The invention relates to bacteria that have increased levels of protein secretion due to genetic modification, to nucleotide sequences and gene structures containing at least one gene coding for a SecA protein having increased levels of protein secretion, to a SecA having increased levels of protein secretion, and to a method for producing desired proteins using the inventive bacteria. The invention also relates to nucleic acids coding for a SecA protein having increased levels of protein secretion, containing a SecA gene sequence or allele, a SecA homologue or derivative, or nucleotide sequences hybridising therewith and comprising at least one mutation. Surprisingly, just one mutation in a nucleotide of a SecA gene leads to increased levels of protein secretion or to protein secretion for the first time.