Sept 30 (Reuters) - U.S. agribusiness company Archer Daniels Midland Co said on Tuesday that it has acquired a stake in Portland, Oregon, export terminal Columbia Grain by expanding its Kalama Export Company joint venture with Japanese grain trader Marubeni Corp.

The stake in Columbia Grain, previously a wholly owned subsidiary of Marubeni, broadens ADM's export capacity in the U.S. Pacific Northwest, a key export gateway for U.S. agricultural goods to Asia.

"This action represents another important step in our ongoing efforts to build ADM's Agricultural Services value chain from origination to destination," said Joe Taets, ADM senior vice president and president, Agricultural Services.

Marubeni acquired a 45 percent stake in Kalama Export Company, which operates a bulk grain export terminal in Kalama, Washington, with its purchase of U.S. grain trader Gavilon in 2013. ADM has a 45 percent stake in the Kalama terminal and Mitsubishi Corp controls 10 percent.

ADM and Marubeni also announced that it plans to rename its joint venture Pacificor LLC.

Shares of ADM were 0.4 percent lower at $51.07 on Tuesday afternoon while Marubeni shares fell about 3.6 percent.

(Reporting by Karl Plume in Chicago; editing by Matthew Lewis)