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Simões S, Canhoto C, Bärlocher F, Gonçalves AL. Hydrological contraction patterns and duration of drying period shape microbial-mediated litter decomposition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 785:147312. [PMID: 33957592 DOI: 10.1016/j.scitotenv.2021.147312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 04/19/2021] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
The length and number of streams experiencing intermittency is expected to increase in response to human population growth, associated water use, and climate change. In these streams, habitat contraction may occur at distinct rates giving rise to drying periods of distinct duration. To date, the impact of drought installation rate and duration have been mostly overlooked. In this microcosm study, stream conditioned oak leaf litter was subjected to either a short (5 weeks) or a long (8 weeks) drying period, originating from a very slow, slow, or abrupt contraction. The effects of these treatments were compared at the end of the drying period in terms of microbial-mediated litter mass loss, fungal biomass, respiration, and sporulation rates. A very slow contraction pattern led to 1.3 times higher mass loss than both slow or abrupt contraction. Fungal biomass, respiration and sporulation rates were up to 2.3 times lower under slow than abrupt contraction. Both drying period durations inhibited leaf decomposition, suggesting an early, critical effect of drying on microbial-mediated processing, regardless of contraction pattern. This seems to be related to an impoverishment of leaf associated fungal communities and resultant lower functional efficacy - species richness decreased by up to 75% in response to a long (vs. short) drying period, despite the maintenance of mycelial biomass. Our results show the relevance of aquatic hyphomycetes to litter decomposition in dry streambeds, particularly following slower habitat contraction patterns. Faster wet-to-dry transitions and longer drying periods strongly impaired microbial functioning, with potential impacts on global processing rates and cascading effects through changes of detritus quality. If confirmed in field tests, such impacts on stream functioning may be mitigated by preserving riparian forests, which may protect against extreme drying events by buffering temperature changes.
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Affiliation(s)
- S Simões
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal.
| | - C Canhoto
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal.
| | - F Bärlocher
- Department of Biology, Mt. Allison University, Sackville E4L1G7, New Brunswick, Canada.
| | - A L Gonçalves
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal.
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Abstract
Enzyme immobilization to solid matrices often presents a challenge due to protein conformation sensitivity, desired enzyme purity, and requirements for the particular carrier properties and immobilization technique. Surface display of enzymes at the cell walls of microorganisms presents an alternative that has been the focus of many research groups worldwide in different fields, such as biotechnology, energetics, pharmacology, medicine, and food technology. The range of systems by which a heterologous protein can be displayed at the cell surface allows the appropriate one to be found for almost every case. However, the efficiency of display systems is still quite low. The most frequently used yeast for the surface display of proteins is Saccharomyces cerevisiae. However, apart from its many advantages, Saccharomyces cerevisiae has some disadvantages, such as low robustness in industrial applications, hyperglycosylation of some heterologous proteins, and relatively low efficiency of surface display. Thus, in the recent years the display systems for alternative yeast hosts with better performances including Pichia pastoris, Hansenula polymorpha, Blastobotrys adeninivorans, Yarrowia lipolytica, Kluyveromyces marxianus, and others have been developed. Different strategies of surface display aimed to increase the amount of displayed protein, including new anchoring systems and new yeast hosts are reviewed in this paper.
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Gonçalves AL, Simões S, Bärlocher F, Canhoto C. Leaf litter microbial decomposition in salinized streams under intermittency. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 653:1204-1212. [PMID: 30759560 DOI: 10.1016/j.scitotenv.2018.11.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/03/2018] [Accepted: 11/04/2018] [Indexed: 06/09/2023]
Abstract
Human-induced salinization of freshwaters constitutes a growing global problem, whose consequences on streams functioning are largely unknown. Climate change projections predict enhanced evaporation, as well as an increase in extreme events and in variability of precipitation. This will result in more frequent, extended and severe drought periods that may aggravate water salinization of streams and rivers. In this study we conducted a microcosm experiment to assess the combined effects of three drought regimes - abrupt (AD), slow (SD) and very slow transition to dryness (VSD) - and three levels of salinization (0, 4, 6 g L-1 NaCl) on microbial-mediated oak leaf decomposition over ten weeks. Salinization did not affect mass loss and associated microbial respiration of colonized oak leaves but significantly reduced the biomass and eliminated the sporulating capacity of fungi. Desiccation negatively affected leaf decomposition regardless of regime. Even though microbial respiration did not react to the different treatments, lower fungal biomass, diversity, and conidial production were observed under AD; for fungal biomass these effects were amplified at higher salt concentrations (particularly at 6 g L-1). Our results indicate that effects of leaf litter desiccation depend on the rate of transition between wet and dry conditions and on the level of salt in the water. The two factors jointly affect decomposer survival and activity and, by extension, the dynamics of detrital food webs in streams.
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Affiliation(s)
- Ana Lúcia Gonçalves
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal.
| | - Sara Simões
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
| | - Felix Bärlocher
- Department of Biology, Mt. Allison University, Sackville, New Brunswick, Canada
| | - Cristina Canhoto
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
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Gonçalves AL, Carvalho A, Bärlocher F, Canhoto C. Are fungal strains from salinized streams adapted to salt-rich conditions? Philos Trans R Soc Lond B Biol Sci 2018; 374:rstb.2018.0018. [PMID: 30509917 DOI: 10.1098/rstb.2018.0018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2018] [Indexed: 11/12/2022] Open
Abstract
Anthropogenic salinization of freshwater is a global problem with largely unknown consequences for stream functions. We compared the effects of salt addition (6 g l-1 NaCl) in microcosms on leaf mass loss and microbial parameters in single- and multispecies assemblages of fungal strains (Heliscus lugdunensis, HELU; Tetracladium marchalianum, TEMA; Flagellospora curta, FLCU) isolated from a reference (R) or salinized (S) stream. Fungal growth and interactions were also assessed. Salinization inhibited leaf decomposition and fungal biomass, but no differences were observed between species, strains or species combinations. Sporulation rates in monocultures were not affected by added salt, but differed among species (FLCU > HELU > TEMA), with S strains releasing more conidia. Fungal assemblages did not differ significantly in total conidia production (either between strains or medium salt concentration). HELU was the dominant species, which also had highest growth and most pronounced antagonistic behaviour. Fungal species, irrespective of origin, largely maintained their function in salinized streams. Strains from salt-contaminated streams did not trade-off conidial production for vegetative growth at high salt levels. The expected reduction of fungal diversity and potential changes in nutritional litter quality owing to salinization may impact leaf incorporation into secondary production in streams.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.
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Affiliation(s)
- Ana Lúcia Gonçalves
- CFE, Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
| | - Adriana Carvalho
- CFE, Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
| | - Felix Bärlocher
- Department of Biology, Mt. Allison University, Sackville, New Brunswick, Canada E4L1G7
| | - Cristina Canhoto
- CFE, Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
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Canhoto C, Simões S, Gonçalves AL, Guilhermino L, Bärlocher F. Stream salinization and fungal-mediated leaf decomposition: A microcosm study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 599-600:1638-1645. [PMID: 28535592 DOI: 10.1016/j.scitotenv.2017.05.101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/11/2017] [Accepted: 05/11/2017] [Indexed: 06/07/2023]
Abstract
Salinization is of major global concern due to its effect on stream biota, and ecosystem functions and services. In small streams, litter decomposition is a key ecosystem-level process driven by decomposers, mainly fungi (aquatic hyphomycetes), which link litter and invertebrates. Here we assessed the effects of an environmentally relevant range of salt additions (0, 2, 4, 8, 16gL-1 NaCl) on (1) fungal growth and species-specific reproductive output and (2) fungal mediated-decomposition of Quercus robur leaves. Growth rates of eight out of nine species of aquatic hyphomycetes were negatively affected by salinity at concentrations ≥4gL-1. EC50s were species-specific and ≥7.80gL-1. Distinct thresholds were observed for reproduction: only five species sporulated at 2gL-1, and a single one (Flagellospora curta) sporulated at 4 and 8gL-1 NaCl. Based on these results, we evaluated if tolerant fungal assemblages, with increasingly fewer species (9, 5, 1), were able to maintain similar functional functions and processes at the different salt levels. No significant differences were found in oak mass loss or sporulation rates at 0 or 2gL-1 NaCl; a clear inhibition of both parameters was observed at the highest concentrations (i.e., 4 and 8gL-1 NaCl). Different dominance patterns in multi-species fungal assemblages may determine bottom-up impacts on the stream food webs through effects on detritivore feeding preferences. Specific growth rate, characterized by RNA concentration, was higher in the single species, at the highest salt-concentration, and lower in the 9-species assemblage. Respiration was almost 2-times higher in mixed assemblages without added salt. Under salt-contamination, trade-offs between growth and sporulation seem to guarantee high levels of fungal growth and decomposition, particularly in multi-species assemblages. In the presence of salt contamination, aquatic hyphomycetes, even at reduced diversity, remain important drivers of leaf decomposition and ensure organic matter recycling.
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Affiliation(s)
- Cristina Canhoto
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal.
| | - Sara Simões
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
| | - Ana Lúcia Gonçalves
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
| | - Lúcia Guilhermino
- ICBAS & CIIMAR, University of Porto, CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, Research Group of Ecotoxicology, Stress Ecology and Environmental Health, ICBAS - Institute of Biomedical Sciences of Abel Salazar, Department of Population Studies, Laboratory of Ecotoxicology, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Felix Bärlocher
- Department of Biology, Mt. Allison University, Sackville, New Brunswick E4L1G7, Canada
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Wucherpfennig T, Hestler T, Krull R. Morphology engineering--osmolality and its effect on Aspergillus niger morphology and productivity. Microb Cell Fact 2011; 10:58. [PMID: 21801352 PMCID: PMC3178489 DOI: 10.1186/1475-2859-10-58] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 07/29/2011] [Indexed: 05/26/2023] Open
Abstract
Background The filamentous fungus Aspergillus niger is a widely used strain in a broad range of industrial processes from food to pharmaceutical industry. One of the most intriguing and often uncontrollable characteristics of this filamentous organism is its complex morphology, ranging from dense spherical pellets to viscous mycelia depending on culture conditions. Optimal productivity correlates strongly with a specific morphological form, thus making high demands on process control. Results In about 50 2L stirred tank cultivations the influence of osmolality on A. niger morphology and productivity was investigated. The specific productivity of fructofuranosidase producing strain A. niger SKAn 1015 could be increased notably from 0.5 to 9 U mg-1 h-1 around eighteen fold, by increasing the culture broth osmolality by addition of sodium chloride. The specific productivity of glucoamylase producing strain A. niger AB1.13, could be elevated using the same procedure. An optimal producing osmolality was shown to exist well over the standard osmolality at about 3.2 osmol kg-1 depending on the strain. Fungal morphology of all cultivations was examined by microscope and characterized by digital image analysis. Particle shape parameters were combined to a dimensionless Morphology number, which enabled a comprehensive characterization of fungal morphology correlating closely with productivity. A novel method for determination of germination time in submerged cultivations by laser diffraction, introduced in this study, revealed a decelerated germination process with increasing osmolality. Conclusions Through the introduction of the versatile Morphology number, this study provides the means for a desirable characterization of fungal morphology and demonstrates its relation to productivity. Furthermore, osmolality as a fairly new parameter in process engineering is introduced and found to affect fungal morphology and productivity. Osmolality might provide an auspicious and reliable approach to increase the productivity in industrial processes. Because of the predictable behavior fungal morphology showed in dependence of osmolality, a customization of morphology for process needs seems feasible.
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Affiliation(s)
- Thomas Wucherpfennig
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
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Breuer U, Harms H. Debaryomyces hansenii — an extremophilic yeast with biotechnological potential. Yeast 2006; 23:415-37. [PMID: 16652409 DOI: 10.1002/yea.1374] [Citation(s) in RCA: 189] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We illuminate the ecological, physiological and genetic characteristics of the yeast Debaryomyces hansenii in the view of our belief that this metabolically versatile, non-pathogenic, osmotolerant and oleaginous microorganism represents an attractive target for fundamental and applied biotechnological research. To this end, we give a broad overview of extant biotechnological procedures using D. hansenii, e.g. in the manufacture of various foods, and propose research into the heterologous synthesis of a range of fine chemicals.
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Affiliation(s)
- Uta Breuer
- UFZ-Centre of Environmental Research Leipzig-Halle, Department of Environmental Microbiology, Permoserstrasse 15, D-04318 Leipzig, Germany.
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