61C-21 |
Recovery of hyperthermophilic microorganisms at 95°C from spray-drier exhaust vents via PCS cable |
P. S. MAK1, J. Gvozdenovic-Jeremic1, A. L. Pometto, III1, and A. A. DiSpirito2. (1) Food Science and Human Nutrition, Iowa State University, 0636 Food Sciences Building, Ames, IA 50011, (2) Microbiology, Iowa State University, 205 Science I, Ames, IA 50011 Extremophiles are microorganisms capable of growing at high temperatures, extreme pH's, high salt concentrations and high pressures. Potentially, extremophiles can be isolated from man-made extreme environments associated with food processing industries. The goal of this research is to isolate new hyperthermophilic microorganisms which produce key hyperthermostable hydrolytic enzymes to improve industrial processing of wastes or to improve current food processing. Plastic composite supports (PCS) is a novel material developed at Iowa State University for stimulating biofilm formation. For this research PCS discs containing 50% polypropylene, 40% ground soyhulls, 5% yeast extract, and 5% bovine albumin and salts were attached to a cable (3 m) suspended in a spray drier exhaust vent for one year in an effort to recover new hyperthermophilic microorganisms. Cultures were removed from the PCS using the stripping sand method developed by Ho et. al.(1997) and they were used to inoculate repeated batch reactors containing filter paper, PCS, and minimal medium with (NH4)2SO4, or LB broth. Each repeated batch reactor was incubated at 90-95oC with continuous aeration with filter sterilized air, and culture medium exchanged every one or two weeks for six months. Results indicated that cultures from supports closest to the heating source showed greater activity in terms of CO2 production (23.8 and 19.8 mg CO2/week) than cultures farthest away (24.8 and 14.6 mg CO2/week). Biomass in spent culture medium followed the same pattern for cultures closest to heating source (2.84 and 1.26 x 10^5 cells/ml) than those farthest away (2.44 x 10^5 and 3.4 x 10^4 cells/ml) as determined by BacLight fluorescent stain flowcytometry. These results suggested that hyperthermophiles that will grow at 95oC were isolated from spray drier exhaust vents via PCS cables, demonstrating the usefulness of PCS to recover microorganism from extreme environments.
Session 61C, Food Microbiology: General I
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