanying pathogenic attributes: a potential threat. Application of biofertilizers containing living or dormant plant growth promoting bacterial cells is considered to be an ecofriendly alternative of chemical fertilizers for improved crop production. Biofertilizers opened myriad doors towards sustainable agriculture as they effectively reduce heavy use of chemical fertilizers and pesticides by keeping soils profuse in micro and macronutrients, regulating plant hormones and restraining infections caused by the pests present in soil without inflicting environmental damage. Generally, pathogenicity and biosafety testing of potential plant growth promoting bacteria (PGPB) are not performed, and the bacteria are reported to be beneficial solely on testing plant growth promoting characteristics. Unfortunately, some rhizosphere and endophytic PGPB are reported to be involved in various diseases. Such PGPB can also spread virulence and multidrug resistance genes carried by them through horizontal gene transfer to other bacteria in the environment. Therefore, deployment of such microbial populations in open fields could lead to disastrous side effects on human health and environment. Careless declaration of bacteria as PGPB is more pronounced in research publications. Here, we present a comprehensive report of declared PGPB which are reported to be pathogenic in other studies. This review also suggests the employment of some additional safety assessment protocols before reporting a bacteria as beneficial and product development.202235221573
8636190.9916Insights into the synthesis, engineering, and functions of microbial pigments in Deinococcus bacteria. The ability of Deinococcus bacteria to survive in harsh environments, such as high radiation, extreme temperature, and dryness, is mainly attributed to the generation of unique pigments, especially carotenoids. Although the limited number of natural pigments produced by these bacteria restricts their industrial potential, metabolic engineering and synthetic biology can significantly increase pigment yield and expand their application prospects. In this study, we review the properties, biosynthetic pathways, and functions of key enzymes and genes related to these pigments and explore strategies for improving pigment production through gene editing and optimization of culture conditions. Additionally, studies have highlighted the unique role of these pigments in antioxidant activity and radiation resistance, particularly emphasizing the critical functions of deinoxanthin in D. radiodurans. In the future, Deinococcus bacterial pigments will have broad application prospects in the food industry, drug production, and space exploration, where they can serve as radiation indicators and natural antioxidants to protect astronauts' health during long-term space flights.202439119139