Praxair Receives Patent for Fermentation Method Using Oxygen.

DANBURY, Conn.--(BUSINESS WIRE)--Nov. 16, 1998--Praxair, Inc. (NYSE: PX) today announced receipt of U.S. Patent No. 5,798,254 for a direct oxygen injection process for fermentation that can increase productivity up to 100 percent over air-based processes without major capital expenditures.

Praxair estimates that chemical and life sciences companies producing antibiotics, food additives and other chemicals produced by fermentation will use the Praxair technology to lower the unit operating costs of existing bio-reactors.

The Praxair patent covers an air and oxygen injection process in airlifted fermentation equipment. The Praxair technology injects highly dispersed oxygen bubbles into the fermentation broth, allowing oxygen to be introduced through any conventional port in the fermenter while minimizing coalescence with air bubbles traveling through the broth.

The air provides agitation and strips carbon dioxide and other byproducts from the process, while the oxygen sustains organism growth rates to desired levels during primary and secondary metabolism. In some processes, yield or selectivity may be improved due to the availability of oxygen. The Praxair technique also allows the fermenters to operate at higher oxygen uptake rates than other means, resulting in the highest possible yield or selectivity improvements.

In addition to yield and productivity benefits, the direct injection technology improves the efficiency of oxygen use, lowers air compression costs, and minimizes batch failure during emergency power failures.

The process was tested at commercial scale in a Pfizer Inc (NYSE: PFE) pharmaceutical facility.

In addition, Praxair offers technologies for direct injection in stirred tank reactors which provide similar benefits.

Praxair is the second largest supplier of industrial and specialty gases to chemical companies worldwide, with 1997 sales of more than $700 million to this segment. Using its industrial gas know-how and patented technologies, Praxair works with chemical customers to help them lower costs, improve productivity and meet environmental goals.

Praxair is the largest industrial gases company in North and South America, and one of the largest worldwide, with 1997 sales of $4.7 billion. The company produces, sells and distributes atmospheric, process and specialty gases, and high-performance surface coatings. Praxair is a recognized leader in the commercialization of new technologies that bring productivity and environmental benefits to a diverse group of industries. For more information, visit Praxair on the Internet at www.praxair.com.