Two bacteria causing farmer's lung: fine structure of Thermoactinomyces vulgaris and Saccharopolyspora rectivirgula.

The fine structure of Thermoactinomyces vulgaris and Saccharopolyspora rectivirgula is described by transmission electron microscopy. These two bacteria are the most common microbes causing farmer's lung. The fine structure of hyphae, germination of endospores and the details of conidial wall layers of T. vulgaris, as well as the fine structure of septate hypha and globose, polygonal conidia of S. rectivirgula are described. The conidial wall of T. vulgaris consisted of an inner multilayered spore coat, intermediate spore coat and outer spore coat. The findings are important for the investigations to find fragments of these bacteria in the lungs of exposed patients and experimental animals.