Aspergillus

11 Key excerpts on "Aspergillus"

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  eBook - ePub

  New and Future Developments in Microbial Biotechnology and Bioengineering

  Aspergillus System Properties and Applications

  • Vijai Kumar Gupta(Author)
  • 2016(Publication Date)
  • Elsevier

    (Publisher)

  Aspergillus comprehension has led to improvement of production processes and developments of new products.

  Aspergillus Role in Nature

  Aspergillus is a filamentous saprophytic genus of fungi whose essential role in nature is aerobic decomposition of organic material. Aspergillus is a truly ubiquitous fungus. In addition to being found in soil and plant remains, it is found throughout the year at homes, schools, workplaces, libraries, and in such improbable places as desert (Schuh and Hogaboam, 2005 ). Aspergillus species are widely distributed in nature and can cause different diseases based on their degree of immune competence. Pathogenic fungus grows easily and quickly in routine culture media used for bacteria and fungi (Garcés Jarque et al., 2003 ).

  Aspergillus as Pathogen

  While the vast majority of Aspergillus species do not represent a threat to humans, at least 19 species are known opportunistic pathogens. The most important of the pathogenic strains is A. fumigatus (Latgé, 2001 ). This is the most common species recovered from cases of invasive aspergillosis. The next most commonly recovered species are Aspergillus flavus , Aspergillus niger , and Aspergillus terreus (Hope et al., 2005 ; Walsh et al., 2008 ).

  In environments outside of a host, Aspergillus produces conidia (asexual spores) that can be easily dispersed in the air. Inhalation of conidia in aerosol form is usually the initial route of entry for Aspergillus infection (Weigt et al., 2013 ). Aspergillus species have emerged as important causes of morbidity and mortality in immune-compromised patients. Invasive aspergillosis currently constitutes the most common pneumonic cause of infectious mortality in patients undergoing hematopoietic stem cell transplantation (HSCT) and is an important cause of opportunistic respiratory diseases and disseminated infection in other immune-compromised patients. Moreover, Aspergillus species also produce a wide range of chronic, saprophytic, and allergic conditions. Although other forms of aspergillosis, such as allergic bronchopulmonary aspergillosis (ABPA), allergic sinusitis, and saprophytic infection, are also causes of morbidity, they are rarely fatal (Walsh et al., 2008 ; Yoshida et al., 2015

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  The Aspergilli

  Genomics, Medical Aspects, Biotechnology, and Research Methods

  • Gustavo H. Goldman, Stephen A. Osmani(Authors)
  • 2007(Publication Date)
  • CRC Press

    (Publisher)

  11 References .......................................................................................................................................... 11 Few fungi are as important as members of the genus Aspergillus . This taxonomic group encompasses organisms whose characteristics are of high pathological, agricultural, industrial, pharmaceutical, scien-tific, and cultural importance. Superb agents of biodeterioration, aspergilli have been isolated from sources as varied as alligator nesting material, aviation fuel, Egyptian mummies, electrical fuses, plastic products, and old sauna boards. Indeed, this large and cosmopolitan group of molds is a major player in the ecosystem, involved in the degradation of a wide range of natural organic substrates, particularly plant materials. Aspergillu s species are generalists in that they will grow and reproduce on many different carbon sources; they have an amazing nutritional flexibility. The diversity of enzymes and organic acids used in nutrition is complemented by the metabolic capacity to secrete numerous low molecular weight secondary metabolites believed to be important in ecological signaling. Because these molds can be found almost everywhere on the planet, degrading both natural and human-made substrates, Aspergillus and human history have been intertwined intimately for centuries. 1.1 Early History and Taxonomy People have known about mushrooms and molds since the beginning of recorded history, but it is easier to find historical references to mushrooms––which are easily visible to the naked eye––than it is to find mention of mold. Microscopic fungi such as Aspergillus are usually referenced indirectly by their meta-bolic action as agents of rot and decay.

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  Genomics of Plants and Fungi

  • Rolf A. Prade, Hans J. Bohnert, Rolf A. Prade, Hans J. Bohnert(Authors)
  • 2003(Publication Date)
  • CRC Press

    (Publisher)

  1Aspergillus

  Michael J. Anderson and Jayne L. Brookman

  University of Manchester, Manchester, England

  David W. Denning

  University of Manchester and Wythenshawe Hospital, Manchester, England

  I. INTRODUCTION

  Aspergillosis, the name given to all diseases caused in animals by fungi in the genus Aspergillus, includes allergic, superficial, saprophytic, and invasive disease. More than 180 species of Aspergillus are recognized (1 ), but only a few cause disease with any regularity: A. fumigatus, A. flavus, A. terreus, and A. niger group species. Aspergilli are common saprophytes in the environment, especially in composting facilities. The pathogenic Aspergilli are found the world over, but soil isolation rates do increase towards the equator. Most aerobiology studies have been done in Europe and some have shown a seasonal variation in airborne Aspergillus counts. Aspergillus species comprise from 1% to 6% of the total air flora outside and, if speciated, A. fumigatus comprises from 4% to 41% of the Aspergillus total (2 ). The usual concentration of Aspergillus conidia in outside air is 1 to 30 conidia/m3 , but can rise to as high as 7 × 107 /m3 inside a barn, after hay or straw disturbance. In hospitals, conidia concentrations in air also vary typically from 0 to 1 × 102 /m3 with much variation in the same site (3 –5 ). Inside human dwellings, Aspergillus species may be found in high concentrations in potted plants (50 conidia/g soil) (6 ), damp cellars, dusty crawl spaces, and condiments, especially pepper (106 conidia/g) (2 ) and ground spices.

  Human disease has been increasing over the 5 decades since invasive aspergillosis was first described in the immunocompromised patient (7 ). Invasive aspergillosis (IA) is the most common life-threatening invasive mold infection worldwide. It usually complicates treatments and diseases associated with immunosuppression, including allogeneic bone marrow transplantation, lung and liver transplantation, the treatment of acute leukemia, late-stage acquired immunodeficiency syndrome (AIDS) and a variety of other diseases treated with corticosteroids (8 ). Invasive aspergillosis rarely affects nonimmunocompromised patients. The incidence of invasive aspergillosis was calculated to have risen 14-fold in the 15-year period up to the end of 1992, as seen in autopsy data from one major teaching hospital in Frankfurt, Germany, with 5% of autopsied patients having invasive aspergillosis in the last year of this survey (9 ). In a national autopsy survey in Japan from 1969 to 1994, invasive aspergillosis increased from 0.4% to 1.3% in all autopsies (10 ). Another autopsy series in a European teaching hospital demonstrated a 4% rate of invasive aspergillosis in unselected autopsies (11 ). A culture-based population study in the San Francisco area (requiring cases to have, for example, two culture-positive bronchoscopy specimens or a sterile site positive by culture, which probably underrepresents invasive aspergillosis by perhaps 90%) showed increasing rates of disease over the last 25 years (12

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  Molecular Detection of Human Fungal Pathogens

  • Dongyou Liu(Author)
  • 2011(Publication Date)
  • CRC Press

    (Publisher)

  171 23.1 INTRODUCTION 23.1.1 E PIDEMIOLOGY AND M ORPHOLOGY 23.1.1.1 Epidemiology Filamentous. fungi. belonging. to. the. genus. Aspergillus . are. found. widespread. in. nature . . They. are. commonly. isolated. from.soil,.decaying.plants.and.vegetables,.and.from.indoor. air.environment . 1–5 . Aspergillus .conidia.are.widely.dispersed. and.are.inhaled.on.a.daily.basis.unless.special.air.filtration. measures.are.taken . . Aspergillus . species. may. cause. disease. due. to. inhalation. of. conidia. or. ingestion. of. mycotoxins. resulting.in.allergic.or.toxic.disease,.chronic.infection,.and/ or.acute.infections . 6 .Allergic.aspergillosis.occurs.largely.in. patients.with.asthma,.atopy,.or.cystic.fibrosis.(CF), 7,8 .while. invasive. pulmonary. disease. usually. only. occurs. in. immu-nocompromised.patients.with.inhalation.being.the.primary. route. of. infection . . Over. recent. decades,. the. number. of. patients. with. invasive. aspergillosis. (IA). has. increased. due. largely. to. advances. in. the. treatment. of. malignant. diseases. with. an. increasing. number. of. patients. undergoing. severe. immunosuppression,. as. part. of. intensive. chemotherapeuti-cal. regimes,. hematopoietic. stem. cell. or. organ. transplanta-tion. 9–15 . A. fumigatus .is.the.most.common.species.involved. in.infections.(85%–90%),.but. A. flavus ,. A. niger ,. A. terreus ,. and. A. nidulans .are.also.regularly.recovered,.with.varying. species.distribution.dependent.on.geographical.differences,. antifungal.selective.pressure,.anatomical.site,.and.host.group. involved. 23.1.1.2 Morphology Macromorphology :.The.growth.rate.of.aspergilli.is.rapid.to. moderately. rapid. (1–9.cm. in. diameter. after. 7. days. of. cul-ture.at.25°C),.with.the.exception.of.the.slow.growing.species. A. nidulans .and. A. glaucus . .Colonies.are.powdery,.granular,. or.cottony.with.a.variety.of.colors.depending.on.the.species. and.the.culture.medium.used.(Table.23 .1). .Only. A.

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  Agriculture and Food Production

  • (Author)
  • 2001(Publication Date)
  • Elsevier Science

    (Publisher)

  Applied Mycology and Biotechnology Volume 1. Agriculture and Food Production G.G. Khachatourians and D.K. Arora (editors) 9 2001 Elsevier Science B.V. All rights reserved. 239 Aspergillus nidulans as a model organism for the study of the expression of genes encoding enzymes of relevance in the food industry A.P. MacCabe, M. Orejas and D. Rambn Departamento de Biotecnologia; Instituto de Agroquimica y Tecnologia de Alimentos (CSIC), PO Box 73, 46100-Burjassot, Valencia, Spain 1. INTRODUCTION Filamentous fungi are of considerable importance in the food and beverage industries as producers of metabolites possessing either beneficial (food enzymes) or detrimental (mycotoxins) properties. Whilst these fungi are able to produce a very wide range of enzymatic activities only a restricted number of these enzymes are currently used in commercial food production. Nevertheless, this restricted number represents a large percentage of the total number of enzymes employed by the food industry. In general, enzymatic activities of industrial interest are obtained from fungal cultures as components in mixtures containing other non-required activities. Given the advances in the molecular characterisation of genes encoding enzymes of industrial relevance, a potentially useful alternative to screening programs for strain improvement may reside in the application of molecular genetic technology. For the purposes of optimising the industrial production of enzymes by molecular means a logical first step is the study of the regulation of expression of the corresponding genes. The principal industrial scale fungal enzyme producers are predominantly members of the genera Aspergillus (Aspergillus awamori, Aspergillus niger, Aspergillus oryzae) and Trichoderma (Trichoderma longibrachiatum, Trichoderma reesei). Although not employed at the industrial level, Aspergillus nidulans is without doubt the organism of choice for carrying out such studies on gene regulation.

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  Molecular Biology of Food and Water Borne Mycotoxigenic and Mycotic Fungi

  • R. Russell M. Paterson, Nelson Lima, R. Russell M. Paterson, Nelson Lima(Authors)
  • 2015(Publication Date)
  • CRC Press

    (Publisher)

  151 12 Aspergillus and Aspergillosis Malcolm D. Richardson and Riina Richardson 12.1 INTRODUCTION Aspergillosis is a term used to refer to infections caused by molds belonging to the genus Aspergillus . 1 These conditions are seen worldwide. In immunocompromised individuals, inhalation of conidia or hyphal fragments can give rise to life-threatening invasive infection of the lungs or sinuses: dissemination to other organs often follows. This condition is termed invasive aspergillosis (IA). In nonimmunocompromised persons, these molds can cause localized infection of the lungs, sinuses, and other sites. Human disease can also result from noninfectious mechanisms: inhalation of conidia of these ubiquitous organisms can exacerbate allergic symptoms in both atopic and non-atopic individuals. Several Aspergillus species produce mycotoxins that are harmful to humans and animals when ingested. Molds of the anamorphic genus Aspergillus are widespread in the environment, growing in the soil, on plants, and on decomposing organic matter. These molds are often found in the outdoor and indoor air, in water, on food items, and in dust. Aspergilli are saprophytes that commonly grow on decaying plant material. They are able to utilize a wide range of organic substrates and adapt well to a broad range of environmental conditions. In contact with air, the mycelium forms specialized structures, the so-called conidiophores. These produce large numbers of conidia (asexual spores) that are efficiently dispersed through the air and inhaled by humans. 12.2 Aspergillus SPECIES Aspergillus includes over 185 species. Around 20 species have so far been reported as caus-ative agents of opportunistic infections in man. 1 Among these, Aspergillus fumigatus is the most commonly isolated species, followed by A. flavus and A. niger , A. clavatus , A. glaucus group , A. nidulans , A. oryzae , A. terreus , A. ustus , and A.

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  Microbes Diversity and Biotechnology

  • Sati, S C(Authors)
  • 2021(Publication Date)
  • Daya Publishing House

    (Publisher)

  Chapter 23 Aspergillus spp. Association with Major Crops and its Pathogenic Effects M.R. Swain and H.N. Thatoi Department of Biotechnology, College of Engineering and Technology, Techno Campus, Ghatkia, Bhubaneswar – 751 003 ABSTRACT Aspergillus are widespread in nature due to their capability to grow and develop in a wide range of environmental conditions i.e. under dry conditions (9.5 per cent of moisture), in temperature between 4 to 45ºC and 65-100 per cent relative humidity. More than 200 species of Aspergillus spp. have been documented as per the literature. Due to their saprophytic and opportunistic nature, Aspergillus spp. are found to be responsible for several disorders in agricultural crops and commodities such as pulses, cereals, oilseeds, vegetables, fruits, spices, condiments etc. Aspergillus spp. have ability to produce various toxic metabolites known as mycotoxins in a wide range of agricultural crops. Mycotoxins produced by Aspergillus group have several negative effects on human health such as carcinogenic, immunosuppressive, tremorgenic, teratogenic, hepatotoxic and many more. Besides this there are other manifestations by Aspergillus spp. inside seeds which also cause damage to crops. This ebook is exclusively for this university only. Cannot be resold/distributed. Keywords : Aspergillus spp., Mycotoxin, Agricultural crops. Introduction Fungi in the genus Aspergillus are comparatively more widespread than others due to their capability to grow and develop in a wide range of environmental conditions i.e. under dry conditions, in temperature between 4 to 45ºC and 65-100 per cent relative humidity (Doijode, 2001). Although this group of fungus is not considered to be a major cause of plant diseases, due to their saprophytic and opportunistic nature, Aspergillus species are found to be responsible for several disorders in various plants, plant products and in agricultural commodities.

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  Microbial Biofilms

  • Mahmoud Ghannoum, Matthew Parsek, Marvin Whiteley, Pranab K. Mukherjee, Mahmoud Ghannoum, Matthew Parsek, Marvin Whiteley, Pranab K. Mukherjee(Authors)
  • 2015(Publication Date)
  • ASM Press

    (Publisher)

  8

  Aspergillus Biofilm In Vitro and In Vivo

  ANNE BEAUVAIS1 and JEAN-PAUL LATGÉ1

  INTRODUCTION

  Aspergillus fumigatus is the most important airborne fungal pathogen in the world. The conidia are inhaled by the entire population and cause a wide range of diseases from simple rhinitis to fatal invasive aspergillosis (IA) in immunocompromised patients (1 ). The number of A. fumigatus chronic infections is constantly increasing in immunocompetent patients suffering from respiratory problems such as chronic obstructive pulmonary disease (22%), asthma (1 to 5%), and cystic fibrosis (5 to 10%), along with 15% allergic bronchopulmonary aspergillosis. Aspergillus is also the cause of lung and sinus aspergilloma and serious fungal keratitis infections (2 , 3 ).

  Until a few years ago, most studies undertaken to understand Aspergillus physiology and virulence were performed with the fungus growing in shaken liquid flasks or fermentors. Such an experimental set-up was the most appropriate to obtain an important biomass to undertake biochemical studies and to purify secreted molecules or antigens from the culture filtrates or mycelial extracts. In contrast, in all Aspergillus infections, as well as in nature on a solid substratum, A. fumigatus grows as a colony characterized by multicellular and multilayered hyphae which are embedded in an extracellular matrix (ECM) (4 , 5 ). This type of growth is consistent in general with the definition of a biofilm: a structural microbial community of cells enclosed in an ECM. However, A. fumigatus biofilms are very different from yeast biofilms (6 ). In this regard, biofilms formed by filamentous fungi contain septate hyphae that are structurally attached to form microbial colonies. Thus, a better understanding of the infectious process should be based on the study of the biofilm colonies rather than on cells grown in planktonic form in shaken flasks. This article will summarize our present knowledge of biofilms formed by A. fumigatus and the role of ECM components during biofilm growth in vivo and in vitro . In addition, we will discuss the molecular resistance of A. fumigatus

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  Fungal Disease in Britain and the United States 1850–2000

  • Michael Worboys, Aya Homei(Authors)
  • 2013(Publication Date)
  • Springer Open

    (Publisher)

  fumigatus Aspergillosis: A Disease of Modern Technology 125 the most pathogenic species. Rothwell’s thesis had similar conclusions, concentrating on the differences between A. fumigatus and the more benign A. niger . Humphry Rolleston, a leading London physician who specialised in pulmonary tuberculosis, published an account of pulmonary aspergillo-sis in 1898. 50 He stated that it was almost exclusively a trade disease amongst millers, agricultural labourers, and others who worked with contaminated grains and with processes that created dust. He was clear that both A. fumigatus and A. niger could also infect the ear and skin, and wondered how many people diagnosed as suffering from pulmonary tuberculosis might really have aspergillosis, or have the fun-gus and bacillus acting synergistically. 51 The symptoms of pulmonary aspergillosis – a cough, purulent expectoration, coughing blood, bron-chitis, consolidation at the top of the lung and raised temperature – were similar to those of pulmonary tuberculosis, which left the microscopic examination of sputum as the only means for differential diagnosis. As a primary infection, the prognosis with aspergillosis was ‘less grave’ than for pulmonary tuberculosis, but as a secondary complication it was said to be very serious and ‘in fact a terminal complication’. 52 In the inter-war period aspergillosis disappeared from the medical gaze; and when it was discussed it was to admit ignorance, especially of its relation to pulmonary tuberculosis. 53 Instead, the period witnessed great interest in the use of the Aspergilli in human food production, building on knowledge from Japan. The Aspergilli became a prime inter-est of industrial chemists, they were termed ‘cell factories’, because of their role in the production of citric, gluconic, itaconic and kojic acids, in what would now be termed biotechnology.

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  Pathogenic Fungi in Humans and Animals

  • D.H. Howard(Author)
  • 2002(Publication Date)
  • CRC Press

    (Publisher)

  Anamorphic Species in A. Subgenus Fumigati Section Fumigati Gams et al. (Formerly Aspergillus fumigatus Group). Aspergillus {aff. Neosartorya} fumigatus Fres. (Synonym: Aspergillus phialoseptus Kwon-Chung). A. fumigatus is the best known and most commonly seen of the filamentous fungal opportunistic pathogens in most parts of the world (11, 68, 69). It causes opportunistic disease in the severely immunocompromised patient, usually beginning from a primary infection in the lungs but also occasionally in other sites, such as the nasal sinuses. Systemic and deep tissue Figure 36 Neosartorya pseudofischeri CBS 109512, ascospores. ASCOMYCETES 303 infections, often limited to a single site such as a lung lobe, may be caused in people who are apparently immunocompetent or only weakly immunocompromised. AIDS patients, although relatively rarely affected unless secondarily neutropenic due to cancer or immunosuppressive therapy (e.g., ganciclovir), may develop unusual aspergillosis presentations, such as primary cutaneous lesions (179). A. fumigatus also causes various chronic colonizing infections of people with certain predispositions. For example, it is the major agent of chronic bronchopulmonary aspergillosis, a disease featuring an exacerbated allergic response to aspergilli growing on upper respiratory surfaces, mostly in long-term asthmatic and cystic fibrosis patients (150). Other colonizing infections include pulmonary aspergilloma (fungus ball) in the lungs of persons with pre-existing cavitation, chronic mycotic sinusitis, and otomycosis (outer ear canal surface infestation) (11). The species also causes the full spectrum of opportunistic mycoses of specially vulnerable body sites (e.g., ocular infections subsequent to traumatic introduction, otomycosis, onychomycosis, dialysis- related peritonitis, and endocarditis).

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  Pollen and Spores

  Applications with Special Emphasis on Aerobiology and Allergy

  • S N Agashe(Author)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  CHAPTER

  16

  Significance of Fungi as Aeroallergens

  HISTORICAL ACCOUNT: HISTORY OF ALLERGIC DISEASES CAUSED BY FUNGAL AEROALLERGENS

  The possibility of fungal allergy was first mentioned by Cadham (1924) and Van Leeuwen (1924). However, the first systematic studies of fungal allergy were those of Feinberg (1935). The first systematic aerobiological work including airborne fungi in India was carried out by Cunningham (1873) in Calcutta. Agnihotri (1980) studied the fungi in the bedroom of bronchial asthma patients and found Aspergillus niger, Aspergillus flavus, Aspergillus versicolor, Aspergillus fumigatus and Helminthosporium sp. as dominant fungi. The percentage of fungal spores in the air is approximately 10 times higher than that of pollen grains, however by volume the pollen dominate.

  Ravindran (1991) investigated the aeromycoflora of Kerala and reported the dominance of Aspergillus, Penicillium, Cladosporium and Alternaria. Agashe et al. (1983) studied the aeromycoflora of Bangalore and found Cladosporium sp. and Alternaria sp. to be predominant. Agashe and Anuradha (1996) isolated the dominant fungal types Cladosporium, Penicillium, Aspergillus, Trichoderma and Fusarium from the hospital ward exposures of Petri dishes.

  Hyde (1972) had suggested that a fungal spore to be qualified as a potential aeroallergen has to satisfy following features:

  1.  The spore must be produced in large quantities. 2.  The spore must be sufficiently buoyant to become airborne. 3.  The spore-producing species must be widely and abundantly distributed. 4.  The spore should contain an excitant of hay fever or asthma. 5.  Symptoms must occur when the spores are numerous in the air.

  Regional spore calendars are based on seasonal variation and circadian periodicity. This has proved significantly useful for the clinicians in proper treatment of innumerable ailing patients of allergy. There is an absolute need of trained aerobiologists and clinicians working in close cooperation and also need of an extensive network of allergy clinics in the Indian subcontinent.

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