What characteristic differentiates Chryseobacterium spp. from Acinetobacter spp. in a culture?

Chryseobacterium species are notably characterized by their production of yellow pigments, which can be a significant distinguishing feature when cultured. This pigmentation is due to the presence of carotenoid pigments that can give colonies a yellow or orange appearance on solid media. The ability to produce such pigments is a unique trait that helps microbiologists identify and differentiate these organisms from others in a laboratory setting, particularly from Acinetobacter species, which typically do not produce yellow pigments.

In contrast, the other characteristics listed do not serve as reliable differentiators between these two genera. For instance, while Acinetobacter species can be oxidase negative, so can many Chryseobacterium species, making this feature less definitive. Growth on MacConkey agar is common to both groups, as they can both grow on this selective medium, further blurring the lines of differentiation. Additionally, motility is not a distinguishing feature, as both genera consist of rod-shaped bacteria, with some species being motile and others being non-motile.

Therefore, the production of yellow pigment is a standout characteristic for Chryseobacterium spp., setting it apart from Acinetobacter spp. in culture.