Effects of Junlon and Hostacerin on the Electrokinetic Properties of Spores of Aspergillus niger

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 (0.010.4%, 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.