The present invention relates to mutants of lactic acid bacteria which are resistant towards the antibiotic D-cycloserine and/or functionally equivalent antibiotics and which were found to give an increased texture when grown in milk while maintaining the other growth properties of the parent strain. The present invention, furthermore, relates to compositions comprising such mutants, and to dairy products fermented with the lactic acid bacteria resistant towards D-cycloserine and/or functionally equivalent antibiotics.