Bacterial Isolation & Microscopy

Isolates recovered from the feed samples were cultured on a panel of selective and differential media, including nutrient, blood, MacConkey and Salmonella–Shigella agar, to separate and presumptively distinguish the organisms present. Colonies were then characterised by Gram-stain microscopy and a standard battery of biochemical tests to reach genus- or species-level identification. This combination of culture, microscopy and biochemistry is the classical, internationally taught workflow for identifying bacteria from a mixed environmental sample. The step demanded meticulous aseptic technique and careful interpretation of colony and cellular morphology, skills Jessica later carried into mammalian cell culture and immunofluorescence microscopy.