Bacterial cocultures expressing a bacteriocin system

A co-culture of lactic acid bacterial cells for making ethanol from a biomass, the co-culture comprising:

• a first recombinant lactic acid bacteria (LAB) cell:
• expressing at least one bacteriocin;
• and
• comprising heterologous nucleic acid molecules encoding polypeptides for converting the biomass into ethanol;
• and
• a second recombinant LAB cell:
• capable of converting the biomass into ethanol;
• comprising heterologous nucleic acid molecules encoding polypeptides for converting the biomass into ethanol;
• and comprising one or more heterologous nucleic acid molecules encoding one or more polypeptides for conferring immunity against the at least one bacteriocin expressed by the first recombinant LAB cell
• wherein the polypeptides for converting the biomass into ethanol comprise at least:
• a pyruvate decarboxylase;
• and
• an alcohol dehydrogenase,
• wherein the at least one bacteriocin comprises a lantibiotic, a cyclic bacteriocin, a Class IIA bacteriocin, a Class IIB bacteriocin, or a combination thereof.