Xanthomonas

Part of speech: noun

Definitions

1. A genus of gram-negative rod-shaped bacteria found in soil and water that causes wilts, spots, and blights in many plant species
2. A group of pathogenic bacteria characterized by yellow pigmentation and rod shape, responsible for serious diseases affecting crops and ornamental plants
3. Rod-shaped bacterial organisms belonging to a genus known for infecting plants and producing yellow-pigmented colonies on culture media

Etymology: Xanthomonas is a modern scientific coinage built from two Greek words. "Xanthos" meant yellow or golden-yellow, and "monas" meant a unit or single entity, a term later adopted in biology for single-celled organisms. Together they describe a single-celled organism that appears yellow. The colour comes from yellow pigments called xanthomonadins, which many members of the genus produce. On culture plates, their colonies look bright yellow, a feature that helps microbiologists recognise them. Many species are plant pathogens that cause blights and leaf spots in crops. Ancient Greek writers had no concept of bacteria, so the name was assembled by scientists from classical roots to label a newly identified group. The components are used literally, so the name refers to the yellow colour of the colonies.