Fundamentals of Microbiology

4.3.6.2 Microbial associated assimilation or immobilization

Many compounds serve as sulphur sources for microbial assimilation. Sulphur is present in inorganic and organic sources. Whatever its sources, sulphur in its elemental form cannot be utilized by plants and animals. Sulphur in soluble form, mostly as SO₄, is absorbed through plant roots. In the plants SO₄ is incorporated into amino acids and then to proteins. Plants utilize sulphur in the form of sulphates and then reduce it within the cells to H₂S before it is utilized mainly in the synthesis of sulphur amino acids and vitamins.