<p>The present invention relates to a method for the production of methionine or its derivatives by culturing a microorganism in an appropriate culture medium comprising a source of carbon and a source of sulphur. The microorganism and/or the culture medium and/or the process parameters were modified in a way that the accumulation of the by-product N-acetyl-methionine (NAM) is reduced. The isolation of methionine or its derivatives from the fermentation medium is also claimed.</p>
