Browsing by Subject "Shrimps--Microbiology"
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Item Ecological role of bacteria in the digestive tract of Penaeid shrimp(1984) Dempsey, Amy Claire; Not availableCompositions and abundances of viable bacteria associated with juvenile penaeid shrimp (on their exterior, through their digestive tract, and among their available foods) were examined. Shrimp were collected from open bays and seagrass meadows of the Northwest Gulf of Mexico, and immediately were sampled for internal and external bacteria growing rapidly on nutrient rich media. They appeared to represent the same bacteria that appeared in cultures on shrimp hindgut extract media, and those quickly growing bacteria possibly important as symbiotic bacteria among the shrimp. Penaeus aztecus (brown shrimp) and Penaeus setiferus (white shrimp) were sampled. All individuals sampled ranged from 7 cm. to 15 cm. in length. The average abundances of viable bacteria were 7.5 x 10⁶ bacteria/gram of stomach and 2.6 x 10⁷ bacteria/gram of intestine. When hindgut linings and their contents were sampled separately, the empty gut lining yielded as many such bacteria/gram as did the contents. Total attached bacteria observed with epifluorencence accounted for about 10% of the cultured densities. The number of bacteria in the shrimp's environment ranged from 10⁴ bacteria active in high nutrients/ml of ambient water to 10⁶ such bacteria/gram of seagrass epiphytes and 10⁷ such bacteria/gram of sediment material. Based on colony morphology, a great diversity in both bacterial genera and bacterial abundance was apparent among individual shrimp. From the environment of the shrimp an average of nine common colony types were found in the seagrass epiphytes and sediment, and five common colony types in the ambient seawater. The shrimp averaged three common colony types in their stomachs and two common colony types in their hindguts. In separate samples the hindgut lining had as many colony types as its contents. Nine different genera of bacteria were identified. Vibrio, Alcaligenes, Aeromonas, Chromobacterium, and the pseudomonas-like group of bacteria (Pseudomonas, Xanthomonas, and Alteromonas) appeared to be the most abundant in the digestive tract