Cheese bacteria. Scanning electron micrograph (SEM) of Lactococcus sp. bacteria from gorgonzola blue cheese. This lactic acid-producing bacteria is used in the production of cheese and other fermented products. They are found in chains, in pairs, or singly, and are gram-positive, catalase-negative, non-motile cocci. Magnification: x8000 when printed at 10 centimetres wide.