100A-9 |
Isolation protocol for hyperthermophilic microorganisms (>90oC) from food processing facilities |
J. Gvozdenovic-Jeremic1, P. S. MAK1, 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 the man-made extreme environments that are often 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. We designed a repeated-batch bioreactor that would maintain temperature > 90oC by sand baths. Continuous aeration with sterile CO2 free, humidified, air was provided with condenser to reduce water loss. Aseptic removal of culture medium and refilling with sterile culture medium was performed every one to two weeks using a sterile liquid break. Culture isolation was enhanced by the addition of 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 or cellulose, 5% yeast extract, 5% bovine albumin and salts was employed. Repeated-batch reactors contained PCS and filter paper and were operated for four to six months using LB or minimal medium. Sites sampled were from Penford Products (Cedar Rapids, Iowa) corn wet milling facility. The sites include light corn steep liquor (CSL), dry material on CSL Pipe, hot CSL, biofilm from stack, and scrapings from drier tunnel window. Results indicated that in long-term repeated batch fermentations, we were able to isolate hyperthermophiles, which consist of Gram positive cocci, Gram positive rods, and some endosporeformers. In general, PCS containing soybean hulls showed more biological activity than PCS containing cellulose in terms of CO2 production and biological activity as determined by BacLight fluorescent stain flowcytometry. These results suggested that our protocol did enable us to isolate and enumerate hyperthermophilic microorganisms obtained from food processing facilities.
Session 100A, Food Microbiology: General II
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