Intraspecific variability and exopolysaccharide production inAureobasidium pullulans

Abstract

Forty seven strains of the black yeasts,Aureobasidium pullulans andHormonema dematioides, and the type strain ofHormonema macrosporum were examined using PCR-ribotyping and universally primed PCR with subsequent hybridization. Four groups (populations) were distinguished withinA. pullulans with PCR-ribotyping, which largely coincided with UP-PCR/hybridization groups. The UP-PCR technique revealed a greater degree of heterogeneity between the groups studied. Five strains identified asHormonema dematioides on the basis of physiological and morphological data formed a group recognizable with PCR-ribotyping and UP-PCR/hybridization, which also includedH. macrosporum.

Aureobasidium pullulans is characterized by the absence of RsaI restriction sites in rDNA amplified with primers 5.8S-R and LR7, whileHormonema species possessed several bands after RsaI digestion. For analysis of distance between populations, PCR-ribotyping with AluI and MspI is sufficient. Strains ofA. pullulans produce exopolysaccharides in liquid media with different nitrogen sources, while the strains ofHormonema synthesize minor amounts of polysaccharides in media with peptone. Populations ofA. pullulans differ slightly from each other in their optimal, medium-dependent production of polysaccharides.