U.S. biotech company Codexis priced shares in its initial public offering at the bottom of the expected range on Wednesday in its second attempt to list its shares for public trade.

The Redwood City, Calif.-based company sold 6 million shares for $13 each, raising about $78 million. It had planned to sell shares for between $13 and $15 each. Codexis sells enzymes and microbes modified to make industrial processes cleaner and faster. It also sells its "biocatalysts" to pharmaceutical companies including Merck & Co, Pfizer and Dr Reddy's Laboratories. It is also working with Royal Dutch Shell on cellulosic biofuels -- biofuels that are made from plants like wheat straw.

Total revenue rose more than 64% to $82.9 million in 2009. The company cut its losses 55% to $20.3 million in the same period. Codexis said in its prospectus that it does not expect to be profitable until at least 2011. Major shareholders in Codexis include funds associated with Maxygen, Shell, the Singaporean government, CMEA Ventures, FirstMark Capital and Chevron Corp. Underwriters were led by Credit Suisse. The shares are expected to begin trading on the Nasdaq on Thursday under the symbol "CDXS."