(Adds background on bankruptcy filing, judge decision on labor agreement)

By Phil Wahba

NEW YORK, April 29 (Reuters) - Bidders in Bruno's Supermarkets LLC [BRUNS.UL] bankruptcy auction that began on Wednesday include Gordon Brothers Group, Hilco Merchant Resources LLC and a joint venture made up of liquidators Great American Group, Tiger Capital, SB Capital and Hudson Capital Partners, sources familiar with the matter said.

It was unclear how much each group's bid was or whether other bidders had made offers for the chain's remaining 56 stores, which are mostly located in the U.S. South.

A lawyer for Bruno's could not be reached for comment.

On Monday, U.S. Bankruptcy Judge Benjamin Cohen in Birmingham, Alabama upheld the collective bargaining agreement with Bruno's employees, which the supermarket chain had sought to invalidate, saying it makes it harder to find a buyer for its stores.

At the time of its bankruptcy filing, in February, Bruno's said it had a total of 66 locations in Alabama and the Florida Panhandle, and employed about 4,200 people. In March, it said it would close 10 stores.

The company listed assets and liabilities in the range of $100 million to $500 million in its bankruptcy filing.

Bruno's was founded in 1933 by Joe Bruno who started the company's first grocery store in Birmingham, Alabama.

The case In re Bruno's Supermarkets LLC, U.S. Bankruptcy Court, Northern District of Alabama, No 09-00634. (Reporting by Phil Wahba and Emily Chasan; Editing by Andre Grenon)