Basic Bacterial Morphology Bacteria and fungus (mold and yeast) grow in a variety of shapes, sizes and colors. Although it is difficult to make a definite identification of cultures growing in broth or solid media many have distinguishing characteristics that give us clues to identification. Many Microbiologist can make a tentative identifications by growth characteristics but definitive id requires further testing (ie Gram stain, chemical testing, etc). The palm of a hand print print done on TSA agar. There is a mix of different textured and colored colonies on the plate some bacterial some yeast. By looking at color, texture, growth times and various growth temperatures you can get an idea as to what is on the plate. Ex: the orange colonies are yeast and tend to grow better at room temperature or refrigerated temperatures where the large colony on the left ( Bacillus spp) and the white colonies ( Staphylococcus ) grows wel...