nonsulfur

Nonsulfur is an adjective used in chemistry, biology, and nutrition to indicate the absence of sulfur in a substance or organism. In chemistry, nonsulfur compounds are those that do not contain sulfur atoms in their molecular formula. This includes most hydrocarbons, many oxygen- and nitrogen-containing organic compounds, and most inorganic substances. The lack of sulfur differentiates these compounds from sulfur-containing groups such as thiols, sulfides, sulfates, and sulfonates, and it can influence properties such as odor, reactivity, and redox behavior. The term is often used for clarity in comparisons or when cataloging materials.

In microbiology, nonsulfur bacteria has been used historically to describe bacteria that do not utilize sulfur compounds for energy or growth, in contrast with sulfur bacteria that oxidize reduced sulfur compounds. The usage is less common in modern literature, where more precise metabolic descriptors are preferred, but the term may appear in older textbooks and in some teaching contexts.

In nutrition and biochemistry, the phrase non-sulfur amino acids refers to the standard amino acids that do not contain sulfur atoms, contrasting with the sulfur-containing amino acids cysteine and methionine. This distinction is relevant for studies of protein composition, dietary requirements, and metabolism.