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Seekles SJ, van den Brule T, Punt M, Dijksterhuis J, Arentshorst M, Ijadpanahsaravi M, Roseboom W, Meuken G, Ongenae V, Zwerus J, Ohm RA, Kramer G, Wösten HAB, de Winde JH, Ram AFJ. Compatible solutes determine the heat resistance of conidia. Fungal Biol Biotechnol 2023; 10:21. [PMID: 37957766 PMCID: PMC10644514 DOI: 10.1186/s40694-023-00168-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 10/25/2023] [Indexed: 11/15/2023] Open
Abstract
BACKGROUND Asexually developed fungal spores (conidia) are key for the massive proliferation and dispersal of filamentous fungi. Germination of conidia and subsequent formation of a mycelium network give rise to many societal problems related to human and animal fungal diseases, post-harvest food spoilage, loss of harvest caused by plant-pathogenic fungi and moulding of buildings. Conidia are highly stress resistant compared to the vegetative mycelium and therefore even more difficult to tackle. RESULTS In this study, complementary approaches are used to show that accumulation of mannitol and trehalose as the main compatible solutes during spore maturation is a key factor for heat resistance of conidia. Compatible solute concentrations increase during conidia maturation, correlating with increased heat resistance of mature conidia. This maturation only occurs when conidia are attached to the conidiophore. Moreover, conidia of a mutant Aspergillus niger strain, constructed by deleting genes involved in mannitol and trehalose synthesis and consequently containing low concentrations of these compatible solutes, exhibit a sixteen orders of magnitude more sensitive heat shock phenotype compared to wild-type conidia. Cultivation at elevated temperature results in adaptation of conidia with increased heat resistance. Transcriptomic and proteomic analyses revealed two putative heat shock proteins to be upregulated under these conditions. However, conidia of knock-out strains lacking these putative heat shock proteins did not show a reduced heat resistance. CONCLUSIONS Heat stress resistance of fungal conidia is mainly determined by the compatible solute composition established during conidia maturation. To prevent heat resistant fungal spore contaminants, food processing protocols should consider environmental conditions stimulating compatible solute accumulation and potentially use compatible solute biosynthesis as a novel food preservation target.
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Affiliation(s)
- Sjoerd J Seekles
- TiFN, P.O. Box 557, 6700 AN, Wageningen, the Netherlands
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, the Netherlands
| | - Tom van den Brule
- TiFN, P.O. Box 557, 6700 AN, Wageningen, the Netherlands
- Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584 CT, Utrecht, the Netherlands
| | - Maarten Punt
- TiFN, P.O. Box 557, 6700 AN, Wageningen, the Netherlands
- Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands
| | - Jan Dijksterhuis
- TiFN, P.O. Box 557, 6700 AN, Wageningen, the Netherlands
- Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584 CT, Utrecht, the Netherlands
| | - Mark Arentshorst
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, the Netherlands
| | - Maryam Ijadpanahsaravi
- Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands
| | - Winfried Roseboom
- Mass Spectrometry of Biomolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1090 GE, Amsterdam, the Netherlands
| | - Gwendolin Meuken
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, the Netherlands
| | - Véronique Ongenae
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, the Netherlands
| | - Jordy Zwerus
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, the Netherlands
| | - Robin A Ohm
- TiFN, P.O. Box 557, 6700 AN, Wageningen, the Netherlands
- Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands
| | - Gertjan Kramer
- Mass Spectrometry of Biomolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1090 GE, Amsterdam, the Netherlands
| | - Han A B Wösten
- TiFN, P.O. Box 557, 6700 AN, Wageningen, the Netherlands
- Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands
| | - Johannes H de Winde
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, the Netherlands
| | - Arthur F J Ram
- TiFN, P.O. Box 557, 6700 AN, Wageningen, the Netherlands.
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE, Leiden, the Netherlands.
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Wang D, He M, Zhang M, Yang H, Huang J, Zhou R, Jin Y, Wu C. Food yeasts: occurrence, functions, and stress tolerance in the brewing of fermented foods. Crit Rev Food Sci Nutr 2023; 63:12136-12149. [PMID: 35875880 DOI: 10.1080/10408398.2022.2098688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
With the rapid development of systems biology technology, there is a deeper understanding of the molecular biological mechanisms and physiological characteristics of microorganisms. Yeasts are widely used in the food industry with their excellent fermentation performances. While due to the complex environments of food production, yeasts have to suffer from various stress factors. Thus, elucidating the stress mechanisms of food yeasts and proposing potential strategies to improve tolerance have been widely concerned. This review summarized the recent signs of progress in the variety, functions, and stress tolerance of food yeasts. Firstly, the main food yeasts occurred in fermented foods, and the taxonomy levels are demonstrated. Then, the main functions of yeasts including aroma enhancer, safety performance enhancer, and fermentation period reducer are discussed. Finally, the stress response mechanisms of yeasts and the strategies to improve the stress tolerance of cells are reviewed. Based on sorting out these related recent researches systematically, we hope that this review can provide help and approaches to further exert the functions of food yeasts and improve food production efficiency.
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Affiliation(s)
- Dingkang Wang
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
| | - Muwen He
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
| | - Min Zhang
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
| | - Huan Yang
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
| | - Jun Huang
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
| | - Rongqing Zhou
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
| | - Yao Jin
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
| | - Chongde Wu
- College of Biomass Science and Engineering, Sichuan University, Chengdu, China
- Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, China
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Seekles SJ. The breaking of fungal spore dormancy: A coordinated transition. PLoS Biol 2023; 21:e3002077. [PMID: 37083593 PMCID: PMC10121016 DOI: 10.1371/journal.pbio.3002077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
The transition from dormant spore to germling has been topic of study and debate. A recent discovery in PLOS Biology shows that chaperone Hsp42 plays a crucial role in resolubilizing the proteome during dormancy breaking, although a role of trehalose cannot be excluded.
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Affiliation(s)
- Sjoerd Johan Seekles
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
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Response and regulatory mechanisms of heat resistance in pathogenic fungi. Appl Microbiol Biotechnol 2022; 106:5415-5431. [PMID: 35941254 PMCID: PMC9360699 DOI: 10.1007/s00253-022-12119-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 12/03/2022]
Abstract
Abstract Both the increasing environmental temperature in nature and the defensive body temperature response to pathogenic fungi during mammalian infection cause heat stress during the fungal existence, reproduction, and pathogenic infection. To adapt and respond to the changing environment, fungi initiate a series of actions through a perfect thermal response system, conservative signaling pathways, corresponding transcriptional regulatory system, corresponding physiological and biochemical processes, and phenotypic changes. However, until now, accurate response and regulatory mechanisms have remained a challenge. Additionally, at present, the latest research progress on the heat resistance mechanism of pathogenic fungi has not been summarized. In this review, recent research investigating temperature sensing, transcriptional regulation, and physiological, biochemical, and morphological responses of fungi in response to heat stress is discussed. Moreover, the specificity thermal adaptation mechanism of pathogenic fungi in vivo is highlighted. These data will provide valuable knowledge to further understand the fungal heat adaptation and response mechanism, especially in pathogenic heat-resistant fungi. Key points • Mechanisms of fungal perception of heat pressure are reviewed. • The regulatory mechanism of fungal resistance to heat stress is discussed. • The thermal adaptation mechanism of pathogenic fungi in the human body is highlighted.
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Punt M, Seekles SJ, van Dam JL, de Adelhart Toorop C, Martina RR, Houbraken J, Ram AFJ, Wösten HAB, Ohm RA. High sorbic acid resistance of Penicillium roqueforti is mediated by the SORBUS gene cluster. PLoS Genet 2022; 18:e1010086. [PMID: 35704633 PMCID: PMC9200314 DOI: 10.1371/journal.pgen.1010086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/11/2022] [Indexed: 12/04/2022] Open
Abstract
Penicillium roqueforti is a major food-spoilage fungus known for its high resistance to the food preservative sorbic acid. Here, we demonstrate that the minimum inhibitory concentration of undissociated sorbic acid (MICu) ranges between 4.2 and 21.2 mM when 34 P. roqueforti strains were grown on malt extract broth. A genome-wide association study revealed that the six most resistant strains contained the 180 kbp gene cluster SORBUS, which was absent in the other 28 strains. In addition, a SNP analysis revealed five genes outside the SORBUS cluster that may be linked to sorbic acid resistance. A partial SORBUS knock-out (>100 of 180 kbp) in a resistant strain reduced sorbic acid resistance to similar levels as observed in the sensitive strains. Whole genome transcriptome analysis revealed a small set of genes present in both resistant and sensitive P. roqueforti strains that were differentially expressed in the presence of the weak acid. These genes could explain why P. roqueforti is more resistant to sorbic acid when compared to other fungi, even in the absence of the SORBUS cluster. Together, the MICu of 21.2 mM makes P. roqueforti among the most sorbic acid-resistant fungi, if not the most resistant fungus, which is mediated by the SORBUS gene cluster. Chemical preservatives, such as sorbic acid, are often used in food to prevent spoilage by fungi, yet some fungi are particularly well-suited to deal with these preservatives. First, we investigated the resistance of 34 Penicillium roqueforti strains to various food preservatives. This revealed that some strains were highly resistant to sorbic acid, while others are more sensitive. Next, we used DNA sequencing to compare the genetic variation between these strains and discovered a specific genetic region (SORBUS) that is unique to the resistant strains. Through comparative analysis with other fungal species the SORBUS region was studied in more detail and with the use of genetic engineering tools we removed this unique region. Finally, the mutant lacking the SORBUS region was confirmed to have lost its sorbic acid resistance. This finding is of particular interest as it suggests that only some, not all, P. roqueforti strains are potent spoilers and that specific genetic markers could help in the identification of resistant strains.
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Affiliation(s)
- Maarten Punt
- TiFN, Wageningen, The Netherlands
- Microbiology, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Sjoerd J. Seekles
- TiFN, Wageningen, The Netherlands
- Department Molecular Microbiology and Biotechnology, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Jisca L. van Dam
- Department Molecular Microbiology and Biotechnology, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | | | - Raithel R. Martina
- Microbiology, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Jos Houbraken
- TiFN, Wageningen, The Netherlands
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | - Arthur F. J. Ram
- TiFN, Wageningen, The Netherlands
- Department Molecular Microbiology and Biotechnology, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Han A. B. Wösten
- TiFN, Wageningen, The Netherlands
- Microbiology, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Robin A. Ohm
- TiFN, Wageningen, The Netherlands
- Microbiology, Department of Biology, Utrecht University, Utrecht, The Netherlands
- * E-mail:
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van den Brule T, Punt M, Seekles SJ, Segers FJ, Houbraken J, Hazeleger WC, Ram AF, Wösten HA, Zwietering MH, Dijksterhuis J, den Besten HM. Intraspecific variability in heat resistance of fungal conidia. Food Res Int 2022; 156:111302. [DOI: 10.1016/j.foodres.2022.111302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/21/2022] [Accepted: 04/23/2022] [Indexed: 11/29/2022]
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Lang X, Xu A, Wang Y, Song Z. Seasonal variation of aerosol fungal community structure in reed constructed wetlands. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:19420-19431. [PMID: 34718950 DOI: 10.1007/s11356-021-17138-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/17/2021] [Indexed: 06/13/2023]
Abstract
In recent years, the impact of biological aerosols produced by sewage treatment plants on air quality and human health has become a hot spot of concern. Airborne fungi were characterized via KC-1000 large-flow air sampler and Anderson-type six-stage sampler, at free surface flowing reed constructed wetland located in Qingdao City, Shandong Province. The high-throughput sequencing technology and fungal culture-dependent method were selected to analyze the composition and dynamic changes of the fungal community attached to the atmospheric particulate matter in the free surface flow constructed wetland. The results showed that the aerosol concentration of fungi in the constructed wetlands varied from 587 to approximately 3382 CFU m-3, with a peak at the range of 1.10 to 2.10 μm particle size, and the particles (< 4.70 μm) that easily entered the lungs accounted for 57.03 ~ 96.03%. Significant seasonal differences in fungal richness and community diversity were found. The particle size distribution of fungi in atmospheric particles was not obvious. Fungal genera in the atmospheric particulate matter were mainly driven by humidity. However, other factors, i.e., temperature, NO2, SO2, and PM10 contents, also contributed.
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Affiliation(s)
- Xiulu Lang
- School of Geography, Nanjing Normal University, Nanjing, 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing, 210023, China
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China
| | - Ailing Xu
- School of Environment and Municipal Engineering, Qingdao University of Technology, Qingdao, 266033, China
| | - Yanhua Wang
- School of Geography, Nanjing Normal University, Nanjing, 210023, China.
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing, 210023, China.
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China.
| | - Zhiwen Song
- School of Environment and Municipal Engineering, Qingdao University of Technology, Qingdao, 266033, China.
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Fungal morphology: a challenge in bioprocess engineering industries for product development. Curr Opin Chem Eng 2022. [DOI: 10.1016/j.coche.2021.100729] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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The Protective Role of 1,8-Dihydroxynaphthalene-Melanin on Conidia of the Opportunistic Human Pathogen Aspergillus fumigatus Revisited: No Role in Protection against Hydrogen Peroxide and Superoxides. mSphere 2022; 7:e0087421. [PMID: 34986316 PMCID: PMC8730813 DOI: 10.1128/msphere.00874-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Previously, 1,8-dihydroxynaphthalene (DHN)-melanin was described to protect Aspergillus fumigatus against hydrogen peroxide (H2O2), thereby protecting this opportunistic human pathogen from reactive oxygen species generated by the immune system. This was based on the finding that the ATCC 46645 mutant with mutations in the pksP gene of the DHN-melanin synthesis pathway showed increased sensitivity to reactive oxygen species compared to the wild type. Here, it is shown that deletion of the pksP gene in A. fumigatus strain CEA10 did not affect sensitivity for H2O2 and superoxide in a plate stress assay. In addition, direct exposure of the dormant white conidia of the pksP deletion strains to H2O2 did not result in increased sensitivity. Moreover, complementation of the ATCC 46645 pksP mutant strain with the wild-type pksP gene did result in pigmented conidia but did not rescue the H2O2-sensitive phenotype observed in the plate stress assay. Genome sequencing of the ATCC 46645 pksP mutant strain and its complemented strain revealed a mutation in the cat1 gene, likely due to the UV mutagenesis procedure used previously, which could explain the increased sensitivity toward H2O2. In summary, DHN-melanin is not involved in protection against H2O2 or superoxide and, thus, has no role in survival of conidia when attacked by these reactive oxygen species. IMPORTANCE Opportunistic pathogens like Aspergillus fumigatus have strategies to protect themselves against reactive oxygen species like hydrogen peroxides and superoxides that are produced by immune cells. DHN-melanin is the green pigment on conidia of Aspergillus fumigatus and more than 2 decades ago was reported to protect conidia against hydrogen peroxide. Here, we correct this misinterpretation by showing that DHN-melanin actually is not involved in protection of conidia against hydrogen peroxide. We show that UV mutagenesis that was previously used to select a pksP mutant generated many more genome-wide mutations. We discovered that a mutation in the mycelial catalase gene cat1 could explain the observed phenotype of increased hydrogen peroxide sensitivity. Our work shows that UV mutagenesis is not the preferred methodology to be used for generating mutants. It requires genome sequencing with single-nucleotide polymorphism analysis as well as additional validations to discard unwanted and confirm correct phenotypes.
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Anastasiou R, Kazou M, Georgalaki M, Aktypis A, Zoumpopoulou G, Tsakalidou E. Omics Approaches to Assess Flavor Development in Cheese. Foods 2022; 11:188. [PMID: 35053920 PMCID: PMC8775153 DOI: 10.3390/foods11020188] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/03/2022] [Accepted: 01/09/2022] [Indexed: 12/27/2022] Open
Abstract
Cheese is characterized by a rich and complex microbiota that plays a vital role during both production and ripening, contributing significantly to the safety, quality, and sensory characteristics of the final product. In this context, it is vital to explore the microbiota composition and understand its dynamics and evolution during cheese manufacturing and ripening. Application of high-throughput DNA sequencing technologies have facilitated the more accurate identification of the cheese microbiome, detailed study of its potential functionality, and its contribution to the development of specific organoleptic properties. These technologies include amplicon sequencing, whole-metagenome shotgun sequencing, metatranscriptomics, and, most recently, metabolomics. In recent years, however, the application of multiple meta-omics approaches along with data integration analysis, which was enabled by advanced computational and bioinformatics tools, paved the way to better comprehension of the cheese ripening process, revealing significant associations between the cheese microbiota and metabolites, as well as their impact on cheese flavor and quality.
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Affiliation(s)
- Rania Anastasiou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece; (M.K.); (M.G.); (A.A.); (G.Z.); (E.T.)
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Penicillium roqueforti conidia induced by L-amino acids can germinate without detectable swelling. Antonie Van Leeuwenhoek 2021; 115:103-110. [PMID: 34800185 DOI: 10.1007/s10482-021-01686-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 11/11/2021] [Indexed: 10/19/2022]
Abstract
Penicillium roqueforti is used for the production of blue-veined cheeses but is a spoilage fungus as well. It reproduces asexually by forming conidia. Germination of these spores can start the spoilage process of food. Germination is typically characterized by the processes of activation, swelling and germ tube formation. Here, we studied nutrient requirements for germination of P. roqueforti conidia. To this end, > 300 conidia per condition were monitored in time using an oCelloScope imager and an asymmetric model was used to describe the germination process. Spores were incubated for 72 h in NaNO3, Na2HPO4/NaH2PO4, MgSO4 and KCl with 10 mM glucose or 10 mM of 1 out of the 20 proteogenic amino acids. In the case of glucose, the maximum number of spores (Pmax) that had formed germ tubes was 12.7%, while time needed to reach 0.5 Pmax (τ) was about 14 h. Arginine and alanine were the most inducing amino acids with a Pmax of germ tube formation of 21% and 13%, respectively, and a τ of up to 33.5 h. Contrary to the typical stages of germination of fungal conidia, data show that P. roqueforti conidia can start forming germ tubes without a detectable swelling stage.
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Polozsányi Z, Kaliňák M, Babjak M, Šimkovič M, Varečka Ľ. How to enter the state of dormancy? A suggestion by Trichoderma atroviride conidia. Fungal Biol 2021; 125:934-949. [PMID: 34649680 DOI: 10.1016/j.funbio.2021.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 06/12/2021] [Accepted: 07/01/2021] [Indexed: 10/20/2022]
Abstract
It is generally accepted that conidia, propagules of filamentous fungi, exist in the state of dormancy. This state is defined mostly phenomenologically, e.g., by germination requirements. Its molecular characteristics are scarce and are concentrated on the water or osmolyte content, and/or respiration. However, a question of whether conidia are metabolic or ametabolic forms of life cannot be answered on the basis of available experimental data. In other words, are mature conidia open thermodynamic systems as are mycelia, or do they become closed upon the transition to the dormant state? In this article, we present observations which may help to define the transition of freshly formed conidia to the putative dormant forms using measurements of selected enzyme activities, 1H- and 13C-NMR and LC-MS-metabolomes, and 14C-bicarbonate or 45Ca2+ inward transport. We have found that Trichoderma atroviride and Aspergillus niger conidia arrest the 45Ca2+ uptake during the development stopping thereby the cyclic (i.e., bidirectional) Ca2+ flow existing in vegetative mycelia and conidia of T. atroviride across the cytoplasmic membrane. Furthermore, we have found that the activity of α-ketoglutarate dehydrogenase was rendered completely inactive after 3 weeks from the conidia formation unlike of other central carbon metabolism enzymes. This may explain the loss of conidial respiration. Finally, we found that conidia take up the H14CO3- and convert it into few stable compounds within 80 d of maturation, with minor quantitative differences in the extent of this process. The uptake of H13CO3- confirmed these observation and demonstrated the incorporation of H13CO3- even in the absence of exogenous substrates. These results suggest that T. atroviride conidia remain metabolically active during first ten weeks of maturation. Under these circumstances, their metabolism displays features similar to those of chemoautotrophic microorganisms. However, the Ca2+ homeostasis changed from the open to the closed thermodynamic state during the early period of conidial maturation. These results may be helpful for studying the conidial ageing and/or maturation, and for defining the conidial dormant state in biochemical terms.
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Affiliation(s)
- Zoltán Polozsányi
- Institute of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37, Bratislava, Slovakia
| | - Michal Kaliňák
- Central Laboratories, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37, Bratislava, Slovakia
| | - Matej Babjak
- Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37, Bratislava, Slovakia
| | - Martin Šimkovič
- Institute of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37, Bratislava, Slovakia.
| | - Ľudovít Varečka
- Institute of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37, Bratislava, Slovakia
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Doğan M, Tekiner İH. Evaluating starter culture potential of wild Penicillium roqueforti strains from moldy cheeses of artisanal origin. FOOD BIOSCI 2021. [DOI: 10.1016/j.fbio.2021.101253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Seekles SJ, Teunisse PPP, Punt M, van den Brule T, Dijksterhuis J, Houbraken J, Wösten HAB, Ram AFJ. Preservation stress resistance of melanin deficient conidia from Paecilomyces variotii and Penicillium roqueforti mutants generated via CRISPR/Cas9 genome editing. Fungal Biol Biotechnol 2021; 8:4. [PMID: 33795004 PMCID: PMC8017634 DOI: 10.1186/s40694-021-00111-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/11/2021] [Indexed: 01/25/2023] Open
Abstract
Background The filamentous fungi Paecilomyces variotii and Penicillium roqueforti are prevalent food spoilers and are of interest as potential future cell factories. A functional CRISPR/Cas9 genome editing system would be beneficial for biotechnological advances as well as future (genetic) research in P. variotii and P. roqueforti. Results Here we describe the successful implementation of an efficient AMA1-based CRISPR/Cas9 genome editing system developed for Aspergillus niger in P. variotii and P. roqueforti in order to create melanin deficient strains. Additionally, kusA− mutant strains with a disrupted non-homologous end-joining repair mechanism were created to further optimize and facilitate efficient genome editing in these species. The effect of melanin on the resistance of conidia against the food preservation stressors heat and UV-C radiation was assessed by comparing wild-type and melanin deficient mutant conidia. Conclusions Our findings show the successful use of CRISPR/Cas9 genome editing and its high efficiency in P. variotii and P. roqueforti in both wild-type strains as well as kusA− mutant background strains. Additionally, we observed that melanin deficient conidia of three food spoiling fungi were not altered in their heat resistance. However, melanin deficient conidia had increased sensitivity towards UV-C radiation. Supplementary Information The online version contains supplementary material available at 10.1186/s40694-021-00111-w.
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Affiliation(s)
- Sjoerd J Seekles
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands.,Department Molecular Microbiology and Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333BE, Leiden, The Netherlands
| | - Pepijn P P Teunisse
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands.,Department Molecular Microbiology and Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333BE, Leiden, The Netherlands
| | - Maarten Punt
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands.,Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Tom van den Brule
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands.,Applied & Industrial Mycology, Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584 CT, Utrecht, the Netherlands
| | - Jan Dijksterhuis
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands.,Applied & Industrial Mycology, Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584 CT, Utrecht, the Netherlands
| | - Jos Houbraken
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands.,Applied & Industrial Mycology, Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584 CT, Utrecht, the Netherlands
| | - Han A B Wösten
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands.,Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Arthur F J Ram
- TIFN, Agro Business Park 82, 6708 PW, Wageningen, The Netherlands. .,Department Molecular Microbiology and Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333BE, Leiden, The Netherlands.
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15
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Conidial heat resistance of various strains of the food spoilage fungus Paecilomyces variotii correlates with mean spore size, spore shape and size distribution. Food Res Int 2020; 137:109514. [PMID: 33233149 DOI: 10.1016/j.foodres.2020.109514] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 11/18/2022]
Abstract
Contamination by spores is often the cause of fungal food spoilage. Some distinct strains of the food spoilage fungus Paecilomyces variotii are able to produce airborne conidia that are more heat-resistant than similar species. These ellipsoid asexual spores can vary in size between strains, but also within strains. Here, we compared four measurement techniques to measure conidia size and distribution of five heat-sensitive and five heat-resistant P. variotii strains. Light microscopy (LM), Scanning Electron Microscopy (SEM) and Coulter Counter (CC) were used to measure and compare the spherical equivalent diameter, while CC and flow cytometry were used to study spore size distributions. The flow cytometry data was useful to study spore size distributions, but only relative spore sizes were obtained. There was no statistic difference between the method used of spore size measurement between LM, SEM and CC, but spore size was significantly different between strains with a 2.4-fold volume difference between the extremes. Various size distribution and shape parameters were correlated with conidial heat resistance. We found significant correlations in mean spore size, aspect ratio, roundness and skewness in relation to heat resistance, which suggests that these parameters are indicative for the conidial heat resistance of a P. variotii strain.
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16
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Dijksterhuis J, van Egmond W, Yarwood A. From colony to rodlet: "A six meter long portrait of the xerophilic fungus Aspergillus restrictus decorates the hall of the Westerdijk institute.". Fungal Biol 2020; 124:509-515. [PMID: 32389314 DOI: 10.1016/j.funbio.2020.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/23/2020] [Accepted: 03/26/2020] [Indexed: 10/24/2022]
Abstract
The extreme xerophilic fungus Aspergillus restrictus is used as a model for a large artwork created out of five microscopic pictures in total measuring 80 cm by 624 cm. The artwork is printed on aluminium and located at the entrance of the Westerdijk Institute, Utrecht, The Netherlands. The first picture is made from a colony of the fungus, which has a dimension of 1 cm and the last picture shows details of ornamentation on conidia and phialides of the fungus. The first two pictures of the artwork are made using a unique method of light microscopy in which many hundreds of pictures are made at different focal depths resulting in high detail and resolution of the pictures. For three other pictures, cryo-electron scanning microscopy was used including both a conventional system for lower magnification and a field emission scanning electron microscope for high resolution micrographs. The range of magnification is, at real size, between 78 and 63,000 times. When the observer passes the artwork it acts like a virtual microscope, just by walking past it you zoom-in to the smallest possible details. This coherent increase of magnification of one fungus, with very high quality light- and electron microscopy micrographs, shows different layers of fungal organization and emergent properties. These include the occurrence of secondary outcrops of hyphae and conidiophores in a colony; the formation of a stipe on a thin aerial hyphae; the presence and formation of characteristic structures on stipes, vesicles and phialides and a continuous zone between the forming conidia and phialides.
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Affiliation(s)
- Jan Dijksterhuis
- Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584, CT, Utrecht, the Netherlands.
| | - Wim van Egmond
- Studio: Bacinol 2, Hooikade 13, 2627, AB, Delft, the Netherlands
| | - Andrew Yarwood
- JEOL (UK) Ltd, JEOL House, Silver Court Watchmead, Welwyn Garden City, Herts, AL7 1LT, UK
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