Fundamentals of Microbiology

4.3.6.1 Decomposition of sulphur compounds

Plants obtain their sulphur requirement from sulphur compounds, while animals do so by feeding on plant materials or other animals. In these systems sulphur is found mostly as a component of sulphur containing amino acids such cystine and methionine. The dead organic matter contains large molecules. The decomposers like bacteria, actinomycetes and fungi excrete digestive enzymes. These enzymes convert large molecules into small ones. Sulphur containing amino acids are converted to inorganic compounds like H₂S and NH₃. For example, the amino acid cysteine releases H₂S and NH₃ as follows: