The role of initial spore adhesion in pellet and biofilm formation in Aspergillus niger

Priegnitz, Bert-Ewald; Wargenau, Andreas; Brandt, Ulrike; Rohde, Manfred; Dietrich, Sylvia; Kwade, Arno; Krull, Rainer; Fleißner, André

doi:10.1016/j.fgb.2011.12.002

Cited by 59 publications

(39 citation statements)

References 53 publications

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“…This was obviously also true for zeta potentials obtained at pH 5 for instance. Since electrophoretic measurements of an albino mutant with similar background resulted in negative zeta potentials at this pH [4], it is most likely that the effective surface charge density at the boundary to the outer wall layer is actually negative. At pH 2.5, where albino spores exhibited a positive zeta potential, however, the electrophoretic mobility of the melanized spores first decreased but then increased again when the NaCl concentration was further reduced from 0.05 to 0.01 mol L −1 .…”

Section: Discussionmentioning

confidence: 97%

“…It was found that the zeta potential of the spores at pH 2 was shifted from a negative to positive values when the amount of melanin pigments was reduced by the preceding pigment extraction at higher pH values. From the results of an electrokinetic investigation of a melanin-deficient mutant [4] and chemical analysis of the extracted material, it was concluded that the surface potential of A. niger spores at low pH values is mainly determined by a net positively charged outer spore wall and a surface coating containing only acidic groups.…”

Section: Discussionmentioning

confidence: 99%

“…Forces originating from the electric surface charge of fungal spores are generally suspected to play a key role in both spore-surface [1][2][3][4] and spore-spore [4][5][6] attraction. Characterization of these forces is, hence, of great interest, especially in consideration of biofilm formation [7] and spore aggregation during submerged cultivation [8].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Linking aggregation of Aspergillus niger spores to surface electrostatics: a theoretical approach

Wargenau¹,

Kampen²,

Kwade³

2013

Biointerphases

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The effect of medium pH on conidial aggregation during submerged cultivation of Aspergillus niger is considered to originate from the electrostatic surface properties of the spores. As previously shown, these properties are greatly influenced by the presence of a melanin-containing surface coating covering the outer spore wall layer. The present study was designed to elucidate the impact of such a coating on the spores' surface potential and their electrostatic repulsion under acidic conditions. A Poisson-Boltzmann model was proposed and potential profiles across the surface coating of noninteracting and interacting spores were calculated. The surface potentials thus obtained were in line with the observed pH dependence of the zeta potential. This dependence was consistent with the outcome of aggregation experiments. Apparently contradictory results regarding the zeta potential and the aggregation behavior of the spores were obtained when the ionic strength was varied. However, both of these observations could be explained by the model.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Linking aggregation of Aspergillus niger spores to surface electrostatics: a theoretical approach

Wargenau¹,

Kampen²,

Kwade³

2013

Biointerphases

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“…Quorum sensing might be an important factor in dispersal of bio-film cells (Blankenship & Mitchell 2006). The adhesion process of ff (spore adhesion) as for bacteria has been described as a two-step process, comprising the initial attachment of ungerminated conidia followed by further adhesion of the developing germtubes and growing hyphae (Priegnitz et al 2012). Spores, hyphal fragments and other fungal propagules can be functionally equiva-lent to planktonic bacterial cells even if ff do not generally exist as single cells (Harding et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Kinetics of biofilm formation by drinking water isolated Penicillium expansum

Simões

Lima

2015

Biofouling

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Current knowledge on drinking water (DW) biofilms has been obtained mainly from studies on bacterial biofilms. Very few reports on filamentous fungi (ff) biofilms are available, although they can contribute to the reduction in DW quality. This study aimed to assess the dynamics of biofilm formation by Penicillium expansum using microtiter plates under static conditions, mimicking water flow behaviour in stagnant regions of drinking water distribution systems. Biofilms were analysed in terms of biomass (crystal violet staining), metabolic activity (resazurin, fluorescein diacetate and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide [MTT]) and morphology (epifluorescence [calcofluor white M2R, FUN-1, FDA and acridine orange] and bright-field microscopies). Biofilm development over time showed the typical sigmoidal curve with noticeable different phases in biofilm formation (induction, exponential, stationary, and sloughing off). The methods used to assess metabolic activity provided similar results. The microscope analysis allowed identification of the involvement of conidia in initial adhesion (4 h), germlings (8 h), initial monolayers (12 h), a mono-layer of intertwined hyphae (24 h), mycelial development, hyphal layering and bundling, and development of the mature biofilms (≥48 h). P. expansum grows as a complex, multicellular biofilm in 48 h. The metabolic activity and biomass of the fungal biofilms were shown to increase over time and a correlation between metabolism, biofilm mass and hyphal development was found.

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“…Unfortunately, with the exception of pellet sizes, no further morphological characterisation was conducted; thus, it remains unclear whether the subpopulations of larger and smaller pellets might have been different in their morphological form as well. Additionally, the condition of conidia used as starter cultures contributes to the heterogeneity in a submerged cultivation, with some evidence that melanin content influences the size of later formed pellets [86,87]. Further studies showed heterogeneity within the mycelium.…”

Section: Interdependence Between Morphology and Productivitymentioning

confidence: 99%

The Taming of the Shrew - Controlling the Morphology of Filamentous Eukaryotic and Prokaryotic Microorganisms

Walisko

Moench-Tegeder

Blotenberg

et al. 2015

Advances in Biochemical Engineering/Biotechnology

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One of the most sensitive process characteristics in the cultivation of filamentous biological systems is their complex morphology. In submerged cultures, the observed macroscopic morphology of filamentous microorganisms varies from freely dispersed mycelium to dense spherical pellets consisting of a more or less dense, branched and partially intertwined network of hyphae. Recently, the freely dispersed mycelium form has been in high demand for submerged cultivation because this morphology enhances the growth and production of several valuable products. A distinct filamentous morphology and productivity are influenced by the environment and can be controlled by inoculum concentration, spore viability, pH value, cultivation temperature, dissolved oxygen concentration, medium composition, mechanical stress or process mode as well as through the addition of inorganic salts or microparticles, which provides the opportunity to tailor a filamentous morphology. The suitable morphology for a given bioprocess varies depending on the desired product. Therefore, the advantages and disadvantages of each morphological type should be carefully evaluated for every biological system. Because of the high industrial relevance of filamentous microorganisms, research in previous years has aimed at the development of tools and techniques to characterise their growth and obtain quantitative estimates of their morphological properties. The focus of this review is on current advances in the characterisation and control of filamentous morphology with a separation of eukaryotic and prokaryotic systems. Furthermore, recent strategies to tailor the morphology through classical biochemical process parameters, morphology and genetic engineering to optimise the productivity of these filamentous systems are discussed.

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The role of initial spore adhesion in pellet and biofilm formation in Aspergillus niger

Cited by 59 publications

References 53 publications

Linking aggregation of Aspergillus niger spores to surface electrostatics: a theoretical approach

Linking aggregation of Aspergillus niger spores to surface electrostatics: a theoretical approach

Kinetics of biofilm formation by drinking water isolated Penicillium expansum

The Taming of the Shrew - Controlling the Morphology of Filamentous Eukaryotic and Prokaryotic Microorganisms

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