San Diego, California
January 7, 2003

Diversa Corporation (Nasdaq: DVSA) announced today the appointment of Edward T. Shonsey as Senior Vice President, Internal Development. He joins Diversa from Syngenta Seeds Inc., a leading plant biology and genomics company, where he served as President.

Mr. Shonsey has more than 20 years of experience leading the development and commercialization of new products. Earlier while at Novartis and subsequently at Syngenta, Mr. Shonsey was responsible for leading research, product development, and regulatory teams to develop new product lines and to access new markets. In addition, he was responsible for the oversight of numerous governmental and regulatory registrations. Mr. Shonsey's extensive business experience includes the founding of Global Trading Resources, an international trade corporation. He also served in executive financial and operations positions with Pioneer Hi-Bred International, a $1.3 billion plant biology company (now a subsidiary of DuPont), and Proctor & Gamble. Mr. Shonsey received his MBA from Creighton University, and his BSEE from Marquette University.

"Ed brings with him an outstanding record of achievements in applying genomics technologies to the development of new products," said Jay M. Short, Ph.D., President and Chief Executive Officer of Diversa. "We are delighted to have Ed join the Diversa team."

Diversa Corporation is a leader in applying proprietary genomic technologies for the rapid discovery and optimization of novel products from genes and gene pathways. Diversa is directing its integrated portfolio of technologies to the discovery, evolution, and production of commercially valuable molecules with pharmaceutical applications, such as optimized monoclonal antibodies and orally active drugs, as well as enzymes and small molecules with agricultural, chemical, and industrial applications. The Company has formed significant joint ventures with The Dow Chemical Company (named Innovase LLC) and with Syngenta Seeds AG (named Zymetrics, Inc.) focused on near-term commercialization of products for the industrial and agricultural markets, respectively. In addition, the Company has formed alliances with market leaders, such as Celera Genomics, The Dow Chemical Company, DuPont Bio-Based Materials, GlaxoSmithKline plc, Invitrogen Corporation, and Syngenta Biotechnology, Inc.

Additional information is available at Diversa's website: www.diversa.com. In addition, Diversa recently announced that it had entered into a series of agreements with Syngenta Participations AG pursuant to which it and Syngenta will, among other actions, form a broad collaboration to establish a shared biotechnology research platform and to discover products. Consummation of Diversa's proposed transactions with Syngenta is subject to the approval of federal regulators under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, as well as approval of Diversa stockholders, among other conditions. The press release announcing Diversa's agreements with Syngenta has been filed as an exhibit to a Current Report on Form 8-K that Diversa filed with the Securities and Exchange Commission, or SEC, on December 4, 2002.

Where You Can Find Additional Information About Diversa's Proposed Transactions With Syngenta

Diversa has filed a preliminary proxy statement concerning its proposed transactions with Syngenta with the SEC. Investors and security holders are advised to read the preliminary proxy statement related to the proposed transactions, because it contains important information related to the transactions. Investors and security holders may obtain a free copy of the preliminary proxy statement and other documents filed by Diversa with the SEC at the SEC's website at http://www.sec.gov. The preliminary proxy statement and any other documents filed by Diversa with the SEC may also be obtained free of charge from Diversa by directing such request to Diversa Corporation, 4955 Directors Place, San Diego, CA 92121, Attn: Investor Relations, or by calling Diversa at (858) 526-5000 or e-mailing Diversa at information@diversa.com. Diversa will file a definitive proxy statement with the SEC relating to its proposed transactions with Syngenta prior to the consummation of those transactions, which may contain additional or different information from that contained in the preliminary proxy statement. Investors and security holders are advised to read the definitive proxy statement when it becomes available because it will contain important information relating to Diversa's proposed transactions with Syngenta. The definitive proxy statement (when available) may be obtained from the same sources as are described above with respect to the preliminary proxy statement.

Information Concerning Participation In Diversa's Proxy Solicitation

Diversa and its executive officers and directors may be deemed to be participants in the solicitation of proxies from the stockholders of Diversa with respect to Diversa's proposed transactions with Syngenta. Information regarding such executive officers and directors is included in Diversa's Proxy Statement for its 2002 Annual Meeting of Stockholders filed with the SEC on April 2, 2002. This document is available free of charge at the SEC's website at http://www.sec.gov. Investors and security holders may obtain additional information about the interests of the executive officers and directors of Diversa in Diversa's proposed transactions with Syngenta by reviewing the preliminary proxy statement related to those transactions that has been filed with the SEC, and, when it is available, the definitive proxy statement related to those transactions that will also be filed with the SEC.