Is there a Normal Flora in Crustaceans?


Jessica Smith

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Many animals have a normal flora in their intestines; a normal flora is a collection of bacteria that lines the epithelium of the intestine.Normal flora are often beneficial to the host in assisting with the digestion and absorption of nutrients, the production of vitamins and other essential factors. Normal flora may also help fight off infection by pathogenic microbes. My question was, 'Is there a normal flora in the midgut trunk of the shrimp Sicyonia ingentis?' The midgut trunk (MGT) is not an intestine in that it is not involved in digestion or absorption. However, it secretes a peritrophic membrane that wraps ingested food, including bacteria, and moves it out of the MGT. The membrane also persists as the wrapper of the fecal pellet. The literature on normal flora in crustaceans is contradictory; one report states that there is not a normal flora, while others say that it is present. The following three approaches were used to address my research topic: 1)Culturing ground up MGTs and plating them onto LBS agar to test for the presence of bacteria. 2) Examining sections of the MGT with and without staining by DAPI in an attempt to determine the distribution of bacteria using fluorescence microscopy.


Gary Martin




National Science Foundation-Research Experience for Undergraduates Fellowship

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