Yeast-yeast interactions in guava and tomato fruits

The host specificity of yeast-yeast interactions was investigated for two y east types, represented by six pairs of Pichia membranifaciens clade yeasts (Pichia membranifaciens or Issatchenkia occidentalis) with apiculate yeast s (Kloeckera apis, Kloeckera africana, or Saccharomycodes ludwigii), common ly found in fruits. Competitive interactions between the two types were det ected in both ripe tomato and guava. fruit pulp. The differences in growth rates and carrying capacities depended on fruit type (host) and culture con ditions (monocultures versus bicultures). These differences were probably d ue to nutrient composition of each fruit. Pichia membranifaciens did not sh ow host dependent responses, but the apiculate yeasts and Issatchenkia occi dentalis did. Depending on yeast strain and culture conditions (i.e., monoc ulture or biculture), carbon, nitrogen, and vitamins were investigated as p otential limiting growth factors in guava fruit. Both singular and multiple limiting nutrients were implicated.