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1.
Cyclophilins: Less Studied Proteins with Critical Roles in Pathogenesis.
Singh, K, Winter, M, Zouhar, M, Ryšánek, P
Phytopathology. 2018;(1):6-14
Abstract
Cyclophilins (EC 5.2.1.8) belong to a subgroup of proteins known as immunophilins, which also include FK506-binding proteins and parvulins. Members of the immunophilins have two main characteristic properties: (i) peptidyl-prolyl cis-trans isomerase activity and (ii) the ability to bind immunosuppressant molecules of fungal origin. Cyclophilins are some of the most conserved proteins present in eukaryotes and prokaryotes, and they have been implicated in diverse cellular processes and responses to multiple biotic and abiotic stresses. Cyclophilins have been exploited in humans and plants extensively, but they have only recently received attention in regard to phytopathogens. In Phellinus sulphurascens and species of the genus Leptosphaeria and Phytophthora, high expression of cyclophilins was found to be related to infection. Moreover, recent studies of cyclophilins in certain phytopathogens, such as Magnaporthe oryzae, Botrytis cinerea, Cryphonectria parasitica, and Puccinia triticina, demonstrated their roles as a pathogenicity factors. In addition to pathogenicity, cyclophilins have high affinity for the immunosuppressive drug cyclosporin A, which is a potent antifungal agent. Although cyclophilins are highly conserved in phytopathogens, because they have been less studied, their role remains largely unknown. In this review, we provide detailed information on the cyclophilins in several phytopathogens, including fungi and oomycetes, as well as their role in suppressing plant immunity.
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2.
[Non-allergenic impact of indoor mold exposure].
Gautier, C, Caillaud, D, Charpin, D
Revue des maladies respiratoires. 2018;(6):652-658
Abstract
The proportion of moldy housing in France is around 20%. It is not simple to establish that a health impact of mold is not allergic, because the identification of allergy is itself difficult. Moreover, exposure to molds and their metabolites may have a protective effect. Non-allergic health impacts may occur due to the multiple aerocontaminants found in damp or mold-containing dwellings: glucans, microbial volatile organic compounds, mycotoxins, bacteria and endotoxins. The heath impacts of indoor mold have been addressed by numerous toxicologic and epidemiologic investigations, the results of which have been summarized in three notable reports. These conclude that mold exposure is linked to a risk of ENT and bronchial symptoms, both the genesis and exacerbation of asthma and, lastly, hypersensitivity pneumonitis. Finally, other studies highlight the protective role of fungal metabolites with respect to asthma and allergy. Pulmonologists should be aware of these data, which can be useful in clinical practice and also in legal work.
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3.
Drought consistently alters the composition of soil fungal and bacterial communities in grasslands from two continents.
Ochoa-Hueso, R, Collins, SL, Delgado-Baquerizo, M, Hamonts, K, Pockman, WT, Sinsabaugh, RL, Smith, MD, Knapp, AK, Power, SA
Global change biology. 2018;(7):2818-2827
Abstract
The effects of short-term drought on soil microbial communities remain largely unexplored, particularly at large scales and under field conditions. We used seven experimental sites from two continents (North America and Australia) to evaluate the impacts of imposed extreme drought on the abundance, community composition, richness, and function of soil bacterial and fungal communities. The sites encompassed different grassland ecosystems spanning a wide range of climatic and soil properties. Drought significantly altered the community composition of soil bacteria and, to a lesser extent, fungi in grasslands from two continents. The magnitude of the fungal community change was directly proportional to the precipitation gradient. This greater fungal sensitivity to drought at more mesic sites contrasts with the generally observed pattern of greater drought sensitivity of plant communities in more arid grasslands, suggesting that plant and microbial communities may respond differently along precipitation gradients. Actinobateria, and Chloroflexi, bacterial phyla typically dominant in dry environments, increased their relative abundance in response to drought, whereas Glomeromycetes, a fungal class regarded as widely symbiotic, decreased in relative abundance. The response of Chlamydiae and Tenericutes, two phyla of mostly pathogenic species, decreased and increased along the precipitation gradient, respectively. Soil enzyme activity consistently increased under drought, a response that was attributed to drought-induced changes in microbial community structure rather than to changes in abundance and diversity. Our results provide evidence that drought has a widespread effect on the assembly of microbial communities, one of the major drivers of soil function in terrestrial ecosystems. Such responses may have important implications for the provision of key ecosystem services, including nutrient cycling, and may result in the weakening of plant-microbial interactions and a greater incidence of certain soil-borne diseases.
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4.
Enhanced production of Lovastatin by filamentous fungi through solid state fermentation.
Kamal, S, Akhter, N, Khan, SG, Kiran, S, Farooq, T, Akram, M, Shah, SMA, Tahir, IM, Akhlaq, M, Said, F, et al
Pakistan journal of pharmaceutical sciences. 2018;(4(Supplementary)):1583-1589
Abstract
Lovastatin is a natural competitive inhibitor of 3-hydroxy-3-methyl glutaryl coenzyme-A (HMG-CoA) reductase and inhibits specifically rate limiting step in cholesterol biosynthesis. Further, lovastatin in comparison with synthetic drugs has no well-reported side effects. Four pure isolated filamentous fungal strains including Aspergillus niger IBL, Aspergillus terreus FFCBP-1053, Aspergillus flavus PML and Aspergillus nidulans FFCBP-014 have been cultured by solid state fermentation (SSF) using rice straw as substrate for the synthesis of lovastatin. After selecting Aspergillus terreus FFCBP-1053 as the best producer of lovastatin, various selected physical parameters including pH, temperature, inoculums size and moisture content were optimized through response surface methodology (RSM) under center composite design (CCD) for lovastatin hyper production. Maximum lovastatin production of 2070±91.5 was predicted by the quadratic model in the medium having moisture content 70% and pH 4.5 at 35°C which was verified experimentally to be 2140±93.25µg/g DW of FM (microgram/gram dry weight of fermentation medium), significantly (P<0.05) high as compared to un-optimized conditions while it was noted that lovastatin production is independent on inoculum size (P>0.05) measured by spectrophotometer at 245 nm against standard. It was determined that optimized conditions for the hyper-production of lovastatin from fungal sources have a significant effect.
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5.
Induction of abiotic stress tolerance in plants by endophytic microbes.
Lata, R, Chowdhury, S, Gond, SK, White, JF
Letters in applied microbiology. 2018;(4):268-276
Abstract
UNLABELLED Endophytes are micro-organisms including bacteria and fungi that survive within healthy plant tissues and promote plant growth under stress. This review focuses on the potential of endophytic microbes that induce abiotic stress tolerance in plants. How endophytes promote plant growth under stressful conditions, like drought and heat, high salinity and poor nutrient availability will be discussed. The molecular mechanisms for increasing stress tolerance in plants by endophytes include induction of plant stress genes as well as biomolecules like reactive oxygen species scavengers. This review may help in the development of biotechnological applications of endophytic microbes in plant growth promotion and crop improvement under abiotic stress conditions. SIGNIFICANCE AND IMPACT OF THE STUDY Increasing human populations demand more crop yield for food security while crop production is adversely affected by abiotic stresses like drought, salinity and high temperature. Development of stress tolerance in plants is a strategy to cope with the negative effects of adverse environmental conditions. Endophytes are well recognized for plant growth promotion and production of natural compounds. The property of endophytes to induce stress tolerance in plants can be applied to increase crop yields. With this review, we intend to promote application of endophytes in biotechnology and genetic engineering for the development of stress-tolerant plants.
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6.
Biosynthesis of pneumocandin lipopeptides and perspectives for its production and related echinocandins.
Li, Y, Lan, N, Xu, L, Yue, Q
Applied microbiology and biotechnology. 2018;(23):9881-9891
Abstract
Fungal diseases are a global public health problem. Invasive fungal infections pose a serious threat to patients with compromised immune systems, such as those undergoing organ or bone marrow transplants, cancer, or HIV/AIDS. Pneumocandins are antifungal lipohexapeptides of the echinocandin family that noncompetitively inhibit of 1,3-β-glucan synthase of fungal cell wall and provide the precursor for the semisynthesis of caspofungin, which is widely used as first-line therapy for invasive fungal infections. Recently, the biosynthetic steps leading to formation of pneumocandin B0 and echinocandin B have been elucidated, and thus, provide a framework and attractive model for further design new antifungal therapeutics around natural variations in echinocandin structural diversities via genetic and chemical tools. In this article, we analyze the biosynthetic pathway of pneumocandins and other echinocandins, provide an update on the array of pneumocandin analogues generated by genetic manipulation, and summarize advances in the enhancement of pneumocandin B0 production by random mutagenesis and fermentation optimization. We also give offer advice on the development of improved pneumocandin drug candidates and more efficient production of pneumocandin B0.
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7.
Influence of fungal endophytes on plant physiology is more pronounced under stress than well-watered conditions: a meta-analysis.
Dastogeer, KMG
Planta. 2018;(6):1403-1416
Abstract
A meta-analysis of published articles shows that the influence of fungal endophytes on plant performance is dependent on plant water status. The magnitude of endophytic effects is higher in plants grown in water-limiting environments than those in adequate watering environments. The outcome of plant-endophyte interactions depends on the identity of the plant host and fungal symbionts. Water limitation often hinders plant productivity in both natural and agricultural settings. Endophytic fungal symbionts can mediate plant water stress responses by enhancing drought tolerance and avoidance, but these effects have not been quantified across plant-endophyte studies. A meta-analysis of published studies was performed to determine how endophytic fungal symbionts influence plant response under non-stressed versus water-stressed conditions. A significantly positive or neutral overall effect of fungal endophyte was noted under water-stressed conditions. In contrast, under non-stressed conditions, the overall effect of fungi on plants was mostly neutral. In general, the presence of fungal endophytes increased plant's total biomass, chlorophyll content, and stomatal conductance irrespective of water availability. In addition, plant shoot biomass, tiller density, plant height, maximum quantum yield (Fv/Fm), net photosynthesis, relative water content (RWC), amounts of ascorbate peroxidase (APX), glutathione (GSH), polyphenol oxidase (PPO), superoxide dismutase (SOD), and phenolics were significantly increased by endophyte colonisation under stressed conditions. Malondialdehyde (MDA) and hydrogen peroxide (H2O2) were reduced in endophytic plants under stress as compared with non-endophytic counterparts. Categorical analysis revealed that accumulation in plant biomass is influenced by factors such as host and fungi identity, the magnitude of which is greater under stressed than non-stressed conditions.
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8.
The Genome Biology of Effector Gene Evolution in Filamentous Plant Pathogens.
Sánchez-Vallet, A, Fouché, S, Fudal, I, Hartmann, FE, Soyer, JL, Tellier, A, Croll, D
Annual review of phytopathology. 2018;:21-40
Abstract
Filamentous pathogens, including fungi and oomycetes, pose major threats to global food security. Crop pathogens cause damage by secreting effectors that manipulate the host to the pathogen's advantage. Genes encoding such effectors are among the most rapidly evolving genes in pathogen genomes. Here, we review how the major characteristics of the emergence, function, and regulation of effector genes are tightly linked to the genomic compartments where these genes are located in pathogen genomes. The presence of repetitive elements in these compartments is associated with elevated rates of point mutations and sequence rearrangements with a major impact on effector diversification. The expression of many effectors converges on an epigenetic control mediated by the presence of repetitive elements. Population genomics analyses showed that rapidly evolving pathogens show high rates of turnover at effector loci and display a mosaic in effector presence-absence polymorphism among strains. We conclude that effective pathogen containment strategies require a thorough understanding of the effector genome biology and the pathogen's potential for rapid adaptation.
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9.
What are the advantages of living in a community? A microbial biofilm perspective!
Santos, ALSD, Galdino, ACM, Mello, TP, Ramos, LS, Branquinha, MH, Bolognese, AM, Columbano Neto, J, Roudbary, M
Memorias do Instituto Oswaldo Cruz. 2018;(9):e180212
Abstract
Biofilm formation is the preferred mode of growth lifestyle for many microorganisms, including bacterial and fungal human pathogens. Biofilm is a strong and dynamic structure that confers a broad range of advantages to its members, such as adhesion/cohesion capabilities, mechanical properties, nutritional sources, metabolite exchange platform, cellular communication, protection and resistance to drugs (e.g., antimicrobials, antiseptics, and disinfectants), environmental stresses (e.g., dehydration and ultraviolet light), host immune attacks (e.g., antibodies, complement system, antimicrobial peptides, and phagocytes), and shear forces. Microbial biofilms cause problems in the hospital environment, generating high healthcare costs and prolonged patient stay, which can result in further secondary microbial infections and various health complications. Consequently, both public and private investments must be made to ensure better patient management, as well as to find novel therapeutic strategies to circumvent the resistance and resilience profiles arising from biofilm-associated microbial infections. In this work, we present a general overview of microbial biofilm formation and its relevance within the biomedical context.
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10.
Fungal microsclerotia development: essential prerequisites, influencing factors, and molecular mechanism.
Song, Z
Applied microbiology and biotechnology. 2018;(23):9873-9880
Abstract
Microsclerotia (MS) consist of an outer layer of pigment parenchyma cells and an inner layer of colorless medulla cells. In nature, MS are formed as overwintering and spreading structures in phytopathogenic fungi. For biological applications, MS can be induced in artificial liquid medium. To understand the complicated structure of MS and molecular mechanism of MS development in entomopathogenic and phytopathogenic fungi, data from different studies can be integrated. In this review, the essential prerequisites, environmental cues, and internal stimulating factors for MS development are explored. Emerging knowledges about the association between transcriptional regulatory circuits and signaling pathways involved in MS development in entomopathogenic and phytopathogenic fungi is also highlighted.