Effects of Junlon and Hostacerin on the Electrokinetic Properties of Spores of Aspergillus niger, Phanerochaete chrysosporium and Geotrichum candidum

Abstract

The electrophoretic behaviour of freshly harvested spores of Aspergillus niger, Phanerochaete chrysosporium and Geotrichum candidum was determined in solution at various pH values. Freshly harvested spores of all three species lacked positive mobility at low pH values, suggesting a preponderance of acidic surface groups. Spores of the 'non-aggregating' fungus, G. candidum, had a pH-mobility curve (peak of negative mobility between pH 3 and 4) which was quite different to those of spores of the 'aggregating' fungi, A . niger and P. chrysosporium. The pH-mobility curve of swollen spores of A . niger which had been incubated in medium differed from that of freshly harvested spores, suggesting that changes in the wall that occur during germination alter the electrophoretic properties of the spores; swollen spores of A . niger, unlike freshly harvested spores, had a negative mobility maximum at pH 5.0.After treatment with Junlon-110 (a polyacrylic acid), spores of all three species had similar pH-mobility curves and all had peaks of negative mobility at pH 4.0. The electrophoretic mobility of spores of P. chrysosporium at pH 6.5 increased linearly with the concentration (0.01-0.4%, w/v) of Junlon used in the pre-treatment ; electrophoretic mobility after pre-treatment with 0.005-0.1 % (w/v) Hostacerin (sodium polyacrylate) increased only up to 0.01 % (w/v) Hostacerin. The results obtained show that Junlon-1 10 and Hostacerin bind to fungal walls, and it is possible that spore and hyphal aggregation is reduced by these compounds because of repulsion between particles resulting from ionized carboxyl groups on the polymer.

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

“…In fact, they observed the opposite aggregation behavior. This difference is particularly remarkable in view of the results by Jones et al [11], who found that incubation of A. niger spores in culture medium of pH 6.5 even caused a significant decrease of their respective electrophoretic mobilities in weakly acidic buffers. On the basis of this finding, it seems reasonable that reversible alterations in the electrostatic properties of the spores-and not biological alterations-are responsible for the apparently contradictory aggregation tendencies observed in certain media.…”

“…Some fungal spores, however, show electrokinetic behavior that indicates negative surface potentials down to pH values of 3 and smaller [11,29]. The same applies to the conidia of A. niger, which even appear to possess negative surface potentials down to a pH of 2 [10,12,20].…”

“…Unfortunately, little is known about the electrostatics of fungal spore surfaces. In the case of the biotechnological workhorse Aspergillus niger, the tendency to form conidial aggregates at the early stage of cultivation has long been recognized [9] and aggregation behavior was attributed to electrostatic surface properties [10][11][12]. However, there is presently no uniform explanation linking the pH dependence of these properties to that of the aggregation behavior during cultivation.…”

Role of the bga1 -Encoded Extracellular β-Galactosidase of Hypocrea jecorina in Cellulase Induction by Lactose

“…Vogel's salts were prepared as a 50ϫ solution and sterilized by membrane (pore size, 0.22 m) filtration. The media for shake flask cultures contained Stabileze QM (methyl vinyl ether-maleic anhydride copolymer cross-linked with 1,9-decadien; ISP Technologies, Wayne, N.J.) or Junlon (18) to promote filamentous growth; the concentrations of Stabileze QM and Junlon used were 0.75 g/liter for cultures used for growth rate and enzyme determinations and 1.5 g/liter for precultures used for bioreactors. To prepare precultures, 40-ml batch cultures were grown in 250-ml Erlenmeyer flasks or 250-ml Nephlos flasks (36).…”

On the origin of the electrostatic surface potential of Aspergillus niger spores in acidic environments

“…Even though the measurement of this quantity is straight forward, the quantitative interpretation in terms of repulsive forces acting between two biological surfaces is not necessarily an easy task. Nevertheless, the role of electrostatic repulsion in the inhibition of spore aggregation has been discussed by various authors (Dynesen and Nielsen, 2003;Gerin et al, 1993;Jones et al, 1988). In a former investigation the effect of pH and ionic strength on the adhesion force between single A. niger spores was studied by us (Wargenau and Kwade, 2010).…”